Homeostasis and Thermoregulation

homeostasis

dynamic psychological processes that keep the body within its ideal range of physical and chemical conditions

• e.g. temperature, water levels, pH, glucose and other nutrient concentrations

homeostasis is maintained by feedback loops

1. stimulus = produces change in variable

2. receptor =change detected by receptor’

3. input (control center) = information sent along afferent pathway to determine response to the change

4. output (control center) = information sent along efferent pathway to take action

5. effector = reponse of effector feeds back to influence magnitude of stimulus and returns variable to homeostasis

hypothalamus (of the brain)

controls many hormone and nerve signals to maintain homeostasis

thermoregulation

the maintenance of a body temperature with a set range where cells function efficiently.

• hymans require body temp very close to 37 degrees celsius

if body is too warm (thermoregulation)

1. sweat glands just under the surface of the skin are stimulated: the liquid water removes heat from the body as it evaporates

2. vasodilation = blood vessels close to the surface of the skin dilate (lumen widens), allowing more heat to leave the blood

   • movement of blood under the skin is the cause of redness when a person is too warm

if the body is too cold (thermoregulation)

1. vasoconstriction = blood vessels close to the surface of skin constrict (lumen narrows) and reflect blood closer to internal organs, reducing heat loss

2. piloerection = hairs of the skin stick-out, trapping an insulating layer of air next to the skin which is warmed by body heat

3. muscle contradiction = shivering engages the body’s energy production pathways, which produce heat as a by-product