Communication & Homeostasis

Question 1

what is homeostasis?

Answer 1

the maintenance of a constant internal environment

via physiological control systems

Question 2

what is negative feedback?

Answer 2

deviation from the set limits
is detected by receptors

so mechanisms are put into place to restore conditions back to within set limits

usually involve nervous system and hormones

Question 3

what is positive feedback?

Answer 3

deviation from set limits

triggers a response to increase the deviation further

e.g. in childbirth when the baby’s head presses on the cervix, it triggers oxytocin to be released which causes the uterus to contract, and even more oxytocin is released.

Question 4

ectotherms

Answer 4

e.g. fish, amphibians, reptiles

cannot regulate their internal environment
can only control through behaviour

aquatic ectotherms don’t have much need to regulate their internal temperature
as water has a high specific heat capacity
thus water temp remains relatively constant.

land ectotherms struggle more
as air temp fluctuates
that’s why they bask on hot rocks
to radiate heat from sun.

Question 5

endotherms

Answer 5

regulate internal body temp by nervous response

peripheral temp receptors in skin detect change in external environment
send an impulse along sensory neurone
hypothalamus coordinates the impulse
triggering muscles and glands to respond

Question 6

endotherm responses

Answer 6

sweating: water has high latent heat of vapourisation so when evaporated off the skin, has cooling effect

shivering: contract and relaxing of muscles increases rate of respiration and more heat is released

standing hairs: to trap and insulate the body or appear bigger to predators

vasoconstriction: to get warmer

vasodilation: to release heat from skin surface