- Negative feedback loop = method of control or maintaining constant conditions. (in humans, this is the idea of our fixed point, our constant body temperature = 37 - 38 degrees)
- In order for it to work we have receptors of body temperature (internal conditions) = Hypothalamus - region of the brain
- Hypothalamus responds to a stimulus = the temperature of the body and the temperature of the blood.
- Body temperature feeds into the brain --> it is compared to the theoretical level of control. If the temperature needs to be altered, it is brought about through the action of the effector such as the skin.
- The response would either be an increase or decrease in the body temperature.
- This feedback to the hypothalamus on the basis of the input, a new output would be produced.
- One of the major components of the skin for the control of body temperature are:
+ sweat glands
+ Capillary network - it allows blood to move closer or further away from the surface of the skin.
- In the graph, x axis is time and the y axis is the 37/38 regulation point.
In a hot environment:
- If body temp. increases, the input to the hypothalamus stimulates responses in the skin which bring about cooling
- One of the responses is sweating.
- Another is when the blood flow to the surface of the skin increases. The blood vessels dilate and widen. This increases the exchange of heat to the outside of the body by processes such as the evaporation of sweat and radiation - vasodilation
- Hairs flat
- This brings the cooling of the blood and brings the body temp back to the fixed level.
In a cold environment:
- Our body temperature will fall. This feeds to the hypothalamus and switches on and brings about regulation to increase the body temperature such as shivering, raised hairs and vasoconstriction.
ไม่มีความคิดเห็น:
แสดงความคิดเห็น