Thermoregulation Flashcards Preview

A Human Physiology > Thermoregulation > Flashcards

Flashcards in Thermoregulation Deck (16)
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1
Q

How do core and shell temperatures differ (range of external temperatures of 23-35 Celsius)?

A

Core temperature precisely regulated between 37 and 37.5 celcius; shell temperature varies considerably depending on environmental conditions, between 31 and 35 Celsius

2
Q

What is the thermoneutral zone?

A

Range of environmental temperatures over which body maintains core temperature with ease; alterations of skin blood flow are enough to achieve a steady core temperature; 27-31 Celsius

3
Q

Why does body temperature follow a diurnal pattern?

A

Due to metabolic activity being low in early hours, and high in early afternoon hours

4
Q

How might daylight affect the diurnal pattern of body temperature?

A

When on bed rest, body will maintain diurnal rhythm initially in response to light as body is accustomed to these patterns

5
Q

What are the four physics-y mechanisms of heat exchange?

A

Sweating (evaporation), conduction, convection, radiation

6
Q

What are the three ways of heat production to regulate body temperature?

A

Shivering thermogenesis. voluntary muscular contraction, non-shivering thermogenesis

7
Q

What are the three ways of heat loss to regulate body temperature?

A

Increase blood to skin, sweating

8
Q

How does the body increase heat loss from blood to skin?

A

Reduced sympathetic stimulation vasodilates vessels; ACh vasodilates vessels in skin away from extremeties

9
Q

How does the body increase sweating?

A

Sympathetic nerve fibres release Epi, which increases perspiration; sympathetic activity stimulates sweating as sweat glands are innervated by cholinergic nerve fibres, and have muscarinic receptors; catecholamines stimulate sweat stimulation

10
Q

What are the dangers of excessive sweating?

A

Body may not have enough time to reabsorb electrolytes (Na+ and Cl-) at high rates of sweating, leading to loss of electrolytes

11
Q

How does the body decrease heat loss from the blood to skin?

A

Sympathetic stimulation vasoconstricts vessels; sympathetic nerve fibres release Epi from adrenal medulla, which vasoconstricts in tissues with alpha adrenergic receptors

12
Q

What is the hunting reaction during long exposure to low temperatures?

A

Skin circulation often shows intermittent periods of vasodilation; theorised is due to periodic insensitivity to NE; possibly to prevent frostbite

13
Q

How do motor neurons compensate for low temperatures?

A

Somatic motor neurons stimulate shivering, a specialised form of muscular contraction in which muscle perform no external work, so virtually all energy released during ATP hydrolysis is converted to heat

14
Q

What occurs to body temperature during exercise?

A

Body temperature undergoes set-point resetting to a higher temperature. Higher set-point has functional implication for muscular contractions, as muscles contract more efficiently at higher temperature

15
Q

What is acclimatisation to heat during exercise?

A

Can regulate temperature more efficiently in a higher temperature environment; causes: more sweating and sooner; more dilute sweat to conserve electrolytes, increased blood flow to skin, increased blood volume and SV, decreased core temperature, HR, and glycogen use (reduced fatigue)

16
Q

How does acclimatisation to heat during exercise occur?

A

Involves repeated exposure to heat, and begins after 5-10 days of prolonged exercise in heat