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integumentary system
Consists of the skin, mucous membranes, hair, and nail
function of the integumentary system
provide a barrier, protect deep tissue, water retention & thermoregulation, excretion, houses cutaneous receptors, synthesizes vitamin d
largest organ
skin (7% of body weight)
subcutaneous membrane
hypodermis
what is skin made up of
dermis and epidermis
what is the epidermis
stratified squamous epithelium
how does thick skin differ from thin skin
thick skin has 5 layers, thin skin has 4, thick also has thicker stratum corneum and stratum lucidum
how are superficial layers created
basal cells are metabolically active and undergo mitosis
what is special about surface cells
are flattened and are keratinized (full of keratin)
what are the four types of cells in the epidermis
keratinocytes, melanocytes, tactile epithelial cells, dendritic cells
what do keratinocytes do
produce keratin
what is a keratin
a tough fiborous protein (an intermediate fiber(cytoskeleton))
What do melanocytes produce?
melanin
what does melanin do
makes dark skin pigment to help protect from UV light
how is melanin transferred
from melanocyte to keratinocyte
what is a tactile epithelial cell
merkel cell
what is the function of a tactile epithelial cell
a receptor for tough and is associated with sensory nerve endings
what is a dendritic cell
immune cell system
what is the function of a dendritic cell
patrol the epidermies for foreign entities and engulf them
what is the deeper region of the skin
dermis
what are the two layers of the dermis
papillary layer and reticular layer
what type of tissue is the dermis
vascular connective tissue
what is in the dermis
flibroblasts, macrophages, mast cells, white blood cells, various proteins
what plexuses are in the dermal blood vessels
dermal & subpapillary
what is the function of the plexuses in the dermis
provide blood and regulate temperature
where is the papillary layer
deep to the startum basale of epidermis
what makes the papillary layer unique
the fingerlike projections of dermis into the epidermis
where is the reticular layer located
deep to the papillary layer
what makes the reticular layer unique
thick layer of dense irregular connective tissue
what is unique about the hypodermis
it is NOT part of the skin
what is the hypodermis
subcutaneous tissue
what is the hypodermis made up of
areolar and adipose connective tissue
what does the hypodermis do
anchors skin to underlying structures
What are skin appendages?
derived from the epidermis but all extend into the dermis
what are nails
a modification of the epidermis
what are nails made of
hard keratin
how is a nail plate formed
from dividing cells that are proximal to the nail fold known as the nail matrix
what is contained in the nail plate
nail plate, nail folds, free edge, body, root
how does hair develop
from invaginations of the epidermis forming the follicle
what does hair contain
shaft and hair root
what is the shaft of hair
dead kertainized cells that project out of the skin's surface
what is the hair root
embedded in the dermis surrounded by hair follicle
what are the two types of cutaneous glands
sebaceous glands and sudoriferous
what does sebaceous glands produce
sebum
what are sebaceous gland connect to
hair follicles
what does sebum do
flows superficially to cover skin makes hair and skin oily for protection
what is sweat
mostly water with some salts
what are the two types of sudoriferous glands
eccrine and apocrine
what are eccrine glands
produce true sweat and are connected to surface via pores
what are apocrine glands
produce a special sweat containing fats & proteins connected to hair follicles in the axillary and genital areas
three basic layers of skin
epidermis, dermis, hypodermis
three main cell types of the epidermis
keratinocytes: produces the fibrous intermediate filament protein keratin
melanocytes: secrete pigment
dendritic cells
immune surveillance, present antigens to immune system
five layers of the epidermis
stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale
stratum corneum
outermost layer of the epidermis, which consists of flattened, keratinized cells
stratum lucidum
clear layer, thick skin only
stratum granulosum
one helps form keratin, the other contains the glyolopids
stratum spinosum
desmosomes, dendritic cells and melanin
stratum basale
the deepest layer of the epidermis consisting of keratinocyte, melanocytes
Eumelanin
brownish black pigment
Phaeomelanin
red and yellow
Carotene
yellow-orange pigment
Haemoglobin
reddish hue
description, function and location of connective tissue areolar (dermis)
description: three fibres
function: wraps and cushions organs
location: mumcous membrane, epithelia, organs
description, function and location of connective tissue, dense irregular
description: fibroblast
function: structural strength
location: organs, joints, digestive tract
2 layers of dermis
papillary 20%
reticular 80%
dermal ridges
fingerprints, sweat glands
cleavage lines
collagen fibres, heal rapidly, dense irregular tissue
flexure lines
dermis folds, near joint
eccrine sweat glands (cutaneous)
temp control, merocrine (exocytosis)
apocrine sweat glands (cutaneous)
sexual scent glands, merocrine
sebaceous glands
water loss, lubricate skin and hair, sebum
eccrine sweat glands
coiled tubular gland, secrete true sweat
apocrine sweat glands
larger deeper, fatty, proteins
mammary glands
produce milk
three coats of hair
lanugo, vellus, terminal hair
Hair structure
medulla, cortex, cuticle
Cycle of hair growth
anagen, catagen, telogen, early anagen
subcutaneous tissue (hypodermis)
apidose tissue, adipocyte, triglycerides, anchors