WK7-Temperature Regulation Flashcards
List the different ways that the body produces heat. Additionally how effective is the body at using energy ?
The body produces internal heat due to normal metabolic process
Production can be classified as either voluntary or involuntary.
Involuntary heat production comes from hormones that may cause an increase in metabolic function, or shivering. Voluntary would be doing exercise.
The body is only about 20-30% efficient, this results in 70-80% of the energy expended during exercise to be heat.
List the different ways that the body loses heat.
- Radiation-heat loss in infrared waves, heat transfer without direct contact
- Conduction- transfer of heat from a warmer object to a cooler object through direct contact
- Convection- loss of heat through transmission of it to air and water molecules
- Evaporation- evaporation of sweat that has acquired heat from the body
Discuss the thermoreceptors and their function during changes in body temperature during hot and cold.
In the presence of both heat and cold trigger thermoreceptors first in the skin then in the core to send signals to the thermo-regulatory center called the preoptic- anterior hypothalamus which maintains temperature at a ‘set point’.
During heat load, the POAH responds by vasodilating cutaneous vessels to increase heat loss, and triggering sweating from the sweat glands, this stimulation ends when the body has returned to its normal set point.
During Cold exposure, the POAH triggers cutaneous vasoconstriction, shivering, the release of catelcholamines, and release of thyroxin
What is the relationship between exercise intensity and body temperature ?
Body temperature tends to increase as intensity increases regardless of exercise environment temperature as different environments tend to shift heat loss to different mechanisms.
How does heat distribution occur in both the nervous system and the venous system ?
As exercise intensity increases so does heat production, this heat warms the blood and this change in heat is sensed by the thermo sensors in the POAH which compares this temperature to the set point and tries to correct it by initiating sweating and blood flow to the skin. At this point core temperature has reached a steady level but the set point has not changed, instead the body simply cannot regulate well enough.
What is accelerated muscle fatigue and how does it occur ?
Accelerated muscle fatigue describes the fastened muscular fatigue due to hot conditions. Muscle glycogen depletion is increased, the muscle produces more lactate therefore lowering the pH in the muscle, and lastly free radical production is increased.
Why is exercise in hot and humid environments stressful challenge to maintain body temperature ?
Exercise in hot and humid conditions reduces the body’s capacity to release heat through radation/convection and evaporation, this raises core temperature which increases the rate of sweating and results in body fluid loss. This combined effect can lead to hyperthermia, and hyponatremia.
Describe how sweat rates vary during exercise and what factors can affect this rate.
Exercise in hot environments increases the rate of sweat production, people who are accustomed to exercise in the heat may have an earlier onset of sweating and a higher sweat rate, moreover larger individuals may also have a higher rate of sweat production, genetics also play a role.
How does ageing impact thermoregulation ?
Generally, older persons cannot thermoregulate as well as younger people due to reduced skin blood flow during exercise in the heat, heat acclimation however, can improve heat tolerance in older individuals
Contrast acclimatization and acclimation and what acclimation individuals can have to exercise in hot environments.
Acclimatization: long term physiological adaptations to a natural environment
Acclimation: short term, adjustments of the body to stresses; lower HR, and core temp during sub max exercise
What are the physiological changes that occur to a person exercising in a cold environment ?
Vasoconstriction of extremities, increased metabolic heat production, and shivering.
What factors affect body heat loss during cold exposure ?
individuals with a higher percentage of body fat have more insulation against heat exchange with cold environments. age can also have an effect, the children and the elderly tend to have less mass per surface and therefore there is more heat lost.
What are the physiological adaptations to the cold ( acclimation ) ?
Reduced temperature for the onset of shivering, higher mean hand and foot temperature, improved ability to sleep in the cold.
