Integumentary System Study Notes PDF

2 3 Two major groups: Epithelial Membranes Connective Tissue Membranes 4 1. Cutaneous All function in Membrane covering and lining 2. Mucous Always combined Membranes with underlying 3. Serous layer of connective Membranes...

2 3 Two major groups: Epithelial Membranes Connective Tissue Membranes 4 1. Cutaneous All function in Membrane covering and lining 2. Mucous Always combined Membranes with underlying 3. Serous layer of connective Membranes tissue 5  The skin Superficial epidermis composed of keratinizing stratified squamous epithelium A dry membrane 6  Line body cavities that open to the exterior, such as respiratory, urinary, digestive, & reproductive tracts Wet membranes; often adapted for absorption or secretion 7  Line body cavities that are closed to the exterior such as thoracic or abdominal Occur in pairs Parietal layers line the inside wall of the cavity Visceral layers line the outside of the organ Both layers secrete serous fluid which reduces friction 8 9 10  Synovial membranes line the fibrous capsules surrounding joints, bursae, and tendon sheaths Provide a smooth surface and secrete lubricating fluid 11 12  The skin is the body’s largest organ Weighs about 10 pounds Surface area of about 20 square feet 13 14 Superficial epidermis sits on the much thicker dermis. 15  Stratified squamous epithelium in 5 zones 20-50 layers thick Avascular; cells receive nutrients through diffusion of fluids from the dermis Rapid cell division occurs in lower layer Cells die as they migrate towards surface 16  Almost 90% of cells in the epidermis are keratinocytes Produce and the store the protein keratin Keratin makes cells tough, scaly, and water-resistant 17  In lower layer of epidermis Produce the pigment melanin Protects skin from UV radiation Freckles and moles are concentrated melanin 18  Amount & kind of melanin ranges from yellow to brown to black determined by genetics Carotene Hemoglobin 1  Gives skin strength and elasticity Varies in thickness; particularly thick on palms of hands and soles of feet Two Regions Papillary Layer Reticular Layer 2  Superficial layer borders epidermis Projections called dermal papillae hold epidermis & dermis together Capillary loops nourish epidermis Pain receptors – free nerve endings Touch receptors – Meissner’s Corpuscles 3  Blood vessels Sweat & oil glands Deep pressure receptors - Pacinian corpuscles Phagocytes act to prevent bacteria from penetrating more deeply into the body 4  Collagen (left) is a protein that gives toughness and hydration to the skin Elastin is a fibrous glycoprotein that provides elasticity 5  Two Skin Layers ▪ Epidermis ▪ Dermis Papillary Layer Reticular Layer 6  Sudoriferous or Sweat Glands Most are eccrine Sebaceous Glands Hair & Hair Follicles Nails 7  Also called sweat glands Two types: eccrine and apocrine Eccrine is the most common and widely distributed in skin Ducts lead to pores which open at the skin’s surface Sweat reduces body temperature 8  Less numerous than eccrine glands Concentrated in axillary & genital areas Ducts empty into hair follicles Secretion contains fatty acids and proteins in addition to usual products Odor is from associated bacteria Begin to function during puberty 9  Produce oil called sebum Skin & hair lubricant Contains anti-bacterial substances Most have ducts that empty into hair follicles Glands are activated at puberty 10  Grows from root in the hair follicle Consists of tightly packed keratinocytes Melanocytes provide pigment for hair color Protects skin from UV radiation 11  Sheets of hardened keratinocytes Reinforce and protect distal ends of fingers & toes Nail matrix produces new growth Lunula is thick area over matrix 12 1 1. Protection 2. Temperature control 3. Excretion 4. Vitamin D production 5. Detection of stimuli 2 The process of keratin accumulating within keratinocytes As new cells are formed, older cells are pushed towards surface Cells become harder, flatter and tightly packed to form a protective barrier 3 Tough keratin barrier, if unbroken, protects against: Mechanical Damage Chemical Damage Bacterial Damage Desiccation 4 The nervous system responds to high body temperature (hyperthermia) by ○ Activating sweat glands ○ Relaxing blood vessels and increasing blood flow into capillary beds Low body temperature (hypothermia) is corrected by ○ Constricting blood vessels and reducing blood flow into capillary beds 5 Small bands of smooth muscle connect hair follicles to the dermis When the muscles contract, the hair is pulled upright causing a bump in the skin’s surface, often called “goose bumps” 6 Urea, uric acid, ammonia, and lactic acid are eliminated through perspiration by sweat glands. 7 Mostly water Some salts (electrolytes) Vitamin C Metabolic wastes ○Urea ○Uric acid ○Ammonia ○Lactic acid 8  Modified cholesterol molecules in the skin are converted into Vitamin D by sunlight Vitamin D is necessary for the absorption of calcium and also plays a vital role in immunity 9 The sense of touch is accomplished by a variety of nerve endings. For example: Free nerve endings detect temperature & pain Meissner’s corpuscles detect light touch Pacinian corpuscles detect deep pressure 10 11 12 First-degree Burns ○Only epidermis is damaged ○Skin is red and swollen Second-degree Burns ○Epidermis and upper dermis are damaged ○Skin is red with blisters Third-degree Burns ○Destroys entire skin layer ○Burn is gray-white or black 13 14 Cancer: abnormal cell mass Two types: ○Benign: Does not spread (encapsulated) ○Malignant: Metastasizes (moves) to other parts of the body Skin cancer is the most common type of cancer 15 Most deadly of skin cancers Cancer of melanocytes Metastasizes rapidly to lymph and blood vessels 16 17