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What is the purpose of the viscous gel in the Pacinian corpuscle?

What is the purpose of the viscous gel in the Pacinian corpuscle?


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I have read that 'when the stimulus (in this case pressure) is constantly applied, the gel repositions itself to prevent the formation of an action potential'. I don't really understand what this means.


Short answer
The adaptation process in Pacianian corpuscles (PCs) is mediated via the outer capsule. This capsule is an onion-like structure that quickly molds itself to pressure stimuli, thereby rapidly desensitizing the receptor.

Background
The Pacinian corpuscles are rapidly adapting (RA) skin receptors, as opposed to the slowly adapting (SA) ones, such as the Merkel cells. RA cells become swiftly unresponsive (i.e., they adapt) when a pressure stimulus is applied, but faithfully transmit rapidly changing stimuli (such as vibrations).

Pacinian corpuscles are specialized vibration receptors. Their dendritic region is shaped as an onion-like structure with layers of stacked lamellae:


Specialized dendritic capsule of the Pacinian corpuscle. Source: Biologymad

These lamellae act as high-pass filters that result in a sharp drop in sensitivity below 150 Hz (Johnson, 2001). If this capsule is dissected from the receptor and a pressure stimulus is directly applied to the sensor element underneath the capsule, the receptor response to a sustained stimulus substantially increases (Mendelson & Loewenstein, 1964). Basically, these elastic lamellae slowly mold their shape to the stimulus and pressure stimuli are only transmitted for a few milliseconds, after which the lamellae absorb the pressure. So only a one or a few spikes are generated at the start of a pressure stimulus.

You can imagine it this way, suppose you have a gel-like substance (say Play-Do) on a weight scale. Now suppose you press the Play-Do quickly and hold your finger steady at a certain point above the scale, within the Play-Do. The weight scale will shortly display a certain weight (equal to the pressure applied in Newtons), after which the Play-Do folds itself around your fingertip, and the pressure is released from the scale.

Upon release of the pressure stimulus another spike or two are generated in the PC. Hence, a continued pressure stimulus is not faithfully reproduced. However, vibratory stimuli generate spikes on the pressure onset as well as offset as well, and this happens on every phase of the vibration. Hence, vibratory stimuli are faithfully transmitted.


Response of Pacinian corpuscle to a sustained pressure stimulus (indentation of the skin) and superimposed vibratory stimuli. Note the vigorous response to vibrations, but the rapid adaptation to the static pressure stimulus. Source: Zavantag

References
- Johnson, Curr Opin Neuobiol 2001;11:455-461
- Mendelson & Loewenstein, Science 1964;3618:554-5


Author Summary

We performed computer simulations of the mechanical behavior of the Pacinian corpuscle (PC), a sensory receptor in the skin that helps detect short-term contact and high-frequency vibration. The PC is composed of a series of tissue layers, and we found that this characteristic structure may explain the response of the PC in indentation experiments. We also found that the deep placement of the PC within the skin allows it to detect stimuli over a wide area of the skin but not to distinguish the specific location of the stimulus. These findings are a step but still an early step towards the broad goal of understanding how mechanical stimuli to the skin are translated into neural signals to the spinal cord and brain, and many open questions still remain about how the different sensors of the nervous system work together to create our sense of touch.

Citation: Quindlen JC, Lai VK, Barocas VH (2015) Multiscale Mechanical Model of the Pacinian Corpuscle Shows Depth and Anisotropy Contribute to the Receptor’s Characteristic Response to Indentation. PLoS Comput Biol 11(9): e1004370. https://doi.org/10.1371/journal.pcbi.1004370

Editor: Andrew D. McCulloch, University of California San Diego, UNITED STATES

Received: January 21, 2015 Accepted: June 1, 2015 Published: September 21, 2015

Copyright: © 2015 Quindlen et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Data Availability: All relevant data are within the paper and its Supporting Information files

Funding: This research was supported by a National Science Foundation (http://www.nsf.gov/) Integrative Graduate Education and Research Traineeship (http://www.igert.org/) fellowship in Systems Neuroengineering, Grant Number DGE-1069104. JQ received this funding. This work was also funded by the National Institutes of Health (http://www.nih.gov/) Grants Number EB005813 and EB016638. VB received these grants. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.


Viscoelastic properties of young and old human dermis: A proposed molecular mechanism for elastic energy storage in collagen and elastin

Division of Biomaterials, Department of Pathology and Laboratory Medicine, UMDNJ–Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, New Jersey 08854===Search for more papers by this author

Division of Biomaterials, Department of Pathology and Laboratory Medicine, UMDNJ–Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, New Jersey 08854

Division of Biomaterials, Department of Pathology and Laboratory Medicine, UMDNJ–Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, New Jersey 08854

Collagenesis, Inc., 500 Cummings Center, 464C, Beverly, Massachusetts 01915

Division of Biomaterials, Department of Pathology and Laboratory Medicine, UMDNJ–Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, New Jersey 08854

Division of Biomaterials, Department of Pathology and Laboratory Medicine, UMDNJ–Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, New Jersey 08854===Search for more papers by this author

Division of Biomaterials, Department of Pathology and Laboratory Medicine, UMDNJ–Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, New Jersey 08854

Division of Biomaterials, Department of Pathology and Laboratory Medicine, UMDNJ–Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, New Jersey 08854

Collagenesis, Inc., 500 Cummings Center, 464C, Beverly, Massachusetts 01915

Abstract

We have studied the strain-rate dependency of the viscoelastic mechanical properties of human dermis from young (23-year-old) and old (87-year-old) donors using incremental stress–strain measurements. The elastic spring constant for elastic fibers was found to be strain-rate and age dependent, whereas that for collagen was only age dependent. Fibril lengths were observed to decrease with increased strain rates and age for both elastic and collagen fibers however, the large decrease in collagen fibril viscosity was hypothesized to be a result of thixotropy that results when neighboring collagen fibrils slide by each other. It is concluded that the elastic spring constant measured for elastic fibers may be higher than previously reported and is consistent with stretching of α-helical segments of elastin into a more extended conformation during the initial part of the elastic stress–strain curve. The decrease in the elastic spring constant with increased age observed is consistent with disruption of the elastic fibers and loss of α-helical structure. The pH dependency of the elastic modulus reported previously for collagen suggests that charge–charge interactions within and between collagen molecules are involved in energy storage during stretching. Elastic energy storage is consistent with the stretching of charged pairs located in flexible regions of the collagen molecule. Shear thinning, or thixotropy of skin, is hypothesized to reflect breakage of bonds that occur between collagen fibrils. It is hypothesized that both collagen and elastin are complex macromolecules that are hybrids of flexible and rigid regions. The flexible regions reversibly store elastic energy during stretching by breakage of secondary bonds. After stretching, the flexible regions become extended and transfer stress to the rigid regions of these molecules. This prevents premature mechanical failure of collagen and elastic fibers in the dermis. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1978–1985, 2002


Results

Immunocytochemistry and reverse transcription-PCR

Cross sections of the terminal portion of cat mesenteric PCs ( Fig. 1 A) were used for the immunocytochemical experiments ( Fig. 2 A𠄽). Fluorescent microscopic images in Figure 2 show positive immunoreactivity using primary antibodies to VAMP2 ( Fig. 2 A,B) and GABA receptor 1A ( Fig. 2 C,D), whereas negative controls (i.e., no primary antibody was applied, only secondary antibody) showed no fluorescence. These results show the brightest labeling at the polar tips of the elliptically shaped neurite. At this level of magnification, however, it is difficult to tell whether the labeling is on the neurite or on the tips of the inner-core lamellar cells where they contact the neurite ( Fig. 1 B𠄽). For this reason, it is necessary to consider the reverse transcription (RT)-PCR results using mRNA from lamellar cells of the PC ( Fig. 2 F), which demonstrate VAMP2 expression within the capsule itself. The presence of VAMP2 (synaptobrevin) on the modified Schwann cells of the lamellae of the PCs also has been demonstrated using immunocytochemical techniques (Pawson et al., 2007). These findings suggest that the lamellar cells may be capable of a “synaptic-like” connection with the neural portion of the PC (neurite), a connection not thought previously to exist. We cannot at this time demonstrate GABA receptors on the neurite with RT-PCR, because those experiments would have to be performed using mRNA that is isolated from PC cell bodies, which are identified in either the trigeminal or dorsal root ganglia.

Light and electron microscopic images of cross-sections cut through the terminal portion of cat mesenteric Pacinian corpuscles. A, Light micrograph image of a 1 μm section depicting the inner core (ic) and outer core (oc) lamellar cells as well as the neurite (N). Scale bar, 20 μm. B, Low-magnification electron micrograph of an 80 nm cross-section through the terminal portion of a PC, displaying a prominent nucleus (Scn) of one of the modified Schwann cells of the inner core (ic). Scale bar, 5 μm. C, Magnification of the area in the small rectangle encompassing one tip of the neurite seen in Figure 1 B, showing a filopodium (f) extending into the hemi-lamellar cleft (Cl) formed by the inner-core hemi-lamellae (L). Red arrowheads point to clear-core vesicles within the lamellae, and black arrows point to clusters of clear-core vesicles in the neurite in close proximity to the Mts. Within the neurite, a multivesicular body (mvb) and several mitochondria (M) are visible. Scale bar, 640 nm. D, High-magnification EM depicting the Mts of the lamellar cells and the neurite where they contact each other. Scale bar, 460 nm.

