Skin and Body Membranes Chapter Four Skin and Body Membranes

Classification of Membranes Epithelial Cutaneous Skin Stratified squamous Mucous (mucosa) Lines cavities Simple columnar Serous One layer Simple squamous Serous fluid Parietal & Visceral Lines body cavities Around organs Pleura & Pericardium

Functions of the Skin Protection Defense Prevention of Dehydration Against disease Insulates & cushions UV protection Chemical protection Defense 1st line of defense Prevention of Dehydration Keratin Keeps H2O in & out

Functions of the Skin Maintenance of Body Temp. Excretion of Wastes Heat loss – sweat Heat retention – blood flow Excretion of Wastes Salts Urea H2O Reception of Stimuli Touch, pressure, pain, cold, heat Vitamin D Synthesis Cholesterol molecules  Vitamin D (sunlight)

Layers of the Skin - integumentary Epidermis Strata Stratum basale Closest to dermis Undergoes mitosis Nutrients from diffusion Stratum spinosum Flattened cells w/ spines Stratum granulosum Granules w/ keratin Stratum corneum “horny” 20-30 cell layers Soles. Palms, fingertips-stratum lucidum

Cell Types Keratinocytes Melanocytes Langerhans cell Make keratin Make melanin Secretes melanin – basale layer Langerhans cell Macrophages-eat foreign substances

Skin Color – amount and kind Pigments Melanin Reddish brown, or black Carotenes yellow Hemoglobin rosy Emotional Redness (sympathetic) Embarrassment Anger Fear Allergies

Dermis – “hide” leather Thick connective tissue layer beneath stratum basale. Collagen Elastin Papillary layer Upper, uneven Receptors (pain, touch) Dermal papillae Fingers-fingerprints Soles-footprints

Dermis cont… Reticular layer Deepest Blood vessels Sweat and oil glands Blood supply when restricted Degeneration Ulceration – bed sore

Appendages of the Skin Glands Sebaceous glands Oil Sebum: lubricant, bacteria killing Whiteheads (blocked oil gland)  blackhead acne Seborrhea – excess oil Sweat glands – 500 ml a day (25 million) Eccrine Sweat Clear 99% water Salts, urea, lactic acid, pH 4-6 Apocrine Axillary & genital areas Fatty acids, proteins, sweat (yellowish) Empty into hair follicles

Appendages of the Skin cont.. Nails Modified epidermal cells Keratin Hair 100,000 hairs scalp Follicle Keratinized cells Arrector Pili (goose bumps)– smooth muscles -Hairs erect-increase blood flow to skin Cuticle Keep hairs separate

Infections and Allergies 1000 different conditions Fungi Athletes foot fungus Ringworm Bacterial Boils and carbuncles Staphylococcus into hair follicles Oil glands Impetigo Viruses Herpes “cold sores” Warts

Allergies Unknown Yeasts Eczema Contact dermatitis “rash” Psoriasis Hives Yeasts

Skin in Stress Wound Repair Wound Inflammatory reaction Edema Clots Blood flow Edema swelling Clots Stop bleeding WBC’s Fight bacteria Pus Dead blood cells Dead bacteria Scabs

Skin in Stress cont… Burns Thermal First degree Second degree Heat Chemical – electrical - UV First degree Epidermis “red” Heal 2-3 days Second degree Epidermis & dermis Blisters Third degree Skin blackens Skin grafts Risk of death Fluid loss , imbalance of electrolytes Kidney failure Replace proteins , infection

Skin Cancer Basal Cell Carcinoma Squamous Cell Carcinoma Most common Alters stratum basale cells Uncontrolled mitosis can’t form keratin Squamous Cell Carcinoma Stratum spinosum Scaly reddish papulae Spreads to lymph nodes Malignant Melanoma – (5%) Brown black patches Lymph & blood vessels ABCD rule moles Asymmetrical, border, color, diameter 76mm

Disease States Erythema Pallor, blanching Jaundice Porphyria Bruises Turns red Pallor, blanching Anemia Low blood pressure Jaundice Yellowing Liver disorder Porphyria purple Bruises Hematoma Broken capillaries Cyanosis “bluish” Low 02 in blood