Accessory Structures of Skin PDF

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Summary

Human Form and Function...

Description

Accessory Structures of Skin HAIR Characteristics: • •

Covers whole body except palms & soles Around 5 million on body

Functions • •

Protection from sun and particles (eyebrows/eyelashes prevents dust getting into eyes) Prevention of heat loss (thermoregulation) We get goosebumps when we’re cold hairs stand up  Shaft is visible section (Medulla, cortex, cuticle)  Root is not visible (below surface) located in dermis  Follicles surround root (2 sheaths)  Papilla of hair contains blood vessels which transport nutrients to the matrix

Sebaceous (oil) glands Sebum: combination of cholesterol, proteins, fats & salts keeps hair and skin soft and inhibits growth of bacteria & fungi (ringworm) Oil glands have a secretory portion and a extratory portion.

Sudoriferous (sweat) glands      

3 million Regulate temperature Excrete water & nitrogenous waste Densest on soles, palms, forehead 2 Types: Excrine and Apocrine Eccrine: functioning at birth

 Apocrine: starts functioning after birth ECCRINE SWEAT GLANDS:  In most areas of skin except for genital areas, lips, nail beds, and eardrums  Secretory part in the deep dermis  regulate body temperature with perspiration  Sweat contains: water, ions, urea, uric acid, ammonia, amino acids, glucose and acid lactic. APOCRINE SWEAT GLANDS  In Armpit, groin, face  secretory portion in dermis with duct that opens onto hair follicle  Sweat contains lipids and proteins too

Ceruminous glands      

Present in the external auditory canal Produces ear wax (too much wax can reduce hearing) Modified sweat glands: ear wax Cerumen contains oil & wax Helps form barrier for entrance of foreign bodies Impacted cerumen may reduce hearing

Nails Tightly packed, keratinized cells Has 3 portions:  Body = visible part  Free edge = extension past end of finger/toe  Root = not visible

 Lunula = white due to thickened stratum Basale in that area  Cuticle (eponychium) is stratum corneum  Growth is 1mm per week: faster in summer & on...