Results of immunocytochemical and RT-PCR experiments depicting synaptic proteins. A, Fluorescence micrograph from the same region as Figure 1 A depicts labeling for VAMP2. B, A higher-magnification image of the neurite of Figure 2 A. C, Fluorescence micrograph image as in Figure 2 A labeled with anti-GABA receptor. The labeling is very similar to that seen in Figure 2 A. D, A higher-magnification image of the neurite of Figure 2 C. Scale bars: A, C, 6.5 μm B, D, 2.5 μm. E, A Polaroid image of a 1% agarose electrophoresis gel depicting PCR results from mesenteric PC cDNA mixed with primers for feline β-actin as well as a 50 bp ladder. A prominent band at � bp was expected using these β-actin primers (for control positive purposes). F, A 2% gel showing results of a PCR product using the cDNA from mesenteric PCs mixed with primers designed for VAMP2 as well as a 50 bp ladder. The � bp band was expected using these VAMP2 primers. * denotes the 350 bp band on the ladders. ic, Inner core N, neurite.

Electrophysiology

Electrophysiological experiments (n = 12) were designed to test the hypothesis that chemical inhibition contributes to the RA response of the PC. PST histograms of action potentials (spikes) over 10 stimulus presentations (bin width of 20 ms) depict the firing rate of the receptor when presented with ramp-and-hold stimuli ( Fig. 3 ).

In the first two experiments ( Fig. 4 i,ii), GABA was applied to the preparation to test for inhibition of action potentials. Gabazine was used in these experiments as the GABA receptor antagonist and was predicted to produce an increase in the discharge rate. The concentration of gabazine varied ( Fig. 4 , 0.3 m m in i, 0.1 m m in ii), whereas that of GABA (0.5 m ) remained constant. In experiments i and ii ( Fig. 4 ), the PCs responded from the beginning as RA receptors ( Fig. 4 A,G), with slightly more activity seen in A than in G after the onset. With the addition of GABA, the PC in experiment of Figure 4 i became even more rapidly adapting ( Fig. 4 B), as determined by the complete absence of spikes in the static portion of the stimulus. In all the cases in which GABA was applied to the bathing solution, no static spikes occurred ( Fig. 4 B,E,H,K). With the addition of gabazine, static spikes appear ( Fig. 4 D,J), with the greatest number of spikes occurring when the highest concentration of gabazine (0.3 m m ) was applied to the bathing solution ( Fig. 4 D). The results seen in Figure 4 , C, F, L, and I, in which the bathing solution was returned to saline alone indicate that the effects of GABA (and gabazine) were reversible.

Figure 4 shows that static, but not dynamic, action potentials (although the dynamic were sometimes lowered) disappeared in the presence of GABA and appeared in abundance in the presence of gabazine in a dose-dependant manner. On the basis of these results, it was hypothesized that the static spikes, which appeared when GABA was blocked, were caused by glutamatergic excitation. To test this theory, kynurenate, the glutamate receptor antagonist, was applied to our preparation (as in the study by Fagan and Cahusac, 2001), and it was predicted that the static spikes would decrease.

The PSTs of Figure 5 are the results of experiments in which picrotoxin (GABA receptor antagonist) and kynurenate (a glutamate receptor antagonist) were used. In Figure 5 , i and ii, the PCs did not have an RA response from the beginning of the experiments. However, with the application of kynurenate (20 m m ), a more typical RA response was produced ( Fig. 5 C,F). This would be expected if glutamate were responsible for the static spikes. In all cases, when 4 m m picrotoxin was applied to the bathing solution, many static spikes were observed ( Fig. 5 B,G). In all cases, the effects of picrotoxin and kynurenate were reversible as evidenced when the PCs subsequently were bathed in saline only ( Fig. 5 D,H).

Concentrations of GABA and its antagonists were similar to those used in iontophoretic experiments (Caspary et al., 1994 Backoff et al., 1997, 1999 Jha et al., 2001 Gai and Carney, 2008). The neurite and the modified Schwann cells of the inner core are covered by at least 30 layers of outer lamellae that are joined by tight junctions, as well as an outer five layers of external capsule, making this preparation less readily accessible to drugs than cell-culture studies or other tactile receptor preparations, for example, those of Panek et al. (2002) or Fagan and Cahusac (2001). The experimental pharmacological agents were left in the bathing solution until we saw an effect (� min) before returning to pure Krebs' solution. The data for the PSTs of Figure 6 were collected the same as in Figure 5 , except that the hold portion of the stimulus was 4 s in duration. Figure 6 A was collected before the application of any pharmacological agent, whereas in Figure 6 B, 4 m m picrotoxin was added to the bathing solution. During the 4 s duration of Figure 6 B, spikes were maintained throughout, and this is similar to the stimulus parameters used in experiments done with the slowly adapting MCN mechanoreceptors (Fagan and Cahusac, 2001).

In Figure 7 , we show the “pre”, 𠇍uring,” and “recovery” stages of each pharmacological agent that was used in this study. To make comparisons, the intensity of the ramp-and-hold stimulus was kept the same in each case. The presence of spikes in Figure 7 , B (0.2 m m gabazine) and E (4 m m picrotoxin), during the application of GABA antagonists is dramatically different from H (0.5 m GABA) in which the inhibitor is applied to the PC. With the application of 10 m m kynurenate ( Fig. 7 K), a glutamate antagonist, spikes are no longer seen in the hold or in mid-ramp portions of the stimuli. The PC in this condition only fires at the on and off portions of the ramps ( Fig. 7 K). The time course of the ramp-and-hold stimuli in experiment Figure 7 iv differed from all others in this study. In Figure 7 iv, the stimulus time was as follows: 10 ms off, 100 ms on-ramp, 500 ms hold, 100 ms off-ramp. For the experiments shown in Figures 4 ​ 4 ​ – 7 , the average time from addition of pharmacological agent (or pure saline) until data collection was 25.1 ± 1.3 min.

A total of 12 PCs were used in our experiments. GABA was tested on seven PCs, gabazine was used on six, picrotoxin was tested on six, and kynurenate was used on five. A summary of the electrophysiological–pharmacological results can be seen in the scatter plots of Figure 8 . These plots depict the difference between the control (saline alone) condition (always in blue) and experimental (drug added) condition (green, light–green, red, or orange) for each corpuscle. The points represent the number of spikes observed during the “static” ( Fig. 8 E, #4) plus the mid-rise ( Fig. 8 E, #2) and mid-fall ( Fig. 8 E, #6) portions of the ramps. When 0.3 m m gabazine ( Fig. 8 A, light green) was added to the bathing solution (n = 6), the spike count in the #2, 4, and 6 ( Fig. 8 E) portions of the stimulus increased. Using a Wilcoxon's matched-pairs signed-rank test, the control condition was significantly lower than the experimental condition (p = 0.0277). When 4 m m picrotoxin ( Fig. 8 B, dark green) was the experimental pharmacological agent (n = 6), the control condition was significantly lower than the experimental condition (p = 0.0277), using the same statistical test. However, when 0.5 m GABA ( Fig. 8 C, red) was added to the bathing solution (n = 7), the experimental condition was significantly lower than the control condition (p = 0.0431). The addition of 20 m m kynurenate ( Fig. 8 D, orange) to the bathing solution (n = 5) also significantly (p = 0.0431) reduced the spikes seen in the #2, 4, and 6 portions of the stimulus ( Fig. 8 E). It appears that these parts of the ramp-and-hold stimulus (#2, 4, and 6) are “glutamate mediated,” whereas the odd numbered portions (the on and off of both ramps) are the 𠇍ynamic” portions of the stimulus and are most probably mediated by the opening of mechanogated channels. The spike count did not significantly differ between the control and experimental conditions during the dynamic ( Fig. 8 E, #1, 3, 5, 7) parts of the ramp-and-hold stimulus. There were no spikes seen before ( Fig. 8 E, letter B) or after ( Fig. 8 E, letter A) the presentation of the stimuli, which is consistent with the fact that PCs have no spontaneous activity under the normal conditions (Bolanowski and Zwislocki, 1984).

Because the concentrations for picrotoxin and GABA were higher than those used by other investigators (Panek et al., 2002), we decided to use gabazine at much lower concentrations (10� μ m ) and also to look at dose-related responses. PSTs from six different PCs in response to ramp-and-hold stimuli acquired just before and 𢏀.5 h after addition of gabazine (at six different concentrations) to the bathing solution of the receptor are shown in Figure 9 . In each case, additional spikes occur with the addition of gabazine, with more occurring as the concentration of the GABA antagonist is increased. This increasing dose–response curve can be seen in Figure 9 M. Also, with the higher doses of GABA blocker, the increase of spikes in the hold portion of the stimulus becomes greater.

