Transcript The Integumentary System

The Integumentary System
Newark High School
Mr. Taylor
Three types of epithelial
membranes
• Serous Membranes
– Line cavities and cover organs
– Simple squamous epithelium over loose
connective tissue
– Parietal and visceral portions
– Secrete a serous (watery) fluid for lubrication
• Mucous membranes
– Line cavities that open to the exterior
– Layer of epithelium over connective tissue;
epithelium varies with location
– Tight junctions and goblet cells
• Cutaneous membrane is the skin
– the major organ of the integumentary system
• Integumentary system is the skin and the
organs derived from it (hair, glands, nails)
• One of the largest organs
– 2 square meters; 10-11 lbs.
– Largest sense organ in the body
• The study of the skin is Dermatology
Functions:
1. Regulation of body temperature
– Cellular metabolism produces heat as a
waste product .
– High temperature
• Dilate surface blood vessels
• Sweating
– Low temperature
• Surface vessels constrict
• shivering
2. Protection
physical – mechanical damage
dehydration
ultraviolet radiation
3. Sensation
touch
vibration
pain
temperature
4. Excretion - sweating
5. Immunity/ Resistance
6. Blood Reservoir
8-10 % in a resting adult
7. Synthesis of vitamin D
UV light
aids absorption of calcium
Anatomy
• Epidermis
Skin
• Dermis
• Hypodermis or Subcutaneous tissue
Epidermis
• Stratum basale (stratum germinativum)
– Single layer of cuboidal to columnar cells
– Stem cells that produce keratinocytes
– Melanocytes - # the same for all races
• Stratum spinosum (thorn-like, prickly)
– 8-10 layers attached by desmosomes
• Stratum granulosum
– 3-5 layers
– Keratinization begins here
– Cells beginning to die
• Stratum lucidum (lucid = clear)
– More apparent in thick skin
– 3-5 layers of clear cells
• Stratum corneum
– Dead, flat cells full of keratin
– Keratin is waterproof
– Cells are shed
Basal cell to surface – about 2-4 weeks
Dermis
• Contains Connective tissue layer
• Collagen and elastic fibers, nerves, blood
vessels, muscle fibers, adipose cells, hair
follicles and glands.
• Papillary layer (superior)
– 1/5 of dermis – loose areolar connective
tissue
– Highly vascular
– Dermal papillae - fingerprints, increase
surface area for absorption of nutrients
• Reticular (net) layer
– Dense irregular connective tissue
– Sebaceous (oil) glands
– Hair follicles
– Ducts of sudoriferous (sweat) glands
– Striae or stretch marks
– Meissner’s corpuscles
– Pacinian corpuscles
Hypodermis
• Attaches the reticular layer to the
underlying organs
• Loose connective tissue and adipose
tissue
• Provides for insulation and protection (acts
as a cushion) to internal organs
Accessory organs or epidermal
derivatives
• Hairs
– Epidermal growths that function in protection
– Shaft, root, and folllicle
– Sebaceous glands, arrector pili muscle, and
hair root plexus (touch)
– Hair growth and replacement have a cyclical
pattern
– ‘male-pattern’ baldness (alopecia)
Nails
• Plates of highly packed, keratinized cells
• Protection, scratching, & manipulation
• Formed by cells in nail bed called the
matrix ( in area of lunula)
• 1 mm / week
• Eponychium – (cuticle) proximal nail fold
that projects onto the nail body
Skin Glands
• Sebaceous (oil) glands
– Usually connected to hair follicles
– Found all over the skin, except on the palms
of the hands and soles of the feet
– Ducts usually empty into a hair follicle
– Moistens hair and waterproofs skin
– Product is sebum – mix of oily substances
Skin Glands
• Sebum contains chemicals that kill
bacteria on the skin surface
• Very active when male sex hormones are
produced in increased amounts
• Whitehead – when a sebaceous gland is
blocked by sebum
• Blackhead – when accumulated material
dries and oxidizes, it darkens
• Sweat (sudoriferous) glands
– Eccrine sweat glands
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Numerous in the body to produce sweat
Water, some salts, wastes
Function is to cool the body (also nervous)
Is acidic (pH from 4 to 6) to inhibit bacterial
growth through a pore on the skin surface
– Apocrine sweat glands
