thermoregulation

Question 1

what is thermoregulation?

Answer 1

ability of an organism to keep its body temperature within certain boundaries

Question 2

what happens when body temp rises?

Answer 2

blood vessels dilate resulting in heat loss to enviro

increase blood flow to specific areas to increase heat lost

sweat glands secrete fluid and when evaporates, heat lost from body

Question 3

what happens when body temp falls?

Answer 3

blood vessels constrict so heat is conserved

reduce blood flow to certain areas where heat would be lost

sweat glands don’t secrete fluid

shivering (involuntary contraction of muscles) generates heat, warming body

Question 4

what are homeotherms?

Answer 4

ability to maintain constant internal body temp regardless of external stimuli
(humans have ability to do this)

Question 5

what do endotherms do?

Answer 5

generate heat internally
maintain high basal heat production

e.g mouse

Question 6

what do ectotherms do?

Answer 6

depend on external heat sources
body temp changes with the enviro

e.g snake

Question 7

what is a human’s internal core body temp?

when does it change?

at what temp is the optimal function?

Answer 7

36.5-37.5 *C

changes based on time of day

optimal function between 36.5-40*C

Question 8

what is defined as a low internal core body temp?

Answer 8

<35*C

hypothermia sets in

Question 9

what is the lowest survivable internal core temperature?

Answer 9

14.4*C

Question 10

what occurs during hypothermia?

Answer 10

loss of motor skills
shivering
decrease in blood circulation and skin temp

severe:
confusion
loss of consciousness

Question 11

when does hyperthermia occur and what happens?

Answer 11

when body temp above 38*C

results in either heat exhaustion: e.g sweating and cold skin and weak pulse

or heat stroke: e.g no sweating and hot skin and strong pulse

Question 12

at what temp does damage to cells occur and what is the highest survivable internal core body temp?

Answer 12

> 42*C

highest survivable: 46.5*C

Question 13

what are some of the factors which influence core body temp?

Answer 13

1. body mass and composition (morphology)
   e. g better at adapting to temp if taller as more skin surface area
2. enviro
3. skin
4. metabolic heat production

Question 14

what is body temp a balancing act between?

Answer 14

heat gain and loss

Question 15

which part of the brain activates blood vessel dilation/contstriction?

Answer 15

hypothalamus

Question 16

how to measure core body temp?

Answer 16

thermometer probe at accessible site

hypothalamus, oesophagus, rectum, intestinal, under tongue and ear drum

Question 17

what should be considered when measuring skin temp?

Answer 17

ambient temp
distance from core
skin blood flow

Question 18

what is the definition of specific heat capacity?

Answer 18

amount of energy required to raise the temperature of a given substance by 1*C

Question 19

which part of the body has the lowest skin temp when it is less than 15*C and in room temp?

Answer 19

feet

Question 20

what is the specific heat capacity of water and human body tissue?

Answer 20

water = 4.186

human body tissue = 3.48

Question 21

how to calculate specific heat capacity?

Answer 21

change in thermal energy / mass x change in temp

Question 22

how much heat does 1 litre of O2 consumed produce?

Answer 22

20kJ of heat

Question 23

how is heat produced?

Answer 23

chemical energy in food
resynthesise ATP
inefficient as energy released doesn’t = ATP resynthesis
releasing energy in form of heat

during exercise

Question 24

voluntary and involuntary heat production?

Answer 24

voluntary - exercise - 70-80% EE appears as heat

involuntary - shivering, action of hormones (catecholamine and thyroxin)

Question 25

which factors are in external heat gain?

Answer 25

sky thermal radiation solar radiation ground thermal radiation

Question 26

what are the 4 factors of heat loss?

Answer 26

1. conduction 2. convection 3. radiation 4. sweat evaporation

Question 27

what is the thermal gradient?

Answer 27

heat transfer is always from higher to lower temps

Question 28

what is radiation? in terms of heat loss

Answer 28

transfer of heat in the form of electromagnetic waves body loses 60% of heat through radiation when at rest (biggest factor)

Question 29

what is evaporation? in terms of heat loss

Answer 29

vaporisation of sweat from water to vapour 1g of sweat = 2.41kJ of heat (biggest factor for heat loss in exercise)

Question 30

what is conduction? in terms of heat loss

Answer 30

heat transfer from the body to an object with direct contact

Question 31

what is convection? in terms of heat loss

Answer 31

conduction of heat to or from air or water from one place to another by the movement of fluids more accountable for heat loss at room temp than conduction

Question 32

describe sweating? released activated increased

Answer 32

sweat is released from sweat glands stimulated by SNS increased SNS and therefore sweating when exercising, in anticipation or nervous

Question 33

what are the 3 factors influencing evaporation?

Answer 33

air temp (high humidity = evaporation decreases as high conc of water) convective currents (high wind = increased evaporation) skin exposure (larger surface = increased evaporation)

Question 34

how to calculate sweat loss?

Answer 34

change in mass + fluid intake - urine units are kg or L

Question 35

how to calculate sweat rate?

Answer 35

sweat loss/time in h units are L/h

Question 36

what does sweat loss depend on?

Answer 36

``` body size absolute VO2 aerobic fitness heat acclimatisation enviro ``` rugby is highest due to being large size and surface

Question 37

what explains why those with tattoos have a lower sweat rate?

Answer 37

changes skin sensors delayed signal to hypothalamus can't sweat as efficiently from tattoed areas

Question 38

which areas of the body has the greatest heat loss?

Answer 38

the groin and armpits (not head)

Question 39

how does hyperthermia improve sprint/power performane?

Answer 39

decreased resistance in muscles/joints faster nerve conduction velocity faster metabolic rate (Q10 effect) so muscles activated quicker increased SNS activity

Question 40

what does hyperthermia impair?

Answer 40

endurance performance and repeated sprint ability

Question 41

what is the Q10 effect?

Answer 41

measure of the rate of change of a biological or chemical system as a consequence of increasing the temp by 10*C

Question 42

what may reverse the effects of hyperthermia?

Answer 42

hydration

Question 43

why is performance impaired when core temp increases?

Answer 43

increased swet rate | decrease in plasma volume, blood volume, venous return and end diastolic volume

Question 44

what are some of the cognitive consequences of high core temp?

Answer 44

fatigue perception increase decreased reaction time and attention decreased scanning

Question 45

what are the levels of warning signs of hyperthermia?

Answer 45

heat cramps to heat exhaustion (fatigue, nausea) to heatstroke (most dangerous due to loss of consciousness and stopping of sweating)

Question 46

what are the effects of heat acclimation?

Answer 46

body temp lower at certain heat sweat rate increases skin blood flow reduced, more blood to muscles blood volume increases stroke volume maintained

Question 47

what is heat acclimation?

Answer 47

complex series of changes or adaptations that occur in response to heat stress between 7-14 days

Question 48

what is the impotance of hydration?

Answer 48

cool drinks can help lower temp and are absorbed in the GI tract faster

Question 49

what is homeostasis? and what is the process of correcting an imbalance?

Answer 49

ability or tendency to maintain internal stability in a human organism to compensate for environmental changes detect change - received by receptors - send signal through afferent pathway to control centre - signal sent via efferent pathway to receptor - effector responds to change