THERMOREGULATION PROCESSES OF HUMAN AND ANIMAL BODY TEMPERATURE

In organism body (individual level) always any regulation mechanism  for achieve situation which homeostatic. Homeostatic is effort to defending or making condition which steady state which assure of optimization all process of physiology in body. For achieve this situation, body doing many regulation activity, as mechanism to achieve the homeostatic which be provided. Regulation and homeostatic which happen in big organism level, that are in population level  and community in a ecosystem. Regulation system have function to manage a work in all of organ system which any in the human body. Regulation system is work to accept the stimulation, processing the stimulation and receive the stimulation. (Rikky Firmansyah, 2009: 129)

All of system in organism body play along with the other for defending the homeostatic in our body. Homeostasis as need by cell and tissues of our body to can work very well to confronted the external environment change. Some homeostatic mechanism which important, that are: thermoregulation, osmoregulation, water and electrolit regulation and glucoregulation. In human body, the regulation be done by nerve and hormon. (Tati suryati syamsudin Subahar, 2009: 67)

When any change in our body, any 2 respond mechanism which happen possible, that are:

1.      Negative feedback

A process which happen when our body system need stoping  according to complete  a process which was happening.

The example when the blood pressure increase, receptor in artery carotid will be detecting and sending signal to the brain. The brain will send message to heart to decelerate the throb so the blood current which pumped more little and cause decrease of blood pressure.

2.      Positive Feedback

A respond to make a process physiologist or action from a system. Usually this respond is a siklik process which can be continue to consolidate a action or a process until respond of negative feedback take change position. (Rikky Firmansyah, 2009: 131)

The example of regulation process is thermoregulation. Thermoregulation is a physiological process that is the integration and coordination of activities that are actively used to maintain core body temperature against cold or warm temperature changes. Human is homeothermik creature which can manage a body temperature for achieve a equilibrium so body temperature disposed constant which not influence by environment temperature. Human enzim work effective in 37⁰ C temperature. Center of temperature manage in brain part of hypothalamus. There are some effector which engage between variation mammals. Temperature managed with some mechanism. Fluctuation temperature detected by receptor which called thermoreceptor, the example is skin.

If we very hot or cold because influence from out environment or in our body, so thermoreceptor will be send nerve impuls to hypothalamus. After that hypothalamus will be send message response to effector like skin to increase or decrease the lose of heat from surface with:

a.       Increase body temperature responded with stand hair feather (pyloerection) because contraction skin muscles whereas decrease body temperature responded with restraint body heat with flat the feather hair because skin muscle relaction.

b.      Glands under skin will be secretion sweat to skin surface for increasing the lose of heat with evaporation if temperature body increasing. Secretion of sweat will stop if body temperature have been comeback normal.

c.       Blood vessel which currrent skin will broad for bring a more some heat out from body (vasodilatation) if body temperature increase, and blood vessel will shrink (vasoconstriction) to minimalition loosing of heat through skin if body temperature have been normal again.

If happen decrease long temperature, so hypothalamus will be increasing the secretion of hormon TRH to stimulate output TSH by hypophysis which will be stimulate increase secretion hormon tyrocsin by thyroid gland. This hormon will impedance metabolism which have other product heat energy. Other that, non specific mechanism to bridge decrease body temperature is with contraction of muscles extremity for producting of heat.

In the regulation of body temperature, the animal must regulate heat received or are lost to the environment. Mechanism changes the animal's body heat can occur with 4 processes, namely conduction, convection, radiation and evaporation. Conduction is the change in the animal's body heat due to contact with an object. Convection is heat transfer due to the movement of air or fluids through the body surface. Radiation is the emission of electromagnetic energy. Radiation can transfer heat between objects that are not in direct contact. For example, solar radiation. Evaporation heat loss from the surface of the liquid is transformed in the form of gas.

The hypothalamus is a very sensitive part, which is the main integration center to maintain energy balance and body temperature. The hypothalamus serves as the body's thermostat, to receive information from various parts of the body in the skin. Coordinated with the adjustment mechanism is very complicated in addition and subtraction as appropriate temperatures for core temperature any deviation from the normal reference values​​. The hypothalamus is able to respond to changes in blood temperature as small as 0.01 º C.

The hypothalamus constantly informed of skin temperature and core temperature through specific receptors that are sensitive to temperature called thermoreseptor (receptor warm, cold and pain in the periphery). Temperature receptors are very active during temperature changes. Primary temperature sensation adapted very quickly. Core temperature is monitored by a central termoreseptor located in the hypothalamus and in the central nervous system and abdominal organs.

In the center of the hypothalamus known to have 2 temperature settings, ie in the posterior region and anteror. Posterior region is activated by cold temperatures and then trigger the reflex that mediates heat production and heat conservation. Moderate, anterior region that is activated by a sense of warmth, triggering a reflex that mediates heat reduction.

Thermoregulation in Humans

Human thermoregulation centered on the anterior hypothalamus, there are three components making up the system controller or heat settings, namely thermoreseptor, hypothalamus, and efferent nerves and thermoregulation can maintain body temperature, the temperature-specific constant temperature is usually higher than the surrounding environment.

Body temperature regulation mechanism is a combination of the functions of organs interconnected. regulation of body temperature in mammals, there are two types of temperature control sensors, heat sensors and sensor is cool different places on the network around (outside receivers) and core network (receiver inside) of body. From both types of sensors, the signals received directly transmitted to the central nervous system and then sent to the motor neurons that regulate heat expenditure and heat production to proceed to the heart, the lungs and the whole body.

Once that happens the feedback, which signals, received back by the sensor heat and cold sensors through the bloodstream.

