Integumenatry System Ch 5

The Skin as an Organ

Function Protection- mechanical, chemical, bacterial Body temperature regulation Prevent water loss Metabolic- synthesize vitamin D Cutaneous Sensation Blood reservoir Excretion Prevent UV damage

The Skin Facts: Weighs 9-11 lbs s.a. = 1.5-2m2 An organ, cells constantly dying and being replaced Facts: Weighs 9-11 lbs s.a. = 1.5-2m2 1 cm2 has 70 cm blood vessels, 55 cm nerves, 100 sweat glands, 15 oil glands, 230 sensory receptors New skin produced in 25-45 days

The Epidermis

Cells of the Epidermis Keratinocytes (90%)- waterproofs & protects skin, nails, hair, stratum corneum Melanocytes (8%)- produce melanin Merkel Cells- slow mechanoreceptors Langerhans’ Cells- macrophages immunological defense

Layers of the Epidermis Stratum Corneum Stratum Lucidum Stratum Granulosum Stratum Spinosum Stratum Basale- (Germinativum)

Layers of the Epidermis

The Dermis Dermis

Layers of the Dermis papillary dermis reticular dermis

Components of the Dermis a. Cellular Fibroblasts (synthesize collagen, elastin, and reticulin), histiocytes, endothelial cells, perivascular macrophages and dendritic cells, mast cells, smooth muscle, and cells of peripheral nerves and their end-organ receptors. b. Fibrous Collagen & reticulin - provide tensile strength Elastic fibers- provide for restoration of shape after a deformation c. Ground substance glycosaminoglycans: hyaluronic acid, chondroitin sulfate, and dermatan sulfate.

The Hypodermis Hypodermis This layer contains adipose tissue and serves to attach the dermis to its underlying tissues.

Skin Color Skin color due to (Sub-Saharan African, Indian, Southern European, and Northwest European) Skin color due to Hemoglobin = red pigment of red blood cells Carotene = yellow pigment concentrates in stratum corneum and fat Melanin = yellow, brown, and black hues pigment synthesis stimulated by UV radiation

Skin Colors (Pigmentation) Melanin Pigments: Eumelanin: Phaeomelanin > Eumelanin: Phaeomalanin- darker skin and hair color; < Eumelanin: Phaeomalanin- lighter skin and hair color

Melanosome transport to keratinocyte Immature melanosome UV light, stress, certain hormones Melanin Actin filaments Plasma membrane Skin & hair darkening Melanocyte

Melanosome transport to keratinocyte Melanin pigment in keratinocyte Melanin pigment Melanocyte Basement membrane

Skin Color Human complexions are generally classified into six skin types: I -light skinned, burns easily, never tans II - light skinned, burns easily, tans some III - light skinned, burns occasionally, tans well IV - light skinned, tans well, rarely burns V - brown skinned (Asian, Indo-Asian, Chinese, Japanese), tans well, burns rarely, can sunburn after prolonged exposure to UVR VI - black skinned (Afro-Caribbean), deeply pigmented, can burn after prolonged exposure to UVR 25% US pop

Skin Color Conditions Cyanotic Jaundice Erythema Pallor

Skin Color Conditions Cyanotic Jaundice Erythema Pallor

Skin/Hair Color: Pigmentation Pigmentation levels usually increase with age. - exception: premature graying Normal pigmentation may be altered by genetic defects or by acquired diseases. -Hyperpigmentation- age spots -Hypopigmentation- vitiligo, albinism

Skin/Hair Color: Pigmentation External agents can also alter skin color. lightening agents carotene dyes Some internal compounds--such as the byproducts of hemoglobin metabolism--may color the skin.                              Sunless tanning

Skin Appendages Sweat Glands Eccrine (merocrine) glands- sweat Apocrine glands- axillary & anogenital areas Ceruminous glands- ears canal Mammary glands- female reproductive glands Sweat glands Ceruminous glands

Skin Appendages Sebaceous

Sebaceous (oil) glands Entire body except palms and soles Produce sebum by holocrine secretion Oils and lubricates

Sweat glands Entire skin surface except nipples and part of external genitalia Prevent overheating 500 cc to 12 l/day! (is mostly water) Humans most efficient (only mammals have) Produced in response to stress as well as heat

Types of sweat glands Eccrine or merocrine Apocrine Most numerous True sweat: 99% water, some salts, traces of waste Open through pores Apocrine Axillary, anal and genital areas only Ducts open into hair follices The organic molecules in it decompose with time - odor Modified apocrine glands Ceruminous – secrete earwax Mammary – secrete milk

Hair Bulb

Hair Shaft Three layers of the hair in cross-section from inside out Hair shaft cross-section Hair cuticle cortex medulla

Keratin Keratin is the essential component of hair (and rhino horn). It is a protein formed by the combination of 18 amino acids. Cysteine, being rich in Sulphur, plays an important role in the cohesion of the hair. It is produced by the keratinocytes. These cells, situated in the bottom of the dermal papilla.

