Thermoregulation

Question 1

When is body temperature the lowest and highest?

Answer 1

3-6 AM -1C

3-6 PM + .3-.5C

Question 2

What percent of heat is lost via conduction?

Answer 2

3%

Question 3

What percent of heat is lost via convection?

Answer 3

12%

Question 4

What percent of heat is lost via radiation?

Answer 4

60%

Question 5

What percent of heat is lost via evaporation?

Answer 5

25%

Question 6

What is the heat balance equation?

Answer 6

(M-W) - (R+C+E) = S

Question 7

Where is the thermoreceptor for blood located?

Answer 7

Hypothalamus

Question 8

Where do peripheral receptors send signals to?

Answer 8

Hypothalamus

Question 9

What systemic affects does the cold have?

Answer 9

Shivering, increased ventilation, increased HR, increased CO, vasoconstriction, increased BP, increased NE/T3

Question 10

What systemic affects does heat have?

Answer 10

Sweating, vasodilation, increased HR, increased CO

Question 11

How is a febrile condition induced?

Answer 11

Infection or pyrogen enters the body and macrophages recognize and release cytokines

Question 12

Which cytokines come from macrophages and induce fever?

Answer 12

IL-1 IL-6

Question 13

How do interleukins work?

Answer 13

Affecting hypothalamus and prostaglandin E2 change temperature resetting it to higher temperature

Question 14

Why does shivering occur in febrile states?

Answer 14

Because your core temperature is at 37 and the hypothalamus has been set to a higher temperature so you shiver to increase body temperature

Question 15

How do cytokines cause fever?

Answer 15

They cross the BBB and affect the OVLT endothelial cells to release PGE2 which affects the hypothalamus to increase the bodies normal temperature

Question 16

At what temperature can the nervous system begin to be affected?

Answer 16

40C

Question 17

What are the benefits of exercise?

Answer 17

Increasing the temperature by 10C increases enzyme activity 10x

Question 18

Why does body heat increase quickly during exercise?

Answer 18

Because the mechanisms to get rid of excess heat are not present until the temperature gets higher

Question 19

At rest which mechanism causes the most heat loss?

Answer 19

Radiation

Question 20

In exercise which mechanism causes the most heat loss?

Answer 20

Evaporation

Question 21

Why is it easier to run in cooler weather?

Answer 21

Because more blood can be sent to the SM instead of skin for heat loss

Question 22

Why does heart rate increase over long periods of exercise?

Answer 22

Because decreased blood volume and decreased stroke output

Question 23

At what point below normal body temperature does the body lose the ability to regulate temperature?

Answer 23

34.5C

Question 24

What physiological changes occur with heat acclimization?

Answer 24

Blood volume increases (plasma volume)
Sweat increases
Cardiac output increases (increased SV)
Heart rate decreases
Core temperature decreases
More blood to SM not skin