Thermoregulation

Question 1

Define shell temperature?

Answer 1

Temp which is 1-6 degrees lower than core temperature.

Question 2

How does a body maintains their core temperature ?

Answer 2

If the rate of body heat production equals the rate of heat loss, the body maintains a constant core temperature.

Question 3

Disadvantages of core temperature ?

Answer 3

• A core temperature that is too high kills by denaturing body proteins
• A core temperature that is too low causes cardiac arrhythmias that result in death

Question 4

What are the factors that affect heat production?

Answer 4

• exercise
• Hormones : Thyroid hormones (thyroxine and triiodothyronine), Insulin, testosterone, growth, hormone increases BMR
• Nervous System: Epinephrine and norepinephrine increases the metabolic rate of body cells
• Illness: Metabolic rate may be increased substantially during fever
• Food induced thermogenesis
• Age and gender

Question 5

What are the main regulators of BMR?

Answer 5

Thyroid hormone - thyroxine and triiodothyronine

Question 6

How does age and gender influence in production of heat

Answer 6

• Metabolic rate of a child is higher
• The rate is higher for males rather than females

Question 7

Define TEF

Answer 7

The thermic effect of food or diet-induced thermogenesis is a small increase in metabolic rate that occurs after eating as a result of digestion, absorption, and utilization of the ingested nutrient.
( proteins produced the largest metabolic rate.)

Question 8

What are the mechanisms of heat transfer?

Answer 8

• Maintaining the normal body temperature depends on the ability to lose heat to the environment at the same rate as it is produced by metabolic reaction
• 3% is lost via conduction to solid materials in contact with the body.
• Contact of air or water with your body results in heat transfer by both conduction and convection
  Rest 15% of body heat is lost that way
• At room temp. 21 degree, about 60% of heat loss occurs via Radiation in a resting person
• 22% of heat loss occurs via evaporation.
  Water loss through skin and mucous membranes of the mouth and respiratory system.

Question 9

What is hypothalamic thermostat?/
What is preoptic area?

Answer 9

• Body’s thermostat is a group of neurons in the anterior part of the hypothalamus called the preoptic area
  -Neuron impulse propagates from the preoptic area to 2 other parts of the hypothalamus- heat losing center and heat-promoting center which gives out the response.

Question 10

How is thermoregulation maintained ?

Answer 10

They are maintained by negative feedback loops.

Question 11

What are the different effectors?

Answer 11

• Skin : Vasoconstriction decreases heat loss
• Adrenal medulla hormones increase cellular metabolism
• Skeletal muscles: contract in rep. cycle called shivering
• Thyroid gland: releases thyroid hormones which increases metabolic rate

Question 12

What happens if core temperature rises ?

Answer 12

• Nerve impulses from heat losing center causes dilation of blood vessels in the skin
• High temp. of the blood stimulates sweat glands via hypothalamus