269 Temperature ⭐️

What are homeotherms

(What humans are)

Maintains constant body core temperature

Heat loss must match heat gain

What is the normal core temperature

37° C

What can too high core temp cause

Damaged proteins and enzymes

What can too low core temperature cause

Decrease metabolism and cardiac arrhythmias

What gradient exists between body core and skin temperature and what is the ideal gradient

A thermal gradient

Ideal = 4°C

How is core temp measured

At there rectum, ear or esophagus

How is skin temp measured

Thermistos in various locations then averaging the total of them

What are the involuntary ways of producing heat

Shivering or action of hormones (non-shivering thermogenesis)

What are the mechanisms of heat loss

Radiation - transfer of heat via infrared rays

Conduction - heat loss due to contact with other surfaces

Convection - heat transfered from body to air or water

Evaporation - water (sweat) gains sufficient heat, water is converted to has. Requires vapor pressure gradient between skin and air.

What does evaporation depend on

• Temp and relative humidity

• Convective currents around the body

• Amount of skin surface exposed to the environement

• Aerobic fitness level

What is the body’s internal thermostat

The preoptic anterior hypothalamus (POAH)

What does the preoptic anterior hypothalamus control

Body’s control of core temp: Sweat glands and shivering mechanisms

What is a fever

When body temp is above normal due to pyrogens (proteins or toxins from bacteria)

What are the effects of exercise related to temperature

Heat production increases

Body temp increases

Core temp increases proportionally to active muscle mass

Increased reliance on evaporation heat loss

What does an increase in ambient temp cause

Exercise-induced heat production remains constant

Lower convective and radient heat loss

Higher evaporative heat loss

What does exercising in a hot environment cuase

Reduces the ability to lose body heat

This causes

• Higher core temp

• Higher heart rate

• Risk of hyperthermia

Higher sweat rate

• Increases risk of dehydration

What is the heat index

Measure of bodys perception of how hot it feels

Ex. air temp is 28 C but body feels like 32 C

What are some ways to prevent exercise-related heat injuries

• Exercise during the coolest part of the day

• Minimize exercise intensity and duration on hot/humid days

• Expose maximal surface area of skin

• Give frequent breaks with equipment removal

• Drink lots of water

• Rest in shared areas

• Measure body weight at the start and end of training to determine the fluid replacement required

What factors contrimute to imparied exercise performance in the heat

• Accelerated muscle fatigue

• Cardiovascular dysfunction

• Central nervous system dysfunction

What is acclimation

Rapid adaption to environment change (days to weeks)

What is acclimatization

Apadtion over a long time period (weeks to months)

What are the physiological adapatations during heat acclimation

1. Increased plasma volume

2. Earlier onset of sweating and higher sweat rate

3. Reduced sodium chloride loss in sweat

4. Reduced skin blood flow

5. Increased cellular heat shock proteins

What are heat shock proteins

Protect cells from thermal injury and can stabilize and refold damaged proteins

What is hypothemia

Large decrease in body core temp

How does age impact cold tolerance

Elderly individuals who dont have much muscle mass are at greater risk of hypothermia due to the reduced shivering-induced thermogenesis