Thermoregulation Flashcards
How do core and shell temperatures differ (range of external temperatures of 23-35 Celsius)?
Core temperature precisely regulated between 37 and 37.5 celcius; shell temperature varies considerably depending on environmental conditions, between 31 and 35 Celsius
What is the thermoneutral zone?
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
Why does body temperature follow a diurnal pattern?
Due to metabolic activity being low in early hours, and high in early afternoon hours
How might daylight affect the diurnal pattern of body temperature?
When on bed rest, body will maintain diurnal rhythm initially in response to light as body is accustomed to these patterns
What are the four physics-y mechanisms of heat exchange?
Sweating (evaporation), conduction, convection, radiation
What are the three ways of heat production to regulate body temperature?
Shivering thermogenesis. voluntary muscular contraction, non-shivering thermogenesis
What are the three ways of heat loss to regulate body temperature?
Increase blood to skin, sweating
How does the body increase heat loss from blood to skin?
Reduced sympathetic stimulation vasodilates vessels; ACh vasodilates vessels in skin away from extremeties
How does the body increase sweating?
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
What are the dangers of excessive sweating?
Body may not have enough time to reabsorb electrolytes (Na+ and Cl-) at high rates of sweating, leading to loss of electrolytes
How does the body decrease heat loss from the blood to skin?
Sympathetic stimulation vasoconstricts vessels; sympathetic nerve fibres release Epi from adrenal medulla, which vasoconstricts in tissues with alpha adrenergic receptors
What is the hunting reaction during long exposure to low temperatures?
Skin circulation often shows intermittent periods of vasodilation; theorised is due to periodic insensitivity to NE; possibly to prevent frostbite
How do motor neurons compensate for low temperatures?
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
What occurs to body temperature during exercise?
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
What is acclimatisation to heat during exercise?
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)