PST histograms for six different PCs, depicting the response to ramp-and-hold stimuli, before and after the addition of gabazine (Gz) (from 10 to 400 μm). A, C, E, G, I, PST histograms just before addition of gabazine for each concentration. B, Gabazine at 10 μ m added to the bathing solution D, 50 μ m gabazine F, 100 μm gabazine H, 200 μ m gabazine J, 300 μ m gabazine L, 400 μ m gabazine M, dose–response curve for gabazine. The ordinate depicts the additional spikes present during ramp-and-hold stimuli with the addition of gabazine to the bathing solution of the PC at each concentration (e.g., number of spikes in B minus those in A). Gabazine concentration is depicted on the abscissa.

Although some of the PCs showed the classic RA response to indentation in the presence of saline alone ( Fig. 4 G,), some did not ( Figs. 4 A, ​ ,5 5 A,E). In one of the corpuscles ( Fig. 5 A), many static spikes were seen in response to the ramp-and-hold stimuli. We placed this corpuscle in fixative (2% paraformaldehyde and 2% glutaraldehyde) at the end of the experiment and subsequently examined 1 μm sections ( Fig. 10 ). Although a very typical “terminal” portion of the neurite is seen in Figure 10 A, at the distal 200 to 300 μm, it divides into three distinct neurites ( Fig. 10 B), each having their own inner core. Thus, it is possible that, because of the position of the contactor on the PC, each may fire at different intervals, producing dynamic spikes during the hold portion of the stimulus.

Light micrographs of 1 μm cross-sections through the terminal portion of the PC from Figure 5 i. A, Neurite (N) inner-core hemi-lamellae (ic) and outer core (oc) lamellae. B, Section approximately 300 μm from the ultra-terminus in which three distinct neurites (N) are seen, inner-core (ic) hemi-lamellae, and the outer-core (oc) cells surround all three groups (neurite + ic.) Scale bars, 25 μm.

In all 12 experiments, the PCs demonstrated classic U-shaped frequency characteristic curves for sinusoidal stimuli ranging from 10 to 500 Hz when using a criterion of 𢏁 spike/s (Bolanowski and Zwislocki, 1984 Bell et al., 1994). In 11 of the experiments, the PCs responded to the best frequency (bf) range (200 to 300 Hz) at between � and 𢄥.5 dB (relating to 1 μm peak). This pattern did not change with the addition of any of the pharmacological agents for these 11 experiments. Frequency characteristics that are representative of these 11 experiments are shown in Figure 11 , A and B. For Figures 5 i and ​ and10 10 B, the curve flattened out over time ( Fig. 11 C). Note also that this experiment was 𢏄 h longer than others. However, this receptor ( Figs. 5 i, ​ ,10 10 B) responded to the pharmacological agents in a similar manner to that of the PCs that were more sensitive. Figure 11 D–G shows tuning curves taken before application of any pharmacological agent (i.e., the PC is bathed in saline alone blue) and the tuning curve while the receptor is in the presence of a drug. In the presence of 0.3 m m gabazine ( Fig. 11 D), 4 m m picrotoxin ( Fig. 11 E), and 0.5 m GABA ( Fig. 11 F), the sensitivity at the bf (as well as all other frequencies) remains unchanged. Only with the addition of 20 m m kynurenate ( Fig. 11 G) does the sensitivity at the bf change slightly (by 3 or 4 dB). However, it is safe to say that there does not appear to be any significant difference of sensitivity in the frequency characteristics with the addition of the pharmacological agents used in this study. Because the frequency characteristics represent the working of only the dynamic phase of a sustained indentation response, this once again suggests that the static and dynamic portions of the response represent very different mechanisms at work.


1. Mechanism and application of PRP and acupuncture to promote cell regeneration……….p3

zou lihuang

Platelet-rich plasma (PRP) therapy is very mature and popular in western clinical departments The beauty industry is also working on PRP therapy, which works by promoting cell regeneration and repairing cell damage. PRP can also be called the sister of stem cells. It is also the most effective non-surgical treatment in the 21st century.

Does acupuncture and hot and cold therapy in traditional Chinese medicine also have the function of promoting cell regeneration? The answer is yes.

Keyword: PRP Acupuncture Cell regeneration.

1.The origin and mechanism of PRP therapy

In fact, today’s fashionable of the western world of PRP therapy, from the beginning did not leave the stimulation of acupuncture and hemorrhagic coagulation mechanism.

1.1 The transplanted hair fell out, but it grew out later.

Hair transplant process is to use a needle acupuncture in the region of the need to transplant several holes, then remove the hair from the hair area into need to transplant area, the whole process is accompanied by a large number of hemorrhage and blood coagulation, but half a year later, all the old hair implants are off, hair follicle didn’t survive, but why grow new hair, experts found, because the stimulation of needles, the bleeding and clotting process, platelets release a large number of growth factors, and growth factors to activate the atrophy of hair follicles, and make the hair regeneration.

1.2 Recognition of platelet function in recent years

Platelet derived growth factor (PDGF) is an alkaline protein stored in platelet-derived growth factor (PDGF). It’s low molecular weight pro-cytokinin. It can stimulate fibro blasts, glia cells, smooth muscle cells and other cells that are stagnant at G0/G1 stage to enter the cycle of division and proliferation. PDGF platelet-derived growth factor in 1974 found a connective tissue and other tissue cell growth peptide regulatory factor, because it comes from the name of platelets and, within the normal physiological state under lies in the alpha particles of platelets, released when blood clots by disruption of platelet and activated, can stimulate cell chemotaxis and promote specific biological activity of certain cell growth.

In addition, when tissues are damaged, macrophages, vascular smooth muscle cells, fibroblasts, endothelial cells, embryonic stem cells, etc. can also synthesize and release PDGF. When liver is damaged, PDGF can be secreted by macrophages, platelets, infiltrated inflammatory cells, damaged endothelial cells and active hepatic astrocytes.

It works in the form of autocrine and paracrine. Binding PDGF is A thermostable glycoprotein with A molecular weight of 30 KD. It is A disulfide binding disulfide to form A dimer.

When a tissue in the body is damaged, a clot stops the bleeding. Blood clots cannot be formed without platelets, which gather at the bleeding point and form a material barrier to prevent further loss of blood. At the same time, platelets release several growth factors — most notably platelet-derived growth factors (PDGF) — that stimulate the growth of neighboring connective tissue cells.These connective tissue cells are the vanguard of rebuilding damaged tissue and healing wounds. Experiments show that PDGF is one of the early growth factors in wound healing, playing an important role in the whole process of wound healing, mainly in promoting wound healing. “PDGF is a kind of promote the growth of endogenous protein, in the process of wound healing, PDGF can be released, by a variety of cells and PDGF into AA/AB/BB three physiological activity forms, including BB type can promote the growth of fibroblast, so promoting wound repair related cells chemical touch reinforcing and cell proliferation, enhance the formation of granulation tissue, promote wound healing and shorten the healing time.(reference 1)

At present, the application of platelet-derived growth factor is very extensive in developed countries such as the United States, and the research on this aspect is also making progress. Recombinant human Platelet derived growth factor (rhPDGF) is the only one of many growth factors that has been approved by the us FDA as a biological engineering product used as a clinical prescription drug. One of its applications is REGRANEX Gel, a recombinant human platelet-derived growth factor Gel, which is used as a debridement and healing of the ulcer of the extremities of the advanced stage of diabetes. In addition, great progress has been made in the application of platelet-derived growth factor PDGF in severe burns, skin patients, bone and tooth defects and regeneration for joint repair.

2. The application of PRP therapy in arthritis and pain syndrome

2.1 If Liu, xiang receives PRP therapy

Mention the London 2012 Olympic Games, the Chinese people most regrettable is liu xiang single-leg completion of the emotional scene, But if, like Bryant, liu underwent PRP therapy in 2011, it could have been a game-changer Sports career China country could win one more gold medal, and the meaning and value of one more gold medal, I think Every doctor knows that, so don’t underestimate the meaning of your work, because of your hard work Work is likely to rewrite the history of an athlete and give the country more MEDALS.

2.2 The PRP treatment made Bryant 10 years younger

Kobe Bryant went to Germany for a new form of knee therapy that helped send the flyer flying

October 5, 2013 11:43 am. (Source: sohu sports writer: dongguan daily)

Bryant left the U.S. last night and will undergo medical treatment, lakers officials said yesterday.Interestingly, this is not related to the Achilles injury he suffered in April.

Bryant, who is visiting Germany, will undergo platelet-rich plasma therapy on his right knee and is expected to return to the U.S. early next week to prepare for the NBA season. This isn’t the first time Bryant has had platelet rich plasma therapy.

The lakers star twice traveled to Germany in the 2011 offseason for a new form of knee therapy called platelet-rich plasma. Bryant has had three surgeries on his knee since 2003 and two trips to Germany in 2011 and 2012 for platelet-rich plasma therapy.

Both sessions rejuvenated Bryant, especially in the 2011/2012 season, when he averaged 27.9 points per game (the highest since 2007), added 5.4 rebounds and 4.6 assists, and had the second-highest round share of 35 percent of his career, behind him in 2005/2006, when he averaged 35.4 points per game.

