Flashcards in Homeostatic Mechanisms Deck (27)
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1
Humans are endoderms and homeotherms, what does this mean?
We are able to generate our own body heat, and mantain our core body temp within a narrow range despite large fluctuations outside
2
What is radiation?
Transfer of heat as electromagnetic waves btwn objects not in contact - proportional to temp difference btwn body surface and envmt
3
What is conduction?
intermolecular thermal heat transfer btwn solid objects in direct contact
-usually minimal in clothed person
4
What is convection?
Loss or gain of heat by movement of air or water over the body - heat rises and is carried away from the body
5
What is evaporation?
loss of water from the skin and resp tract
-generates lots of heat - large amount needed to transform water from liq to gas phase
6
At rest, indoors, what mechanism is most body heat lost by?
Radiation
7
A body immersed in water exchanges most heat by what?
Convection
8
What heat loss mechanism is most effective during exercise?
Evaporation
9
When a person is running, what mechanism of heat loss would result from skin blood flow?
Convection
10
When a person is running, what mechanism of heat loss would result from Muscle blood flow?
convection
11
When a person is running, what mechanism of heat loss would result from feet against pavement?
Conduction
12
Where is most of your body heat generated?
In deep organs by cellular metabolism
13
Is fat a good conductor of heat?
NO - it is a great insulator tho
14
When someone is acclimating to hot weather, what is occuring?
Change in sweat glands to increase sweating
-dec in loss of NaCl
-aldosterone secretion
15
What is congenital anhidrosis?
The genetic inability to secrete sweat
16
What innervates a sweat gland ?
An acetylcholine secreting sympathetic nerve
17
What receptors are more plentiful in the skin cold or hot?
Cold
18
What receptors are more plentiful in the hypothalmus cold or hot?
Hot
19
What mechanism does the skin use to respond to local changes in temperature?
Anticipatory mechanism - prevents core temp from changing at all
20
What mechanism controls internal body temperature?
Negative feedback
21
What provides the error signal that sustains sweating during exercise?
Body core temp rises by 1 degree
--heat production exceeds dissipation
22
Is skin temperature changed during exercise?
nearly maintained constant due to sweating, but does decrease slightly due to evaporation of sweat
23
What is a pyrogen?
Fever producing stimuli
24
Why does a person get the chills when they have a fever?
The body sees a high set point temperature value as the new normal and tries to prevent heat loss
25
What do aspirin and acetaminophen inhibit, which allows fever reduction?
Prostaglandin synthesis
26
Why is fever beneficial?
Immune cells often function optimally at high temps
27
