Exam Phys concepts extra Flashcards
Which type of sweat gland is used for thermoregulatory sweating?
Eccrine
Are eccrine sweat glands regulated by cholinergic or adrenergic innervation?
cholinergic
Are eapocrine sweat glands regulated by cholinergic or adrenergic innervation?
adrenergic
Where on the body are eccrine sweat glands more nuerous?
Thick skinned areas: soles of feet, palms, axillae
Do eccrine glands respond to emotional or gustatory influence?
Yes
Describe the tonicity of eccrine sweat production?
Primary secretion is isotonic to blood. By the time it reaches the surface of the skin, it is hypotonic.
Structure of eccrine sweat gland:
Simple, coiled tubular structure divided into 2 parts:
- Deep sub dermal coiled portion which secretes the sweat.
- A duct portion which passes the secretion to the skin surface.
Describe the mechanism of eccrine sweat glands in presence of ‘slight’ stimulation:
- Almost all Na+ and Cl- is reabsorbed thus sweat = 5mMol-1.
- Osmotic pressure falls thus water reabsorbed
- this in turn concentrates other constituent (lactic acid, urea, K+)
Describe the mechanism of eccrine sweat glands in the presence of a strong stimulus
- Reabsorption of approx. 50% of Na & Cl-; sweat 60mMl-1
- Unacclimatised person: this can represent a large loss of Na and Cl
- Water reabsorption is greatly reduced: keeps other constituents at a low concentration.
What is the unit for Metabolic rate?
W/m^2
What is the average metabolic rate?
40-50W/m2
What can metabolic rate reach during shivering?
500W/m2
What does metabolic rate need to reach via exercise to be considered protective of excessive peripheral vasoconstriction in cold stress?
100W/m2
What factors affect efficiency of evaporative heat loss?
- Evaporative heat transfer coeffient (air movement, surface shape, permeability of clothing)
- Water vapour gradient from skin to outside
- The “wetted” skin area.
