Ch 4 Flashcards
Integumentary System
Cutaneous membrane: epidermis and dermis
Accessory structures: hair, nails, glands
Functions of integumentary system
protects: mechanical, chemical, bacterial, and thermal damage, UV radiation, and desication, aids in heat regulation, excretion of urea and uric acid, synthesis of vitamin D
Epidermis characteristics
stratified squamous epithelium
lacks blood vessels but can divide
as new ones grow, push old to surface
Epidermal cell types
keratinocytes, melanocytes, lagerhan cells, merkel cells
Keratinocytes
produce keratin, provide protection
Melanocytes
produces melanin
Lagerhan cells
from bone marrow, part of immune response
Merkel cells
in deepest layer, form touch receptors with sensory neurons
Keratinization and Epidermal Growth
stem cells divide to produce keratinocytes at the basal lamina
as keratinocytes are pushed up towards the surface they fill with keratin and oils and slowly die
4 week journey
Layers of epidermis
stratum germinativum, stratum spinosum, stratum granulosum, stratum corneum
Stratum germinativum
deepest single layer of cells
combination of merkel cells, melanocytes, keratinocytes, and stem cells that divide repeatedly
attached to each other and to basal lamina
Stratum Spinosum
8 to 10 cell layers held together by desmosomes
melanin taken in by phagocytes from nearby melanocytes
Stratum granulosum
3-5 layers of flat dying cells
show nuclear degeneration
contain dark staining keratohylin granules
Stratum lucidum
seen in thick skin on palms and soles of feet only
three to five layers of clear, flat, dead cells
Stratum corneum
25 to 30 layers of flat dead sells filled with keratin and surrounded by lipids
continuously shed
barrier to light, heat, water, chemicals, and basteria
friction stimulates callus formation
Thick skin
palmer and platar surface
about 30 layers of s. corneum
all 5 layers
Thin skin
rest of body surface
fewer layers of s. corneum
no s. lucidum
Epidermal ridges (finger tips)
stratum germinativum forms ridges that extend into the dermis
increases area of contact for better grip
Melanin
melanin produced in epidermis by melanocytes
similar number of melanocytes in everyone
different amounts of pigment produced
UV light
increases melanin production, which it absorbs
too much UV can damage chromosomes
Types of melanin
melanocytes convert tyrosine to melanin
brown or black is called eumelanin
red brown is called pheomelanin
Carotene in dermis
yellow orange pigment
found in stratum corneum and subcutaneous
Hemoglobin
red oxygen carrying pigment in blood cells
if other pigments are not present, epidermis is transulcent so pinkness will be evident
Dermis
Papillary layer and reticular layer
Papillary layer
areaolar CT
capillaries and neurons
dermal papillae
Reticular layer
anchoring layer
large vessels, nerves, adipocytes, arrector pili muscle
dense irregular CT- collagen and elastic
Blood supply to skin
cutaneous plexus and papillary plexus
Cutaneous plexus
network of arteries and veins supplying skin
in subcutaneous layer
Papillary plexus
follows epidermal/dermal boundary
helps nourish epidermal layer
lines of cleavage
dermal collagen and elastic fibers are arranged in semi parallel bundles that differ throughout the skin
resist tension best in those directions
gaps filled with scar tissue and become stretch marks
Hypodermis
also called superfiscial fascia/ subcutaneous layer
consists of areolar CT and adipose CT
collagen and elastic fibers
major blood vessels and nerves
Hair
on all surfaces except palmer and plantar, parts of digits, lips, eyelids
number fixed at birth
3 types: vellus, terminal, intermediate
composed of dead, keratinized epidermal cells
Vellus hair
peach fuzz
Terminal hair
thicker with darker pigment
Intermediate hair
arms
Each hair consists of:
- shaft which projects above surface of skin
- root which peetrates into the dermis
- base of follicle, bulb
- cuticle
- cortex
- medulla
Functions of hair
protection, reduction of heat loss, sensing light touch
Root hair plexus
sensory nerves surrounding follicle
detect hair movement
Arrector Pili
smooth muscle, moves hair
goose bumps- remnant of ancestors
Hair growth
anagen stage, catagen stage, telogen stage
Anagen stage
may last up to 6 years depending on the body part
matrix cells at base of hair root producing length
Catagen stage
lasts up to 2 weeks
matrix cells inactive and follicle atrophies
Telogen stage
hair follicle
hair is eventually pushed out by new hair as cycle renews
Hair color
result of melanin produced in melanocytes
Brown/black hair
large amounts of eumelanin
Blonde hair
little eumelanin
Red hair
high relative pheomelanin
Grey hair
decline in all melanin production
Glands of the skin
specialized exocrine glands found in dermis
Sebaceous glands
secrete sebum (oil) by holocrine secretion sebum decreases evaporation and decreases bacterial growth 2 types: with hair and without
Sudoriferous glands
sweat glands, coiled tubular gland, under neural control
2 types: apocrine and merocrine sweat glands
Merocrine sweat glands
use merocrine system of exocrine secretion on most body surfaces(palm) not associated with follicle sensible perspiration function is to cool, excrete and protect
Apocrine sweat glands
use merocrine system
associated with hair follicle
in armpit , nipple, and groin
produces viscous secretion starting at puberty
reduces friction, cools, and secretes pheromones
Modified apocrine glands
mammary, ceruminous
Mammary
(lactiferous) for milk production- modified sweat
Ceruminous
in external ear
secretion mixes with sebum to create ear wax
Nail body
keratinized plate-like structures
Nail bed
surface of skin that covers nail body
Nail root
source of nail production
Lunula
whitish half-moon region at base of nail plate due to obscured blood vessels
Burns
tissue damage and cell death caused by heat, electricity, UV radiation or chemicals
can cause: dehydration, electrolyte imbalance, and circulatory shock
First Degree burns
skin red and swollen, only epidermis damaged, sun burn peels off
Second Degree burns
skin red with blisters, epidermis and upper dermis damaged
Third Degree burns
grey-white or black, destroys entire layer, hypodermis is cooked
Effects of aging
less hair, reduced blood supply, dermis tends to thin, drying of epidermis (less oil), fewer melanocytes (paler)