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Only found in axillary and genital regions
Ducts empty into hair follicles – milky/yellowy
More viscous – fatty acids and proteins
Odor occurs when broken down by bacteria
• Ceruminous glands
– Modified sudoriferous glands
– Secrete cerumen (ear wax)
• Mammary glands
– Secrete milk
Skin color
• 3 pigments contribute:
1. Melanin – yellowish, reddish brown
2. Carotene – orange-yellow pigment is
affected when eating large amounts of
carotene-rich foods
3. Hemoglobin – amount of oxygen in
red blood cells in dermal blood vessels
Changes in Skin color
• Erythema – redness of the skin ; embarrassed,
fever, allergy, hypertension
• Pallor – paleness; emotional stress, fear,
anemia, low BP, impaired blood flow
• Jaundice – abnormal yellow skin tone; liver
disorder from excess bile deposited in body
tissues
• Bruises – blood escapes and clots in tissue
spaces. Vitamin C deficiency
• Cyanosis – blueness due to low oxygen levels
Wound healing
• Inflammation (is non-specific)
– Blood vessels dilate and become permeable
• Heat, redness, swelling and pain
• Immune response (very specific)
– Mounts a vigorous attack against recognized
toxins, bacterias
Wound healing
• Occurs in 2 major ways:
– Regeneration: replacement of destroyed
tissue by the same kind of cells
– Fibrosis: involves repair by dense c.t. formed
by scar tissue
Wound healing
• Tissue repair:
1. capillaries become permeable,
inflammatory chemicals are released
2. a clot is formed by clotting proteins, air
dries and hardens the clot forming a scab
3. granulation tissue forms – a delicate
pink tissue composed of capillaries
- phagocytes that disposes of the clot
- collagen fibers form a scar
Wound healing
4. Epithelium begins to regenerate just
beneath the scab
5. Scab soon detaches
6. Scar is visible or invisible depending on
severity of the wound
Scar tissue is strong but lacks the flexibility
to perform normal functions of the tissue it
replaces.
Burns
• First degree or partial thickness burn
– Only epidermis is damaged
– Erythema, mild edema, surface layer shed
– Healing – a few days to two weeks
– No scarring
• Second degree- deep partial-layer burn
– Destroys epidermis
– Blisters form
– Healing depends on survival of accessory
organs
– No scars unless infected
• Third degree or full-thickness burn
– Destroys epidermis, dermis and accessory
organs of the skin
– Healing occurs from margins inward
– Skin grafting may be needed
• Autograft
• Homograft
• Rule of Nines
Homeostatic Imbalances of Skin
• Athlete’s foot – itch, red, peeling condition
from fungus infection. Tinea pedis.
• Boils and carbuncles – inflammation of
hair follicles and sebaceous glands
caused by bacterial infection
• Cold sores – small, fluid-filled blisters that
itch and sting, caused by herpes simplex
infection. Emotional upset, fever, UV
Homeostatic Imbalances of Skin
• Contact dermatitis – itching, redness,
swelling of the skin progressing to
blistering. Caused by exposure of the skin
to chemicals (poison ivy); allergic
• Impetigo – pink, water-filled raised lesions
that develop yellow crust in mouth/nose.
• Psoriasis – reddened epidermal lesions;
cause unknown
Cancers of the skin
• Basal cell carcinoma – least malignant,
most common form. Basale layer cells
altered, no keratin filling, invade dermis;
most common on the face where are sun
exposed. Is slow growing. Surgical
removal of the lesion.
Cancers of the skin
• Squamous cell carcinoma – from the
spinosum layer. Forms an ulcer with firm,
raised border. Most often seen on the
scalp, ears, hands, lower lip. Grows
rapidly and is sun induced
Cancers of the skin
• Malignant melanoma – cancer of the
melanocytes. About 5% of skin cancers.
Begins wherever there is pigment like in
moles. Appears as a spreading brown to
black patch
Recognizing Melanomas – ABCD Rule
• (A) – Asymmetry: the two sides of the
pigmented spot or mole do not match
• (B) – Border irregularity: the borders of
the lesion are not smooth but show
indentations
• (C) – Color: pigmented spot contains
areas of different colors
• (D) – Diameter: the spot is larger than
6mm in diameter (size of pencil eraser)