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chapter 5 skin and the integumentary system (5-1 epidermis (stratum…
chapter 5 skin and the integumentary system
skin structure
epidermis, dermis, subcutaneous
hair shaft, pore of sweat gland duct, epidermal ridge, dermal papilla, sebaceous gland, arrector pill muscle, sweat gland duct, touch and pressure receptors, hair follicle, artery, vein, sweat gland, nerve fibers, fat
5-1 epidermis
structure: keratinized atratified squamous epithelium
stratum corneum
outermost layer
stratum lucidum
translucent layer cells separating corneum from granulosum
stratum granulosum
3-5 layers of flattened granular cells
stratum spinosum
many layers of spiky cells with large nuclei
stratum basale
innermost layer
5-2 skin color
genetic factors
different races have essentially the same # of melanocytes, but amount of melanin produced varies
environmental factors
UV rays, chemicals, drugs (antihistamines & antibiotics)
physiologic factors
carotene may accumulate in s. corneum
orange
hemoglobin in dermal blood vessels
pink
lack of Hb in dermal blood vessels
blue (cyanosis)
inability to breakdown Hb (liver problems)
yellow (jaundice)
5-3 sunlight and vitamin D3 production
liver converts vitamin D into calcitriol
adds in absoption of calcium
weak and flexible bones without it
skin cancers
basal cell carcinoma
squamous cell carcinoma
malignant melanoma
intro
general structure
epidermis= outermost layer
dermis= inner layer
subcutaneous layer- adipose tissue
skin functions
protection
physical barrier
from water loss
from injury
from chemical and microorganisms
excretion
urea; uric acid
cutaneous sensation
light touch detection= meissner's corpuscle's
egg-shaped
located in dermal papillae
populate areas in the fingertips, palms, soles, eyelids, tip of tongue, nipples, clitoris, tip of penis
pressure detection= pacinian corpuscle's
onion-shaped
located in deep dermis and subcutaneous regions
5-4 structure and function of the dermis
dermis: inner layer of skin
structure
papillary layer
(20%) is below epidermis
composed of loose areolar CT
surface forms dermal papillae (finer like projections) that forms fingerprints in thick skin
meissner's corpuscles (sensory receptors for deep pressure)
reticular layer
(80%) dense irreg CT
bundles of collagen fibers
collagen fibers which gives your skin strength and resiliency
pacinian corpuscles - sensory receptors for deep pressure
5-5 structure and function of the hypodermis
subcutaneous layer (hypodermis) = beneath skin
structure: adipose tissue and blood vessels
function: insulation
5-6 mechanism that produce hair and the structural basis for hair texture/color
hair follicles
structure: hair root- or base in deep dermis
follicles throughout dermis
hair shaft in epidermis
cuticle outer shingle like layer
cortex middle layer, flexible soft keratin
medulla inner layer, hard keratin
growth:
grows for 2-5 years / new cycle pushes old hair out
0.3 mm per day
2.5 million on body / 500,000 hairs on the head
keratinization
cells are epithelium
cells in root = active mitosis
cells in follicle = maturing & accumulating keratin
pigment
melanin decrease with age
genetically determined
white / gray hair
lack of melanin and air bubbles
hair papilla
peg of connective tissue
nerves and capillaries
arrector pili muscle
a bunch of smooth muscle associated with every hair follicle
causes hair to stand on end (goosebumps) when frightened or cold
5-7 kinds of glads in the skin and those secretions of those glands
sebaceous glands
holocrine glands (simple cuboidal epithelium)
associated with every hair follicle
secretion (holocrine) = sebum (oil)
sebum is secreted into hair follicles
secretion keeps skin and hair soft, pliable, and virtually waterproof
fat
cellular material
disorders: acne and seborrhea (oily scales)
skin glands (sweat)
merocrine glands
structure: coil in deep dermis, duct in dermis, pore at surface
characteristics:
respond to elevated temp. (exercise)
no odor in secretion
function throughout life
not associated with hair follicles
location: forehead, neck, back
secretion (merocrine) 99% water plus salts and wastes (urea and uric acid)
apocrine glands
structure: ducts terminate into hair follicles
characteristics
respond to stress / emotions
odor is secretion
begin to function at puberty and continues through life
associated with hair follicles
location: armpits, groin
secretion (apocrine) = sweat plus oil and cellular debris
modified apocrine glands
ceruminous glands = external ear
secretion= earwax (cerumen)
mammary glands = breasts; milk
5-8 anatomical structure of nails and how theyre formed
nails
epithelium undergoing keratinization (actice mitosis in lunula)
fuctions
manipulation and protection of digit ends
structure
nail body covers the nail bed
nail root
nail production by an epithelial fold
lunula: pale crescent near nail root
cuticle- fold of stratum corneum
5-9 regulation of body temp
heat production is mostly a by-product of cellular metabolism
heat loss is controlled by regulating dermal blood flow
vasodilation - increase dermal blood
vasoconstriction - decrease dermal blood
heat loss is by four methods
radiation
heat loss by this mode
infrared heat rays move from area of high heat
conduction
less heat loss
heat moves by physical contact
reason the seat you sit in is warm when you stand
convection
heat loss to surrounding air
increases as air movement increases
evaporation
heat loss varies
if heat increases our sweating increases, so we lose more heat by evaporating sweat
burns
1st degree- superficial partial- thickness
epidermis only, mild pain, common on sunburn, heals in a couple weeks
2nd degree- deep partial- thickness
moderate pain, heals 2-6 weeks, epidermis and some dermal damage, without scars, contact with hot objects
3rd degree- full- thickness
epidermis, dermis, maybe subcutaneous damage, severe pain, skin replacements (grafts) are usually needed