Skin The Body’s Protection Integumentary System. Skin: Two principle layers Epidermis Dermis.

Skin

The Body’s Protection

Integumentary System

Skin: Two principle layers

• Epidermis

• Dermis

Epidermis• A. Epidermis- Outer, thinner portion of the

skin– 1. Composed of both dead and living cells.

• a. Keratin- protein in dead epidermal cells that helps waterproof and protect living layers beneath it.

• b. Melanin- Melanin is a cell pigment that colors the skin and protects the cell from solar radiation.

– 2. Epidermal ridges- “fingerprints” and “footprints” – Important for gripping because they increase friction. They are also used to identify individuals.

Dermis• Dermis- The inner, thicker portion of the

skin.– 1. Varies in thickness- 3-4 mm on the palms of

the hands and soles of the feet. 0.5mm thickness on the surface of the eye.

– 2. Adaptations of the Dermis:• a. Blood vessels• b. Nerves• c. Nerve endings• d. Sweat glands• e. Oil glands• f. Fat deposits- cushion, insulate, store food• g. Hair follicles

Memorize p. 934!!!

Skin: Vital Functions Homeostasis- maintaining

equilibrium

1. Heat response- capillaries in the dermis dilate, blood flow increases, heat is lost by radiation, and glands in the dermis produce sweat and, as the sweat evaporates, the body cools.

Skin: Vital functions

• 2. Cold response- blood vessels in the skin constrict and heat is conserved.

Skin: Vital functions

• 3. First line of defense- serves as a protective layer to underlying tissues. Skin protects the body from physical and chemical damage and from the invasion of microbes.

Skin: Vital Functions• 4. Sense organ-

nerve cells in the dermis receive stimuli from the environment and relay information about pressure, pain, and temperature. (We’ve all stepped on a sharp object or have been sunburned.)

Review Video

• YouTube – National Geographic What is Skin?

Skin: Injury

• A. Scrapes- the epidermis undergoes mitosis and fills in the gap left by the abrasion.

• B. Injury of the dermis- painful and bleeding usually occurs

Burns• Burns- exposure to sun, heat, or chemicals

– 1. First degree- redness and mild pain; death of epidermal cells.

– 2. Second degree- damage to the dermis, blistering may occur.3. Third degree- destroys epidermis and dermis; skin function is lost and regrowth of skin is slow with much scarring. Skin grafts may be required.

Aging/Wrinkles- the cause:• 1. Skin becomes less elastic with age• 2. Oil glands produce less oil resulting in

dry skin• 3. Prolonged exposure to ultraviolet rays

can damage skin cells and accelerate the aging process

• 4. Smoking- ties up oxygen to facial tissue

Acne

• Bacterial infection of the oil glands of the skin

How long does skin last?

• The entire epidermal layer is replaced every 28 days.

World Records

Garry Turner, of Caistor, Lincolnshire, England, stretched the skin of his stomach to a distended length of 15.8 cm (6.25 in) on the set of Guinness World Records: Primetime in Los Angeles, California, USA, on October 29, 1999.Garry has a rare medical condition called Elhers-Danlos Syndrome, a disorder of the connective tissues affecting the skin, ligaments and internal organs. With this condition, the collagen that strengthens the skin and determines its elasticity becomes defective, resulting in, among other things, a loosening of the skin, and "hypermobility" of the joints. In more serious cases, it can cause the fatal collapse or rupturing of blood vessels.

World’s Strechiest Skin

The current world recorder holder for the longest fingernails is Lee Redmond (Utah). Ms. Redmond, who hasn’t cut her nails since 1979, has grown and carefully manicured them to reach a total length of 7 m 51.3 cm (24 ft 7.8 in).

World’s Longest Fingernails

Skin Problems & Disorders

*Some of these images may not be suitable for the squeamish.*

Acne

Skin Cancer- Basal Cell Carcinoma

Basal cell carcinoma is the most common type of skin cancer. It usually occurs on areas of the skin that have been in the sun, most often the nose. Often this cancer appears as a small raised bump that has a smooth, pearly appearance. Another type looks like a scar and is flat and firm to the touch. Basal cell carcinoma may spread to tissues around the cancer, but it usually does not spread to other parts of the body.

Squamous cell carcinoma occurs on areas of the skin that have been in the sun, such as the ears, lower lip, and the back of the hands. Squamous cell carcinoma may also appear on areas of the skin that have been burned or exposed to chemicals or radiation. Often this cancer appears as a firm red bump. Sometimes the tumor may feel scaly or bleed or develop a crust. Squamous cell tumors may spread to

nearby lymph nodes.

Skin Cancer- Squamous Cell Carcinoma

Skin Cancer- Melanoma

Melanoma is a form of cancer that begins in melanocytes (cells that make the pigment melanin). It may begin in a mole (skin melanoma), but can also begin in other pigmented tissues, such as in the eye or in the intestines. Melanomas, the most dangerous form of skin cancer, are responsible for the deaths of 20 Americans each day.

Check Y

our Moles!!!

Chicken Pox & Shingles (Herpes zoster)

Warts are a skin growth that is caused by a virus called the human papilloma virus. These viruses enter the skin and cause a wart to grow. They are usually the same color as skin, and can be flat, raised or smooth. Most warts are harmless but some can be cancerous. As it is caused by a virus, warts are contagious to others who may be susceptible to the same virus. Therefore care needs to be taken when coming into contact with another person.

Warts

Plantar wart

Common warts

Genital wart

• A skin infection that often involves a group of hair follicles. The infected material forms a lump, called mass, which occurs deep in the skin.

• A carbuncle is a swollen lump or mass under the skin. It may be the size of a pea or as large as a golf ball. The carbuncle may be red and irritated and might hurt when you touch it.

• It may also: grow very fast, have a white or yellow center (pustule), weep, ooze, or crust, spread to other skin areas

• Most carbuncles are caused by the bacteria Staphylococcus aureus.

Carbuncle

Vitiligo

(vit-ih-LI-go) A skin condition in which there is loss of pigment (color) from areas of skin, resulting in irregular white patches that feel like normal skin. Vitiligo affects both genders and all races, but is more noticeable in people with darker skin.

Gangrene

Gangrene is a medical term used to describe the necrosis (death) of tissue. It develops when the blood supply is cut off to the affected part as a result of various processes, such as infection, vascular (pertaining to blood vessels) disease, or trauma. Gangrene can involve any part of the body; the most common sites include the toes, fingers, feet, and hands.

Quiz over your notes tomorrow!!!

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