Thermoregulation
Thermoregulation is the control of body temperature in the body. Animals that can have a fairly constant body temperature are called ectotherms, while those that cannot (all others) are called ectotherms. The thermoregulatory centre is where the body temperature is controlled, located in the hypothalamus. The receptors in the hypothalamus monitors the blood as it passes through the brain, receptors in the skin monitor the external temperature and both are necessary to make the appropriate adjustments where impulses are sent to different parts of the body.
When behavioural responses are not enough the thermoregulatory centre is stimulated. Sometimes the response is to generate heat and not just conserve heat.(Science aid, ©2006-2012)
Increase in the body’s metabolic rate from the minimal amount needed to maintain basis vital bodily processes increase the production of heat. There are quite a few things that can affect this metabolic rate and cause basic heat production including exercise, hormones, nervous system, body temperature, and ingestion of food, age as well as others. There are also ways to cause basic heat loss such as radiation (heat loss infrared radiation emissions), evaporation (every gram of water removed removes heat from body, around 0.58 Cal per gram of water, around 22% of heat loss occurs due to this), conduction (transfer of heat through physical contact, around 3% heat loss), and convection (transfer of heat by movement of liquid or gas between areas of temperature). Around 40% of heat loss is due to evaporation, conduction and convection.
When core temperature drops, it activates the negative feedback system to get the temperature to increase. The impulses sent out from the
receptors, the hypothalamus sends signals to the preoptic heat-promoting centre, which causes the secretion of thyrotropin-releasing hormone. This causes responding functions for example:
· Vasoconstriction - “The SNS (sympathetic nerves supplying) is stimulated to constrict blood vessels at
the periphery, and the warm blood is moved deeper within the body preventing
heat loss.”
· Sympathetic Stimulation – “The heat-promoting centre stimulates the release of epinephrine and norepinephrine from the adrenal medulla. This increases cellular metabolism increasing heat production (chemical thermogenesis).”
· Skeletal muscles –“Muscle tone increased inducing shivering (involuntary
thermogenesis).”
· Thyroid hormones – “An increased production of thyroid hormones increasing the metabolic rate.”
Or clothing can be used to help the heating process.
One the other side of the spectrum, when the heat rises, the prep optic heat-losing centre receives nerve impulses in aim to lose heat. A few
examples of the mechanisms that control this is:
· Vasodilation – “Blood vessels in the skin vaso-dilate, the skin warms and excess heat goes out in to
the surroundings.”
· Metabolic rate – “The metabolic rate lowers, lowering the heat from the body produced.”
· Perspiration – “The hypothalamus is stimulated by the high blood temperature to activate the sweat glands, producing sweat. Skin cooled because of evaporation.”
(Peter Stevenson, ©2002)
The body does well to compensate for factor that cause out body temperature to rise or drop but these mechanisms are limited, and if are exceeded, sickness becomes prominent and is serious.
Below, the diagram shows responses the body has to control the body temperature
When behavioural responses are not enough the thermoregulatory centre is stimulated. Sometimes the response is to generate heat and not just conserve heat.(Science aid, ©2006-2012)
Increase in the body’s metabolic rate from the minimal amount needed to maintain basis vital bodily processes increase the production of heat. There are quite a few things that can affect this metabolic rate and cause basic heat production including exercise, hormones, nervous system, body temperature, and ingestion of food, age as well as others. There are also ways to cause basic heat loss such as radiation (heat loss infrared radiation emissions), evaporation (every gram of water removed removes heat from body, around 0.58 Cal per gram of water, around 22% of heat loss occurs due to this), conduction (transfer of heat through physical contact, around 3% heat loss), and convection (transfer of heat by movement of liquid or gas between areas of temperature). Around 40% of heat loss is due to evaporation, conduction and convection.
When core temperature drops, it activates the negative feedback system to get the temperature to increase. The impulses sent out from the
receptors, the hypothalamus sends signals to the preoptic heat-promoting centre, which causes the secretion of thyrotropin-releasing hormone. This causes responding functions for example:
· Vasoconstriction - “The SNS (sympathetic nerves supplying) is stimulated to constrict blood vessels at
the periphery, and the warm blood is moved deeper within the body preventing
heat loss.”
· Sympathetic Stimulation – “The heat-promoting centre stimulates the release of epinephrine and norepinephrine from the adrenal medulla. This increases cellular metabolism increasing heat production (chemical thermogenesis).”
· Skeletal muscles –“Muscle tone increased inducing shivering (involuntary
thermogenesis).”
· Thyroid hormones – “An increased production of thyroid hormones increasing the metabolic rate.”
Or clothing can be used to help the heating process.
One the other side of the spectrum, when the heat rises, the prep optic heat-losing centre receives nerve impulses in aim to lose heat. A few
examples of the mechanisms that control this is:
· Vasodilation – “Blood vessels in the skin vaso-dilate, the skin warms and excess heat goes out in to
the surroundings.”
· Metabolic rate – “The metabolic rate lowers, lowering the heat from the body produced.”
· Perspiration – “The hypothalamus is stimulated by the high blood temperature to activate the sweat glands, producing sweat. Skin cooled because of evaporation.”
(Peter Stevenson, ©2002)
The body does well to compensate for factor that cause out body temperature to rise or drop but these mechanisms are limited, and if are exceeded, sickness becomes prominent and is serious.
Below, the diagram shows responses the body has to control the body temperature