SDL 🧑‍💻

Question 1

what are the heat generating mechanisms in response to cold?

Answer 1

• Thyroid Hormone
• Sympathetic Fibers
• Shivering

Question 2

what is the effect of thyroid hormone in response to cold?

Answer 2

• Increases metabolic rate and heat production by stimulating Na K* ATPase.

Question 3

what is the effect of sympathetic fibers in response to cold?

Answer 3

Activate beta-receptors in brown fat, increase metabolic rate and heat production.

Question 4

what is the most potent mechanism for increasing heat production?

Answer 4

Shivering

Question 5

what is the site of the shivering Center?

Answer 5

posterior hypothalamus.

Question 6

what is the effect of shivering in response to cold?

Answer 6

alpha-Motoneurons and y-motoneurons are activated, causing contraction of skeletal muscle and heat production.

Question 7

Heat-loss mechanisms in response to heat

Answer 7

Question 8

where does heat-loss Mechanisms take place?

Answer 8

Anterior hypothalamus

Question 9

what is the site and the function of temperature sensors?

Answer 9

On skin and in hypothalamus read the core temperature and relay this information to the anterior hypothalamus.

Question 10

what is the function of heat regulatory Center?

Answer 10

Compares the detected core temperature to the set-point temperature

• If the core temperature is below the set point: heat-generating mechanisms (eg. increased metabolism, shivering, vasoconstriction of cutaneous blood vessels) are activated by the posterior hypothalamus
• If the core temperature is above the set point: mechanisms for heat loss (eg, vasodilation of the cutaneous blood vessels, increased sympathetic outflow to the sweat glands) are activated by the anterior hypothalamus.

Question 11

what is the mechanism of fever?

Answer 11

• Pyrogens as interlukin 1 (IL- 1)acts on the anterior Hypothalamus to increase prostaglandins production.
• Prostaglandins increase the set-point temperature.
• Core temperature will be recognized as lower than the new set-point temperature by the anterior hypothalamus. As a result, heat generating mechanisms (eg, shivering) will be initiated.

Question 12

how does aspirin reduce fever?

Answer 12

• Inhibiting COX leading to inhibition of the production of prostaglandin leading to decrease of the set-point temperature.
• In response, mechanisms that cause heat loss (eg, sweating, vasodilation) are activated.

Question 13

how do steroids reduce fever?

Answer 13

• Blocking the release of arachidonic acid from brain phospholipids, thereby preventing the production of prostaglandins.

Question 14

what causes heat exhaustion?

Answer 14

excessive sweating

Question 15

what is the result of excessive sweating in heat exhaustion?

Answer 15

blood volume and arterial blood pressure decrease and syncope (fainting)occurs.

Question 16

when does heat stroke Take place?

Answer 16

Occurs when body temperature increases to the point of tissue damage. (Due to severe hypotension)

Question 17

what happens in heat stroke?

Answer 17

The normal response to increased ambient temperature (sweating) is impaired, and core temperature increases further.

Question 18

what causes hypothermia?

Answer 18

Results when the ambient temperature is so low that heat-generating mechanisms (e.g. shivering, metabolism) cannot adequately maintain core temperature near the set point.

Question 19

what causes malignant hyperthermia?

Answer 19

• Caused in susceptible individuals by inhalation anesthetics.

Question 20

what are the characteristics of Malignant hyperthermia?

Answer 20

• Characterized by a massive increase in oxygen consumption and heat production by skeletal muscle, which causes a rapid rise in body temperature.