Physiological and behavioral mechanisms regulate the balance between heat lost and produced or more commonly referred to as thermoregulation. The body's mechanism must maintain the connection between heat production and heat loss so that the body temperature remains constant and normal. This relationship is governed by neurological and cardiovascular mechanisms. (Potter and Perry, 2010)
Fever Mechanism
According to Potter and Perry (2005), the mechanism of fever is as follows.
Hyperpiracy or fever occurs because the heat dissipation mechanism is not able to maintain the speed of excess production of heat, which causes an increase in abnormal body temperature. Fever is actually a result of changes in the hypothalamic set point. Pyrogens such as bacteria and viruses cause an increase in body temperature. When bacteria and viruses enter the body, pyrogens work as antigens, affecting the immune system. More white blood cells are produced to increase the body's defense against infection. This substance also triggers the hypothalamus to reach the set point.
To reach a new set point higher, the body produces and saves heat. It takes several hours to reach a new set point of body temperature. During this period people shiver, tremble and feel cold even though their body temperature rises.
The shivering phase ends when a new set point, higher temperatures are reached. During the next phase, the period is stable, the chills are gone and the patient feels warm and dry. If the new set point has exceeded the limit, or pyrogen has been removed (eg bacterial reconstruction by antibiotics), there will be a third phase of febrile episodes. The set point of the hypothalamus goes down, causing a response to heat dissipation. The skin becomes warm and reddish due to vasodilation. Fever is an important defense mechanism. Fever also fights infection because the virus stimulates interferon, this substance that is against the virus. The pattern of fever is different, depending on pyrogens. The duration and degree of fever depend on the strength of pyrogens and the individual's ability to respond.
Factors Affecting Body Temperature
According to Potter and Perry (2010), factors that affect body temperature include:
a. Age
In infants and toddlers the temperature regulation mechanism has not yet matured so that drastic body temperature changes can occur in the environment. Body temperature regulation only reaches stability at puberty. Normal temperatures will continue to decline when someone gets older. They are more sensitive to extreme temperatures due to deterioration in regulatory mechanisms, especially vasomotor regulation (poor vasoconstriction and vasodilation), reduced subcutaneous tissue, reduced sweat gland activity, and decreased metabolism.
b. Sports
Muscle activity requires more blood and increased carbohydrate and fat breakdown. Various forms of exercise increase metabolism and can increase heat production and increase body temperature.
c. Hormone Levels
Generally women experience greater body temperature fluctuations. This is because there are hormonal variations during the menstrual cycle. Progesterone levels rise and fall according to the menstrual cycle. This temperature variation can help detect a woman's fertile period. Changes in body temperature also occur in women at menopause. They usually experience intense periods of body heat and perspiration for 30 seconds to 5 minutes. In this period there was an increase in temporary body temperature by as much as 40 C, which is often called hot flashes. This is due to instability in the vasomotor setting.
d. Cadence of Circadian
Normal body temperature changes from 0.5 to 10C for a 24 hour period. The lowest temperature is between 1am and 4am. During the day, body temperature rises and reaches a maximum at 6 pm, then decreases again until morning. This temperature pattern does not change in individuals who work at night and sleep during the day.
e. Stress
Physical and emotional stress increases body temperature through hormonal and nerve stimulation. These physiological changes increase metabolism, which will increase heat production.
f. Environment
The environment affects body temperature. Without the right compensation mechanism, the temperature of the human body will change according to the temperature of the environment.
Heat Expenditures
According to Potter and Perry (2005), heat production and expenditure occur constantly, discharging heat normally through radiation, conduction, convection, and evaporation.
a. Radiation
Radiation is the transfer of heat from the surface of an object to the surface of another object without both touching. Heat moves through electromagnetic waves. Blood flow from the core internal organs brings heat to the skin and to the surface blood vessels. The amount of heat carried to the surface depends on the level of vasoconstriction and vasodilation regulated by the hypothalamus. Heat spreads from the skin to each of the more dense objects around it. The spread increases when the temperature difference between objects also increases.
b. Conduction
Conduction is the transfer of heat from one object to another with direct contact. When warm skin touches a cooler object, heat disappears. When the temperature of two objects is the same, conductive heat loss stops. Heat conducts through solid, gas, liquid matter.
c. Convection
Convection is heat transfer due to air movement. Heat is first carried out on air molecules directly in contact with the skin. Air currents carry warm air. When the velocity of air currents increases, convective heat loss increases.
d. Evaporation
Evaporation is the transfer of heat energy when the liquid turns into gas. During evaporation, approximately 0.6 calories of heat are lost for every gram of water that evaporates. When body temperature rises, the anterior hypothalamus gives a sweat gland signal to release sweat. During exercise and emotional or mental stress, sweating is one way to get rid of excess heat created by increasing metabolic rate. Excessive evaporation can cause itchy and scaly skin, and dry nose and pharynx.
e. Diaphoresis
Diaphoresis is a visual prespiration of the upper forehead and thorax. The sweat glands are under the dermis of the skin. Glands secrete sweat, an aqueous solution containing sodium and chloride, which passes through small ducts on the surface of the skin. Glands are controlled by the sympathetic nervous system. When the body temperature increases, the sweat glands emit sweat, which evaporates from the skin to increase heat loss. Diaphoresis is less efficient if the air movement is minimal or if the air humidity is high.
