5.1.1 Communication and homeostasis Flashcards
what happens to the liver when temp rises
activity decreases
reduces heat energy given off metabollic process
what happens to hair on skin when your body temp rises
lie flat
what happpens to blood vessels when your temp rises
vasodilate close to surface of skin to release more heat
what does the hypothalmus do
monitors body temp
2 ways the hypothalmus recieves inputs
monitors body temp of blood
recieves nervous signals from thermoreceptors to measure skin temp
stimulus response pathway
stimulus- detected a receptor
sensory neurons
central nervous system - for processing
motor neurones
response- effector e.g muscle or glands
negative feedback
reversal of any changes in internal environment to return to an optimium steady state / “normal state”
positive feedback
increases any changes that is deletected by receptors
examples of positive feedback
hypothermia
dilation of cervix at end of pregnancy
ectotherms
body temp fluctuates with external temperature
advantages of ectotherms
use less food in respiration
need less food
greater proportion of energy used for growth - grow quickly
disadvantages of ectotherms
less active in cooler temperatures
may not be capable of activity in winter months
can’t live at poles
what do ectotherms do if they’re too hot
orientate body away from sun
hide in burrow
alter body shape
increase body movement
what do ectotherms do if they’re too cold
expose body to sun
orientate body to sun
what is an endotherm
maintain body temp within strict limits
independant of external temperature
advantages of an endotherm
constant body temp so enzymes work effectively
activity possible even when cool
inhabit colder parts of planet
disadvantges of an endotherm
enzyme used up to maintain constant temp
more food required
less energy used in growth
features/adaptations of endotherms
use internal sources of heatto maintain body temp
many chemical reactions in the body are exergenic
show behavioural and physiological adaptations
what happens to your breathing when temp increases
increases- pant to help exchange hot air
what happens to liver activity when body temp decreases
activity increases so more metabolism occurs and gives out heat
what happens to blood vessels when body temp decreases
vasoconstrict
muscles constrict and blood vessels constrict
less blood is in contact with the external environment
what happens to the muscles when body temp decreases
contract of skeletal muscles - shivering
increased respiration to give out heat
what happens to skin and hair when body temp decreases
no sweating
erector pili muscles contract raise hairs
traps air next to skin which is easily warmed
heat gain center
controls mechanism which increase body temp
awheat loss center
controls mechanism which reduces body temp
how does organism lose heat
`evaporation of water
conduction to surroundings
convection to surroundings
radiation to surroundings
how does organism gain heat
waste heat from cell respiration
conduction from surroundings
convection from surroundings
radiation from surroundings
benefits of multiple feedback mechanisms
more control
faster response
positive feedback definition
mechanism that amplifies a small change into a big change
example of positive feedback
oxytocin triggering contractions
why is the hypothalmus an important part of the brain for thermoregulation
recieves info from peripheral receptors on the skin
monitors external temps compared to internal temps
signals effectors in the skin and muscles to respond appropriately
what percentage of cells in the pancreas are islets of langerhans
5%
