module 5 - homeostasis

Question 1

what is negative feedback?

Answer 1

small change in direction of a system is detected by sensory receptor which causes effectors to work to reverse this change and return back to normal levels

Question 2

what is an example of negative feedback?

Answer 2

blood glucose levels = insulin an dglucagon work to control levels

Question 3

what is positive feedback?

Answer 3

a change in internal environmentof body is detected by sensory receptors - effectors are stimulated to reinforce the change and increase the responce

Question 4

how do effectors and receptors work in P/N FB?

Answer 4

sensory receptors detect the changes in systems which causes the stimulation of effectors which produce responce

without these there would be no responce

Question 5

what are endothermes?

Answer 5

rely on metabolic processes to maintain a stable core body temperature e.g mammels

therefore can live in a large variety of environments

metabolic activity is usually around 5x faster then that of ectothermes

Question 6

what are ectothermes?

Answer 6

cannot internally regulate their core body temperature so rely heavily on surrounding environment to cool down/ heat up

they have developed a large range of stratagies to cope with this

Question 7

BEHAVIOURAL

what do ectothermes do to warm up?

Answer 7

• bask in sunlight - absorb and reflect more uv radiation
• orientate body so largest SA is exposed to sun
• press body against warm surface
• increase exothermic metabolic reactions - contacting muscles = shivering

Question 8

BEHAVIOURAL

what do ectotherms do to cool down?

Answer 8

• shelter from sun by seeking shade
• burrowing
• press body against cold serface
• move to available water/mud
• orientate body so minimum SA is exposed to sun

Question 9

how do ectothermes recuglate their body temp (physiologically)?

Answer 9

• lizards living in colder climates tend to be darker coloured then those in warm climates - dark colours absorb more radiation
• some may alter their heat rate

Question 10

advantages of ectothermes:

Answer 10

• use less energy trying to regulate body temp
• need to consume less food due to low metabolic rate

Question 11

disadvantages of ectothermes:

Answer 11

• metabolism slow at low temps - reaction are slower - more vulnerable to predators

Question 12

how do endothermes detect heat changes?

Answer 12

> receptors on skin are required to detect changes in environment
pheripheral temp receptors on the skin detect changes in surface temp
temp receptors in hypothalamus detect changes in temp of blood

combining the two gives body great sensitivity to temp allowing it to respond to actual canges and also pre-empt them

Question 13

how do ectothermes cool down?

3

Answer 13

1. vasodilation
2. sweating
3. reducing insulation layer

Question 14

explain prosess of vasodilation:

Answer 14

• atrioles near surface of skin dilate due to temp rise
• vessels provide direct route of blood from atriole to venules which constrict
• forces blood through capillary network towards surface of skin = skin flushes as result and cools due to increased radiation

Question 15

explain the process of sweating:

Answer 15

• core temp increases = rate of sweating increases
• it spreads across the bodys surface and then evapourates cooling the surface

Question 16

how do animanls with less glands sweat?

Answer 16

e.g dogs
open mouths and pant when they get hot = lose heat when H2O evapourates

Question 17

explain process of reducing insulating layer:

Answer 17

body temp increases = erector pilli muscles (hair erector muscle) in the skin relaxes
this avoids trapping a layer of hot air

Question 18

how do endothermes warm up?

4

Answer 18

• decrease sweating
• vasoconstriction
• shivering
• anatomical adaptations