Kobe Bryant wants to go to Germany again to heal his knee

On June 9, 2012 Beijing time, according to the basket world, kobe Bryant went overseas last offseason to treat his injured knee and wrist.

Then came the just-ended season, when even though the lakers were eliminated by the thunder in the playoffs, it didn’t mask Bryant’s superior performance, with the 34-year-old Bryant physically returning to 24. This offseason, Bryant is ready to continue the same treatment.

The treatment is platelet rich plasma therapy, which has led to Bryant’s sudden rejuvenation in the second half of his career.The procedure is to extract Bryant’s own blood, and then use a centrifuge to extract platelets.Finally, platelet — rich plasma was injected into the knee.

Sina sports — (http://sports.sina.com.cn on June 9, 2012 05:10 weibo sina sports)

Kobe Bryant went overseas last offseason to treat his injured knee and wrist, according to the basketball world.Then came the just-ended season, when even though the lakers were eliminated by the thunder in the playoffs, it didn’t mask Bryant’s superior performance, with the 34-year-old Bryant physically returning to 24. This offseason, Bryant is ready to continue the same treatment.

The treatment is platelet rich plasma therapy, which has led to Bryant’s sudden rejuvenation in the second half of his career.

The procedure is to extract Bryant’s own blood, and then use a centrifuge to extract platelets. Finally, platelet — rich plasma was injected into the knee.

To receive the treatment, Bryant must rest his knee for at least a week.

A source with knowledge of the situation said Bryant could fly to Germany as early as this weekend, so that after treatment he would have plenty of time for the dream team training in Las Vegas in June.

Platelet rich plasma therapy has become a favorite treatment for the world’s top athletes, including Tiger Woods and alex rodriguez. In addition to Bryant, the NBA included Tracy McGrady and gilbert arenas, two injury-plagued players who continue to struggle in the league.

Bryant’s teammate Andrew bynum is expected to undergo treatment in August, as well as former no. 1 overall pick Greg oden, who is currently on hiatus.It shows how much trust the players have in the treatment.

Bryant averaged 27.9 points per game after treatment this season, second only to Kevin durant’s 28.0, his highest point total since 2007–08. What will Bryant do when he gets treatment again? Next season is worth looking forward to. (by white)

2.3 PRP has a wide range of applications

The use of PRP in severe burns, skin patients, bone and tooth defects and regeneration, and joint repair has been described with great progress.

In chapter 14 of the PRP manual for the treatment of arthritis and tendinitis, the diseases that can solve the joints of the limbs are as follows:

What kinds of problems can PRP solve?

Include:• Spine • Sacroiliac joints • Iliolumbar ligaments • Facet joints • costoarch (rib) joints.

Wrist/Hand,Hip/Pelvis,Rotator cuff tendinosis/tears Biceps tendinosis,Collateral ligament, Distal biceps tendon, Osteoarthritis

• Chronic ulnar collateral injury of thumb • Osteoarthritis of the base • Tendinosis • Osteoarthritis • Hip Osteoarthritis • Spinal ligaments,Shoulder,Elbows and so on…

PRP treats rheumatoid arthritis by promoting the regeneration of chondrocytes and bone cells.

Although the causes of rheumatoid arthritis are different from those of kobe’s joint injuries, they have similar similarities, that is, the knee joint is damaged with different degrees of synovial, cartilage and bone damage. The difference is caused by wear and tear, while rheumatoid arthritis is eaten by whom.

It’s eaten by the autoimmune cells, so the wind-like X-ray can see that the bone is like being bitten by a bug, like SARS, the lung tissue is eaten by the autoimmune cells, so you can say it’s no match for me, it kills itself.

3 .Mechanism and application of acupuncture to promote cell regeneration

Now that you have a general understanding of PRP, it is necessary to reassess the mechanism of our ancient acupuncture and heat therapy:

1.1. A $100 skin needle

Dermal needle mentioned, we will think of plum needle, seven stars needle or Luo Hanzhen, and I am here, if is now popular in Europe and America beauty and hair transplant doctors use and production in South Korea cylinder needle, the needle roller to make why Europe and the United States doctors fondle admiringly, we take a look at the English website about needle roller mechanism:

Micro-needle Dermal-Roller Therapy for Your skins-love Microneedle skin roller treats your skin — favorite Microneedle action — contact roller with skin, also known as collagen induction therapy for acupuncture, promotes natural production of collagen and elastin.Collagen and elastin are skin cells that are responsible for the structure of the skin and the protein fibers found within the elasticity. The Chinese have known for centuries that the needle has a positive effect on skin thickness, elasticity and softness when applied. As early as the song dynasty (

960a.d.), the rolling needle was a technique to rejuvenate the face, used by the empress and the emperor to maintain healthy, youthful, yet natural looking skin. Brand for AcuLift skin micro needle ™ 540 adopted very fine needles, like tiny acupuncture needle.

These needles penetrate the skin just enough to stimulate the production of collagen and elastin without harming the skin.The AcuLift ™ is an ideal reducing aging, such as fine lines and wrinkles, reduce acne scars, stretch marks, signs and tighten sagging skin.(reference 2)

In short, the so-called microneedle skin roller treatment is to make the skin show microscopic coagulation hemorrhage reaction, and promote the skin collagen hyperplasia to achieve cosmetic effect through controllable and dense micro hemorrhage caused by microneedle stimulation.

3.2. Amazing small needle knife therapy

The small needle knife is a kind of surgical tool with dual functions of “needle” and “knife”. It was developed by founder zhu hanzhang on the basis of ancient nine needles and combined with modern medical surgical knife in 1976. Over the past 30 years, with the unremitting efforts of tens of thousands of acupotomists nationwide, small acupotoms have been valued by the world and presented a good trend of development. It plays a very good role in the treatment of human soft tissue and internal organs. It has the features and advantages of little damage, strong radical cure, good safety, convenience, efficiency, and low price, which are very popular among the patients.

Broken skin by traditional ideas, needle knife pierced after all is to avoid the nerves and blood vessels, and developed in recent years “needle knife nervous shock” touch on operation just want to touch close to the nerve and the nerve excitation (not), the operation also make a lot of doctors and patients to worry about whether I will hurt nerve, however, a large number of clinical practice showed that the needle knife touch nerve excitation technique not only have no injury and nervous anxiety, and has obvious analgesic and convulsion.

“Acupotomer nerve palpation” was established by professor Ren yuehlin, and it was proposed in 1996 and passed national level identification in 2002. The technique developed from the early spinal nerve touch to the present sympathetic nerve and nerve trunk (plexus) touch, which broadens the types of acupotomology. Stress (Stress) of the main significance is to mobilize the potential of human resistance to damage, and the damage is the regeneration and repair, therefore in the process of small needle knife operation caused by caused by a small amount and controlled bleeding and then release a large amount of various growth factors, will lead to tendon nervous tissue regeneration, such as to repair the corresponding parts of the injury, treatment and to achieve. (reference 3)

3.3. Puncture and bloodletting therapy of three-sided needle

It is known that the application of acupuncture and bloodletting therapy in clinical practice often sees remarkable achievements.

Actual is through hole or specific acupoints in ah prick or bleeding, caused by a small amount of bleeding and controllable, after stimulating the bleeding and clotting mechanism, platelets will release a large amount of various growth factors, and these tendons nerve growth factor can stimulate skin cell regeneration, and repair the corresponding parts of the injury, treatment and to achieve.

By stimulating the distal acupoint with bloodletting, the tissue cells around the acupoint were regenerated, and the acupoint was stimulated for a long time to reach the therapeutic effect.

Liu’s Achilles tendon had already been found to be damaged and partially ruptured. If the original Achilles tendon was punctured with bloodletting stimulation, it would probably be repaired.

3.4 $3,000 for one time heat treatment

Say to Thermage everyone may not have heard of, but if the rf lift and grid therapy may have heard that this is actually a kind of qualitative quantitative depth of heat treatment, the so-called qualitative probe by vibration of five million times (5 m) heat energy, the so-called quantitative is through probe the heat energy released five to ten seconds at a time, the temperature at 45 degrees or so, in this limited damage to the stimulation and make the skin collagen hyperplasia The so-called fixed depth, if you know how the ultrasound works, you can know that the higher the frequency, the shorter the wave length. In order to make the thermal depth of the probe reach only about 5 millimeters under the skin, scientists selected the frequency of five million times of super vibration frequency, which is called radiofrequency in China.

In order to make the maximum profit, the manufacturer designed the probe as a disposable or a number of probes, and we know that the medical diagnostic ultrasonic probe can be used for tens of thousands of times.

To put it bluntly this treatment can completely implementation in the basin, as opposed to a familiar bubble foot therapy should we can call it bubble face treatment, in order to we can add a thermostat and temperature, equipment costs only $16 is about 100 yuan RMB, rather than the hundreds of thousands of dollars, roughly equivalent to the cost of a few yuan RMB per treatment.

Now you may understand why moxibustion is so magical and so widely used, because the relatively controllable heat generated by moxibustion causes limited damage to the acupoints or the local area, which leads to local cell proliferation and repair.

