Thermoregulation (Karius)

Question 1

What parts of the body change temperature the most rapidly?

Answer 1

Feet, then hands, then skin

Question 2

About how much does the core temperature change throughout the day?

Answer 2

1-2 degrees

Lowest at 6 am

Question 3

What measures core temperature & the temperature around us?

Answer 3

Thermal Receptors

Question 4

What are the cutaneous thermoreceptors most sensitive to?

Answer 4

Cold (10x as much as warm)

Question 5

What information do the visceral thermoreceptors transmit?

Answer 5

Threats from ingested food that may change body temperature => hypothalamus

• Example: ice cream (causes brain freeze which would decrease blood temp. of brain)

Question 6

Where are the thermoreceptors of the brain located?

Answer 6

Pre-optic and superoptic region of hypothalamus

Question 7

What are the thermoreceptors in the brain most sensitive to?

Answer 7

Heat (3x as much as cold)

Question 8

What structure determines the set body temperature, receives info about current temperature and decides what to do?

Answer 8

Hypothalamus

Question 9

What happens to the core temperature when you sleep and exercise?

Answer 9

• Sleep: T decreases b/c set point decreases
• Exercise: T increases b/c set point increases

Question 10

What receptors determine the core temperature of the body

Answer 10

Visceral and hypothalamic (preoptic & superoptic) thermal receptors

Question 11

What does the posterior region of hypothalamus respond to?

Answer 11

Responds to cold by activating heat producing behavior

Question 12

What does the anterior region of the hypothalamus respond to?

Answer 12

Responds to heat by activating heat loss behaviors

Question 13

Why do babies need more adipose tissue?

Answer 13

Babies have higher surface area in proportion to size and will lose heat faster than adults

Question 14

What systems can be used to produce heat

Answer 14

• Autonomic nervous system (esp. sympathetic)
• Endocrine
  
  • Thyroxine
  • Epinephrine
• Muscular activity
  
  • Voluntary
  • Involuntary (shivering)
• Non-shivering thermogenesis
  
  • increase in metabolism

Question 15

What part of the hypothalamus is responsible for shivering?

How does it do this?

Answer 15

Dorsomedial posterior hypothalamus => increase motor neuron excitation

You are cold and trying to produce heat

Question 16

What division of the autonomic nervous system is involved in heat production?

Answer 16

Sympathetic Nervous System

Question 17

In non-shivering thermogenesis, what hormone is released in response to cold?

Answer 17

Thyroxin-Releasing hormone => Thyroxin

Epinephrine

Question 18

What activates hydrolysis of ATP in brown fat?

Answer 18

Sympathetic fibers & circulating Epinephrine

Question 19

How is Brown Adipose Tissue used to produce heat

Answer 19

Hydrolysis of ATP via uncoupling proteins leads to heat production

Question 20

What are the two kids of evaporative heat loss?

Answer 20

Insensible (respiratory)

Sweating (controlled)

Question 21

What is convection?

Answer 21

Movement of molecules away from contact

Air Heating and Rising

Question 22

What is conduction?

Answer 22

Transfer of heat between objects in physical contact with one another

heat from body dissipating to chair

Question 23

What is radiation?

Answer 23

Transfer of heat between 2 objects that are not in physical contact

Question 24

What is the innervation to the sweat glands?
Activated by what NT & what receptor does it bind?

Answer 24

Sympathetic cholinergic innervation

NT: Acetylcholine - binds mAChR

Question 25

If there is a low flow rate of sweat, what is the sodium concentration in sweat?

Answer 25

High (couldn't follow water)

Question 26

If there is a high flow rate of sweating, what is the sodium concentration?

Answer 26

Low (no time to reabsorb water)

Question 27

What happens to the body when there is a fever?

Answer 27

Set Point increases and will be greater than body temperature * Endotoxins and Prostaglandin released

Question 28

**Explain the following characteristics of a Fever** 1. Core Temp 2. Set Point 3. Active Thermoregulatory response 4. Signs present 5. Subjective perception 6. Cause

Answer 28

1. Increased 2. Increases 3. Heat production 4. Pallor, shivering, behavioral changes associated with being cold 5. Subjectively cold 6. Infectious agents producing inflammatory mediators acting in brain

Question 29

**Explain the following characteristics of Hyperthermia** 1. Core Temp 2. Set Point 3. Active Thermoregulatory response 4. Signs present 5. Subjective perception 6. Cause

Answer 29

1. Increased 2. Normal 3. Heat loss 4. Flushes skin, sweating, behavioral changes associated with being hot 5. Patient describes as being hot 6. Increased heat production or decreased ability to eliminate heat (dehydration)

Question 30

How does the hypothalamus regulate the autonomic nervous system for thermoregulation

Answer 30

* Dorsal longitudinal fasiculus (MAJOR) * Medial forebrain bundle * Mammillotegmental tract

Question 31

What is the major hypothalamic nucleus associated with autonomic control of temperature

Answer 31

Paraventricular nuclei via dorsal longitudinal fasciculus (DLF)

Question 32

Where does the dorsal longitudinal fasciculus send it's axons

Answer 32

Dorsal motor nucleus of the vagus Nucleus ambgiguous Parasympathetic and sympathetic neurons in spinal cord