Sunday, September 18, 2016

Ch. 4 | the integumentary system

integumentary system: composed of skin, hair, oil, sweat glands, nails, sensory receptors
skin/cutaneous membrane; covers external surface of the body
epidermis: superficial, thinner layer of skin made of epithelial tissue

dermis: deeper, thicker layer of skin made of connective tissue 
papillary region: upper part of dermis- provides epidermis w nutrients, produces keratincoytes, regulates temperature
reticular region: lower part of dermis- strengthens skin, provides elasticity, contains hair follicles & glands

Meissner's (a.k.a. tactile) corpsucle: touch receptor
Pacinian (a.k.a. lamellated) corpsucle: pressure receptor
arrector pili muscles: pulls hairs into upright position

skin color is caused by pigments
  • melanin: dark black/brown/yellow pigment 
  • hemoglobin: red pigment 
  • carotene: yellow/orange pigment
hair protects the skin & other structures of the body
  • shaft: above skin surface
  • root: below surface 
  • hair follicle: surrounds the root 
  • hair root plexuses: nerve endings that surround hair follicles 
androgens: masculinizing sex hormone produced by testes in males & adrenal cortex in both genders

glands produce secretions that perform a variety of functions
  • sebaceous: secrete sebum (oily substance), softens skin, prevents hair from drying out 
  • sudoriferous: sweat glands 
-eccrine: all over the body- regulates body temperature
-apocrine: in axillary & pubic regions 
  • ceruminous: sweat glands in ear canal & outer ear, secrete cerumen (earwax)
parts of the nail:
dividing cells of a nail are located in nail matrix

skin plays a number of roles in the body:
  • regulates body temperature
  • forms a protective barrier for the internal organs
  • absorbs & excretes substances through its surface 
  • plays a role in calcium homeostasis 
edema: abnormal accumulation of interstitial fluid

1st degree: damages epidermis; redness, mild pain
2nd degree: damages epidermis & superficial part of dermis; blisters, edema
3rd degree: damages epidermis & dermis; marble-white to black color 
4th degree: damages epidermis, dermis, & additional soft tissue underlying the skin
rule of nines: used to estimate the surface area affected by burns in an adult 

skin cancers can develop from repeated exposure to UV radiation:
  • basal cell carcinoma (78% of all skin cancers)
  • squamous cell carcinoma (20% of all skin cancers)
  • malignant melanoma (2% of all skin cancers)

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