Transcript The Integumentary System

The
Integumentary
System
• The Integumentary system consists of the skin,
hair, nails, and various glands.
• It is the most visible organ system of the body
• The Integumentary system has two major
components:
• The cutaneous membrane (skin) is an organ
composed of the superficial epithelium, (epidermis)
and the underlying connective tissues of the dermis
• The accessory structures include hair, nails and a
variety of exocrine glands
• MAJOR FUNCTIONS:
• Protection- covers/ protects underlying tissues
and organs from impacts, chemicals, and
infections, prevents the loss of body fluids.
• Temperature maintenance-HOW?
• Synthesis and storage of nutrients- the
epidermis synthesizes vitamin D3 , a steroid
building block for a hormone that aids calcium
uptake. The dermis stores large reserves of
lipids in adipose tissue.
• Sensory reception- receptors detect touch,
pressure, pain, and temperature stimuli
• Excretion and secretion-?
Epidermis
• Thick skin- palms of hands and soles of
feet, contains five layers. (about as thick
as a paper towel)
• Thin skin- covers the rest of the body and
has only four layers. (about as thick as a
plastic sandwich bag)
Layers of the Epidermis
• Stratum Germinativum- deepest
epidermal layer, cells firmly attach to the
basement membrane. Forms epidermal
ridges which extend into dermis
• Dermal projections called dermal papillae
extend upward between adjacent ridges,
obtain nutrients by dermal blood vessels
• Intermediate Strata- combines three
layers to form the outer protective barrier
of the skin
– 1) Stratum Spinosum (spiny layer)daughter cells continue to divide and
add to the thickness of the epithelium
– 2) Stratum Granulosum (grainy layer)
consists of cells displaced from the
Statum Spinosum. Site of keratin
production: extremely durable and
water-resistant- skin and hair, calluses,
nails (hooves), horns
– 3) Stratum Lucidum (clear layer in
palm/sole)- covers the stratum
granulosum and cells are flattened,
densely pack and filled with keratin
• Lastly = Stratum Corneum- flattened, dead
outer layer
Skin Color
• Pigmentation- the epidermis contains variable amounts
of two pigments: carotene and melanin
• Carotene is an orange-yellow pigment that normally
accumulates in epidermal cells
• Melanin is a brown, yellow-brown, or black pigment
produced by melanocytes
• Melanocytes manufacture and store melanin within
intracellular vesicles, they slowly increase activity with
sunlight
• Ultraviolet light is beneficial because it stimulates
synthesis of vitamin D3 in the epidermis
• However excessive amounts and long term exposure
damages the skin and can cause skin cancer.
3 Factors Determining Skin Color
• 1) Genetic- all people have the same # of
melanocytes
• What differs? Amount of melanin
produced and size/ distribution of melanin.
Production controlled by several genes
• Albinism- lack of pigment in skin, hair, iris.
• Avg. 1 in 20,000 people, 1 in 200 for Hopi
• 2) Environmental factors- Tanning!
• Light ( UV rays) stimulate melanocytes
3) Physiological
• Dilation/ constriction of blood vesselsflush/pale
• Presence of carotene- accumulates in
adipose tissue
• Jaundice- if newborn infants, signals
immature liver. Adults, signals liver failure
Skin Cancer
• Skin cancer is the most common type of cancer
• The most common type is basal cell carcinoma
which originates in the stratum germinativum
• The less common are squamous cell
carcinomas which involve more superficial
layers of the epidermis
• Melanomas are the most dangerous, usually
starting as moles and can appear anywhere on
the body.
Dermis
• Papillary layer- loose connective tissue
that supports and nourishes the epidermis,
contains capillaries and nerves
• Reticular layer- interwoven meshwork of
dense, irregular connective tissue, elastic
and collagen fibers are present The elastic
fibers provide flexibility and prevent
damage
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Next:
Accessory structures: nails, hair, glands
Injury repair
Aging
Student Lectures
(That sounds like work!!)
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1) The Dermis 121-122
2) Subcutaneous layer 122
3) Structure of hair 122
4) Function of hair/ hair color 122-123
5) Sebaceous glands 124
6) Apocrine sweat glands/ nails 124-126
7) Merocrine sweat glands 124-125
8) Burns ( include table 5-1) 128
9) Injury repair 126-127
10) Aging 128
11) Questions pg 121/123/126
12) Interconnectedness 132