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 DUV 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

• 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• 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 released2. a clot is formed by clotting proteins, air dries and hardens the clot forming a scab3. 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 scab5. Scab soon detaches6. 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)