The Integumentary System Health & Anatomy
Review of Membranes -Serous Membranes are composed of simple squamous epithelium resting on a thin layer of areolar connective tissue. *Name depends on the location in the body.
Synovial Membranes -soft areolar connective tissue (no epithelial cells). -lines capsule surrounding joints. -smooth surface /fluid. *Bursae & Tendon Sheath- small sacs/tubes of connective tissue for cushioning organs or joints.
What are the major characteristics of the skin? l Waterproof, stretchable, washable, automatically repairs small cuts, rips and burns and is guaranteed to last a lifetime. l Surface area of up to 2.2 square meters l 11 pounds l 7% of total body weight l Pliable yet tough
l Epidermis (epi-upon) Composed of epithelial tissue (stratified squamous) Non-vascularized l Dermis underlies the epidermis Tough leathery layer composed of fibrous connective tissue Good supply of blood l Hypodermis (not considered skin) Made of adipose and areolar tissue Stores fat, anchors skin, protects against blows What are the 3 major layers of the skin? Epidermis Dermis Hypodermis
Epidermis Dermis Basement membrane
What are the different types of l Keratinocytes cells in the epidermis? Produce a fibrous protein called keratin Are formed in the lowest levels of the epidermis. Pushed upward by the production of new cells beneath them. Become dead and scale-like Millions rub off everyday
What are the different types of cells in the epidermis? l Melanocytes Synthesizes the pigment melanin Melan/o-black Can transfer melanin to keratinocytes Protects skin from ultraviolet light. melanocyte Melanin in keratinocytes
What are the different types of cells in the epidermis? l #1: Langerhans cells Formed in bone marrow. Move to the skin Macrophages (cells that engulf or eat) Langerhans cell Macr/o-large Phag/o-to eat
What are the different types of cells in the epidermis? l #2: Merkel Cells Has a spiked appearance Connected to nerve cells from dermis Function as sensory receptors for touch.
l Stratum basale: deepest layer of the epidermis, undergoes rapid cell division. l Stratum spinosum: intermediate layer, contain spiny shaped keratinocytes. l Stratum corneum: outermost layer 20-30 cells thick of dead keratinized cells. Dandruff Average person shed 40 pounds of these cells in their lifetime. Everything you see on a human is dead! What are the layers of the epidermis?
What are the characteristics of the dermis? l Made up of connective tissue l Richly supplied with blood vessels and lymph vessels l Has hair follicles, oil and sweat glands and sensory receptors l Ridges formed from the papillary layer can form finger prints.
Reticular layer of the dermis l Filled with dense irregular fibrous connective tissue l Matrix is filled with thick bundles of collagen fibers (give the skin strength) l Less dense regions are called lines of cleavage or tension lines; surgeons use these to make incisions because they heal quicker.
What causes the color of skin? l 3 pigments contribute to skin color Melanin- protein pigment (natural sunscreen) l Can range in color from yellow to reddish-brown to black l Everyone has the same number of melanocytes but make varying amounts and colors (differences in skin color) l Increased melanin production can be caused by sunlight. Carotene-yellow to orange pigment found in carrots. l Most commonly found in the palms or soles. Most intense when large amounts of carotene-rich foods are eaten. Hemoglobin- Red blood gives a pinkish hue to fair skin
What are the major appendages of the skin? l Sweat glands l Sebaceous glands l Hairs l Nails
What are the types of glands found in the skin? l 1.) Sweat glands-sudoriferous Merocrine- common sweat glands l Hot sweats vs. Cold sweats Apocrine- produce sweat plus a milky or yellowish substance composed of fat and protein. l Found in the arm pits and genitalia l Thought to be scent glands. Ceruminous- produce cerumen (ear wax) Mammary glands- produce milk l 2.) Sebaceous glands- oil glands (sebum) Softens and lubricates hair and skin Slows water loss and kills bacteria Stop Day 1 Notes J
Why is hair useful? l Senses insects that land on the skin. l Hair on the head protects the head from a blow, sunlight and heat loss. l Eyelashes shield the eye l Nose hairs filter the air
What are hairs? l Made from hair follicles l Made of dead keratinized skin cells l Two parts shaft and root l Shaft has 3 layers of cells Medulla(central core) Cortex (bulky layer) Cuticle (heavily keratinized; protects hair)
What are the parts of nails? l A nail is a scalelike modification of the epidermis l Made of tightly compressed keratinized cells l Useful tools to pick up small objects or scratch an itch. l Nail matrix is the region responsible for nail growth.
What are the primary functions of the Integumentary System? l 1. Protection: provides 3 types of barriers A.) Chemical barriers: low ph of skin secretions slows bacterial growth. Human defensin is an antibiotic that destroys bacteria (produced by human skin)
Physical barriers B.) Physical barriers: very few substance are able to enter the skin. Substances able to pass. l Lipid-soluble substances: oxygen, carbon dioxide, some vitamins l Oleoresins- poisons (poison ivy) l Organic solvents- dry-cleaning fluid, paint thinner l Salts of heavy metals- lead, mercury, nickel l Penetration enhancers- drug agents that help substances into the body.
c.) Biological barriers l Langerhans cellsact as macrophages police the epidermis for viruses and bacteria.
Functions cont. l 2.) Thermoregulation- skin contains sweat glands that secrete watery fluid, that when evaporated, cools the body. l 3.) Sensation- Skin contains sensory receptors that detect cold, touch, and pain. l 4.) Vitamin D synthesis- cholesterol in the skin is bombarded by sunlight and converted to vitamin D
Functions cont. l 5.) Blood reservoir- blood will be moved from skin to muscles during strenuous activity. l 6.) Excretion- Sweating is an important outlet for wastes such as salt and nitrogen containing compounds. (urine)
Skin Cancer l Benign tumors such as warts and moles are not serious. l Malignant tumors can start on the skin and invade other body areas. l Crucial risk factor- overexposure to UV radiation
Types of Skin Cancer l Basal cell carcinoma- most common, 30% of all white skin people get it. Arises from the stratum basale layer of the skin 99% curable if caught early Dome shaped nodules that form an ulcer in the center. l Squamous Cell carcinoma- Arise from stratum spinosum Grows rapidly and metastasizes if not removed Small red rounded elevation on the skin
Skin Cancer Types cont. l Melanoma Cancer of melanocytes (very dangerous) 5% of skin cancers but rising fast Can arise from preexisting moles Appears as a spreading brown or black patch Chance of survival is poor if the lesion is greater than 4 mm thick
Causes of Skin Cancer Video: Melanoma
Lesion removed from patient Basal Cell Carcinoma
Squamous cell carcinoma
What is the ABCD rule? l Used for recognizing melanoma l A-Asymmetry: two sides of the pigmented mole do not match l B-Border irregularity: borders are not smooth l C- Color: lesion has multiple of colors l D- Diameter the spot is larger than 6 mm in diameter (size of a pencil eraser)
What are the 3 types of burns? l First-degree burns: only the epidermis is damaged. Redness, swelling and pain are common. (sunburn) 2-3 days to heal l Second-degree burns: epidermis and upper layers of dermis. Blistering can occur. 3-4 weeks to heal. l Third-degree burns: involves the entire thickness of the skin. (pg. 164-165)
Second-degree burns Third-degree burn