The regeneration of tissue cells near acupoint can make the acupoint get a long time stimulation and reach the therapeutic effect.

This article through to the ancient acupuncture mechanism to evaluate again, stress the needle of a small amount of bleeding and controllable, the bleeding and clotting mechanism, stimulate the body’s blood platelets will release a large amount of various growth factors, and these tendons nerve growth factor can stimulate skin cell regeneration, and repair the corresponding parts of the damage, and achieve treatment Hyperthermia is also able to regenerate and repair tissue cells by stimulating them with limited control.

I want you to remember the words: where there is oppression there is resistance, no, where there is damage there is regeneration There is repair, it’s a biological instinct, and we use that instinct in the body to make it better.

The significance of this paper is: by exploring the mechanism of promoting cell regeneration through acupuncture and other therapies, we can explore effective approaches of acupuncture and other therapies with purpose and direction in the future, reduce blindness, avoid detours, improve curative effect and better serve patients.

REFERENCES: Omitted.

Zou, Lihuang Director of the Los Angeles institute of regenerative medicine


What is the purpose of the viscous gel in the Pacinian corpuscle? - Biology

The migration seen as the settling in one region. Immigrating "to" a placee

D. RuBP carboxylase fixes O2 as well as CO2. The Calvin cycle occurs when CO2 is combined with RuBP. When

O2 combines with RuBP, photorespiration occurs. As O2 concentration increases, more O2 and less CO2 is fixed.

E. A CO2 uptake of less than zero means that CO2 is being released. This occurs when the CO2 concentration is

so low that photosynthesis cannot be supported and cellular respiration begins.

E. Transformation is the process that describes the absorption of DNA by bacteria that is subsequently expressed.

Bacteria can also acquire foreign DNA through viruses (transduction) or from other bacteria (conjugation).

Do all cells have a nucleus?

All cells have hereditary material (DNA), but not all cells have a membrane bound nucleus.

-In eukaryotic cells, the cell nucleus serves to protect the DNA of the organism

-Prokaryotic cells do not have a centralized nucleus and do not have many of the other cell organelles that eukaryotic cells have with the exceptions of ribosomes. They instead have a nucleoid region

Neurodegenerative diseases characterized by excessive apoptosis

Alzheimer's, Parkinson's, and Huntington's diseases

If a scientist wants to detach a peripheral membrane protein from the exterior of a cell membrane, what would be the best method to do so?

Change the salt concentration

-Peripheral membrane proteins are held in place by electrostatic interactions and hydrogen bonding. They are generally hydrophilic. Changing the salt concentration or the pH would disrupt both of these types of bonds and release the peripheral membrane protein from the cell membrane.

How are integral proteins extracted?

A detergent is added. Usually a hydrophobic detergent will destroy the membrane and expose the hydrophobic integral protein.

This used ammonia, methane, water and hydrogen sealed in a sterile arrangement of tubes and flasks with connecting loops.

Three different methods for particles to get through the cell membrane

1. Simple diffusion: particles are able to move directly through the phospholipid bilayer-- very small and uncharged particles

2. Facilitated diffusion: particles are able to cross the membrane but with the help of integral proteins that span the length of the cell membrane

3. Active transport: Occurs when particles are pumped or forced across the membrane against their concentration gradient. This transport requires ATP or energy.

Muscle cells and microfilaments

Muscles are made of long chains of cytoskeleton comprised of two filaments- actin and myosin. Of these, actin is a microfilament, while myosin is a motor protein. If actin degenerates, then our muscles would not contract.

Occurs when an inhibitor is able to prevent the enzyme from binding with the reactant by binding to the enzyme at a site away from the active site, and change the enzyme's conformation so it cannot bind to the reactant.

Occurs when the inhibitor competes directly with the reactant at the active site, and this substrate takes the place of the reactant and prevents the reaction from occuring

Small short "hairs" called fimbriae on the surface of bacteria that can be used in the exchange of genetic material between bacteria and in cell adhesion.

A long "tail" made of flagellin that provides locomotion to a bacterial cell

A receptor protein on the surface of a cell

Are only found on gram-positive bacteria and help keep the cell wall rigid

Amount of CO2 and resulting rate of photosynthesis

As a plant performs photosynthesis, the amount of Co2 present should decrease over time as the plant consumes the carbon to make glucose.

Is glycolysis exergonic or endergonic?

It requires the use of energy when the glucose molecule is broken into two pyruvates. The two steps in which ATP is used can be considered endergonic however, overall glycolysis produces energy to be consumed by cells. If energy is released, then the reaction is exergonic.

What type of microscope is used to view the following?

Transmission electron microscope

You can tell that this is a micrograph was taken with a transmission electron microscope because it is a very magnified 2D image of a single bacterla cell, which is very small. A scanning electron microscope would produce a 3D image

Compound light microscope

This is a 100x magnification compound light micrograph of Meissner’s corpuscle at the tip of a dermal papillus. These images often need to be stained with a colored dye to make them visible

This is another name for dissection microscopes, which only offer low magnification to observe the surface of a specimen

Transmission electron microscope

This is a transmission electron micrograph (TEM) of poliovirus, each measuring just 30 nm across. Notice how the TEM micrograph is flat, 2D, and extremely magnified.

This is a photo of a human lymphocyte nucleus from fluorescence microscopy. Fluorescence microscopes produce colorful images by dying the specimen with fluorophores and illuminating them with a specific wavelength of light. Notice how the image is brightly colored, with parts of the nucleus marked green and red with different fluorophores.

Scanning electron microscope

This is a scanning electron micrograph (SEM) of normal circulating human blood. Notice that the SEM micrograph is a 3D image at an extremely high magnification, allowing you to study the morphology and surface of the specimen.

This is a feature that will eventually develop into a part of the spinal discs.

-Complete digestive systems

-Triploblasts with bilateral symmetry

-They are often parasitic and contain a thick protective out layer known as the cuticle

Examples: round worms, hook worms, and C elegans

-Complete digestive system

-Triploblasts with bilateral symmetry

-Coelomates with segmented bodies

-Closed circulatory systems

Examples: earthworms and leeches

-Complete digestive systems

-Triploblasts with bilateral symmetry

-Coelomates with open circulatory systems (except for cephalopods with closed circulatory systems)

Examples: clams, snails, squids, and octupuses

-Complete digestive system

-Triploblasts with radial symmetry as adults

-Coelomates with open circulatory systems

-Deuterostomes (like chordata)

-Bilaterally symmetrical as larvae and radial as adults

Examples: starfish, sea urchins, and sea cucumbers

-Do not have a complete digestive system

-Have a gastrovascular cavity in which two way digestion takes place, rather than the one way digestion through an alimentary canal.

-Triploblasts with bilateral symmetry

Examples: flatwormms, tapeworms, and flukes

Fungi cell wall are made of glucans and chitin

-Only organisms to contain both in its cell walls.

refers to immunity where antibodies are generated by the individual themselves in response to a perceived immune threat

Passive immunity refers to immunity where antibodies are generated by one individual and then transferred to another. When a mother breastfeeds her newborn infant and transfers her antibodies to it in the process, it is passive immunity

Natural immunity refers to when an immune response is generated by natural means (as opposed to an artificial method, such as the use of a vaccine).

Artificial immunity refers to when an immune response is generated by artificial means, such as in vaccination where antigenic material is intentionally introduced to cause an immune response.

Permanent immunity refers to the same concept as secondary response in immunity: having been previously infected by a certain antigen, such as a bacteria or virus, the body will be able to quickly recognize and mount an immune response to the same antigen (much faster than during the initial exposure which results in the primary response).

A reflex is the involuntary, rapid response to a stimulus. This does not relate to the sustained contraction of muscles

Most reflex arcs in humans synapse directly in the spinal cord, rather than integrating in the brain first (allowing for a faster response time). An example of a reflex is the knee-jerk/patellar reflex, which you may remember from a checkup at the doctor: when the patellar tendon below the knee is tapped, the leg reflexively kicks outward.

Tetanus describes a continued state of muscle contraction during which a muscle does not relax. During tetanus, the frequency of action potentials is so high that tension is maintained throughout the muscle. Tetanus can also be used to describe the infection caused by the bacteria Clostridium tetani (often associated with rusty metallic objects), which causes muscle spasms of the jaw (hence the term “lockjaw”) that can spread across the body.

Refraction in biology refers to the refractory period, the time after an action potential during which a neuron will not respond to new stimulus – a muscle cell would not be able to maintain contraction during refraction Once the Na+/K+ pumps of the cell return ions to their resting potential balance, the refractory period will end and the neuron can once again respond to an action potential. Refractory periods can be absolute or relative – during an absolute refractory period, a second stimulus cannot generate another action potential no matter how powerful it is but during a relative refractory period, a sufficiently powerful stimulus can cause an action potential to occur.

Activation in biology can refer generally to the initiation of a biological process, or in immunology to the triggering of proliferation, differentiation, and maturation of defensive cells (e.g. the activation of T-lymphocytes by antigen presenting cells).

a type of simple muscle response caused by one action potential, which produces a single contraction and then complete relaxation. Since the muscle relaxes before another contraction is produced and not sustained continuously. In contrast to twitch contractions, tetanic contractions (tetanus) involve action potentials so frequent that the contraction is maintained before relaxation can occur, resulting in a sustained contracted state.

