Difference between revisions of "Thermoregulation - Anatomy & Physiology"
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| − | {{ | + | {{toplink |
| − | == | + | |backcolour = FAFAD2 |
| + | |linkpage =Endocrine System - Anatomy & Physiology | ||
| + | |linktext =Endocrine System | ||
| + | |linkpage =Endocrine System - Hypothalamus - Anatomy & Physiology | ||
| + | |linktext =Hypothalamus - Anatomy & Physiology | ||
| + | |maplink = Endocrine System (Content Map) - Anatomy & Physiology | ||
| + | |pagetype =Anatomy | ||
| + | }} | ||
| + | <br> | ||
| − | Thermoregulation is the ability of an endothermic organism to maintain a relatively constant body temperature | + | ==Thermoregulation== |
| + | Thermoregulation is the ability of an endothermic organism to maintain a relatively constant body temperature despite fluctuations in temperature of the external environment. This is a vital part of homeostasis. | ||
| − | '''Homeotherm/Endotherm''': | + | *'''Homeotherm/Endotherm''': an organism with an internal temperature which remains relatively constant despite external temperature fluctuations. |
| − | + | *'''Poikilotherm/Ectotherm''': an organism having a body temperature which fluctuates with the external environment - eg Fish, Reptile. | |
| − | '''Poikilotherm/Ectotherm''': | ||
==Mechanism of Action== | ==Mechanism of Action== | ||
The thermoregulatory mechanism consists of: | The thermoregulatory mechanism consists of: | ||
| + | #'''Sensory Component''': neurones that possess nerve endings with thermoreceptors continuously monitor body temperature and transmit it to the integrating centre. These neurons may be within the skin or internal organs. | ||
| + | #'''Integrating Centre:''' the [[Endocrine System - Hypothalamus - Anatomy & Physiology|Hypothalamus]] is the control centre in the brain which compares the temperature information with an ''Internal Reference'' or ''Set point''. | ||
| + | #'''Motor Component''': neurons which send signals to alter the internal temperature - altering heat production or heat loss. | ||
| + | #*These command signals may travel via the somatic motor system and affect heat production in skeletal muscle. | ||
| + | #*These command signals may travel via the Sympathetic Nerve Fibres and change | ||
| + | #**Blood Flow to the Skin | ||
| + | #**Sweat Gland Activity | ||
| + | #**Activity of the smooth muscles which regulate fur/plumage thickness | ||
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==Adaptation to Heat== | ==Adaptation to Heat== | ||
| − | + | *Sweating - causes heat loss via evaporation. | |
| − | Sweating causes heat loss via evaporation. | + | *Reduction of the resistance of cutaneous arterioles = ''Vasodilation''. This allows more heat from the circulation to be transferred to the air. |
| + | *[[Hair - Anatomy & Physiology|Hairs]] on the skin lie flat - the ''arrector pili'' muscle attached to the proximal end of each hair follicle relax to minimise heat being trapped by the hairs. | ||
==Adaptation to Cold== | ==Adaptation to Cold== | ||
| − | + | *Sweating Stops | |
| − | + | *Cutaneous arteries constrict - ''Vasoconstriction''. This minimises heat loss from the blood to the body surface. | |
| − | + | *[[Hair - Anatomy & Physiology|Hairs]] on the skin are raised involuntarily by the ''arrector pili'' muscles attached to each hair follicle. This layer acts as an insulator, trapping heat. | |
| − | + | *Increased Heat Production - muscles receive messages from the brain causing shivering. This causes increased heat production as the muscle cells respire. | |
| − | + | *Respiration - this may be increased as respiration is an exothermic reaction. | |
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Revision as of 14:53, 5 August 2008
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Thermoregulation
Thermoregulation is the ability of an endothermic organism to maintain a relatively constant body temperature despite fluctuations in temperature of the external environment. This is a vital part of homeostasis.
- Homeotherm/Endotherm: an organism with an internal temperature which remains relatively constant despite external temperature fluctuations.
- Poikilotherm/Ectotherm: an organism having a body temperature which fluctuates with the external environment - eg Fish, Reptile.
Mechanism of Action
The thermoregulatory mechanism consists of:
- Sensory Component: neurones that possess nerve endings with thermoreceptors continuously monitor body temperature and transmit it to the integrating centre. These neurons may be within the skin or internal organs.
- Integrating Centre: the Hypothalamus is the control centre in the brain which compares the temperature information with an Internal Reference or Set point.
- Motor Component: neurons which send signals to alter the internal temperature - altering heat production or heat loss.
- These command signals may travel via the somatic motor system and affect heat production in skeletal muscle.
- These command signals may travel via the Sympathetic Nerve Fibres and change
- Blood Flow to the Skin
- Sweat Gland Activity
- Activity of the smooth muscles which regulate fur/plumage thickness
Adaptation to Heat
- Sweating - causes heat loss via evaporation.
- Reduction of the resistance of cutaneous arterioles = Vasodilation. This allows more heat from the circulation to be transferred to the air.
- Hairs on the skin lie flat - the arrector pili muscle attached to the proximal end of each hair follicle relax to minimise heat being trapped by the hairs.
Adaptation to Cold
- Sweating Stops
- Cutaneous arteries constrict - Vasoconstriction. This minimises heat loss from the blood to the body surface.
- Hairs on the skin are raised involuntarily by the arrector pili muscles attached to each hair follicle. This layer acts as an insulator, trapping heat.
- Increased Heat Production - muscles receive messages from the brain causing shivering. This causes increased heat production as the muscle cells respire.
- Respiration - this may be increased as respiration is an exothermic reaction.