Temperature Regulation Flashcards
Mechanisms to REDUCE Body Heat.
POAH Activation
- Vaso-DILATION
- Sweating
- Decrease Heat Production
How is Chem. Thermogenesis related to Brown Fat?
DIRECTLY Related to Brown Fat
What acts as heat insulators?
Skin and SubQ
The Hypothalamus is one of the few brain areas where neurons are found that are what?
Themselves directly sensitive to PHYSICAL and CHEMICAL Variables
Factors that determine Rate of heat loss
How rapidly heat can be:
- CONDUCTED from body Core to Skin
- TRANSFERRED from Skin to Surroundings
Malignant Hyperthermia
- Caused by inhaling anesthetics
- Massive increase in O2 consumption
- Massive heat production by Sk Muscle
- Rapid Rise in Body temp
Uncoupling Protein in Mitochondria
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
How is Chemical Thermogenesis Related to Nor/Epinephrine?
Uncouples oxidative phosphorylation
Feedback Gain Eq.
Change in envrt temp. “E” (~28) divided by the Change in body core temp “B” (~1) minus 1
(E/B) - 1
Heat Exhaustion
- Caused By excessive sweating
- Blood vol and BP decrease
- Faints
Vasoconstriction is almost entirely controlled by what?
Sympathetic System
What principal areas of the brain that affect body temp?
- Ant. Pre-Optic Area
- Medial Pre-Optic Area
* AKA Ant. Preoptic Hypothalamus *
Temperature Set Point is essentially a Fxn of What?
The Activity of the WARM-Sensitive Neurons of the PRE-Optic ANT. Hypothalamus
*POAH
Heat is a byproduct resulting from what?
- BMR
- Muscle activity
- Thyroxine
- Nor/Epinephrine
- Metabolism for digestion/storage
Increase in Aldosterone has what affect on sweat composition?
- Higher [Sodium]
- Lower amount of sweat produced
Heat storage equals:
(Metabolism - Work) +/- (Conv+Cond+Rad) - Evap
Fxn of Aspirin
- Decrease set-point temp
- Inhibiting Cyclooxygenase
- Results in decrease in production of Prostaglandins
Shivering signals originate from where?
Dorso-Medial Portion of the POST. Hypothalamus
Mechanisms of Heat loss from the Skin
- Radiation (60%)
- Infrared heat rays - Conduction (18%)
- Kinetic Energy - Convection
- Removal of heat from the body by air currents - Evaporation (22%)
What increases set point temp?
IL-1 and Prostaglandins
Why do we have fevers?
Most bacteria proliferate poorly at temp above 39 degrees Celsius
What effects of increased thyroxine output has on metabolism?
Activates uncoupling Protein
Malignant Hypothermia
- A Syndrome where heat Production is GREATER than Heat Dissipation
- Due to RYANODINE Receptors in Sk Muscle
(Leads to excess Ca2+) - Triggered by Anesthetics
Mechanisms to INCREASE Body Heat
- Skin Vaso-CONSTRICTION
- Piloerection
- Increase Thermo-genesis
How much increase in conductance b/w fully vasoconstricted state to fully vasodilated state?
8x
