Thermoregulation

Question 1

What is temp regulation related to?

Answer 1

metabolic heat production

Question 2

What is homeosthermic temp?

Answer 2

Range: 35.5-37.7
Average: 37

Question 3

Maintain heat balance

Answer 3

Mass balance (input=output)
Sources of input:
-External (from the environment)
-Internal (metabolism sufficient to maintain temp)
Sources of heat loss
-Radiant (given off by anything greater than 0)
-Conductive (touching)
-Convection (air currents)
-Evaporation (heat loss in water at same temp as air is 2-4x greater)

Question 4

What causes variation on body temperature?

Answer 4

PA level
Emotions
Eating
Environmental conditions

Question 5

If ambient temperatures are above

If ambient temperatures are below

Answer 5

= heat gain>heat loss

=Heat gain<heat loss

Question 6

What controls autonomic temp?

Answer 6

Hypothalamus

determines appropriate response

Question 7

What do thermoreceptors do and where are they located?

Answer 7

monitor change in body temp

send info to the skin and hypothalamus

Question 8

What are the mechanisms that regulate body temp?

Answer 8

1) adjust blood flow distribution
2) sweating
3) Increase metabolism
4) Hormonal regulation

Question 9

1) Adjust blood flow distribution

Answer 9

Convective heat loss/gain through blood distribution
Cutaneous vessels can either
-Gain or lose heat to or from the environment
Change diameter through neural control
Some local vasodialtion
Decrease temp = increase sympathetic neurons = vasoconstriction = more blood to core
Increase temp = sympathetic cholinergic neurons innervate cutaneous vessels = vasodialtion = blood to peripheral

Question 10

2) Sweating

Answer 10

Heat lost though skin by evaporation
increase core temp = sympathetic cholinergic neurons stim sweat glands (secrete hypotonic sweat)
Evaportation is affected by
-Exposed skin area
-Temp and humidity(greatest impact - increase = decrease evap)
-Convective currents

Question 11

3) Increase Metabolism

Answer 11

Increase heat production
Unregulated
-increase voluntary muscle contraction (moving)
Regulated
- shivering (hypothalamic thermoregulatory center initiates contractions
-Non-shivering thermogenesis (increased heat from brown fat)

Question 12

4) Hormonal Regulation

Answer 12

Increase release of epinephrine and norepinephrine increase heat production
Cold exposure thyroid releases more thyroxine to elevate RMR
Cold exposure = many physiological and psychological challenges

Question 13

Thermoregulation and Exercise

Exercise in the cold

Answer 13

Body loses heat 2-4x faster in water at the same temp of air due to conduction
Metabolic heat generated by muscular activity contributes to thermoregulation during cold stress
Better adaptations to heat than cold

Question 14

Wind Chill

Answer 14

The affect of cooling associated with increase velocity

Effects increase with increase exercise velocity