integumentary system ch5

anatomical components of the integumentary system

skin, nails, hair, sweat/oil glands, sensory receptors

system’s physiological functions

-maintain body temperature

-synthesis vitamin D

-homeostatic balance

-provide sensory information

cells of epidermis

keratinocytes- spikey, common, strengthen

melanocytes- produce melanin (dye) has a protective role

intraepidermal macrophages (Langerhans) - first WBC to respond

tactile epithelial (Merkel) cells- connects to sensory neuron, transmit sense of touch.

5 possible strata of skin in epidermis

stratum (deep to superficial): basale, spinosum, granulosum, lucidum, corneum

stratum basale

deepest layer-closest to dermis therefore near blood and nutrient supply, 1 row of cuboidal/columnar keratinocytes, mitosis divide constantly-stem cells get pushed up

stratum spinosum

rows of spikey keratinocytes-more protein making, contain melanocytes and dendritic cells.

stratum granulosum

rows of flattened keratinocytes, begin to degenerate, secrete lamellar granules-oily and partly waterproof

stratum lucidium

ONLY PRESENT IN THICK SKIN

-skin of palms, finger digits (print), sole of feet, plantar of toes

-4-6 ish rows of clear flat dead keratin heavy keratinocytes

stratum corneum

last many rows of dead flat keratinocytes, mostly keratin- it will shed

thick skin vs thin skin

thick

-hairless, palms, palmar of digits, soles

-has stratum lucidum, thicker spinosum and corneum.

thin

-hairy, all body except above structures

-lacks lucidum, thinner spinosum and corneum

what skin structures lead to fingerprints?

epidermal ridges that protrude, forming raised area. u=peg n=papilla

2 regions of the dermis and functions

-connective tissue has collagen and elastic fibers

papillary- superficial; free nerve endings, thin collagen, fine elastic fiber

reticular- deeper; dense irregular connective tissue, thick bundles of collagen, course elastic fiber. spaces include adipose cells hair follicles, nerves, sebaceous glands, sudoriferous glands

structural basis for differences in hair colour

amount and types of melanin in the keratinized cells in hair

structural basis for differences in human skin colour

melanin by melanocytes is basale layer

hemoglobin in blood showing through as flushed skin

carotene-yellow/orange pigment stored in corneum and adipose tissue.

general anatomy of hair

composed of dead, keratinized epidermal cells bonded by extracellular protein.

root- penetrates into the dermis

shaft- above skin so its visible

cuticle- outside of cortex and medulla, outtermost layer of hair shaft

hair follicle function, and what is responsible for growth?

surround root of hair, hair matrix inside hair bulb is where cell division happens

hair function

protect scalp from uv rays, shield and trap moisture and dust, insulate body

anatomy of nails, including nail body, bed, and root

keratinized epidermal calls

free edge- we trim it! doesn’t shed

nail body/plate- on top of nail bed, compared to corneum of skin, execpt much harder type of keratin

lunule- partly keratinized, lighter in colour

cuticle/eponychium- adhere to nail body

root- buried by fold of skin

nail matrix- where cells divide, proximal to nail root

nail growth factors

epidermal healing

1. basale migrate to center,

2. stem cell divide

3. they turn into epidermal cells, NOSCARRING

deep wound healing steps + tissues affected

it extends to dermis and subQ layer , SCARS

4 phases:

1. inflammatory- blood clot forms, bump fors, vessels dialate,

2. connective tissue and collagen builds onto scab

3. proliferatve- more division beneath scab, fibroblasts deposit more connective tissue

4. maturation- clotted blood sloughs off once restored

1st degree burn

-epidermis only, mild pain, redness (erythema) ex sunburn.

2nd degree burn

epidermis and part of dermis, some skin function lost, redness, blister, edema (swell), pain

3rd degree burn

epidermis, dermis, and subQ

most skin function lost, marked edema, numbness due to missing sensory nerve endings, skin graft needed

skin cancer and its 3 types

excessive exposure to UV light, basal cell carcinoma is most common, squamous cell carcinoma, and malignant carcinoma