Temperature Regulation

Question 1

Mechanisms to REDUCE Body Heat.

Answer 1

POAH Activation

1. Vaso-DILATION
2. Sweating
3. Decrease Heat Production

Question 2

How is Chem. Thermogenesis related to Brown Fat?

Answer 2

DIRECTLY Related to Brown Fat

Question 3

What acts as heat insulators?

Answer 3

Skin and SubQ

Question 4

The Hypothalamus is one of the few brain areas where neurons are found that are what?

Answer 4

Themselves directly sensitive to PHYSICAL and CHEMICAL Variables

Question 5

Factors that determine Rate of heat loss

Answer 5

How rapidly heat can be:

1. CONDUCTED from body Core to Skin
2. TRANSFERRED from Skin to Surroundings

Question 6

Malignant Hyperthermia

Answer 6

• Caused by inhaling anesthetics
• Massive increase in O2 consumption
• Massive heat production by Sk Muscle
• Rapid Rise in Body temp

Question 7

Uncoupling Protein in Mitochondria

Answer 7

An INNER Membrane protein can dissipate the PROTON gradient before it can be used to provide energy for oxidative phosphorylation
-> Energy used to generate heat

Question 8

How is Chemical Thermogenesis Related to Nor/Epinephrine?

Answer 8

Uncouples oxidative phosphorylation

Question 9

Feedback Gain Eq.

Answer 9

Change in envrt temp. “E” (~28) divided by the Change in body core temp “B” (~1) minus 1

(E/B) - 1

Question 10

Heat Exhaustion

Answer 10

• Caused By excessive sweating
• Blood vol and BP decrease
• Faints

Question 11

Vasoconstriction is almost entirely controlled by what?

Answer 11

Sympathetic System

Question 12

What principal areas of the brain that affect body temp?

Answer 12

1. Ant. Pre-Optic Area
2. Medial Pre-Optic Area
   * AKA Ant. Preoptic Hypothalamus *

Question 13

Temperature Set Point is essentially a Fxn of What?

Answer 13

The Activity of the WARM-Sensitive Neurons of the PRE-Optic ANT. Hypothalamus

*POAH

Question 14

Heat is a byproduct resulting from what?

Answer 14

• BMR
• Muscle activity
• Thyroxine
• Nor/Epinephrine
• Metabolism for digestion/storage

Question 15

Increase in Aldosterone has what affect on sweat composition?

Answer 15

• Higher [Sodium]

- Lower amount of sweat produced

Question 16

Heat storage equals:

Answer 16

(Metabolism - Work) +/- (Conv+Cond+Rad) - Evap

Question 17

Fxn of Aspirin

Answer 17

• Decrease set-point temp
• Inhibiting Cyclooxygenase
• Results in decrease in production of Prostaglandins

Question 18

Shivering signals originate from where?

Answer 18

Dorso-Medial Portion of the POST. Hypothalamus

Question 19

Mechanisms of Heat loss from the Skin

Answer 19

1. Radiation (60%)
   - Infrared heat rays
2. Conduction (18%)
   - Kinetic Energy
3. Convection
   - Removal of heat from the body by air currents
4. Evaporation (22%)

Question 20

What increases set point temp?

Answer 20

IL-1 and Prostaglandins

Question 21

Why do we have fevers?

Answer 21

Most bacteria proliferate poorly at temp above 39 degrees Celsius

Question 22

What effects of increased thyroxine output has on metabolism?

Answer 22

Activates uncoupling Protein

Question 23

Malignant Hypothermia

Answer 23

• A Syndrome where heat Production is GREATER than Heat Dissipation
• Due to RYANODINE Receptors in Sk Muscle
  (Leads to excess Ca2+)
• Triggered by Anesthetics

Question 24

Mechanisms to INCREASE Body Heat

Answer 24

1. Skin Vaso-CONSTRICTION
2. Piloerection
3. Increase Thermo-genesis

Question 25

How much increase in conductance b/w fully vasoconstricted state to fully vasodilated state?

Answer 25

8x