3.6.4 homeostasis Flashcards
define homeostasis
maintenance of a stable internal environment within restricted limits by physiological control systems
4 examples of homeostasis
core body temperature, blood pH, blood glucose concentration and blood water potential
explain the importance of maintaining a stable core temp
if temp is too high, hydrogen bonds in the tertiary structure break, enzymes denature, active site changes shape and substrates can not bind.
if temp is too low, there is not enough kinetic energy so fewer enzyme substrate complexes are made.
explain the importance of maintaining a stable blood pH
a pH which is variant from the optimum causes ionic and hydrogen bonds in the tertiary structure to break, enzymes will denature and active sites will change shapes so substrates cant bind and fewer enzyme substrate complexes
explain the importance of maintaining a stable blood glucose concentration
too low =hypoglycaemia
not enough glucose for respiration
less ATP produced so active transport cant happen
too high = hyperglycaemia
water potential decreases, water is lost from tissue via osmosis
more water is lost from the kidney
not all the glucose is absorbed by the kidney
describe the role of negative feedback in homeostasis
receptors detect change from the optimum
effectors will respond in order to counteract the change
this will return levels to optimum
why is it important for different conditions to be controlled separate mechanisms
variance from optimum in different direction can be controlled allowing for a greater degree of control
describe negative feedback
when there is a deviation from normal levels which causes changes to occur that reverse the change back to normal
describe positive feedback
receptors detect change from normal, effectors respond to amplify the change producing a greater deviation from normal
examples of positive feedback
contractions during childbirth and blood clotting
