Unit 4 The Integumentary System I. Classification of Body Membranes A. Epithelial Membranes (3) 1. Cutaneous Membrane > Stratified Squamous > Sits on Dense Connective Tissue > Skin: Epidermis & Dermis > Dry Membrane 2. Mucus Membrane > Epithelial Cell type varies > Sits on Loose Connective Tissue > Lines all body cavities that open to exterior > Wet & Moist Membrane 3. Serous Membrane > Simple Squamous > Sits on Areolar Connective Tissue > Lines body cavities closed to exterior > Found in pairs Parietal layer: lines body cavity Visceral layer: covers outside of organ Layers are separated by Serous Fluid > Types: Peritoneum = Abdominal area Pericardium = Heart area Pleura = Lung area 1
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I. Classification of Body Membranes cont'd B. Connective Tissue Membrane (1) 1. Synovial Membrane > Surrounds joints > Provides smooth surface > Secretes lubricating fluid Reduces friction 3
II. Cutaneous Membrane (Skin) A. Structure of the Skin 1. Epidermis New every 35 45 days Avascular Cell Types: > Keratinocytes produce keratin > Melanocytes produce melanin > Dendritic defense > Tactile sensory reception Stratified Squamous epithelium with ability to Keratinize & "Waterproof" > Hardening & drying out of cells through production of Keratin > "Waterproof" from glycolipid produced that coats cells Epidermal Sections: > Stratum Corneum: outermost section 20 30 layers of Keratinized dead cells > Stratum Lucidum > Stratum Granulosum > Stratum Spinosum > Stratum Germinativum/Stratum Basale: deepest layer of epidermis Area of cell division Nourishment from dermis via diffusion 4
; 1. Epidermis cont'd Production of Melanin > by Melanocytes found in S. Germinativum > What happens when skin is exposed to sunlight? Melanocytes are stimulated to make more melanin Melanin phagocytized by Keratinocytes Natural "Sunscreen" «Melanin creates shield/umbrella over underlying nucleus «prevents DNA mutations from UV rays 5
2. Dermis "hide" Composed of mostly Dense Irregular Connective Tissue Split into two regions: > > Papillary: upper dermal region ( dermal papillae) Aerolar Connective Tissue Provide nutrients to epidermis (blood vessels) House pain receptors Phagocytes Creates patterns: "finger prints" Reticular: deepest dermal layer Composed of collagen & elastic fibers (Dense Irregular) Houses blood vessels (vascularized) Houses sweat & oil glands Phagocytes 6
B. General Functions Protection From: > Mechanical, Chemical, Thermal Damage S. corneum (like "bricks & mortar") «Multiple layers of dead keratinized cells = bricks «Glycolipids = mortar > Bacterial Damage Low ph Chemicals in sweat & oil Dendritic cells (epidermis) & macrophages (dermis) > Ultraviolet Radiation Melanin = natural sunscreen > Dessication (drying out) Glycolipids = waterproof barrier Aids in temperature regulation Excretion Vitamin D synthesis C. Skin Color Determined by... > Amount & Type of Melanin > Amount of Carotene deposited in the S. Corneum > Amount of O 2 bound to Hemoglobin in dermal blood vessels Homeostatic Imbalances: > Cyanosis > Jaundice > Anemia 7
III. Accessory Structures A. Glands 1. Sebaceous Glands (oil) Found all over body except palms & soles Most are open to hair follicle Secretes sebum (grease) > Arrector pili muscles contract & force sebum out > Prevent hair from becoming brittle / moisturizes skin > Chemicals that kill bacteria If gland is blocked, sebum backs up = Whitehead 2. Sudoriferous Glands (sweat) Eccrine Gland > Found all over body > Secretes H 2 O, salts, & little urea > Functions: helps regulate body temperature & excretion Apocrine Gland > Found in axillary & pubic regions > Secretes everything eccrine does + fatty acids & proteins > Unknown function > Odorless Bacteria who utilize fatty acids & proteins are not!!!! 8
B. Hair Made of protein (hard Keratin) Protects eyes & respiratory tract Produced by hair follicle > Root is in follicle > Shaft (dead tissue) is mainly above skin Arrector Pili Muscle > Connects hair follicle to dermis > When cold, this contracts and stands hair upright... C. Nails Scale like modifications of the skin Colorless Appears pink because dermis (rich in blood vessels) lies just below 9
IV. Skin Cancer A. Types 1. Basal Cell Carcinoma Most common Slow advancing Stratum Germinativum/Basale cells unable to keratinize Remove lesion (Life is Good) 2. Squamous Cell Carcinoma Grows rapidly Metastasizes Affects cells between S. Corneum & Basale Catch early & remove lesion or Radiation (Life is Good) 3. Malignant Melanoma Cancer of Melanocytes Metastasizes quickly to lymph & blood vessels If not detected early, survival rates are low often resistant to chemotherapy B. ABCD Rule of Cancer A: Asymmetry: 2 sides don't match B: Border Irregularity: not nice and smooth C: Color: different colors (blacks, browns, tans...sometimes blues and reds) D: Diameter: over 6 mm in diameter E: Elevation: some add "E" to the ABCD Rule 10