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

layers:

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

parts:

• 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

burns:

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)