Ch 6: Integumentary System Flashcards
What are the functions of the skin
protection against micro-organisms and water-damage (keratin); regulation of body temperature; excretion of waste materials; synthesis of Vitamin D; respond to stimuli
Epidermis
outer most layer; stratified squamous epi.; avascular; up to 5 sublayers
what are the 5 sublayers of the epidermis
- stratum basale or stratum germinativum (bottom layer; rests on basement membrane; single layer of cuboidal or columnar cells; much mitosis);
- stratum spinosum (several layers; cells have delicate “spines” that protrude from their surface to inter-lock cells; creates a barrier; mitosis);
- stratum granulosum (usually 2 to 4 cells thick; synthesis of keratohyaline, which will migrate to surface and become keratin);
- stratum lucidum (found only in palms and soles; flat cells; synthesis of eleidin, which protects against UV damage);
- stratum corneum (surface layer; very flat, dead cells; cells are constantly shed; offers protection against miro-organisms and dehydration; covered by keratin, which also protects skin)
dermis
middle layer; thicker layer; 2 sublayers
what are the 2 sublayers of the dermis
- papillary layer (directly below epidermis; loose C.T.; contains papillae or folds, which are your fingerprints; vascular; nerve endings;
- reticular layer (deeper layer; dense irregular C.T.; vascular; glands; hair follicles; nerve endings)
hypodermis/ subcutaneous layer
deepest layer; adipose tissue; vascular; glands; cushions and supports
what are the 2 types of sudoriferous glands (sweat glands)
- eccrine gland
2. apocrine gland/ odiferous gland
eccrine glands
(small; distributed over nearly the entire body; none found in eardrums, nail beds, or margins of lips; simple coiled tubular; respond to heat, regulate temperature);
apocrine glands/ odiferous glands
(larger and more deeply situated; locations include armpits; dark region around nipples; anal and genital regions; become active at puberty; can respond to stress; release an “odor”; not for temperature regulation)
sebaceous glands (oil glands)
simple, branched alveolar glands; lubrication and protection; produce sebum; found all over the body, usually at base of hair follicle; not found in palms and soles
minor first degree burn
affects less than 10% of the body; epidermis damaged;
Mild swelling; reddening; some pain; injured cells peel off and skin heals without scarring, usually within 2 weeks
serious second degree burn
affects more than 15% of adult body or more than 10%
of child body; epidermis and part of dermis damaged; new skin may regenerate; red or mottled appearance; swelling; greater pain; blisters may occur
severe third degree burn
affects more than 20% of the body; requires prompt
medical attention; all skin layers damaged; deep tissue destruction; skin cannot regenerate; surgery and skin grafts necessary; white or charred appearance; severe loss of body fluids; usually due to some catastrophic event (fire / chemical)
basal cell epithelioma skin cancer
generally appears on the face where sebaceous
glands and hair follicles are abundant; most frequent in males over 40; three types of lesions are typical (noduloulcerative lesions – small and pink during early stage; enlarge and become ulcerative and scaly…..superficial basal cell epithelioma – erupt on back and chest; lightly pigmented and slightly elevated……sclerosing basal cell epithelioma – waxy, yellowish-white patches that appear on head and neck)
squamous cell carcinoma skin cancer
usually appear as pre-malignant lesions on face,
ears, mouth, and lips; most common in males over 60
malignant melanoma skin cancer
involves pigment-producing melanocytes; usually starts
as small dark growth resembling moles; gradually become larger, change color, ulcerate, and bleed easily; most common in women after puberty (pregnant women must be careful with sun exposure, because hormonal changes may increase risk of Melanoma)
hair
is found all over the body surface, except the palms and soles; consists of 3 parts:
- medulla
- cortex
- cuticle
medulla
the central region
cortex
surrounds the medulla; contains pigments that give rise to hair color
cuticle
the outer protective layer, abrasion of the cuticle results in ‘split ends’
follicle
is a structure from epithelial tissue (internal and external root sheath) which rests on a thick basement membrane (glassy membrane) and dermal tissue (C.T. root sheath); a small portion of the C.T. root sheath protrudes into the hair bulb and provides nutrition to the growing hair, is called the Papilla.
root
is the portion of hair enclosed within the follicle
shaft
is the portion of hair protruding from the scalp surface
hair bulb
is a collection of well-nourished germinal epithelial cells at the basal end of the follicle; as the daughter cells are pushed further away from the growing region, they die and become keratinized; thus the bulk of the hair shaft, like the bulk of the epidermis, is dead material
arrestor pili muscle
are small bands of smooth muscle cells connecting each hair follicle to the papillary layer of the dermis; when these muscles contract (during cold or fright), the slanted hair follicle is pulled up-right, dimpling the skin surface with goose bumps
hair growth
hair cycle consists of three developmental stages:
- anagen stage
- catagen stage
- telogen stage
anagen stage
a) Stem cells from the bulge in the follicle multiply and travel downward, pushing the dermal papilla deeper into the skin and forming the epithelial root sheath
b) Root sheath cells directly above the dermal papilla form the hair matrix; sheath cells transform into hair cells, which synthesize keratin and then die as they are pushed upward away from the papilla
c) The new hair grows up the follicle, often alongside an old club hair left from the previous cycle
catagen stage
a) Mitosis in the hair matrix ceases and sheath cells below the bulge die
b) The follicle shrinks and the dermal papilla draws up toward the bulge
c) The base of the hair keratinizes into a hard club and the hair, now known as club hair, loses its anchorage
d) Club hairs are easily pulled out by brushing the hair and the hard club can be felt at the hair’s end
e) When the papilla reaches the bulge, the hair goes into a resting period called the Telogen Stage
nails
are derivatives of the epidermis; are composed of the following parts: 1. body 2. free edge 3. root 4. nail folds 5. eponychium 6. nail bed 7. nail matrix 8. lunula
body
the visible attached portion
free edge
the portion of the nail that grows out away from the body
root
the part that is embedded in the skin and adheres to an epithelial nail bed
nail folds
skin folds that overlap the borders of the nail
eponychium
the thick proximal nail fold commonly called the cuticle
nail bed
an extension of the stratum basale beneath the nail
nail matrix
the thickened proximal part of the nail bed containing germinal cells responsible for nail growth; as the matrix produces nail cells, they become heavily keratinized and die; thus nails, like hair are mostly nonliving material
lunula
the proximal region of the thickened nail matrix, which appears as a white crescent; it is located at the free edge of the nail; the rest of the nail appears pink, due to underlying blood vessels in the underlying dermis
