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As an instrumentation engineer, I have designed temperature control systems capable of measuring and controlling temperature with a precision of 0.001K over a wide temperature range. I have always wondered how the human body maintains its temperature within a fraction of a degree; specifically, where and how is the temperature measurement done?
Human thermo detection comes from a protein, expressed in high levels in the nervous system.
As per comments, there are a group of transmembrane proteins called transient receptor potential cation channel subfamily V (TRPV) ion channels that can detect temperature changes. Although the exact mechanism of the protein remains unclear, a study published in Nature 2010 showed that a protein called TRPV1 opens and closes to allow increased or decreased sensitivity to temperature change.
There is no specific organ that is responsible for temperature detection, however TRPV1 is expressed in high levels in the nervous system.
How is body temperature regulated and what is fever?
Created: July 30, 2009 Last Update: November 17, 2016 Next update: 2020.
A healthy body functions best at an internal temperature of about 37ଌ (98.6ଏ). But everyone has their own individual "normal" body temperature, which may be slightly higher or lower. Our bodies also constantly adapt their temperature to environmental conditions. It goes up when we exercise, for instance. And it is lower at night, and higher in the afternoon than in the morning.
Our internal body temperature is regulated by a part of our brain called the hypothalamus. The hypothalamus checks our current temperature and compares it with the normal temperature of about 37ଌ. If our temperature is too low, the hypothalamus makes sure that the body generates and maintains heat. If, on the other hand, our current body temperature is too high, heat is given off or sweat is produced to cool the skin.
Strictly speaking, body temperature refers to the temperature in the hypothalamus and in the vital internal organs. Because we cannot measure the temperature inside these organs, temperature is taken on parts of the body that are more accessible. But these measurements are always slightly inaccurate.
Human Organ System
The tissues of two or more types combine to form an organ. An organ is an organized part of the body which performs one or more special functions. Several organs unite for a common function constitutes a human organ system. Organs of a system function in a coordinated manner to carry out major life processes of human beings. The body of human (or any Invertebrate) has the following human organ systems, which work as an integrated unit for the normal functioning of fire body.
It is a human organ system which includes skin and its associated structures. It covers the outside of the body and is protective in function. It also provides shape to the body, regulates the body temperature and helps in excretion of metabolic wastes and excess water.
This human organ system includes alimentary canal and associated glands and carries out digestion and absorption of food.
It is the human organ system that consists of bones and cartilage. It supports and shapes the body, protects the softer internal organs from external injury, provides sites for attachment to muscles and produces red blood cells.
This important human organ system consists of heart, blood and lymph vessels and the blood and lymph that flows through them. It is responsible for the transport of nutrients, respiratory gases, metabolites hormones and waste products to different parts of the body.
It consists of lungs (or gills) and respiratory tract through which gaseous exchange takes place from the external environment of human organ system.
This is the human organ system includes several types of muscles and participates in the movement of various parts and locomotion of the organism. It also protects the internal parts.
This includes brain, spinal cord, associated nerves and various receptors. This human organ system is concerned with receiving information of external and internal changes to give rise to sensations and transmits information among different parts of the body.
It consists of endocrine glands which secrete hormones that are powerful coordinators of various body functions ranging from the development of sexual characteristics to everyday utilization of food.
Urino-genital system includes excretory (urinary) and reproductive systems. The former consists of kidneys, ureters, urinary bladder and urethra, and the latter of gonads and accessory reproductive organs. This human organ system is mainly concerned in the elimination of waste products and reproduction.
In humans, temperature sensation enters the spinal cord along the axons of Lissauer's tract that synapse on first order neurons in grey matter of the dorsal horn, one or two vertebral levels up. The axons of these second order neurons then decussate, joining the spinothalamic tract as they ascend to neurons in the ventral posterolateral nucleus of the thalamus.
In mammals, temperature receptors innervate various tissues including the skin (as cutaneous receptors), cornea and urinary bladder. Neurons from the pre-optic and hypothalamic regions of the brain that respond to small changes in temperature have also been described, providing information on core temperature. The hypothalamus is involved in thermoregulation, the thermoreceptors allowing feed-forward responses to a predicted change in core body temperature in response to changing environmental conditions.