Fever Mechanism
According to Potter and Perry (2005), the mechanism of fever is as follows.
Hyperpiracy or fever occurs because the heat dissipation mechanism is not able to maintain the speed of excess production of heat, which causes an increase in abnormal body temperature. Fever is actually a result of changes in the hypothalamic set point. Pyrogens such as bacteria and viruses cause an increase in body temperature. When bacteria and viruses enter the body, pyrogens work as antigens, affecting the immune system. More white blood cells are produced to increase the body's defense against infection. This substance also triggers the hypothalamus to reach the set point.
To reach a new set point higher, the body produces and saves heat. It takes several hours to reach a new set point of body temperature. During this period people shiver, tremble and feel cold even though their body temperature rises.
The shivering phase ends when a new set point, higher temperatures are reached. During the next phase, the period is stable, the chills are gone and the patient feels warm and dry. If the new set point has exceeded the limit, or pyrogen has been removed (eg bacterial reconstruction by antibiotics), there will be a third phase of febrile episodes. The set point of the hypothalamus goes down, causing a response to heat dissipation. The skin becomes warm and reddish due to vasodilation. Fever is an important defense mechanism. Fever also fights infection because the virus stimulates interferon, this substance that is against the virus. The pattern of fever is different, depending on pyrogens. The duration and degree of fever depend on the strength of pyrogens and the individual's ability to respond.
Factors Affecting Body Temperature
According to Potter and Perry (2010), factors that affect body temperature include:
a. Age
In infants and toddlers the temperature regulation mechanism has not yet matured so that drastic body temperature changes can occur in the environment. Body temperature regulation only reaches stability at puberty. Normal temperatures will continue to decline when someone gets older. They are more sensitive to extreme temperatures due to deterioration in regulatory mechanisms, especially vasomotor regulation (poor vasoconstriction and vasodilation), reduced subcutaneous tissue, reduced sweat gland activity, and decreased metabolism.
b. Sports
Muscle activity requires more blood and increased carbohydrate and fat breakdown. Various forms of exercise increase metabolism and can increase heat production and increase body temperature.
c. Hormone Levels
Generally women experience greater body temperature fluctuations. This is because there are hormonal variations during the menstrual cycle. Progesterone levels rise and fall according to the menstrual cycle. This temperature variation can help detect a woman's fertile period. Changes in body temperature also occur in women at menopause. They usually experience intense periods of body heat and perspiration for 30 seconds to 5 minutes. In this period there was an increase in temporary body temperature by as much as 40 C, which is often called hot flashes. This is due to instability in the vasomotor setting.
d. Cadence of Circadian
Normal body temperature changes from 0.5 to 10C for a 24 hour period. The lowest temperature is between 1am and 4am. During the day, body temperature rises and reaches a maximum at 6 pm, then decreases again until morning. This temperature pattern does not change in individuals who work at night and sleep during the day.
e. Stress
Physical and emotional stress increases body temperature through hormonal and nerve stimulation. These physiological changes increase metabolism, which will increase heat production.
f. Environment
The environment affects body temperature. Without the right compensation mechanism, the temperature of the human body will change according to the temperature of the environment.
Heat Expenditures
According to Potter and Perry (2005), heat production and expenditure occur constantly, discharging heat normally through radiation, conduction, convection, and evaporation.
a. Radiation
Radiation is the transfer of heat from the surface of an object to the surface of another object without both touching. Heat moves through electromagnetic waves. Blood flow from the core internal organs brings heat to the skin and to the surface blood vessels. The amount of heat carried to the surface depends on the level of vasoconstriction and vasodilation regulated by the hypothalamus. Heat spreads from the skin to each of the more dense objects around it. The spread increases when the temperature difference between objects also increases.
b. Conduction
Conduction is the transfer of heat from one object to another with direct contact. When warm skin touches a cooler object, heat disappears. When the temperature of two objects is the same, conductive heat loss stops. Heat conducts through solid, gas, liquid matter.
c. Convection
Convection is heat transfer due to air movement. Heat is first carried out on air molecules directly in contact with the skin. Air currents carry warm air. When the velocity of air currents increases, convective heat loss increases.
d. Evaporation
Evaporation is the transfer of heat energy when the liquid turns into gas. During evaporation, approximately 0.6 calories of heat are lost for every gram of water that evaporates. When body temperature rises, the anterior hypothalamus gives a sweat gland signal to release sweat. During exercise and emotional or mental stress, sweating is one way to get rid of excess heat created by increasing metabolic rate. Excessive evaporation can cause itchy and scaly skin, and dry nose and pharynx.
e. Diaphoresis
Diaphoresis is a visual prespiration of the upper forehead and thorax. The sweat glands are under the dermis of the skin. Glands secrete sweat, an aqueous solution containing sodium and chloride, which passes through small ducts on the surface of the skin. Glands are controlled by the sympathetic nervous system. When the body temperature increases, the sweat glands emit sweat, which evaporates from the skin to increase heat loss. Diaphoresis is less efficient if the air movement is minimal or if the air humidity is high.
