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homeostasis maintaining a stable internal environment - Coggle Diagram
homeostasis
maintaining a stable internal environment
examples of homeostasis
Respiration
Respiration in cells produce carbon dioxide constantly
Excess CO2 needs to be removed
Too much can lower the pH
affect enzymes
removed in the air we breathe out
urea
produced by the liver
filtered by kidneys
stored in bladder
removed in urine
made of excess amino acids
poisonous if built up
human body temperature- 37
thermoregulatory centre: thermostat
receptors sensitive to blood temperature
when you get cold:
hairs stand up: trap air, provides insulating layer
blood vessels near surface
constrict
-less heat can be transferred from the blood to the surroundings
shiver: movement generates heat
when you get hot:
sweat: transfers heat from you to environment
blood vessels close to the surface dilate
transfers heat from the blood to the surroundings
negative feedback
receptors: the body detects a change in the environment
co-ordinator: the Receptor sends information to the hypothalamus
effector :this triggers a response that counteracts the change
positive feedback
Positive feedback is a mechanism in which any change away from the optimum is further increased
It is rare in living organisms as it leads to extreme states which are unstable
examples
blood clotting: clotting factor is activated, it activates the next factor in sequence until a fibrin clot is achieved
In childbirth the hormone oxytocin stimulates muscular contractions of the uterus.
pituitary gland
If we breathe air with a high CO2 concentration leads to high levels of CO2 in the blood
-detected by receptors
-breathing increases
-more CO2
-stimulates the receptors
-breathing gets faster and faster
ectothermy advanatges:
endure shortage of food, water
can live in sandy deserts etc.
avoids cost of high basal metabolic rate
ectothermy disadvantages
rapid exhaustion
restricted to certain hours and habitats
endothermy advantages:
sustained high activity
can be active at variety of times
wide range of habitats
endothermy disadvantages:
require much food, water, o2
definitions:
vasodilation
: relaxation of smooth muscle in walls of arterioles and precapillary sphincters increases blood flow in capillaries
vasoconstriction:
Contraction of smooth muscle in walls of arterioles and precapillary sphincters reduces blood flow in capillaries