Beta cells in the pancreas

Beta cells secrete insulin, which functions to lower blood glucose levels.

G cells secrete the peptide hormone gastrin, which passes into the blood and stimulates the parietal cells of the stomach to secrete acid (HCl) for digestion.

Spermatogonia of the testes

Spermatogonia are located in the seminiferous tubules of the testes and undergo mitosis to produce the diploid primary spermatocytes.

a catecholamine, a class of peptidehormones. While the catecholamines are water-soluble, they are not steroids or otherwise derived from cholesterol. Epinephrine is released from the adrenal medulla and is sometimes referred to as adrenaline. It functions in “fight or flight” response and raises blood glucose levels. It causes vasoconstriction to internal organs and the skin, but causes vasodilation to the skeletal muscles and increases the respiratory and heart rate.

a mineralocorticoid, which are a class of steroid hormones. Steroid hormones are synthesized from cholesterol in the smooth endoplasmic reticulum Aldosterone (released from the adrenal cortex) acts on the distal convoluted tubule and collecting duct of the kidney to increase reabsorption of Na + and excretion of K + . This leads to passive reabsorption of water in the nephron, which causes blood volume and blood pressure to rise.

a glucocorticoid, which are a class of steroidhormones. Steroid hormones are synthesized from cholesterol in the smooth endoplasmic reticulum Cortisol is released from the adrenal cortex and primarily raises blood glucose levels. It is a stress hormone.

a gonadal steroid hormone. Steroid hormones are synthesized from cholesterol in the smooth endoplasmic reticulum Testosterone is primarily produced by the interstitial cells of the testicles. Testosterone functions in spermatogenesis and is responsible for male secondary sex characteristics.

a gonadal steroid hormone. Steroid hormones are synthesized from cholesterol in the smooth endoplasmic reticulum

Progesterone is produced by the ovaries (later in pregnancy, the placenta also produces progesterone) and functions in the menstrual cycle and the development and maintenance of the endometrial wall and fetus. Birth control pills frequently use high doses of progesterone (or progesterone and estrogen together) to cause negative feedback that suppresses LH and FSH levels, which in turn prevents ovulation from occurring.

A marine fish is hypoosmostic to its environment, meaning that it is less salty than the concentrated saltwater surrounding it. Therefore, it will constantly lose water to the environment. To make up for this, the marine fish must constantly drink water. It also rarely urinates to not waste any water, and it secretes the salts it acquires from constantly drinking.

In contrast, freshwater fish are hyperosmotic, or saltier than their environment. Therefore, water will constantly flow into the fish. The fish must constantly urinate to get rid of the excess water. It also rarely drinks, and absorbs salt through its gills to maintain homeostasis.

Fish in freshwater environments:

  1. Are hyperosmotic relative to their environment
  2. Drink very little water
  3. Salt enters the gills via active transport
  4. Produce large volume of urine

In contrast, fish in saltwater environments (i.e. marine fish):

  1. Are hypoosmotic relative to their environment
  2. Constantly drink
  3. Salt leaves the gills via active transport
  4. Produce low volume of urine

The blastopore or the opening in the archenteron (the primitive gut that forms during gastrulation) gives rise to the anus

Cleavage: radial and indeterminate

Coelom formation: folds of archenteron form coelom

Fate of blastopore: Blastopore forms the anus

Cleavage: spiral and determinate

Coelom formation: solid masses of mesoderm split and form coelom

Fate of the blastopore: Blastopore forms the mouth

Eventually form the placenta, but the villi are finger-like sections that burrow into the wall of the uterus near the mother's blood vessel

Disposes of wastes, and forms part of the umbilical cord to carry waste away from the embryo and towards the mother's blood vessels

A thin sac that surrounds the embryo and produces amniotic fluid to provide cushion for growing embryo

In placental mammals the yolk sac is completely empty and contains no yolk. Instead, one of its major functions is to aid in the formation of developing red blood cells.

Sertoli cells are cells located in the male testes and are primarily important for nourishing spermatozoa. Action of Sertoli cells are activated by follicle stimulating hormone (FSH).

The endometrium is the mucous membrane lining of the uterus that is shed during mammalian menstruation. During pregnancy, the developing embryo is implanted within the walls of the endometrium. This helps to shelter the embryo/fetus and will eventually give rise to the placenta.

In complete dominance, one allele completely masks the expression of the other (recessive) allele.

An example of complete dominance is Huntington’s disease, a degenerative nervous system disorder. If an individual possesses one allele for Huntington’s, then the condition will occur regardless of the other allele.

n incomplete dominance, neither allele is fully expressed For example, if a flower possessed one allele for red and a second allele for white, the resulting outcome would be pink if these alleles showed incomplete dominance.

The presence of the AB blood group indicates that both alleles are being expressed simultaneously. In AB type blood, both A and B antigens are expressed on the surface of red blood cells (as a result, no antibodies against either antigen are found in the plasma, and individuals with AB type blood are therefore universal recipients – then can receive blood from any other blood type). Another hypothetical example of codominance: if a flower possessed one allele for red and a second allele for white, and these two alleles were codominant, the resulting outcome would be a flower that had patches of both red and white color.

To confirm the genetic similarity or difference between organisms, which of the following biotechnology processes should be used?

Gel electrophoresis

Gel electrophoresis is a biotechnology process that allows for the separation of DNA, RNA, or proteins on the basis of size and charge (shorter molecules move further). If multiple samples are loaded, they can be compared to determine genetic similarities and differences

In the process of gel electrophoresis of DNA, the DNA is first cut up into pieces using a restriction enzyme. It is then loaded into an agarose gel under an electric field for the separation of DNA based on charge and size (the negatively charged DNA moves towards the positive anode, away from the negative cathode). The DNA is subsequently distributed by size and can be compared to the size of known standard samples and other samples from different sources for comparison. After electrophoresis, the DNA can then be sequenced, or probed to identify the location of a specific sequence of DNA.

Vectors are the vehicles used to transfer foreign genetic material into a cell.

Cloning is the biotechnology process by which the DNA of an organism is copied and maintained separately. It can refer to gene cloning, in which a gene of interest from an organism is replicated and then typically inserted into a plasmid and then introduced into another organism such as bacteria where the plasmid will be replicated so that multiple copies of the gene or genes will be available. It can also refer to the duplication of an entire organism.

Phrenology is a defunct field of study that aimed to deduce a person’s mental abilities and personality based on the shape and measurements of their skull. Phrenology is now considered a pseudoscience, and has little to no scientific validity.

A cladogram is a diagram that shows the evolutionary relationship among organisms based on either morphological characteristics (e.g. differences in physical structures, such as the presence of a notochord or the presence of fins) or molecular characteristics (e.g. differences in DNA sequence). A cladogram is not a process in biotechnology, and is not specific enough to confirm genetic differences between individual organisms

Polymerase Chain Reaction

Polymerase chain reaction (commonly abbreviated as PCR) is a biotechnology process that uses a synthetic primer, nucleotides, and a polymerase enzyme to clone DNA in a way that can rapidly amplify it. This technique is not used as a diagnostic tool therefore the answer choice is incorrect. PCR consists of three main steps:

  1. Denaturation (>90C)
  2. Addition of primers + Annealing (

DNA fingerprinting is a technique used to identify individuals (e.g. in paternity and forensic cases) based on aspects of their DNA unique to them such as short tandem repeats (STR’s). Since the number of STR’s tends to vary significantly in the population, the DNA of an individual (e.g. a suspect in a crime) can be compared to the DNA of a sample (e.g. blood left at the scene of a crime) for a positive match.

Northern blotting is a technique to identify fragments of known RNA sequence in a large population of RNA. First, the fragments of RNA containing the known sequence are put through electrophoresis to separate them by size and charge. Next, the RNA strands are separated into single strands (usually with NaOH) and then the single-stranded fragments are transferred to a nitrocellulose membrane. At this point a probe is added which will hybridize to the known sequence of RNA and mark it with some visual tag, usually fluorescence.

Southern blotting is similar to Northern blotting, but is used on DNA instead of RNA.

similar technique for proteins

Mnemonic for remembering lab techniques

S = Southern blotting -> DNA = D
N = Northern blotting -> RNA = R
O = O = O (nothing)
W = Western blotting -> protein = P

is a general condition describing a situation where the genome has an extra or missing chromosome number, often caused by nondisjunction. If nondisjunction were to occur during meiosis II, and a pair of sister chromatids failed to separate, the resulting two gametes would be produced: one that has an extra chromosome (n + 1) and one that is missing a chromosome (n – 1). As a result, after fertilization, a zygote with aneuploidy would result

Tetraploid refers to the number of sets of chromosomes, specifically four sets (4n). Cells with more than two sets of homologous chromosomes (such as triploids and tetraploids) are said to exhibit polyploidy which is common in plants.

