Homeostatic Mechanisms

Question 1

Humans are endoderms and homeotherms, what does this mean?

Answer 1

We are able to generate our own body heat, and mantain our core body temp within a narrow range despite large fluctuations outside

Question 2

What is radiation?

Answer 2

Transfer of heat as electromagnetic waves btwn objects not in contact - proportional to temp difference btwn body surface and envmt

Question 3

What is conduction?

Answer 3

intermolecular thermal heat transfer btwn solid objects in direct contact

-usually minimal in clothed person

Question 4

What is convection?

Answer 4

Loss or gain of heat by movement of air or water over the body - heat rises and is carried away from the body

Question 5

What is evaporation?

Answer 5

loss of water from the skin and resp tract

-generates lots of heat - large amount needed to transform water from liq to gas phase

Question 6

At rest, indoors, what mechanism is most body heat lost by?

Answer 6

Radiation

Question 7

A body immersed in water exchanges most heat by what?

Answer 7

Convection

Question 8

What heat loss mechanism is most effective during exercise?

Answer 8

Evaporation

Question 9

When a person is running, what mechanism of heat loss would result from skin blood flow?

Answer 9

Convection

Question 10

When a person is running, what mechanism of heat loss would result from Muscle blood flow?

Answer 10

convection

Question 11

When a person is running, what mechanism of heat loss would result from feet against pavement?

Answer 11

Conduction

Question 12

Where is most of your body heat generated?

Answer 12

In deep organs by cellular metabolism

Question 13

Is fat a good conductor of heat?

Answer 13

NO - it is a great insulator tho

Question 14

When someone is acclimating to hot weather, what is occuring?

Answer 14

Change in sweat glands to increase sweating

• dec in loss of NaCl
• aldosterone secretion

Question 15

What is congenital anhidrosis?

Answer 15

The genetic inability to secrete sweat

Question 16

What innervates a sweat gland ?

Answer 16

An acetylcholine secreting sympathetic nerve

Question 17

What receptors are more plentiful in the skin cold or hot?

Answer 17

Cold

Question 18

What receptors are more plentiful in the hypothalmus cold or hot?

Answer 18

Hot

Question 19

What mechanism does the skin use to respond to local changes in temperature?

Answer 19

Anticipatory mechanism - prevents core temp from changing at all

Question 20

What mechanism controls internal body temperature?

Answer 20

Negative feedback

Question 21

What provides the error signal that sustains sweating during exercise?

Answer 21

Body core temp rises by 1 degree

–heat production exceeds dissipation

Question 22

Is skin temperature changed during exercise?

Answer 22

nearly maintained constant due to sweating, but does decrease slightly due to evaporation of sweat

Question 23

What is a pyrogen?

Answer 23

Fever producing stimuli

Question 24

Why does a person get the chills when they have a fever?

Answer 24

The body sees a high set point temperature value as the new normal and tries to prevent heat loss

Question 25

What do aspirin and acetaminophen inhibit, which allows fever reduction?

Answer 25

Prostaglandin synthesis

Question 26

Why is fever beneficial?

Answer 26

Immune cells often function optimally at high temps

Question 27

Is a person sweating when they have heat exhaustion?

Answer 27

Yes!