Thermoreceptors have been classically described as having 'free' non-specialized endings the mechanism of activation in response to temperature changes is not completely understood.
Cold-sensitive thermoreceptors give rise to the sensations of cooling, cold and freshness. In the cornea cold receptors are thought to respond with an increase in firing rate to cooling produced by evaporation of lacrimal fluid 'tears' and thereby to elicit a blink reflex. Other thermoreceptors will react to opposite triggers and give rise to heat and in some cases even burning sensations. This is often experienced when coming in contact with capsaicin, an active chemical commonly found in red chili peppers. When coming in contact with your tongue (or any internal surface), the capsaicin de-polarizes the nerve fibers, allowing sodium and calcium into the fibers. In order for fibers to do so, they must have a specific thermoreceptor. The thermoreceptor reacting to capsaicin and other heat producing chemicals is known as TRPV1. In response to heat, the TRPV1 receptor opens up passages that allow ions to pass through, causing the sensation of heat or burning. TRPV1 also has a molecular cousin, TRPM8. Unlike TRPV1, TRPM8 produces cooling sensations as mentioned previously. Similar to TRPV1, TRPM8 responds to a certain chemical trigger by opening its ion pathways. In this case, the chemical trigger is often menthol or other cooling agents. Studies performed on mice determined that the presence of both these receptors allows for a gradient of temperature sensing. Mice lacking the TRPV1 receptor were still capable of determining areas significantly colder than on a heated platform. Mice lacking the TRPM8 receptor however, were not able to determine the difference between a warm platform and a cold platform, suggesting we rely on TRPM8 to determine cold feelings and sensations.  
Warm and cold receptors play a part in sensing innocuous environmental temperature. Temperatures likely to damage an organism are sensed by sub-categories of nociceptors that may respond to noxious cold, noxious heat or more than one noxious stimulus modality (i.e., they are polymodal). The nerve endings of sensory neurons that respond preferentially to cooling are found in moderate density in the skin but also occur in relatively high spatial density in the cornea, tongue, bladder, and facial skin. The speculation is that lingual cold receptors deliver information that modulates the sense of taste i.e. some foods taste good when cold, while others do not. [ citation needed ]
This area of research has recently received considerable attention with the identification and cloning of the Transient Receptor Potential (TRP) family of proteins. The transduction of temperature in cold receptors is mediated in part by the TRPM8 channel. This channel passes a mixed inward cationic (predominantly carried by Na + ions although the channel is also permeable to Ca 2+ ) current of a magnitude that is inversely proportional to temperature. The channel is sensitive over a temperature range spanning about 10-35 °C. TRPM8 can also be activated by the binding of an extracellular ligand. Menthol can activate the TRPM8 channel in this way. Since the TRPM8 is expressed in neurons whose physiological role is to signal cooling, menthol applied to various bodily surfaces evokes a sensation of cooling. The feeling of freshness associated with the activation of cold receptors by menthol, particularly those in facial areas with axons in the trigeminal (V) nerve, accounts for its use in numerous toiletries including toothpaste, shaving lotions, facial creams and the like.
Another molecular component of cold transduction is the temperature dependence of so-called leak channels which pass an outward current carried by potassium ions. Some leak channels derive from the family of two-pore (2P) domain potassium channels. Amongst the various members of the 2P-domain channels, some close quite promptly at temperatures less than about 28 °C (e.g. TRAAK, TREK). Temperature also modulates the activity of the Na + /K + -ATPase. The Na + /K + -ATPase is a P-type pump that extrudes 3Na + ions in exchange for 2K + ions for each hydrolytic cleavage of ATP. This results in a net movement of positive charge out of the cell, i.e. a hyperpolarizing current. The magnitude of this current is proportional to the rate of pump activity.
It has been suggested that it is the constellation of various thermally sensitive proteins together in a neuron that gives rise to a cold receptor.  This emergent property of the neuron is thought to comprise, the expression of the aforementioned proteins as well as various voltage-sensitive channels including the hyperpolarization-activated, cyclic nucleotide-gated (HCN) channel and the rapidly activating and inactivating transient potassium channel (IKA).
