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INTEGUMENTARY SYSTEM ANATOMY AND PHYSIOLOGY INTRODUCTION • All living things are made of cells • Cells join together to make tissues • Tissues join together to form organs Skin • Skin is the principal organ of the integumentary system • Skin is one of a group of anatomically simple but functionally important sheetlike structures called membranes Membranes Membranes • A membrane is a thin, sheetlike structure with many important functions in the body • Membranes cover and protect the body surface, line body cavities, and cover the inner surfaces of the hollow organs. Two major categories of membranes • Epithelial – composed of epithelial tissue and an underlying layer of specialized connective tissue • Connective tissue membranes – composed exclusively of various types of connective tissue Three types of epithelial membranes – Cutaneous – Serous – Mucous Cutaneous Membrane Cutaneous Membrane • Commonly called the skin • One of the largest and more versatile organs of the body Functions of Cutaneous Membrane • • • • • • Protective covering Regulates body temperature Prevents water loss Houses sensory receptors Synthesizes various biochemical Excretes small qualities of waste Serous Membranes Serous Membranes • Found only on surfaces within closed cavities • Composed of 2 layers of tissue – the epithelial sheet and a thin layer of connective tissue • Secrete serous fluid- watery fluid which lubricates the membranes surface Serous Membranes • Two types: – Parietal – lines the walls of a body cavity – Visceral – covers the surface of organs found in the body cavities Serous Membranes • Pleura – Serous membranes that line the thoracic cavity • Peritoneum – Serous membranes that line the abdominal cavity Mucous Membranes Mucous Membranes • Lines cavities and tubes that are open to the outside • Consist of epithelial overlying a layer of loose connective tissue • Specialized cells within a mucous membrane secrete mucus Mucous Membrane • Examples – linings of: – Respiratory – Digestive – Urinary, and – Reproductive tracts Mucocutanous Junction Mucocutanous Junction The transitional area that serves as a point of “fusion” where the skin and mucous membranes meet Connective Tissue Membranes • Also called synovial membranes • Line the spaces between bones and joints that move • Slick, smooth membranes that secrete synovial fluid, which lubricates the ends of bones within the joint • Reduce friction between bones Cutaneous Membrane (Skin) Composed of the following layers: • Epidermis-outer layer of skin • Dermis- middle layer of skin • Subcutaneous-innermost layer of skin – thick layer of loose connective tissue and fat Epidermis • Tightly packed epithelial cells arranged in layers • Inner – stratum germinativum • Outer – stratum corneum Epidermis • Inner layer – stratum germinativum – cells specialize to increase their ability to protect the tissues below them. This enables the skin to repair itself if it is injured. As the cells approach the surface, the cytoplasm is replaced by keratin, a protein which is tough and waterproof and protects the body • Sometimes called the pigment layer because it is responsible for melanin production Epidermis • Outer layer – stratum corneum • Keratin-filled cells are constantly pushed to the surface and “flake off” • Millions of epithelial cells reproduce daily to replace the millions shed Melanin • Melanocytes are the cells within the pigment layer that produce melanin • Melanin is a dark pigment that provides skin color Melanin • Melanin absorbs light energy and protects deeper cells from the ill effects of UV light. • Skin color is due largely to melanin • Color is mostly genetically determined but can also be modified by sunlight exposure Skin Color Abnormalities • Cyanosis - bluish discoloration of the skin • Jaundice - yellowish discoloration of the skin • Erythemia - reddish discoloration Skin Color Abnormalities • Vitiligo – patchy areas of light skin resulting from the acquired loss of epidermal melanocytes. Most cases are genetic in origin. • Albinism – hereditary condition, characterized by a partial or total lack of melanin. Affected individuals are prone to eye damage and sunburn Dermis • Binds the epidermis to the subcutaneous layer • Contains blood vessels, hair follicles, nerve endings, sweat glands and nerve fibers Dermis • Upper region has parallel rows of peg like projections called dermal papillae • Form the dermal-epidermal junction • Form groves and ridges that make fingerprints • The pattern of these are unique in every person Dermis, cont. • Deeper area of dermis is collagen that gives toughness to skin. • Elastic fibers are present • Makes skin stretchable and elastic • Wrinkles form as skin loses elasticity Appendages • • • • Hair Receptors Nails Skin glands Appendages-Hair • Millions of small hairs cover the body • Follicles - present at birth, required