KIN 103 Midterm (Lecture 6-7) Flashcards
Thermogenesis (Definition)
Temperature regulation is related to metabolic heat production
Human body temperature (What is our average range?)
Body temperature is maintained within a
narrow range.
Average = 37°C.
Range = 35.5°C to 37.7°C
Sources of heat input
- radiant energy
- conductive energy
- metabolism
- muscle contraction
Sources of heat loss
- Radiant (most heat loss)
▫Given off by anything warmer than zero. - Conductive
▫Heat lost when touching cooler object. - Convection
▫Air currents resulting from temperature differences. - Evaporation
▫Heat lost from water evaporation at the skin or lungs.
What controls body temperature?
- Autonomic control of body temperature is
controlled by the hypothalamus.
▫ Thermoregulatory centers.
Thermoreceptors (Where are they found?)
- Thermoreceptors monitor changes in
body temperature and send the sensory
information to the thermoregulatory
centers.
▫ Hypothalamus.
▫ Skin.
Mechanisms To Regulate Body Temperature (What are the 4?)
Mechanisms To Regulate Body Temperature:
1. Adjusting Blood Flow Distribution.
2. Sweating.
3. Increasing metabolic activity.
4. Hormonal Regulation.
Cutaneous blood vessels (What do they do?)
- Cutaneous blood vessel can either:
▫ Gain heat from the environment.
▫ Lose heat to the surrounding air.
What happens if core temperature decreases?
- the hypothalamus activates sympathetic adrenergic neurons innervating the cutaneous blood vessels.
- Vasoconstriction of the cutaneous
blood vessels.
What happens if core temperature increases?
- Sympathetic cholinergic neurons are stimulated
- This causes sweating or vasoconstriction
to send blood to the skin
- This causes sweating or vasoconstriction
Hormonal thermoregulation (What happens?)
Hormonal Regulation
* Increased release of epinephrine and
norepinephrine can increase heat
production during cold exposure.
* When cold exposure is prolonged the
thyroid gland releases more thyroxine
to elevate resting metabolic rate (RMR).
Acclimatization (Definition)
Acclimatization: Living in the hot environment
Acclimation (Definition)
Acclimation: Simulating the hot
environment
Vasopressin does what in thermoregulation?
Vasopressin (a.k.a. Antidiuretic Hormone)
▫ Increases water reabsorption in the renal tubules.
Aldosterone does what in thermoregulation?
Aldosterone (Sodium reobsorbtion)
▫ Increases reabsorption of sodium in the renal tubules reduces involuntary sodium loss.
▫ This also results in more dilute sweat (reduces the osmolarity of sweat) an feature of acclimatization.
▫ In cases of severe dehydration the Aldosterone response could become inhibited.
What is the most we can sweat in an hour?
Sweat loss peaks at approximately
3 liters/hour during intense exercise in
the heat.
Dehydration (Effects on the body?)
Dehydration
* When sweating leads to dehydration a number of consequences can result:
▫ Reduced plasma volume.
▫ Increased heart rate.
▫ Reduced rate of sweating.
▫ Impaired thermoregulation.
▫ Increased fatigue.
▫ Reduced performance.
What happens to cardiac output in hot environments?
- Its max is reduced
- it must be shared with thermoregulatory responses alongside muscles
The Fick equation (Equation)
VO2 = Q x (a – v)O2 difference
10 METs is equal to?
10 METS = 35.0 ml/kg/min
- those who can do 10 METs are said to have low risk of death due to cardiovascular diseases
