2.77b thermoregulation

• negative feedback look - method of control/ mantaining constant conditions

in humans = body temp is constantly 37/8 degrees
• body temperature is feeds into the brain (hypothalamus) and is compared to the theoretical optimum body temp
• if the body temp needs to be changed then this is done by the effector, skin.
• the response will either be a decrease or a increase and feeds this information once again to the brain (hypothalamus)

components that control body temp in skin are sweat glands and the capillary network [which allows blood to move closer or further away from the surface of the skin].

if your body temperature gets too high your hypothalamus regulates to your skin which bring around cooling, like sweating, hairs being flat and blood flow to the surface of the skin increases as blood vessels dilate (get bigger, also called vasodilation) which increases the exchange of heat to the outside of the body e.g. evaporation of sweat and radiation

if your body temperature gets too low your hypothalamus sends messaged to your skin which causes shivering, vasoconstriction and raised hairs. vasoconstriction reduces heat exchange and forces blood to travel further down the tissues

the efficiency of both of these regulations increases the further away your body temperature gets from your optimum temperature

2.77a thermoregulation

• homeostasis - that the conditions are kept constant
• homeothermic temperature is kept constant
• some organisms (mammals) who's body temperature remains the same and carry out a process called thermoregulation
• other organisms body temperature varies on the environment
• the optimum temperature for max rate of reaction for enzyme reactions is approximately the same as the temp as mammals body temeperature

2.76 sensitivity

• sensitivity is what organisms use to respond to changes in the environment
• changes in the environment (stimuli) include changes in:
-light
-temperature
-pressure
-chemical
• in order to be able to detect these changes organisms require to have receptors
• in order to respond to changes in the environment organisms require effectors e.g. muscles, glands
• the response ensures that the organism can survive the changes of the environment