Download Integumentary System

Ch. 6
INTEGUMENTARY SYSTEM
 What is a tissue?
 The integumentary system is a cutaneous
membrane together with certain accessory
organs
Four Major Types of Membranes
1. Serous membrane – line body cavities not
open to outside
 Consists of – simple squamous epithelium and
thing layer of loose connective tissue
 Secrete serous fluid (water, lubricates membrane
surfaces
2. Mucous membranes – line cavities and
tubes that open to outside
 Made of epithelium over a layer of loose
connective tissue
 Includes goblet cells which secrete mucus
3. Synovial membrane – inner linings of joint
cavities between ends of bones
 Dense connective tissue over loose connective
tissue and adipose tissue
 Cells secrete thick, colorless synovial fluid which
lubricates the end of bones
4. Cutaneous membrane – skin
 One of the largest most versatile organs
 Vital in maintaining homeostasis
 Function – protective covering, helps regulate body
temperature, retards water loss from deeper tissues,
houses sensory receptors, synthesizes biochemicals,
excretes wastes
Skin:
2 Layers
 Epidermis – outer layer, stratified squamous
epithelium w/ basement membrane
 Dermis – inner layer, thicker, connective
tissue (collagenous and elasitc fibers,
epithelial tissue, smooth muscle tissue,
nervous tissue, blood)
 Beneath - Subcutaneous layer - loose
connective and adipose tissues
*** skin of a 150 lb person spread flat would
cover about 20 square ft ***
EPIDERMIS
 Lacks blood vessels
 Stratum basale –
deepest layer, close to
dermis, nourished by
dermal blood vessels
 When it divides it pushes older cells
toward skin surface (farther away, less
nutrients  die)
Keratinization
 Keratinization – older cells (keratinocytes)
harden, cytoplasm fill with tough, fibrous,
waterproof keratin protein
 Forms outer layer stratum corneum which is
eventually shed
thickness varies from region
to region
 most areas have just 4 layers
 stratum basale
 stratum spinosum
 stratum granulosum – missing where
epidermis is thin
 stratum lucidum – palms and soles
 Stratum corneum
Stratum Corneum
 Stratum
lucidum
 Stratum
granulosum
 Stratum
spinosum
 Stratum basale
 Skin cell production is
balanced with the loss
of dead cells
 Calluses and corns are
the result of increased
cell division where skin
is rubbed or pressed
regularly
Epidermis continued
 Functions
 Protection
 Shields from excessive water loss, mechanical
injury, and harmful chemicals
 Unbroken it protects against microorganisms
Skin Color
 Skin Color is caused by:
 Melanin – a dark pigment that provides skin
color – is produced by melanocytes in the
epidermis
 Protects from
ultraviolet radiation,
preventing mutations
and other damage
Skin color cont.
 All people have the same number of
melanocytes
 How do we have different skin colors?
 Differences in melanin production
 Size of pigment granules
Environmental Effects on
Color
 Sunlight, UV light from sun lamps, and X-rays
stimulate production of melanin
 Blood can affect skin color
 Diet and chemicals can effect skin color
Dermis
 The boundary between
the dermis & epidermis is
uneven
 Fingerprints are formed
from these and determine
by genes
Dermis continued
 Composed of dense connective tissue
 collagenous & elastic fibers w/ a gel-like matrix
 Dermal blood vessels supply nutrients to all
skin cells
 Pressure ulcer
 Nerve cells processes (endings) found
throughout
 Contains hair follicles, sebaceous glands, and
sweat glands
Subcutaneous Layer
 Also called the hypodermis
 Consists of loose connective and adipose
tissues, and major blood vessels
 Connective tissue is continuous with the dermis so
there is no sharp boundary
 Adipose tissue insulates
Accessory Organs of the Skin
Hair Follicles
Every hair develops from a group of epidermal cells
at the base of a hair follicle
As the cells divide they push
older cells away that
become keratinized
and make up the shaft
Genes determine hair color
trichosiderin – red hair
Hair Follicles cont…
 Each hair has a muscle (arrector pili) attached
to it that when it contract causes the hair to
stand on end
Sebaceous Glands
 Contain groups of specialized epithelial cells
and are usually associated with hair follicles
 Holocrine gland – secrete oily mix of fatty
material and cellular debris (sebum)
 Keeps hair and skin soft, pliable and
waterproof
Nails
 Protective coverings on the ends of fingers
and toes
 Parts – nail plate and nail bed, lunula
 Epithelial cells
 Continuous with
skin divide and
become keratinize
Sweat Glands (sudoriferous)
 Sweat glands
 Exocrine glands that form a ball shaped coil
deep in the dermis
 Coiled portion is made of epithelial cells
which secrete sweat (water, salt and wastes)
 Eccrine gland – most numerous; respond to
elevated body temperature
 Common in the forehead, neck,
and back
Sweat Glands cont…
 Apocrine glands – activated by emotional
upset, fear, or pain; most numerous in axillary
regions and groin; similar to eccrine gland
 Modified sweat glands
 Ceruminous gland – secrete ear wax
 Mammary gland – secrete milk
Regulation of Body
Temperature
 The skin plays a key role in the homeostatic
mechanism that regulates body temperature.
 Releasing heat
 By blood – vasodilation stimulated by
hypothalamus
 Eccrine sweat glands are activated
 Conserving heat
 Vasoconstriction of dermal blood vessels
 Inactive sweat glands
 Skeletal muscles contract slightly and cell
respiration produces heat
 Shivering
 Most of the bodies heat is lost through the head.
Healing of Wounds
 Wounds Heal
 Inflammation
 Blood vessels dilate and become more permeable
 The healing process depends of the extent of
the injury
 Epidermis – epithelial cells divide more rapidly and
fill in the gap
 Dermis/hypodermis – blood clots form and make a
scab
 Fibroblasts migrate and produce collageneous fibers
 Blood vessels extend into the area
 Phagocytic cells remove dead cells and debris
 Large, open wounds
 Granulations form
 New branch of a blood vessel and a cluster of
fibroblasts
 Blood vessels and fibroblasts eventually migrate
away and a scar is left
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Acne – Disease of the sebaceous glands that
produces blackheads and pimples(acne)
Athlete’s foot – Fungus infection usually in
the skin of the toes and soles
Birthmark – congenital blemish or spot on
the skin, visible at birth or soon after
Dermatitis – inflammation of the skin
Erythema – reddening of the skin due to
dilation of dermal blood vessels in response
to injury or inflammation
 Herpes – infectious disease of the skin,
usually caused by the herpes simplex virus
and characterized by recurring formations of
small clusters of vesicles
 Mole – fleshy skin tumor (nevus) that is
usually pigmented; colors range from brown
to black
 Scabies – disease resulting from an
infestation of mites
 Skin Biopsy
 Pressure Ulcer
 Eczema – noncontagious skin rash that
produces itching, blistering, and scaling
( Eczema)
 HowStuffWorks Videos "DNA Damage from
UV Rays“
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Cells with New Drugs“
 Wart – flesh-colored, raised area caused by a
viral infection