5.1.1 - communication and homeostasis

Question 1

homeostasis

Answer 1

maintaining internal conditions in response to stimuli

Question 2

the two communication systemtehs in mammals

Answer 2

• the nervous system
• the endocrine system

Question 3

what factors need to be regulated in the body?

Answer 3

blood glucose, internal temperature, water, pH levels, oxygen and co2 availability etc

Question 4

negative feedback

Answer 4

a small change in one direction is detected by sensory receptors and then work to reverse the initial stimulus.

Question 5

positive feedback systems

Answer 5

a change in the internal environment is detected and effecrors are stimulated to reinforce that change and increase the response.

Question 6

example of a positive feedback system

Answer 6

blood clotting cascade

Question 7

ectotherms

Answer 7

most animals - they use their surroundings to warm their bodies and their core body temperature is heavily dependent on their environment

Question 8

ectotherms in water

Answer 8

do not need to thermoregulate because the high heat capacity of water means that the temperature of their environment does not change much

Question 9

endotherms

Answer 9

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

Question 10

behavioural responses of ectotherms to warm up

Answer 10

• basking in the sun for long periods of time (lizards etc.)
• conduction (pressing bodies against the warm ground

Question 11

behavioural responses of ectotherms to cool down

Answer 11

many of the warming processes are reversed
- hiding in the shade
- digging burrows
- pressing bodies against cool rocks or water

Question 12

how does colour of ectotherms regulate heat?

Answer 12

dark colours absorb more radiation than light colours

Question 13

additional behvioural adaptations of humans to regulate heat

Answer 13

clothes to stay warm, houses are built which can then be heated or cooled

Question 14

what do endotherms mainly rely on to maintain a stable core body temp?

Answer 14

physiological adaptations

Question 15

vasodilation

Answer 15

arterioles dilate near the surface of the skin, forcing the skin to flush amd cools as there is increased radiation

Question 16

how does increased sweating regulate temperature?

Answer 16

as the sweat evaporates from the surface of the skin, heat is lost, cooling the blood below the surface

Question 17

what happens to hair when trying to cool down?

Answer 17

erector pill muscles relax and as a result the hair or feathers of the animal lie flat to the skin

Question 18

vasoconstriction

Answer 18

arterioles near surface of skin constrict, so very little bblood flows through the capillary networks - very little radiation takes place

Question 19

raising body hair

Answer 19

eterctor pili muscles in the skin contract, pulling hairs up, trapping an insulating layer of air and so reduces cooling through the skin

Question 20

shivering

Answer 20

rapid involuntary contracting and relaxing of the large voluntary muscles in body, so the metabolic heat warms up the body

Question 21

two control centres of thermoregulation

Answer 21

the heat loss centre, and the heat gain centre