wk1 thermal balance and pathophysiology

Question 1

what is the formula for heat storage

Answer 1

S = M - W +- E +- C +- R +- K (all in ‘W. m^-2’ watts per square meter)

M - metabolic energy production
w - work done
e - evaporative heat transfer
c - convective heat transfer
r - radiative heat transfer
k - conductive heat transfer

Question 2

what is the formula of heat storage also referred to as

Answer 2

the 1st law of thermodynamics

Question 3

what are the 4 main environmental parameters affecting heat balance

Answer 3

ambient temp
humidity - diffusion gradient reduced when it’s very humid
air velocity
solar radiation

Question 4

what personal factors affect heat balance

Answer 4

age
biological sex
body surface area
aerobic fitness

Question 5

what are the task dependant factors affecting heat balance

Answer 5

rate of metabolic heat production
clothing

Question 6

what measures the total heat generation and exchange

Answer 6

whole body calorimeters

Question 7

what is another example of how we can measure body heat storage and exchange

Answer 7

thermometry

Question 7

on a graph depicting heat loss and production how would you find the ‘whole body heat storage’

Answer 7

it’s the shaded area between the two values

Question 8

what are the efferent responses to cold temps

Answer 8

blood vessels constrict
shivering

Question 9

what is the efferent response to high temps

Answer 9

blood vessels dilate to produce sweat

Question 10

what locations do we measure body core temp

Answer 10

oesophageal - mouth (most accurate)
rectal - anus
gastro intestinal - from mouth to anus (moving blood away from gut during exercise so is slow)
tympnic - ear canal

Question 11

what is the thermoeffector response during heat stress

Answer 11

body temp spikes
effector output increases proportionally to body temp (plateaus at max value)

body temp change is needed to cause effector output

Question 12

how is skin (cutaneous) temp different to core

Answer 12

skin can vary around the body core is always the same, it is not regulated

Question 13

how do we measure skin temp

Answer 13

Has to be at a min of 4 sites

infared thermography - measures radiating energy released from the body
thermocouples - connected wires attached to the body
ibuttons - small metallic buttons placed on the body

Question 14

what is the sweating response across time

Answer 14

steep rise to own plateau - no uniformity in sweat rates

decline local - due to hidromeiosis (reduction of sweating occurring when sweat glands are blocked)
decline central - osmoregulatory and baroreceptive

Question 15

what is vital about sweat loss through evaporation

Answer 15

humans can only dissipate heat from skin if environmental temp > skin temp

Question 16

how do we measure sweat rate

Answer 16

body mass change - respiratory loss and metabolic change
patch collection - Na loss
ventilated capsules - measure of thermoregulation

Question 17

what happens to muscle temp during exercise

Answer 17

rapidly increases, non active muscles have a slower rate of change

Question 18

what happens to intramuscular temps as exercise goes on

Answer 18

become more uniformed (blood = coolant and warmant)

Question 19

what is the heat stress index for

Answer 19

to predict the physiological strain from a stressful environment

Question 20

what are the two types of heat stroke

Answer 20

classic and exertional

Question 21

how to deal with heat related illness

Answer 21

remove from heat
rehydration
rest in ‘supine’ position

Question 22

how can heat stress impair performance

Answer 22

lower brain and muscle blood flow
increased perception of effort and exertion
higher cho oxidation
CNS disorder

Question 23

what is hypernatremia

Answer 23

plasma sodium conc of 145mmoL

Question 24

What is hyponatermia

Answer 24

plasma sodium conc of 135mmoL or less

normally due to lots of water intke and no sodium intake

Question 25

what is heat storage governed by

Answer 25

biophysical properties

Question 26

what are the biophysical of the environment

Answer 26

radiation (out)
convection (out)
wind
evaporation (out)
conduction
direct and diffused radiation
reflected radiation

Question 27

how does our thermoeffector responses change during heat stress

Answer 27

increases effector output
higher change in mean body temp to initiate activation of effector response
lower maximal values

Question 28

what can inhibit sweating process

Answer 28

hidromeiotic effect of skin pressure

Question 29

what drives heat related illness

Answer 29

heat exposure
driven by ambient heat stress and internal metabolic energy production

Question 30

what is heat stroke characterized by

Answer 30

40c temp and CNS dysfunction

Question 31

what are the characteristics of heat exhaustion

Answer 31

profound fatigue, weakness, nausea, headache or dizziness
moderate-serve dehydration
elevated core temp

Question 32

what is heat syncope

Answer 32

fainting due to pooled blood, caused by peripheral vasodilation

Question 33

what is heat edema

Answer 33

swelling of the limbs, caused by peripheral vasodilation and intestinal pooling

Question 34

definition of heat cramps

Answer 34

painful muscle spasms during/after exercise in heat

Question 35

individual susceptibility risk factors heat related illness

Answer 35

age
existing conditions
pregnancy
medication
cognitive impairments
disabled
immobilisation
social isolation

Question 36

sociocultural factors affecting heat illness

Answer 36

poverty
racism
social cohesion
housing status
literacy
worker protections

Question 37

consequences of exertional strokes

Answer 37

CNS disorder
high core temp
tissue/organ damage
endotoxaemia

Question 38

how can sweat loss be counteracted

Answer 38

fluid consumption and activation of the RAAS

Question 39

what are the two types of hyponatremia

Answer 39

asymptomatic and symptomatic

Question 40

what is the capacity of the environment to absorb heat dependent on

Answer 40

water vapour pressure
air movement
resistance to heat transfer - posture/clothing
ambient temp