35. Responses to the cold

Question 1

what two things must a mammal do in a cold environment?

Answer 1

reduce heat loss

increase the heat that is made

Question 2

how does an animal conserve heat loss with body posture?

Answer 2

curls into a ball to reduce surface area exposed to the area. reduces convection, conduction and radiated heat loss

Question 3

which system in the body allows the body temperature to be increased or decreased?

Answer 3

the sympathetic nervous system - involuntry response

eg muscles contracting to make hairs stick up

Question 4

what are three ways an animal can conserve heat?

Answer 4

vasoconstrition

stick up hairs

behavioural responses

Question 5

what happens when the animal is at the lower critical temperature?

Answer 5

there is more heat loss occuring than heat production at basal metabolic rate

Question 6

how does an animal increase temperature at lower critical tempetature and why is it done this way?

Answer 6

its increased through metabolism. this is because there is no more heat that can be used from the enviornment so it must be used from the body

Question 7

what is summit metabolism?

Answer 7

the maximum the metabolism can go for an animal at lower crtitcal temperature, even when it gets colder outside

Question 8

when does hypothermia occur?

Answer 8

at the summit metabolism - heat loss more than heat temp

Question 9

how does thermogenisis occur in animals?

Answer 9

shivering

non shivering thermogenesis by using fat

Question 10

what is shivering and why is it important?

Answer 10

involuntry small contractions of the skeletal muscles. used to make more heat

Question 11

what type of fat helps thermogenesis and where is it commonly seen?

Answer 11

brown adipose tissue

Question 12

what is the difference between brown adipose fat tissue and white fat tissue?

Answer 12

white adipose fat can be stored for later use is evenly distributed around the body

brown adipose tissue - concentrated around shoulder and knec in discrete masses. not for storage, only for heat production

Question 13

what activates the brown adipose fat tissue? three steps

Answer 13

the sympathetic nervous system activates hormones

hormones activate the fat tissue

fat tissue acts like a motor to produce heat

Question 14

what happens if you increase insulation? eg a wolf with a winter coat in winter

Answer 14

the lower critical temperature reduces (not in the thermal neutratl zone and using extra energy).

which is meaning the level at which more energy is needed (more than the BMR) is at a lower temeprature

Question 15

how can animals improve their heat production? two points

Answer 15

increase of brown adipose fat tissue

increase BMR

Question 16

how does BMR increase to produce more heat? a horomone

Answer 16

the thyroid gland increases to turn up the BMR

Question 17

what is two advantages of a big animal living in a cold enviornment?

Answer 17

big -

1. small surface area per unit of volume so less heat loss
2. can carry a bigger and thicker amount of insulation (eg coat, fat)

Question 18

what is one advantage and one disadvantage of being a small animal living in the cold?

Answer 18

small -

1. less effiecent - high surface are per unit of volume so more heat loss
2. lots of brown adipose fat tissue. get out of the cold envirnoment into eg a burrow

Question 19

what is torpor?

Answer 19

hibernating for varying lenghths of time

Question 20

why do animals torpor? two points

Answer 20

its an energy saving strategy -

1. because its cold and heat loss occurs fast
2. less food available in winter so more effiecent

Question 21

what process occurs in torpor to help temperature?

Answer 21

its a controlled process - the animal is still regulating around set point (endothermic) but its at a lower temperature