5.1.1 - communication and homeostasis Flashcards
homeostasis
maintaining internal conditions in response to stimuli
the two communication systemtehs in mammals
- the nervous system
- the endocrine system
what factors need to be regulated in the body?
blood glucose, internal temperature, water, pH levels, oxygen and co2 availability etc
negative feedback
a small change in one direction is detected by sensory receptors and then work to reverse the initial stimulus.
positive feedback systems
a change in the internal environment is detected and effecrors are stimulated to reinforce that change and increase the response.
example of a positive feedback system
blood clotting cascade
ectotherms
most animals - they use their surroundings to warm their bodies and their core body temperature is heavily dependent on their environment
ectotherms in water
do not need to thermoregulate because the high heat capacity of water means that the temperature of their environment does not change much
endotherms
mammals and birds - they rely on metabolic processes to warm them up, and usually maintain a very stable core body temperature due to their adaptations
behavioural responses of ectotherms to warm up
- basking in the sun for long periods of time (lizards etc.)
- conduction (pressing bodies against the warm ground
behavioural responses of ectotherms to cool down
many of the warming processes are reversed
- hiding in the shade
- digging burrows
- pressing bodies against cool rocks or water
how does colour of ectotherms regulate heat?
dark colours absorb more radiation than light colours
additional behvioural adaptations of humans to regulate heat
clothes to stay warm, houses are built which can then be heated or cooled
what do endotherms mainly rely on to maintain a stable core body temp?
physiological adaptations
vasodilation
arterioles dilate near the surface of the skin, forcing the skin to flush amd cools as there is increased radiation
how does increased sweating regulate temperature?
as the sweat evaporates from the surface of the skin, heat is lost, cooling the blood below the surface
what happens to hair when trying to cool down?
erector pill muscles relax and as a result the hair or feathers of the animal lie flat to the skin
vasoconstriction
arterioles near surface of skin constrict, so very little bblood flows through the capillary networks - very little radiation takes place
raising body hair
eterctor pili muscles in the skin contract, pulling hairs up, trapping an insulating layer of air and so reduces cooling through the skin
shivering
rapid involuntary contracting and relaxing of the large voluntary muscles in body, so the metabolic heat warms up the body
two control centres of thermoregulation
the heat loss centre, and the heat gain centre
