Lect 24

Question 1

normal core body temperature

Answer 1

37 C

Question 2

heat exhaustion occurs at a core body temp of

Answer 2

39 C

Question 3

describe the process of development of head exhaustion

Answer 3

1. heat leads to excessive sweating + cutaneous arteriolar dilation -> hypovolemia
2. hypovolemia -> decreased CO and decreased MAP -> circulatory shock

Question 4

heat stroke develops at a core temperature of

Answer 4

41 C or above

Question 5

process in which energetic particiles or energy or waves travel through a medium or space

Answer 5

radiation

Question 6

the transfer of thermal energy through matter

Answer 6

conduction

Question 7

the process of losing heat through the movement of air or water molecules across the skin

Answer 7

convection

Question 8

water loss from respiratory passages and the surface of skin

Answer 8

evaporation

Question 9

heat transfer from core comes from what two processes

Answer 9

• heat passively conduction to skin +
• heat convected by blood from core (majority)

Question 10

what is the primary determinant of heat flow from core to skin?

Answer 10

the ability to alter skin blood flow

Question 11

rate of heat loss from radiation: equation

Answer 11

= radiative heat transfer coefficient x (mean skin temp - radiant temp of another object) x body surface area

Question 12

convective heat transfer coefficient is influenced by

Answer 12

air velocity

Question 13

heat transfer coefficient is what in water compared to air

Answer 13

100 x greater in water

Question 14

what process of heat loss becomes important when exposed to cold water

Answer 14

convection

Question 15

equation for rate of heat loss by convection

Answer 15

= convective haet transfer coefficient x (mean skin temp - ambient temp) x body surface area

Question 16

equation for rate of heat loss by evaporation

Answer 16

= evaporative heat transfer coefficient x (water vapor pressure of skin - water vapor pressure of environment) x body surface area

Question 17

increased air velocity has what effect on vapor gradient

Answer 17

increases vapor gradient

Question 18

What is the “central” coordinating center for temperature regulation

Answer 18

hypothalamus

• integrates information from skin and core receptors

Question 19

What are skin receptors

Answer 19

• free nerve endings in the skin: both warm and cold receptors
• relay information to hypothalamus

Question 20

local heating will produce local vasodilation and sweating caused by

Answer 20

• the local effect of temperature directly on the blood vessels and by local cord reflexes

Question 21

local cooling will produce

Answer 21

local vasoconstriction

Question 22

skin thermoreceptors change the of the response to signals from core thermoreceptors

Answer 22

sensitivity

Question 23

intense aerobic exercise can theoretically increase core temp by

Answer 23

1 C every few minutes

Question 24

What happens to CO when exercising in a hot vs cold environment

Answer 24

CO is reduced in a hot environment because blood is transfered away from core

Question 25

What happens to HR when exercising in a hot vs cold environment

Answer 25

HR increases in a hot environment to compensate for reduced CO

Question 26

what influence does training vs untrained individual have on skin blood flow and sweat rate

Answer 26

* greater skin blood flow * sweat rate is greater in trained individual

Question 27

heat acclimatization takes how long

Answer 27

a few days

Question 28

what are the results of heat acclimatization?

Answer 28

* lowers HR * threshold for cutaneous vasodilation is lower * plasma volume increased * increased sweat production

Question 29

the effects of training and acclimatization on heat dissipation are

Answer 29

complementary!

Question 30

fluid ingestion influences sweat rate and skin blood flow such that what happens to core body temperature

Answer 30

core body temperature is less in a person who drank fluid vs someone who did not