Energy, Work, and Power of Human Body

Energy, Work, and Power of Human Body

Objectives

1-Knowledge of the principles of energy, (Basal conditions).

2-Definition of BMR and physical factors affecting it. 

3. Methods of heat losing. 

4. Thermography applications.

Basal conditions

1-25% of the body s energy used by the skeletal muscle and heart.

2-19% used by the brain.

3-10% used by kidneys.

4-27% used by the liver, spleen


The body uses food energy to operate, its various organs, maintain constant body temperature, and do external work, small percentage (5%) of the body energy excreted in the feces and urine, any energy left over is stored as a body fat.



Methods of heat losing

The main heat loss mechanisms are:

1-Radiation

2-Convection

3-Evaporation (perspiration)

4-Some cooling of the body in lungs

Hypothalamus

The hypothalamus of brain contains body thermostat to keep temperature close to normal value. If the core temperature rises,
the hypothalamus initiate sweating and vasodilatation which increases blood flow to the skin and increase skin temperature which help to get rid of extra heat


If the skin temperature drops, the thermo receptors on the skin inform hypothalamus and it initiate shivering, which causes increase in the core temperature