Disomic refers to the state of having two sets of chromosomes – it can be thought of as interchangeable with the term diploid. The disomic state is standard in humans, and is not the result of nondisjunction during meiosis II and subsequent fertilization

A mix between salt and fresh water, which would be found in an estuary. An estuary is a specific area where freshwater meets seawater. A mangrove swamp often grows near an estuary and is characterized by a mix of salt and freshwater

In commensalism, a form of symbiosis, one of the two organisms benefits while the other remains unaffected. Examples of commensalism include barnacles and whales (the barnacle gets wider feeding opportunities as a result of being attached to the whale, while the whale is unaffected).

Allelopathy is the production of biochemicals by an organism that influences the growth, survival, and reproduction of other organisms. Allelopathy is a form of interference competition, which occurs directly between individuals via aggression. In interference competition, other individuals are directly prevented from physically establishing themselves on a shared habitat.

Exploitation competition is a type of competition that occurs indirectly through depletion of a common resource. For example, lions and cheetahs face exploitation competition in Africa as both hunt for a common resource: the gazelle. If cheetahs were more successful and ate all the gazelles, lions would suffer from depletion of the food resource.

Apparent competition is a type of competition that occurs between two species preyed upon by the same predator. For example, say a species of spider and a species of beetle are both hunted by owls and the amount of spiders suddenly increased. This would lead to survival of more owls (due to the increased food resource of spiders), which would in turn hunt more of the beetles, ultimately decreasing their overall number.

Intraspecific competition is a type of competition that occurs between members of the same species.

The deciduous forest biome is characterized by cold (but not particularly harsh) winters, warm summers, and moderate levels of precipitation. It has deciduous trees that shed their leaves during the winter, not coniferous trees Due to the shedding of leaves, the soil in deciduous forests is rich. This biome is characterized by vertical stratification (plants and animals live on the ground, in low branches, and high in treetops).

The savanna biome is characterized by warm temperature year-round, with some small seasonal variation. There is very little precipitation in terms of rainfall, and the dry season can last many months each year. Plants in this biome consist of grasses and scattered trees with small leaves. Animals in this biome consist primarily of large plant-eating mammals (e.g. zebras) and their predators (e.g. hyenas).

The tundra biome is characterized by cold winters (to the point that the top layer of soil freezes). In the summer, the top layer thaws, but deeper soil (permafrost) remains frozen year-round. The summers are still relatively cold (generally average less than 50° F), and there is very little precipitation or vegetation Plants in this biome consist of shrubs, grasses, mosses, and lichens (permafrost restricts the growth of plant roots). Animals in this biome include musk oxen, caribou, arctic hares, and arctic foxes.

The taiga biome (sometimes referred to as boreal forests), located south of the tundra biome, is the largest terrestrial biome. It is characterized by very long, harsh winters and precipitation in the form of heavy snow, along with short rainy and humid summers. The primary form of vegetation is coniferous forests.

The chaparral biome is characterized by highly seasonal precipitation, with rainy winters and dry summers. The scattered vegetation in this biome consists primarily of shrubs, grasses, and herbs. Animals include deer and goats. The chaparral biome is found along the California coastline, and many California fires happen here.

True statements about plant cell organelles

-Most of the cytoplasmic volume is occupied by a single vacoule

-Plant cell walls are composed of cellulose and function in maintaing cell shape

-Adjacent plant cells contain channels allowing for intercellular communication.

-Plant cells have mitochondria, but do not have a centriole:: they use mitochondria to convert the glucose they produce into ATP.

-Plant cells have both a cell wall and a cell membrane

Which of the following is a reason for why the intracellular binding of the steroid hormone testosterone is slow acting?

Steroids up regulate genes which must be transcribed and translated.

-They act as transcription factors. There is only an effect seen once the mRNA has been translated to protein, which is a slow process.

-Steroid hormones bind directly to the DNA and do not require second messengers

-Steroid hormones are non-polar and pass through the membrane

They aid in providing cell-cell adhesion and mechanical stability

Form a seal to prevent the passage of material between cells

All for passage of ions and small molecules while preventing the cytoplasm of adjacent cells from mixing

Intercalated discs in the heart

Narrow tunnels between plant cells that allow for exchange of material through cytoplasm around a narrow tube of the ER known as the desmotubule

What protein are the microfilaments of the cytoskeleton composed of?

Arranges to make up microtubules

A regulatory protein in skeletal muscle cells that prevents myosin from binding to actin.

Arranges to make up intermediate filaments

-A parasite that infects other cells and uses their machinery to survice

-The viral coats are made up of protein subunits called capsomeres, forming the capsid.

-It has no cell wall, no plasma membrane, nor any organelles.

-Can replicate using the lysogenic or lytic cycles

In the lysogenic cycle the virus binds to the host and inserts its viral DNA into the host cells’ DNA chromosome. The viral DNA will be replicated whenever chromosomal DNA is replicated. The virus is considered dormant and does not harm the host while in the lysogenic stage.

In the lytic cycle the virus attaches to a host, inserts its DNA into that host, and takes over the host cell’s machinery. This includes making many copies of viral DNA and translating viral proteins. The many virions then break out of the host cell, destroying the host cell in the process.

C3 photosynthesis is called C3 because CO2 will become a three carbon (C3) compound. This is conventional photosynthesis, and is what I discussed above. We can contrast this with C4 photosynthesis as well as CAM photosynthesis. C4 and CAM photosynthesis are both techniques that are used to prevent photorespiration.

This method is called C4 photosynthesis because the CO2 molecule integrates into and becomes a four carbon compound first, before it bonds to RuBisCO later on.

PEP carboxylase has even lower affinity for O2 compared to RuBisCO, so even in the presence of O2, it is very unlikely to bind to oxygen. This is an advantage.

The enzyme PEP carboxylase takes CO2 and converts it into oxaloacetate. Oxaloacetate quickly turns into malic acid. Both oxaloacetate and malic acid are four carbon compounds, hence the name C4.

The malic acid will be transferred from the mesophyll cells where PEP carboxylase reaction has occurred, to the bundle sheath cells.

The bundle sheath cells are located in a different area in the leaf anatomy (they surround the vascular bundles of plants), where O2 concentration is much lower.

Here the malic acid can be decarboxylated to release CO2. The CO2 can now undergo the conventional Calvin cycle with RuBisCO, in an environment where O2is not as prevalent, and RuBisCO has low risk of photorespiration.

The C4 photosynthesis process isolates CO2 spatially. Spatial isolation means that CO2 is transported to a different location (a different space) to prevent photorespiration. C4 photosynthesis transports the CO2 to the bundle sheath cells.

CAM plants have a different method of isolation. CAM plants use temporal isolation. Temporal isolation is an isolation based on timing, as a means of preventing photorespiration. There is no spatial separation: the processes occur in the same part of the leaf, but the plant does different processes at different times.

During the day, CAM plants close stomata to prevent excessive loss of water, via transpiration, evaporation out of the stomates (keep in mind this will also limit new gases like O2 from entering the plant). At night, CAM plants have their stomata open, allowing CO2 to enter into the leaf. The same enzyme in C4 photosynthesis is used in CAM photosynthesis: PEP carboxylase will fixate CO2into a four carbon molecule of oxaloacetate which converts into malic acid. In contrast, to the C4 pathway, rather than shuttle the malic acid to a different part of the leaf, the malic acid will be stored in a vacuole, for later use.

During the day, the malic acid will be shuttled out of the vacuole, CO2 will be decarboxylated from the malic acid, and the typical Calvin cycle will occur in a low O2 environment (stomates are closed). During the day the sun shines brightly, and ATP as well as NADPH are being produced plentifully.


Cell bio UTSW 2010

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AQA A2 Biology BIOL5 - 17th June 2015

(Original post by sofja26)
Hey I did the exact same thing as you I feel as if I read it completely wrong now I spoke about : Oestrous cycle, cell division, mitosis, genetic variation, antibiotics, mutations,cancer, protein synthesis. I am so gutted I actually cried about it BUT, I have looked at other peoples answers and some of our answers (from your post) is similar or the same. Yes this is 25 marks but surely we have to get some marks for these answers they cannot be 100% irrelevant. I am so so annoyed with myself, other people in my class spoke about ecology for this question

I'm also looking at all biol 5 mark scheme essay answers there are like 18 different points involved in this answer so who knows maybe we've just answered the unpopular ones but still got it right :/ :/

(Original post by sofja26)
Same here /> />I wrote about the human cycle and stuff for like 95% and then read the word organisms too late with like 5 minutes to go so I just stuck in antibiotics and mutation. I thought it was nicely separated but the more I read over it the more I think I've made such a stupid mistake..

(Original post by ps1265A)
Sure not ATPsynthase?

Okay im not a high achieving biology student lol,so for the essay I did 10)a) and I wrote:
1)Temperature Control
2)Kinesis and Taxis
3)Arc Reflex
4)Sympathetic and Parasympathetic Nervous System
5)Adaptations and how they can survive (very brief)

How many marks would I get?

