Thermoregulation

Question 1

Humans are

Answer 1

homeotherms

Question 2

Normal resting core temp

Answer 2

36.5 - 37.5

heat = 40
cold = 35

Question 3

Core temperature regulation

Answer 3

temp of hypothalamus - thermoregulatory centre of the body

Question 4

Skin temperature degrees

Answer 4

cool = <30
warm = 30-34.9
hot = >35

varies in response to thermal environ

Question 5

Temperature regulation

Answer 5

temp sensors (peripheral and central thermoreceptors)
regulated effectors (adrenal medulla, sweat glands, skin arterioles, skeletal muscles)

Question 6

What happens when body temp increases?

Answer 6

afferent to brain
efferent
blood vessels dilate/sweat galnds secrete fluid
=heat lost to environment
body temp return to normal

Question 7

What happens when body temp falls?

Answer 7

afferent to brain
efferent
blood vessels constrict/sweat glands not secrete fluid = heat consereved
shivering generates heat
= heat retained
body temp return to normal levels

Question 8

Body temp maintained by

Answer 8

balancing heat gain and loss

Question 9

Heat loss

Answer 9

blood reaching the skin
sweating
metabolic reactions during exercise = lose ~75% energy as heat

Question 10

Methods of Heat production/conservation

Answer 10

shivering thermogenesis
voluntary muscular activity
non-shivering thermogenesis
metabolism

Question 11

Energy balance equation

Answer 11

heat storage = M +/ Cv +/ Cd +/ R - evaporative

Watts

Question 12

Heat exchange

Answer 12

between body and environ governed by biophysical properties

air temp/humididty
solar/thermal/ground radiation
sweat/respiratory evaporation
skin/blood/muscle convection
mechanical work
contracting muscle
conduction

Question 13

Aerobic exercise in hot environ

Answer 13

increase demand on heat loss mechanism (skin blood flow/sweating)
reduce gradient between core and skin = skin temp increase

dehydration = exacerbate heat stress impact = decrease sweat rate/plasma volume
decrease CO, max O2 uptake, muscle strength and work capacity

Question 14

Prolonged high-intensity exercise in hot environ

Answer 14

impaired
competing regulatory demands for blood flow between thermoreg, working muscles and CNS
heat-related changes in skeletal muscle function and metabolism

Question 15

Treatment heat-related health impacts

Answer 15

cold water immersion
most rapid way to lower body temp

Question 16

Heat illness

Answer 16

heat cramps
heat exhaustion
heat stroke

Question 17

Warning signs

Answer 17

thirst
fatigue
confusion
faintness or dizziness
headache/nausea

Question 18

Mitigating before

Answer 18

heat acclimatation
aerobic training

Question 19

Mitigating immediately before

Answer 19

pre-cooling
hydration status

Question 20

Mitigating during

Answer 20

hydration
clothing
cooling

Question 21

Hypothermia

Answer 21

core temp below 35

drop 2 = max shivering
drop 6 = unconsciousness
drop further = reduced brain blood flow = death

heat loss exceeds heat production

Question 22

Shivering

Answer 22

O2 consumption higher in cold water during sub-max exercise
but reduced during max exercise

Question 23

Physiological responses in cold

Answer 23

increase submax VO2
increase ventilation
reduce skin blood flow
increase lactate conc
decrease HR during submax exercise

Question 24

Exercise in cold

Answer 24

cold acclimatisation/acclimation = lower skin temp = increase shivering
maintain high hand/foot temp = improve peripheral blood flow

Question 25

How much energy is released as heat?

Answer 25

70-80%

Question 26

Dysfunction during exercise in heat?

Answer 26

cardiovascular
SNS
accelerated muscle fatigue