sweatglands Flashcards
(11 cards)
blood vessels and the skin:
blood supply- deep vessels in subcutaneous layer. superficial vessels in reticular dermis- capillaries from this to basement membrane. control dilation or contraction to regulate flow- controls heat loss.
thermoregulation:
maintain body temperature at 37C- depends on metabolic and physical factors. evaporation of sweat and diversion of blood from deep to superficial vessels.
temperature and forensics:
in hot environment- core body temperature rises, more sweat released, cools the body so that core returns to 37C. leave latent fingerprints- mixture of natural secretions from skin.
skin glands:
exocrine (secrete products into ducts leading to environment not to bloodstream).- sebaceous, sweat.
products keep skin pH between 6-7- discourages microbial growth.
sebaceous glands:
derived from epidermal cells. associated with hair follicles. produce oily sebum (triglycerides, cholesterol, proteins, electrolytes)- flows into hair follicles/travels to skin surface, protects hair and skin from dehydration/cracking, toxic to bacteria to stop infection.
sensitive to androgens (more active at puberty).
most in scalp, face, chest, back/none in hairless skin.
none on soles or palms.
sweat glands:
within dermis. 2.5 million over whole body surface. coiled tubes that secrete watery substance.
2 types: eccrine- most numerous on palms, soles, forehead, armpits. not in mucous membrane. under thermal control for thermoregulation.
apocrine.
composition of sweat:
mainly water, but other chemicals diet dependent.
minerals- sodium, potassium, calcium, magnesium.
trace elements.
urea and lactate.
fatty acids.
some people also secrete amino acids in sweat.
some people do not secrete sweat from palms- non secretors, they will rarely leave a latent print on any surface.
sweat analysis:
take sweat swabs: sterile cotton swabs, remove water by sublimation (freeze drying). leave amino acids and protein matter. analyse by chromatographic methods.
problems of sweat analysis:
generally no biomarkers- lactate also in semen and saliva.
difficult to locate with alternative light sources as is dilute substance.
heterogeneity of composition between donors and samples from a single donor- affected by temperature, beauty products, smoking.
uses of sweat analysis:
used to detect incidental impurities eg drugs and their metabolites.
new biomarker found called dermcidin (human antibiotic)- identified with antibody.
apocrine glands:
large sweat glands. ducts empty into hair follicles. open into hair follicles in armpits, genitals, eyelids. active during puberty. produce sticky, odourless, protein rich secretion.
bacteria cause odour over time.