For B I wrote about :
Oestrous cycle
Oestrogen as a transcription factor
Protooncogenes and tumour suppressors
Stem cells
Intensive farming
Mitosis

I pretty sure these all answer the question, "the importance to humans of the control of growth, development and reproduction in organisms, including themselves"


The thing is I dont think you can get awarded any marks if it doesnt even relate to the question I think I answered it totally different to how they wanted it I know I really thought that too but I doubted myself at the end and also I know a lot of people that spoke about mostly ecology stuff for that question, which Im still confused about. Arhhhh I don't know Obviously I want it to be right.

About the ratio question, If my memory didn't deceive me, it was the ratio of Experiment 2 (top curve) : Experiment 3 (lowest curve)

and the figures I got from extrapolating from the curves were 114 : 48 (dividing both by 48) the simplest ration is 2.37:1

I thought you can leave it as i is or round it to 2.4 : 1 , either way there should be a range, since the Y axis was a bit hard to read accurately .

I know I will have lost marks on graph/how science works questions as always, and there are other questions I thought I answered really well but will have lost marks for not using some specific words etc. as is typical for biology, but still feeling quite confident. Pls note this is not an unofficial mark scheme lol I'm just saying what I got and there were some things I guessed

These were my answers as far as I can remember.

1. a) Actin connects to the Z-line myosin ATPase hydrolyses ATP, I put the myosin part in just in case but don't think necessary tropomyosin binds to actin etc
b) Oh dear. For the myosin mutation thing I said something along the lines of myosin molecules couldn't bind to each other so the power stroke wouldn't work because the filaments wouldn't be able to move relative to each other :|

2. a) LH stimulates release of eggs from ovaries (in hindsight I might have accidentally said into the ovaries, if so ****) and stimulates secretion of progesterone from corpus luteum
b) The testosterone one - so it would inhibit secretion of GnRH so pituitary gland no longer stimulated to secrete FSH and LH, so testes no longer stimulated to secrete testosterone, so testosterone levels in the blood fall, then topped it off with "this is an example of negative feedback" lmao
c) Pretty much wrote the same thing but said testes would no longer be stimulated to produce sperm cells

3. I can't really remember the order of the questions, was this the Pacinian corpuscle one?
a) Mechanical pressure causes membrane of sensory neurone to stretch, sodium ion channels open and sodium ions diffuse into the sensory neurone, making membrane potential less negative. At the end I said something about the layers of connective tissue with viscous gel between just in case haha.
b) Suggest one reason why MS sufferers have less muscle control blah blah, I said less myelin sheath and nerve impulse travels more slowly along unmyelinated axons so slower/delayed muscle contraction
c) It was a hydrophobic molecule so it would pass through the membrane by simple diffusion
d) Why do cannabinoids prevent muscle contraction. calcium ions do not diffuse into synaptic knob so do not bind to receptors on synaptic vesicles which do not fuse with presynaptic membrane so acetylcholine does not diffuse across synaptic cleft and bind to receptors on postsynaptic membrane blah blah blah.
e) Um lol, for the cannabis one I said it would still have its effect on NMJs but since it didn't enter brain tissue it wouldn't have harmful side effects/damage brain tissue/wouldn't prevent synaptic transmission in the brain

4. I really can't remember the question order so I'm going to say this was the smoking one.
a) Questionnaire Q - I said the people who responded to the questionnaire might not be representative of the population and also that kids might lie because they could be ashamed to say that their parents smoke (no offence to anyone whose parents smoke lmao)
b) Support the conclusion, blah blah less expression of that gene and it was significant because SE did not overlap, expression of gene reduced the risk of allergic reactions so those children whose parents smoked would be more susceptible (basically just repeated stem of the question. )
c) DNA methylation, I said RNA polymerase would be less able to bind to promoter region of the gene so less mRNA produced so less translation and therefore less of the encoded polypeptide produced

5. a) tumour suppressor gene? umm think I said it regulates cell division so if it was mutated and became inactive cells would divide uncontrollably
b) not all mutations change the AA sequence because genetic code degenerate/more than one codon encodes the same amino acid so a substitution mutation could be silent (it was only one mark though)
c) The monoclonal antibodies :|.. I said antibodies complementary to the growth factor receptors on cancer cells so would bind to them and prevent growth factors from binding so the cancer cells wold no longer be stimulated to divide

6. I can't remember what part a) was. For the ratio in part b) I put 118:53, based on the June 11 MS I think 118:53, 2.2(7):1 or 1:0.44 (ish - graph reading was subjective) would all get two marks, and if you flipped them round you would get one mark.
c) Oh Jesus I wrote loads for this one about the sympathetic and parasympathetic..
I said it showed that they were both involved in the response: all three curves showed decrease in heart rate with increasing blood pressure heart rate was lower when SNS inhibited (so SNS involved) heart rate higher when PNS inhibited (so PNS involved) PNS had a more important role than SNS because there was bigger difference blah blah

7. I think this was the tropisms one?
a) Similarity is that they are both directional responses to external stimuli, for a difference I just said taxes are in animals and tropisms are in plants
b) Urgh so you had to describe what the pictures showed you for three marks -.-
I just said the first one showed gravity made the roots grow downwards, the second one showed they grew away from the salt, and for a third mark I said maybe it showed that the response to salt outweighed the response to gravity??
c) This IAA one took me a while . on the salt-exposed side there were more carrier proteins so more IAA transported out so lower concentration of IAA on that side, therefore the cells elongated more than the other side and the root tip bent away from the salt

8. a) Why were the able to maintain glucose concentration after not eating for 48 hours? Because pancreas detects drop in blood glucose, alpha cells of islets of Langerhans secrete glucagon which binds to receptors on liver cells and activates glycogenolysis and gluconeogenesis
b) Suggest how mutant mice maintained a constant glucose concentration compared to the normal mice or something..
I said that because the liver wasn't responding to glucagon, eventually blood glucose got very low and glucagon got very high and instead bound to receptors on intestines and kidneys, activating the PKC1 gene or whatever it was, and that enzyme made glucose. This wouldn't happen in the normal mice because glucagon levels don't get high enough for that gene to be stimulated?
c) The mean expression of the gene was significantly higher in the mutant mice both in kidneys and intestines probability that difference is due to chance is less than 1%

9. a) Same restriction enzymes so they would cut at the same recognition sites producing analogous fragments/any difference in fragment size would be due to the different alleles?
b) Primers have complementary sequence to the specific fragment to which they bind - they only form hydrogen bonds/complementary base pairs with this fragment
c) "Use all the information given to explain the results", I was a little worried because it gave the lengths of the two primers used so I felt like I had to use that, yet since they were only the primers and not the whole allele, I didn't feel it was actually possible to identify which one was L and N? So I answered quite vaguely, along the lines of:
L and N/parents both homozygous, one has two copies of r allele, one has two copies of R, so only one and seen, and the alleles are different lengths so they move different distances
All the offspring were heterozygous so they had one r and one R, so they had two bands which were half as thick?

d) Why were the control group used? Umm I said to see the effect of insecticide in the absence of any resistance allele
e) "PM activity is involved in resistance but there are other factors too explain how graph supports this conclusion", thought this was a nice end to the question. yeah in the resistance group with PM inhibited, more of them died than the ones without PM inhibited, so PM must play a role in the resistance but fewer of them died than the non-resistant flies which couldn't have been due to PM so another factor must play a role in the resistance.


Cruciate ligament healing and injury prevention in the age of regenerative medicine and technostress: homeostasis revisited

This clinical concepts paper discusses the essential elements of cruciate ligament recuperation, micro-trauma repair, and remodeling.

Methods

Cruciate ligament mechanobiology and tissue heterogeneity, anatomy and vascularity, and synovial membrane and fluid functions are discussed in relationship to deficiency-induced inflammatory responses, nervous and immune system function, recuperation, repair and remodeling, and modern threats to homeostasis.

Results

Cruciate ligament surgical procedures do not appreciate the vital linked functions of the central, peripheral, and autonomic nervous systems and immune system function on knee ligament injury recuperation, micro-trauma repair, and remodeling. Enhanced knowledge of these systems could provide innovative ways to decrease primary non-contact knee injury rates and improve outcomes following reconstruction or primary repair.

Conclusions

Restoration of knee joint homeostasis is essential to cruciate ligament recuperation, micro-trauma repair, and remodeling. The nervous and immune systems are intricately involved in this process. Varying combinations of high-intensity training, under-recovery, technostress, and environmental pollutants (including noise) regularly expose many athletically active individuals to factors that abrogate the environment needed for cruciate ligament recuperation, micro-trauma repair, and remodeling. Current sports training practice, lifestyle psychobehaviors, and environmental factors combine to increase both primary non-contact knee injury risk and the nervous and immune system dysregulation that lead to poor sleep, increased anxiety, and poorly regulated hormone and cytokine levels. These factors may create a worst-case scenario leading to poor ligament recuperation, micro-trauma repair, and remodeling. Early recognition and modification of these factors may decrease knee ligament injury rates and improve cruciate ligament repair or reconstruction outcomes.


Watch the video: How to Use an EZ Zahn Viscosity Cup (July 2022).


Comments:

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  2. Arak

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  3. Thearl

    and there are such parameters))))

  4. Mijas

    It is true! I think this is a great idea. I agree with you.



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