All of the organs and organ systems of the human body work together like a well-oiled machine. This is because they are closely regulated by the nervous and endocrine systems. The nervous system controls virtually all body activities, and the endocrine system secretes hormones that regulate these activities. Functioning together, the organ systems supply body cells with all the substances they need and eliminate their wastes. They also keep temperature, pH, and other conditions at just the right levels to support life processes.
The process in which organ systems work to maintain a stable internal environment is calledhomeostasis. Keeping a stable internal environment requires constant adjustments. Here are just three of the many ways that human organ systems help the body maintain homeostasis:
- Respiratory system: A high concentration of carbon dioxide in the blood triggers faster breathing. The lungs exhale more frequently, which removes carbon dioxide from the body more quickly.
- Excretory system: A low level of water in the blood triggers retention of water by the kidneys. The kidneys produce more concentrated urine, so less water is lost from the body.
- Endocrine system: A high concentration of sugar in the blood triggers secretion of insulin by an endocrine gland called the pancreas. Insulin is a hormone that helps cells absorb sugar from the blood.
So how does your body maintain homeostasis? The regulation of your internal environment is done primarily through negative feedback. Negative feedback is a response to a stimulus that keeps a variable close to a set value (Figure below). Essentially, it "shuts off" or "turns on" a system when it varies from a set value.
For example, your body has an internal thermostat. During a winter day, in your house a thermostat senses the temperature in a room and responds by turning on or off the heater. Your body acts in much the same way. When body temperature rises, receptors in the skin and the brain sense the temperature change. The temperature change triggers a command from the brain. This command can cause several responses. If you are too hot, the skin makes sweat and blood vessels near the skin surface dilate. This response helps decrease body temperature.
Another example of negative feedback has to do with blood glucose levels. When glucose (sugar) levels in the blood are too high, the pancreas secretes insulin to stimulate the absorption of glucose and the conversion of glucose into glycogen, which is stored in the liver. As blood glucose levels decrease, less insulin is produced. When glucose levels are too low, another hormone called glucagon is produced, which causes the liver to convert glycogen back to glucose.
Feedback Regulation. If a raise in body temperature (stimulus) is detected (receptor), a signal will cause the brain to maintain homeostasis (response). Once the body temperature returns to normal, negative feedback will cause the response to end. This sequence of stimulus-receptor-signal-response is used throughout the body to maintain homeostasis.
Some processes in the body are regulated by positive feedback. Positive feedback is when a response to an event increases the likelihood of the event to continue. An example of positive feedback is milk production in nursing mothers. As the baby drinks her mother's milk, the hormone prolactin, a chemical signal, is released. The more the baby suckles, the more prolactin is released, which causes more milk to be produced. Other examples of positive feedback include contractions during childbirth. When constrictions in the uterus push a baby into the birth canal, additional contractions occur.
Failure of Homeostasis
Many homeostatic mechanisms such as these work continuously to maintain stable conditions in the human body. Sometimes, however, the mechanisms fail. When they do, cells may not get everything they need, or toxic wastes may accumulate in the body. If homeostasis is not restored, the imbalance may lead to disease or even death.
SENSORY ORGANS FACTS
While the five senses are considered the basic starting block for the sensory system, each sense has additional senses that work within its framework, creating a multitude of senses. The sense of touch has pain, cold, heat, and so forth within its framework of additional senses. The senses are considered either general if their pathways of communication are basic and simple and are considered special if the pathway of communication are complex or require distortion by the sensory system.
Thyroid gland is the largest endocrine gland in adult.
You may logically assume that all the persons must have.
Organs and Organ Systems of the Human Body:
Do you know how the functions like communication, transportation, reproduction and growth are executed through the collective effort of different organs of the body? Though you would already be having a vast pool of information about your body, this article aims at revealing some stunning facts which may not be known to you.
In biology, a cell is known as the basic building block and the smallest unit of life. When similar cells combine into a group, they form a tissue. Two or more tissues, on the other hand, combine to form an important entity, called an organ. The grouping of different organs results in the formation of organ system.
There are as many as 80 organs which form groups and work in coordination with one another to accomplish a particular task. A group of organs assigned to complete a specific function, on the other hand, is called an organ system. For example, heart, blood, blood vessels and lungs are the major components of the blood circulatory system.
