Thermoregulation

Question 1

What is the normal range for core body temperature?

Answer 1

36.3 - 37.1 C

Question 2

When is the core body temperature lowest?

Answer 2

Around 06:00

Question 3

What information do cutaneous thermoreceptors convey?

Answer 3

Environmental conditions, are warm or cold sensitive (10x more cold sensitive). Are often both temperature and touch sensitive (bimodal)

Question 4

Why are there thermoreceptors in the gut?

Answer 4

To sense core temp and to monitor potential ingested threats to body (ex: cold ice cream)

Question 5

Which parts of the hypothalamus respond to heat vs cooling?

Answer 5

Anterior responds to heat with heat loss behaviors

Posterior responds to cooling with heat production behaviors

Question 6

As environmental temperature drops, what parts of the body are least regulated in terms of temperature?

Answer 6

Hands and feet

Question 7

How much can core temperature vary throughout the day?

Answer 7

1-2 degrees

Question 8

How are cutaneous thermoreceptors bimodal?

Answer 8

They respond to both temperature and mechanical stimuli

Question 9

Are there more cold or heat thermoreceptors in the skin?

Answer 9

10x more cold sensitive

Question 10

Are there more cold or heat thermoreceptors in the brain?

Answer 10

3x more warm sensitive, specifically in the hypothalamus

Question 11

Where are the thermoreceptors located in the hypothalamus?

Answer 11

Pre-optic and supreroptic regions

there are 3x as many warm-sensitive receptors in the neuron cell bodies

Question 12

How does the hypothalamus respond to temperature changes?

Answer 12

It influences hormonal, autonomic, and behavioral changes

Question 13

How can the “set point” for core temperature change?

Answer 13

Decreases when we sleep and increases with exercise

Question 14

What helps babies stay warm?

Answer 14

Brown adipose tissue

Question 15

How does muscular activity help in heat production?

Answer 15

Shivering and increase in voluntary activity (jumping, running, etc)

Question 16

What part of the brain causes shivering and how?

Answer 16

Dorsomedial posterior hypothalamus - sends axons to motor neurons to increase excitability

Question 17

What types of non-shivering thermogenesis are there?

Answer 17

Hormones - thyroxin (metabolic rate) and epinephrine
Increase food intake (increase metabolism)
Brown adipose tissue - mostly babies

Question 18

What is brown adipose tissue innervated by?

Answer 18

Sympathetic nervous system

Question 19

What kinds of heat loss methods do humans have?

Answer 19

Insensible (respiratory)

Sweating

Question 20

What is convection?

Answer 20

Movement of molecules away from contact (air heating and rising)

Question 21

What is conduction?

Answer 21

Transfer of heat between objects in phpysical contact with one another

Question 22

What is radiation?

Answer 22

Infrared radiation transferring heat between 2 objects not in physical contact

Question 23

What innervates sweat glands?

Answer 23

Sympathetic nervous system - ACh

Question 24

What molecules are reabsorbed along the length of the sweat gland?

Answer 24

Na, Cl, H2O

Question 25

What causes a fever?

Answer 25

In the presence of endotoxins secreted by pathogens, cytokines are released (prostaglandin E2) so the hypothalamus increases the body’s core temperature set point