SEHS: Option A: A2

Environmental Factors

Explain the relationship between cellular metabolism and the production of heat in the human body

Almost all energy on this planet originates from:

Where does it go from there?

plants- animals (stored in “food”)

Carbs, lipids, proteins metabolized stored as ATP via aerobic cellular respiration

Cont’d• ATP = metabolic reactions, including:

• Muscle contraction and movement– 20% of E to movement– 80% lost as heat

Normal physiological range for CORE body temp Tc

• 97.6 - 99.6 oF

• Core body temp – deep within the body

Thermoregulation• Four mechanisms that move heat through the

blood, to the skin, in order to transfer it to the environment:

Cont’d

• Conduction – solid on solid transfer

• Convection – air current transfer

• Radiation – wave transfer (reradiated

• Evaporation – evap cooling

Discuss the significance of humidity and wind in relation to body heat loss

• High humidity = lower heat loss

• Low humidity = higher heat loss

• Why?

• High wind = higher heat loss

• Low wind = lower heat loss

• Why?

The formation of sweat and the sweat response

• Sweat - the production of fluids secreted by the sweat glands in the skin of mammals.

• Two types of sweat glands can be found in humans: Eccrine glands and apocrine glands. The eccrine sweat glands are distributed over much of the body

Skin as organ of thermoregulation

Physiological and anatomical response to temp changes

Discuss the physiological responses to prolonged exercise in the heat

• Recall cardiac drift – as temperature increases, blood volume decreases due to sweating, venous return decreases…………..what happens to HR?

• Metabolically it causes increased muscle glycogen breakdown due to reduced blood flow to the muscles = anaerobic respiration = higher blood lactate levels

HOMEWORK

• Outline 3 health risks associated with exercising in the heat.

• What steps can be taken to prevent these conditions?

• What treatments are used to address these conditions if they occur?