Thermoregulation

Question 1

Humans can tolerate ___ degree decline in body temp, but only a ___ degree increase

Answer 1

10

5

Question 2

normal body temp

Answer 2

98 to 98.8 degrees

Question 3

hypothalamus

Answer 3

central coordinating center for temperature regulation

Question 4

how does the hypothalamus regulate temperature?

Answer 4

cannot “turn off” heat
thermal receptors in skin provide input
changes in blood temp that perfuses hypothalamus

Question 5

thermoregulation process in heat stress

Answer 5

radiation
conduction
convection
evaportation

Question 6

radiation

Answer 6

body emits electromagnetic heat waves

NO molecular contact between objects

Question 7

conduction

Answer 7

direct heat transfer from one molecule to another through a liquid, solid, or gas
heat loss involves warming air molecules and cooler surfaces that contact the skin

Question 8

convection

Answer 8

air or water moving across the skin

swimming

Question 9

evaporation

Answer 9

water vaporization from skin surface to environment- major defense against over heating

Question 10

heat loss by evaporation

how?

Answer 10

evaporation of sweat from skin exerts cooling effect

cooled skin cools blood near surface of skin

Question 11

3 major factors that influence amount of sweat vaporized from skin

Answer 11

surface exposed to environment
temperature and relative humidity of ambiant air
convective air currents around body

Question 12

What reduces evaporation?

Answer 12

if the sweat rolls off the body- sweat needs to evaporate in order to cool skin/blood
or
high humidity at lower temperatures

Question 13

what are the two competitive CV demands when exercising in heat?

Answer 13

1. muscles require delivery of arterial blood to sustain energy metabolism
2. arterial blood diverts to periphery to transport metabolic heat for cooling skin surface; this blood cannot deliver its oxygen to active muscle.

Question 14

dehydration

Answer 14

loss of body mass due to fluid loss

** 3-5% loss of body mass does not degrade muscular strength or anaerobic performance

Question 15

Signs and symptoms of dehydration

Answer 15

thirst
urine color = darker
urine odor
weight loss- 1L of fluid for each pound of weight loss

Question 16

fluid loss coincides with 5 factors:

Answer 16

1. decreased plasma volume = headache
2. reduced skin blood flow for given core temp
3. reduced stroke volume
4. increased hr
5. general deterioration in circulatory and thermoregulatory efficiency in exercise

Question 17

5 factors that modify heat tolerance

Answer 17

1. acclimatization
2. training status
3. age
4. gender
5. % body fat

Question 18

acclimatization

Answer 18

collective physiologic adaptive changes that improve heat tolerance
progressive exposure to daily heat environment with adequate hydration

Question 19

acclimatization increases ____ ____, and ______,

and decreases _____ and ______

Answer 19

cutaneous blood flow, sweat output, exercise tolerance time

salt concentration of sweat, rectal temp per exercise workload

Question 20

training status

Answer 20

higher fitness level respond better physiologically to sudden heat stress than untrained
known CV, immune disease, infectious disease respond poorer to physiologically heat stress

Question 21

age

Answer 21

aging delays onset of sweating and blunts magnitude of sweating response

Question 22

age has these direct effects:

Answer 22

modified sensitivity to thermoreceptors
limited sweat gland output
dehydration-limited sweat output
insufficient fluid replacement

Question 23

gender

Answer 23

women tolerate thermal stress as well as men of comparable aerobic fitness and level of acclimatization

Question 24

%body fat

Answer 24

increase insulation so more difficult to conduct heat to periphery
increased metabolic cost of weight bearing activities
fatal heat stroke occurs 3.5x more frequently in larger individuals

Question 25

heat cramps

Answer 25

severe, involuntary, sustained muscle spasms

imbalance in body fluid level and electrolyte levels

Question 26

what to do when you have heat cramps

Answer 26

drink water than contains salt

Question 27

heat exhaustion

Answer 27

ineffective circulatory adjustments, depletion of extracellular fluid, principally plasma volume from excessive sweating

most common form of heat illness

Question 28

signs and symptoms of heat exhaustion

Answer 28

weak and rapid pulse
hypotensive
headache
dizziness
general weakness

Question 29

what to do when you have heat exhastion

Answer 29

stop exercising, move to cooler environment, get an IV

Question 30

heat stroke

Answer 30

failure of heat-regulating mechanisms from an excessively high core temperature

Question 31

signs and symptoms of heat stroke

Answer 31

elevated body temp greater than 40 C or 104F
CNS dysfunction
multiple organ system failure
diminished sweating, hot/dry skin

Question 32

desired temp in exercise environment

Answer 32

65-72F

Question 33

desired temp in cardiac rehab

Answer 33

65F

Question 34

what to do when you have heat stroke

Answer 34

whole body immersion in cold/ice

water, fluid replacement/IV

Question 35

will a 3% loss of body mass affect anaerobic performance

Answer 35

no

Question 36

will a 3% loss of body mass affect aerobic performance

Answer 36

yes because there is less water to moderate temperature

Question 37

what precautions should be considered in HEP

Answer 37

make sure that the discharge plan includes heat precautions: outdoor temp/humidity considerations; prehydrating; fluid during activity; fluid replacement; sunscreen; light colored, loose clothing; sweating; urine color; exercise early/later in day; shaded areas; mall walking; exercise facility.