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Flashcards in Body Temperature Regulation Deck (32)
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1

Why is it important for core temperature to be regulated?

Cannot survive if not functioning

2

What influences the rate of hear production?

Basal rate metabolism
Metabolism inc by muscular activity
Metabolism inc by sympathetic stimulation
Metabolism inc by hormonal effect on cells
Metabolism inc by inc chemical production
Inc digestion, absorption and storage of food

3

Where is most heat lost?

Through the skin

4

What are some barriers to heat transfer?

Insulation
Skin
SubQ tissue
Fat - conducts 1/3 more heat than other tissues

5

Where are the temperature regulating centers?

Preoptic and anterior hypothalamic nuclei

6

What is the main mediator of fever when there is an infection?

Pyrogenic

7

What regulates homeostatic mechanisms to maintain a body temp set point?

Hypothalamus

8

What ate the mechanism to increase body temp?

Vasconstriction
Thermogenesis
Piloerection

9

What is vasoconstriction?

Tightening of vasculature in the skin

10

What is vasoconstriction mediated by?

Tonic sympathetic control - noradrenergic
Nonglabrous (hairy) glabrous (palm, soles), skin all have sympathetic inn

11

What is thermogenesis?

Shivering to inc heat production
Chemical by sympathetic stimulation and thyroxin

12

What are the chemical thermogenesis agents?

Norepinephrine and epinephrine

13

How is thermogenesis stimulated?

By the uncoupling oxidative phosphorylation in mitochondria so heat, not ATP, is released

14

Where does the most uncoupling oxidative phosphorylation occur?

In brown fat

15

What does thyroxin do as a chemical thermogenesis?

Increases the rate of cellular metabolism

16

When does thyroxin being working?

After a prolonged amount of time (weeks) in exposure to low temps

17

What is piloerection?

Sympathetic stimulation which causes contraction of arrector pili muscles creating a later of insulating air

18

What is hypothermia?

Heat loss occurring from radiation, conduction, convection, evaporation or respiration

19

What are some causes of hypothermia?

Extensive exposure to cold
Endocrine dysfunction
Drugs
Neurologic injury

20

What are some mechanisms to dec body temp?

Vasodilation
Sweating
Dec heat production

21

What is vasodilation?

Opening of the vasculature of the skin
Sympathetically controlled - cholinergic receptors cotransmission with roles for nitric oxide, vasoactive intestinal peptide, protoglandins and substance P

22

Raynaud's syndrome

Hyperreactive vasoconstriction of periphery (vasospasm) activated by cold or emotional stimulus
Severe - ischemia-reperfusion injury

23

Erythromelalgia

Rare disorder that is characterized by burning pain, warmth and redness of extremities

24

What is hyperthermia and what are its causes?

Core temp higher than 38C
Thermoregulatory failure from drugs or severe brain injury

25

What is hyperpyrexia?

Core temperature above 41.5

26

What is malignant hyperthermia?

A genetic disorder, mutation of ryanodine receptor (RYR1)
In response to anesthetics/succinylcholine, intracell Ca2+ release is elevated so muscle metabolism inc and become rigid
Acidosis

27

What is fever?

Controlled inc in core temperature

28

What is the main cause fever response?

Pyrogen (any substance that causes a fever)

29

What are exogenous pyrogens?

Microbial product, toxin or whole microbe
Gram neg (all) - LPS
Gram pos - enterotoxin (S. aureus), group A & B step toxin

30

What are endogenous pyrogens?

Cytokines
IL-1, IL-6, TNF, ciliary neurotrophic factor (CNTF), interferon alpha