Most heat is lost through the process of radiation, the sweat cooling off. Through evaporation serves to keep the body temperature to remain constant. and modification of the circulatory system in the skin. Contrition blood vessels in the skin and countercurrent heat exchange is one way to reduce the loss of body heat. Human wearing is one of the unique behavior in thermoregulation.

Human body temperature tends to fluctuate at any time. Many factors could cause fluctuations in body temperature. To maintain the temperature of the human body in a state of constant, necessary regulation of body temperature. Human body temperature regulated by a feedback mechanism (feed back), played by temperature regulation center in the hypothalamus. If the temperature of the center of the hypothalamus detects body temperature is too hot, the body will conduct a feedback mechanism. This feedback mechanism occurs when the core body temperature has been over the limit of tolerance for maintaining body temperature, which is called a fixed point (set point). Fixed point so that the body is maintained at a constant core body temperature of 37 ° C. when the body temperature rises over a fixed point, the hypothalamus will be stimulated to undertake a series of mechanisms to maintain temperature by reducing heat production and increase the heat so that the temperature back spending on fixed point.

Our bodies are equipped with various advanced system settings, including the regulation of body temperature. Humans have the central regulation of body temperature (thermostat), located in the part of the brain called the hypothalamus. The body temperature regulation center peg our body temperature at one point called the set point.

The hypothalamus duty to always maintain a constant body temperature, ranging at 37 ° C. That's why, wherever humans are, at the poles or in the desert, the body temperature stable should always be pursued, so that the man referred to as being able to adapt. Hypothalamic thermostat works on intake of nerve endings and the temperature of the blood circulating in the body. Hypothalamus in the cold will make the program so that the body is not cold, by raising the set point alias raise body temperature. How to contract the blood vessels, body shiver and look pale.

While in the hot air, of course, must hypothalamus lowers body temperature to prevent heatstroke. You do this by removing heat through evaporation. Blood vessels dilate, breathing becomes more rapid. Therefore, at the time of the heat, in addition to sweating, we also looked reddish skin (flushing).

Organ Regulatory Body Temperature:

-    Heat regulating center in the body is the hypothalamus, the hypothalamus known as the thermostat is located under the brain.

-    Anterior hypothalamus regulates heat dissipation

-    Posterior hypothalamus regulates heat retention efforts

-    Mechanism of temperature regulation

-    Skin -> Receptor ferifer -> hypothalamus (posterior and anterior) -> Preoptica hypotalamus -> Nerve efferent -> loss / heat generation

Factors Affecting Body Temperature

1. Basal metabolic rate

Basal metabolic rate of each individual is different. It impacts the amount of heat produced by the body to be different. As mentioned in the previous description, it is related to the rate of metabolism.

2. Sympathetic nerve stimulation

Sympathetic nerve stimulation can cause the metabolic rate to 100% faster. In addition, sympathetic nerve stimulation can prevent brown fat that accumulate in tissues to be metabolized. Almost all brown fat metabolism is the production of heat. Generally, the sympathetic nerve stimulation affected individuals stress causes increased production of epinephrine and norepineprin that increase metabolism.

3. Growth hormone

Growth hormone (growth hormone) may cause an increase in metabolic rate by 15-20%. As a result, the body's heat production also increased.

4. Thyroid hormone

Function of thyroxine is increased activity of almost all chemical reactions in the body so that the increased levels of thyroxine can affect the rate of metabolism to be 50-100% higher than normal.

5. Sex hormone

Male sex hormones can increase the basal metabolic rate of approximately 10-15% normal speed, causing an increase in heat production. In women, temperature fluctuations are more varied than in men because the hormone progesterone spending to ovulation increases body temperature approximately from 0.3 to 0.6 ° C above the basal temperature.

6. Fever (inflammation)

The process of inflammation and fever may lead to increased metabolism by 120% for each increase in temperature of 10 ° C

7. Nutritional status

Malnutrition is long enough to lower the metabolic rate of 20-30%. This happens because the cells no nutrients needed to conduct metabolism. Thus, people who are prone to mal nutrition drop in body temperature (hypothermia). In addition, individuals with a thick layer of fat are less likely to develop hypothermia because fat is a pretty good insulator, in the sense of delivering hot fat with the speed of the other one-third the speed of the network.

8. Activity

Activity in addition to stimulating an increase in metabolic rate, resulting in friction between the components of the muscle / organ that produces thermal energy. Exercise (activity) can increase body temperature up to 38.3 to 40.0 ° C.

9. Organ disorders

Organ damage such as trauma or malignancy in the hypothalamus, can cause the body's temperature regulation mechanisms impaired. Pyrogen substances released on infection can stimulate an increase in body temperature. Skin disorders such as number of sweat glands which can also lead to impaired body temperature regulation mechanism.

10.Environment

The body temperature can rapidly exchange with the environment, meaning that the body heat can be lost or impaired due to a cooler environment. Vice versa, the environment can affect the temperature of the human body. Temperature displacement between humans and the environment occur mostly through the skin.

Thermoregulation in Animals

Animals have the ability to adapt to changes in environmental temperature. For example, in cold temperatures, mammals and birds will increase the rate of metabolism by changes in hormones that are involved in it, thereby increasing heat production. At ektoterm (eg, the honey bee), adaptation to cold temperatures by groups in the nest. The metabolism of bees as a group capable of generating heat in the nest.

Some animal adaptations to reduce heat loss, such as the fur and hair in birds and mammals, muscles, and modification of the circulatory system in the skin. Contriksi blood vessels in the skin and countercurrent heat exchange is one way to reduce the loss of body heat. Behavior is important in relation to thermoregulation. Migration, relocation, and was found hiding in some animals to lower or raise the body temperature. Elephants in the tropics to lower body temperature by bathing or wag earlobe to the body. Humans use apparel is one of the unique behavior in thermoregulation.