Do you know how many organ systems are there in your body? Well, there are nearly a dozen organ system, each made up of multiple individual organs working in coordination with one another. At the same time, there is coordination and linkage between different organ systems which combine to form an individual.
Among them, brain, heart, lungs, liver and kidneys are considered as the major or vital organs of the human body. The master organ, the brain, serves as CPU or control center, while beating of heart is considered as the sign of life in an individual.
The lungs assist in the supply of oxygen to every individual cell and the removal of carbon dioxide outside the body. The liver attaches with itself at least three superlative degrees, i.e. it is the largest, heaviest and hottest internal organ. Kidney serve as an important component of the excretory system which is responsible for the removal of the excess, unnecessary materials from the body fluids.
8 Major Organs of the Body:
All the organs of the body are not essential for the survival of an individual. There are certain organs, like arms, legs, stomach, large intestine, and tongue the complete removal of which will not put your life at risk. The other organs, like brain, heart, kidney, lungs and pancreas, etc. are indispensable for your survival. They are called the major or vital organs of your body. You can have a bird eye view of the shape, size and functioning of the major body organs through the following description:
Lying on the top of the body and enclosed in an incredibly hard protective cover of skull, the brain serves as the control center for all the functions of the body. Nearly 1.4-kilogram mass of brain occupies over 1200 cubic centimeter of space and accounts for about two percent of the total body weight.
Just like the brain of other mammalian species, it is distinguishable into three basic divisions of forebrain, midbrain and hindbrain. In absolute terms, the human brain is smaller than those of large mammals, like whales and elephants. But, when you take into account the measure of relative brain size, it happens to be twice as large as that of the bottlenose dolphin.
One of the most vital organs in the body, the heart is assigned the role of pumping blood with such a force that it reaches every individual cell. The blood carries with it nutrients as well as oxygen which are to be delivered to all the cells. Another important function of blood is to transport waste substances and gases for elimination out of body.
Measuring 5 inches in length, 3.5 inches in width and 2.5 inches in thickness, the human heart appears to be the size of a fist. However, an athlete’s pumping organ may grow much larger in size due to excessive exercise. There are four chambers in it, with the upper two being atria and the lower ones termed as ventricles.
Lungs are the respiratory organs as they are involved in the exchange of gases. If these vital organs are removed due to some disease, the affected person won’t be able to live anymore. They are found in the chest region on either side of the heart. The major tubular branches are called bronchi which gradually divide into bronchioles and alveoli – the smallest air sacs with single cell lining.
The primary role assigned to them is the extraction of oxygen from the atmospheric air and release carbon dioxide from the body. As you inhale air into lungs, oxygen is transferred to the bloodstream, while carbon dioxide in the bloodstream is transferred to the atmosphere.
Located behind the stomach in the abdominal cavity, the pancreas is a glandular organ. Owing to its dual-functionality, it is the closely associated with both the digestive system and endocrine system. This six-inch large organ can be distinguished into body, tail, neck and head.
Looking at its digestive function, the pancreas secretes and releases an enzyme-containing fluid into duodenum of small intestine, called pancreatic juice. It is known as an exocrine secretion. These enzymes help in the digestion of lipids, proteins and fats. The endocrine secretion of the organ contains some very important hormone, including insulin and glucagon.
The liver, kidney and lungs are the organs that purify blood. The enzymes secreted by liver detoxify various harmful substances and lungs eliminate carbon dioxide (a waste respiratory gas) from the blood. The kidneys, on the other hand, serve as the natural purifiers of your body.
Located in the back of abdomen, there are two bean-shaped kidneys with each measuring five or six inches in length. Their primary function is to filter waste substances from the blood and eliminate the same out of the body in the form of urine.
Metabolically, liver is the most complex organ in humans as it is assigned to form a number of different metabolically important functions. In addition to detoxifying poisonous substances, it also manufactures proteins and hormones. Other functions of the liver include blood clotting, control of blood sugar and killing germs.
As a detoxifier, the liver transforms various harmful substances like ammonia, metabolic wastes, alcohol and chemicals, into less harmful compounds. These neutralized and less harmful substances are then excreted out of the body.
Though not included in the list of vital organs, your eye makes you able to enjoy the soothing and fascinating colors of natural and artificial worlds around you. This complex organ has the potential to detect a single photon as well as distinguish nearly ten million colors!
