Homeostatic Mechanisms Flashcards
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
What is radiation?
Transfer of heat as electromagnetic waves btwn objects not in contact - proportional to temp difference btwn body surface and envmt
What is conduction?
intermolecular thermal heat transfer btwn solid objects in direct contact
-usually minimal in clothed person
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
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
At rest, indoors, what mechanism is most body heat lost by?
Radiation
A body immersed in water exchanges most heat by what?
Convection
What heat loss mechanism is most effective during exercise?
Evaporation
When a person is running, what mechanism of heat loss would result from skin blood flow?
Convection
When a person is running, what mechanism of heat loss would result from Muscle blood flow?
convection
When a person is running, what mechanism of heat loss would result from feet against pavement?
Conduction
Where is most of your body heat generated?
In deep organs by cellular metabolism
Is fat a good conductor of heat?
NO - it is a great insulator tho
When someone is acclimating to hot weather, what is occuring?
Change in sweat glands to increase sweating
- dec in loss of NaCl
- aldosterone secretion
What is congenital anhidrosis?
The genetic inability to secrete sweat
What innervates a sweat gland ?
An acetylcholine secreting sympathetic nerve
What receptors are more plentiful in the skin cold or hot?
Cold
What receptors are more plentiful in the hypothalmus cold or hot?
Hot
What mechanism does the skin use to respond to local changes in temperature?
Anticipatory mechanism - prevents core temp from changing at all
What mechanism controls internal body temperature?
Negative feedback
What provides the error signal that sustains sweating during exercise?
Body core temp rises by 1 degree
–heat production exceeds dissipation
Is skin temperature changed during exercise?
nearly maintained constant due to sweating, but does decrease slightly due to evaporation of sweat
What is a pyrogen?
Fever producing stimuli
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
What do aspirin and acetaminophen inhibit, which allows fever reduction?
Prostaglandin synthesis
Why is fever beneficial?
Immune cells often function optimally at high temps
Is a person sweating when they have heat exhaustion?
Yes!