Hair Color Melanin: Eumelanin Pheomelanin Hair color is mostly the result of pigments, which are chemical compounds that reflect certain wavelengths of visible light. Melanin: Eumelanin Pheomelanin

Melanocyte A cell found in the hair bulb Produces melanin

Structure of Hair and Follicle Eumelanin Color – due to pigment granules in the cells of the cortex brown and black hair high levels of eumelanin red hair – low eumelanin but a high pheomelanin blond hair intermediate amount of pheomelanin; very little eumelanin Gray and white hair scarcity or absence of melanin in the cortex and the presence of air in the medulla Pheomelanin

Texture – related to differences in cross-sectional shape straight hair is round wavy hair is oval curly hair is relatively flat

Fingernail Structure Nail bed- skin on which the nail bed rests Nail plate- clear keratinized portion of the nail Root- proximal end of the nail, under the nail fold Body- major portion of the nail plate Free edge- extends beyond digit Eponychium- cuticle Hyponychium- epithelium of the nail bed Nail matric- zone of mitotic division

Nails Derivative of stratum corneum densely packed cells filled with hard keratin Flat nails allow for fleshy, sensitive fingertips Growth rate is 1 mm per week new cells added by mitosis in the nail matrix nail plate is visible part of nail medical diagnosis of iron deficiency = concave nails

Skin Cancer Malignant melanoma 2% of all cancers Risks: Skin type Sun exposure Family history Age Immunological status                              Normal mole Melanoma A= asymmetry B= border C= color D= diameter

Burns Burns 1st-degree 2nd-degree 3rd-degree (epidermis only; redness) (epidermis and dermis, with blistering) First-degree burns, the mildest of the three, are limited to the top layer of skin. Signs and symptoms: These burns produce redness, pain, minor swelling, but no blistering. The skin often turns white you press on the burned area. Healing time: Healing time is about 3 to 6 days; the superficial skin layer over the burn may peel off in 1 or 2 days. Second-degree burns are more serious and involve the skin layers beneath the top layer. Signs and symptoms: These burns produce blisters, severe pain, and redness. The skin can appear blotchy white to cherry red. Healing time: Healing time varies depending on the severity of the burn. Third-degree burns are the most serious type of burn and involve all the layers of the skin and underlying tissue. Signs and symptoms: The remaining surface can look waxy, leathery, or charred. There may be little or no pain at first because of nerve damage. Healing time: Healing time depends on the severity of the burn. Deep second- and third-degree burns (called full-thickness burns) will likely need to be treated with skin grafts, in which healthy skin is taken from another part of the body and surgically placed over the burn wound to help the area heal. 3rd-degree (full thickness, destroying epidermis, dermis, often part of hypodermis)

Burns What to Do: Seek Medical Help Immediately If: You think your child has a second- or third-degree burn. The burned area is large, even if it seems like a minor burn. For any burn that appears to cover more than 15% to 20% of the body, call for medical assistance. And don't use wet compresses because they can cause the child's body temperature to drop. Instead, cover the area with a clean, soft cloth or towel. The burn comes from a fire, an electrical wire or socket, or chemicals. The burn is on the face, scalp, hands, joint surfaces, or genitals. The burn looks infected (with swelling, pus, increasing redness, or red streaking of the skin near the wound). For First-Degree Burns: Remove clothing from the burned area immediately. Run cool (not cold) water over the burned area (if water isn't available, any cold, drinkable fluid can be used) or hold a clean, cold compress on the burn until pain subsides (do not use ice, as it may cause the burn to take longer to heal). Do not apply butter, grease, powder, or any other remedies to the burn, as these increase the risk of infection. If the burned area is small, loosely cover it with a sterile gauze pad or bandage. Give your child acetaminophen or ibuprofen for pain. If the area affected is small (the size of a quarter or smaller), keep the area clean and continue to use cool compresses and a loose dressing over the next 24 hours. You can also apply antibiotic cream two to three times a day, although this isn't absolutely necessary. For Second- and Third-Degree Burns: Seek emergency medical care, then follow these steps until medical personnel arrive: Keep your child lying down with the burned area elevated. Follow the instructions for first-degree burns. Remove all jewelry and clothing from around the burn (in case there's any swelling after the injury), except for clothing that's stuck to the skin. If you're having difficulty removing clothing, you may need to cut it off or wait until medical assistance arrives. Do not break any blisters. Put wet, sterile bandages on the burned area until help arrives.

Burns First-degree burns, the mildest of the three, are limited to the top layer of skin. Signs and symptoms: These burns produce redness, pain, minor swelling, but no blistering. The skin often turns white you press on the burned area. Healing time: Healing time is about 3 to 6 days; the superficial skin layer over the burn may peel off in 1 or 2 days. Second-degree burns are more serious and involve the skin layers beneath the top layer. Signs and symptoms: These burns produce blisters, severe pain, and redness. The skin can appear blotchy white to cherry red. Healing time: Healing time varies depending on the severity of the burn. Third-degree burns are the most serious type of burn and involve all the layers of the skin and underlying tissue. Signs and symptoms: The remaining surface can look waxy, leathery, or charred. There may be little or no pain at first because of nerve damage. Healing time: Healing time depends on the severity of the burn. Deep second- and third-degree burns (called full-thickness burns) will likely need to be treated with skin grafts, in which healthy skin is taken from another part of the body and surgically placed over the burn wound to help the area heal.

Burns

Burns Skin replacement: http://www.youtube.com/watch?v=eXO_ApjKPaI

Tissue Repair Blood vessels dilate WBC & clotting agents released Scab forms

Tissue Repair Granulation tissue forms Capillary beds invade clot Clean up begins

Tissue Repair Scar area has contracted Epithelium regeneration begins

INQUIRY In which lay of skin are blood vessels located? Where does epithelium regeneration begin? What color is a persons skin if they are cyanotic? List the layer of the epidermis in order from top to bottom. What is the primary tissue of the hypodermis?