The structure of eye can be distinguished into a small corneal segment and a large sclerotic chamber, measuring in 8 mm and 24 mm, respectively. Typically, an adult human eye may measure up to 7.5 gram in weight and six cubic centimeters in volume.
An integral component of the digestive system, the small bowel or small intestine serves as the major organ of food absorption. At the same time, it also plays an important role in the process of digestion. All the major types of food, namely, carbohydrates, lipids and proteins, are further digested and broken down into smaller absorbable products.
The small intestine is a bit longer in human females. It runs for the length of 6.9m and 7.1m in an adult male and female, respectively. It can have the diameter of up to 1 inch or a bit more. Interestingly, the total surface area can be as large as 30 square meters! But how is it possible? Well, these are the folds, villi and microvilli which significantly contribute to the enlargement of the surface area.
Homeostasis is a healthy state that is maintained by the constant adjustment of biochemical and physiological pathways. It is the maintenance (the body’s physiological mechanisms) of relatively stable conditions within the body’s internal environment. It is a key concept in understanding how our body works. It means keeping things constant and comes from two Greek words: ‘homeo,’ meaning ‘similar,’ and ‘stasis,’ meaning ‘stable.’ The word homeostasis (/ˌhoʊmioʊˈsteɪsᵻs/) uses combining forms of homeo- and -stasis, New Latin from Greek: ὅμοιος homoios, “similar” and στάσις stasis, “standing still”, yielding the idea of “staying the same”.
The concept (Homeostasis) was described by French physiologist Claude Bernard in 1865 and the word was coined by Walter Bradford Cannon in 1926. Homeostasis is happening constantly in our bodies. We eat, sweat, drink, dance, eat some more, have salty fries, and yet our body composition remains almost the same. If someone were to draw our blood on ten different days of a month, the level of glucose, sodium, red blood cells and other blood components would be pretty much constant, regardless of our behavior. It is an almost exclusively biological term, referring to the concepts described by Bernard and Cannon, concerning the constancy of the internal environment (or milieu intérieur) in which the cells of the body live and survive.
There are several examples homeostasis in the human body. Learn how our bodies maintain a state of homeostasis in order to ensure our survival.
Acid-Base Balance: The body controls the amounts of acids and bases in the blood. When the number of acidic compounds in the blood increases, body acidity also increases. Acid-base balance refers to the balance between alkalinity and acidity in the blood, as measured on the pH scale. The kidneys and lungs, along with buffer systems, help control acid-base balance.
Body Temperature: Another one of the most common examples of homeostasis in humans is the regulation of body temperature. Normal body temperature is 37 degrees C or 98.6 degrees F. Temperatures way above or below these normal levels cause serious complications. The body controls temperature by producing heat or releasing excess heat.
Calcium Levels: The bones and teeth contain approximately 99 percent of the calcium in the body, while the other 1 percent circulates in the blood. Too much calcium in the blood and too little calcium in the blood both have negative effects.
Glucose Concentration: Glucose concentration refers to the amount of glucose – blood sugar – present in the bloodstream. The body uses glucose as a source of energy, but too much or too little glucose in the bloodstream can cause serious complications.
Fluid Volume: The body has to maintain a constant internal environment, which means it must regulate the loss and gain of fluid. Hormones help to regulate this balance by causing the excretion or retention of fluid.
Controlled Systems of Homeostasis
The body’s homeostatic mechanisms are controlled mainly by the Nervous System, and the Endocrine System. The role of parts of these and other tissues varies according to the specific homeostatic mechanism.
Structures within the nervous system detect variation from the balanced state, i.e. parameters such as heat or pH being within the range of acceptable values, and communicate that information by sending signals in the form of nerve impulses to the glands, organs or tissues in the body responsible for taking action to restore the balanced state.
In many cases the glands of the endocrine system (endocrine glands) take action to restore the body or a part or system there of, to a balanced state by producing and/or secreting hormone molecules into the blood. This controls homeostasis because hormones are chemicals that can move around the body and are targeted to interact with specific cells that have receptors matching the specific hormone. Hormones are described as “chemical messengers” because by interacting with target cells they stimulate those cells to take specific action, e.g. antidiuretic hormone (ADH) directs the kidneys to decrease the volume of urine they produce, whose overall effect is to maintain the stability of the body’s internal environment.
