L2 maintaining body temp Flashcards
what is positive feedback
process that increases any change detected by receptors
example positive feedback
breastfeeding
cervix dilation
non beneficial positive feedback example
breathing in co2
inc co2 in blood
inc breathing rate
more co2 inhaled
why is maintaining body temp important
enzymes require set temperature
bonus of water rather than air
temp more stable due to high SHC
how evolution between land and water animal
greater temp range so greater land diversity due to many different evolutions
what is ectotherm
animal obtain heat from outside of their body so their temp fluctuates with the environment
what animals are ectotherms
fish
reptile
amphibian
why are most ectotherms aquatic
water more stable environment
what is endotherm
animal that generates its heat from within through metabolic processes
what benefit does endotherm gen heat from within give
ability to maintain stable core temperature despite changes in the environment
how is core body temp controlled
thermoregulatory centre of the hypothalamus in the brain detects change in temp
+
nerve impulse from peripheral thermo-receptors in skin and visceral (organs)
physiological ways of regulating temp
vasoconstric/dilation
sweat
hairs
shiver
what is vasodilation
when hot
-arterioles dilate
-more blood flows to capillaries by skins surface
-heat can then be lost by convection and radiation across the epidermis
what is vasoconstriction
when cold
arterioles constrict
less blood flow to capillaries by skins surface
heat is then retained
[can lead to frostbite or tissue death in extremities]
how does sweating help body temp
when hot
sweat glands secrete a dilute solution of water with small quantities of sodium chloride and urea
evaporation of water leads to heat loss due to waters high latent heat of vaporisation so high energy loss
what role do hairs have on body temp
hot:
hair erector muscles relax
hairs lie flat
no insulating layer of air
cold:
hair erector muscles contract
hairs raised
insulating layer of air retains heat
shivering roles in body temp
muscles are contracting
uses ATP
we get ATP from aerobic respiration and byproduct is heat
behavioural of endotherm
cerebellum of brain “makes” people feel hot/ccold so adjust behaviour accordingly
eg drink/shade/move less
