Thermoregulation

Heat produced by the body

Metabolism

Heat transferred through contact with a solid object

Conduction

Heat transfer with H2O or air

Convection

Heat transfer via electromagnetic waves

Radiation

Heat loss as H20 converts to H20 vapor

Evaporation

The goal of heat balance is to maintain storage at what?

S=0

Evaporation accounts for __ to __% heat loss during exercise

80-90%

Goal is to keep core temp at __ to __

36-38 degrees celsius

Heat stroke may occur at what temp?

41 degrees celsius

Death can occur at what temp?

42 degrees celsius

Where are thermoreceptors located?

Skin, muscle, spine and brain

Where is feedback from thermoreceptors sent back to?

Hypothalamus

What does the hypothalamus initiate?

A response

Sympathetic nerves in skin release __ causing __ and activates __

Acetylcholine, dilation, sweat glands

If core temp rises, what does the hypothalamus increase?

Sympathetic nerve activity

What aids heat loss?

Increase in skin blood flow and sweat production

What is sodium absorption facilitated by?

Aldosterone

Sweat glands are activated by what?

Sympathetic nervous system

What does sweat initially have similar to plasma?

Electrolyte

T/F: Sweat initially has electrolyte solution similar to plasma

True

Some sodium and chloride is reabsorbed where?

In sweat ducts

Where are sweat glands activated first?

Trunk

What two stages does sweating occur?

1. Increase in number of active sweat glands

2. Increase in output per sweat gland

Where is sweat derived from?

Extracellular water

Extracellular water is replaced by ___ from ___ and ___

H20, plasma, cells

What % of body weight do you have to lose to be considered dehydrated?

2% body weight

What is the problem during cv adjustment to heat?

1. Skin and muscle compete for BF

2. BP must be protected

In passive heating there is a ___ in skin BF for heat dissapation

Increase

In passive heating there is a ___ in muscle BF

Decrease

In passive heating CO ___

Increases

How much % of CO goes to the skin?

60%

T/F: Skin and muscle compete for blood flow

True

What reduces stroke volume?

Decrease in venous return

Why does heart rate increase?

In attempt to maintain cardiac output

When does cardiac output max fall?

At time of highest demand