The volume of water in the body is measured by stretch receptors in the heart atria, and, somewhat indirectly, by the measurement of the osmolality of the plasma by the hypothalamus. Measurement of the plasma osmolality to give an indication of the water content of the body, relies on the fact that water losses from the body, through sweat, gut fluids, normal fecal water losses, and through vomiting and diarrhea, and the exhaled air, are all hypotonic, meaning that they are less salty than the body fluids compare, for instance, the taste of saliva with that of tears.
Chronic Disease about Homeostasis
Various chronic diseases are kept under control by homeostatic compensation, which masks a problem by compensating for it in another way. However, the compensating mechanisms eventually wear out or are disrupted by a new complicating factor such as the advent of a concurrent acute viral infection, which sends the body reeling through a new cascade of events. Common examples include decompensated heart failure, kidney failure, and liver failure.
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Organ, in biology, a group of tissues in a living organism that have been adapted to perform a specific function. In higher animals, organs are grouped into organ systems e.g., the esophagus, stomach, and liver are organs of the digestive system.
In the more advanced animals, there are usually 10 organ systems: integumentary, skeletal, muscular, nervous, endocrine (hormonal), digestive, respiratory, circulatory, excretory, and reproductive. These systems appear gradually in the lower animals and attain their full complexity and functional specialization in the higher animals. In plants the primary organs are the stem, root, and leaf, all of which help to nourish the plant, and the reproductive organs (e.g., flowers, seed, and spores). As with animals, these organs are responsible for the basic life-sustaining functions of the organism.
The Editors of Encyclopaedia Britannica This article was most recently revised and updated by Adam Augustyn, Managing Editor, Reference Content.
Measuring Body Temperature
Although body temperature can vary between us as human beings, the average body temperature is around 37oC (or 98 Fahrenheit).
Some people have varying temperatures as a result of variances in their metabolism: the higher the rate of metabolism the higher the temperature and likewise the lower the rate of metabolism the lower the body temperature.
The temperature will vary in certain areas of the human body as well. For example the temperature in the mouth will be 37oC (or 98 oC Fahrenheit) but underneath the armpit the temperature reading will be around 36.4 °C (97.6 °C Fahrenheit). Temperatures can also be taken using the tympanic method (from the ear).
By far the most accurate reading of a body temperature is the one that can be taken rectally. Although is not the most pleasant of ways in which to read someone’s temperature it is the most accurate in relation to the body’s core temperature and for this reason it is normally the most used method of determining the temperature of the decease when they are examined at the scene of a crime.
At The Crime Scene
At the scene of a crime the pathologist, who will be charged with initially examining the body in its discovered post mortem condition, will take the body’s temperature in any way appropriate. This can be under the arm, in the ear or rectally because – as we have already mentioned – this is the most accurate reading.
Finding out the temperature of the body while it is still in situ is an important piece of information one that can be used to give the officers at the scene a rough idea as to how long the deceased has been dead.
This formula equates to the body temperature (37oC), which loses 1.5oC (34.7 Fahrenheit) per hour until the temperature of the body is that of the environment around it known as the ambient temperature. This ambient temperature – depending on how low it is – may take minutes or hours to be reached and this is a good indicator as to how long a body has been in situ. Additionally it is worth noting that a body’s temperature will drop much more slowly if the body has been exposed to extreme cold such as being left outdoors, submerged in water or icy conditions.
The pathologist will take into consideration the environment around the body and will also take into consideration clothing that the deceased is wearing and body weight.
What Affects Readings?
Both body fat and clothing are good insulators and as a result can alter the temperature of the deceased by keeping heat in that would normally be lost as the blood supply stops flowing and the muscles begin to relax before going into a state of Rigor.
report this ad It should also be noted that children and the elderly lose body heat faster than adults between the ages of eighteen to sixty five and also that the deceased – should they have been in ill health prior to death – will lose heat more rapidly.
The pathologist will take all of these factors into consideration when taking a temperature reading and having accurately done so should be able to estimate time of death to within a matter of hours. Find out more about the work of the pathologist in forensics.