for hair growth • Newborns are covered with soft, fine hair called lanugo • Areas of body that are hairless are lips, palms of hands and soles of feet • Most visible on scalp, eyelids and eyebrows Appendages-Hair • Growth begins from a small cluster of cells called the papilla. • Cells grow down into the dermis forming a small tube called the hair follicle • The root is the part of the hair that we can’t see (under the skin) • The shaft is the part of the hair we can see Appendages-Hair • Alopecia is hair loss • Arrector pili – involuntary muscle that contracts when we are frightened or cold, producing raised places called “goose bumps” or “goose pimples.” Appendages-Receptors • Act as sense organs • Relay messages such as touch, pain, temperature and pressure • Free nerve endings - respond to pain • Meissner’s corpuscles - located near the surface and detects light touch • Ruffini’s corpuscles – located in dermal layer and subcutaneous tissues of fingers, detect touch and pressure • Pacinian corpuscle- deep in dermis and capable of detecting pressure • Krause’s end bulb-responds to cold Appendages-Nails • Produced by cells in the epidermis • Form when epidermal cells fill with keratin and become hard and platelike Appendages-Nails • Nail body-visible part of the nail • Root-lies in a groove • Cuticle-groove and is hidden by a fold of skin • Lunula-”little moon”, near the root • Nail bed- area beneath nail • Color pink due to abundant supply of blood vessels seen through translucent nail bodies Appendages-Skin Glands • Sweat or Sudoriferous – Most numerous of skin glands – Two types: Eccrine and Apocrine • Sebaceous – Oil-secreting glands Appendages-Skin Glands • Eccrine Sweat Glands – Numerous and widespread throughout the body – Secrete watery liquid called perspiration (sweat) – Sweat assists in the elimination of waste products such as ammonia and uric acid Appendages-Skin Glands • Apocrine Sweat Glands – Found in axilla and in pigmented areas of genitals – Large, secrete milky secretions – Produces odor that is caused by mixing with skin bacteria – Enlarge and begin functioning at puberty Appendages-Skin Glands • Sebaceous Glands – Secrete oil for the hair and skin – Grow where hair grows – Tiny ducts open into hair follicles so that their secretion, called sebum, can lubricate hair and skin. – Sebum darkens to form blackheads – Acne vulgaris is the over secretion of sebum Disorders of Skin • Dermatosis-any disorder of the skin • Dermatitis-inflammation of the skin • Lesion-measurable variation from the normal structure of a tissue – Distinguished by abnormal density, or coloration – Discoloration usually occurs Skin Lesions ELEVATED • Papule • Plaque • Vesicle • Pustule • Crust • Wheal FLAT • Macule DEPRESSED • Excoriation • Ulcer • Fissure Skin Lesions ELEVATED • Papule - warts • Plaque – can be caused by friction • Vesicle – non-genital herpes • Pustule – acne • Crust - scab • Wheal - hives Skin Lesions FLAT • Macule - freckles • Patch - vitiligo DEPRESSED • Excoriation – scratches • Atrophy – stretch marks • Ulcer - bedsore • Fissure – athlete’s foot Classification of Burns • • • • First-degree burns Second-degree burns Third-degree burns Fourth-degree burns • Third- and fourth-degree burns are both called full-thickness burns Burns-Classifications • First-degree burns-causes minor discomfort – Example-sunburn – Reddening of the skin – No blistering – Tissue damage is minimal Burns-Classifications • Second-Degree Burns – Involves deep epidermal layers – Causes injury to upper layers of dermis – Damages sweat glands, hair follicles and sebaceous glands – Blisters, severe pain, generalized swelling – Scarring is common Burns-Classifications • Third-Degree Burns – Complete destruction of the epidermis and dermis – Tissue death extends to subcutaneous layer – Insensitive to pain due to destruction of nerve endings – Increased fluid loss Burns-Classifications • Fourth-Degree Burns – Full thickness burn that extends below the subcutaneous layer to reach muscle or bone – Often result from electrical burns or exposure to intense heat over time – Insensitive to pain due to destruction of nerve endings – Increased fluid loss Burns-Classifications • Serious burns result in over 50,000 hospital admissions each year. • Circulatory shock, fluid loss, respiratory injury, and infections are common complications. • May require skin grafting or amputation of limbs Estimating Body Surface Area • “Rule of Nines”-body is divided into 11 areas of 9% – Each arm is 9% for total of 18% – Head is 9% – Each leg is 18% for total of 36% – Torso is 18% – Back is 18% – Perineal area is 1% Skin Infections Bacterial infections (streptococcal or staphylococcal) • Impetigo • Boils Skin Infections Viral infections • Warts Skin Infections Fungal infections • Tinea – ringworm, jock itch, athlete’s foot Skin Infections Arthropod infestations • Scabies – caused by the itch mite Skin Infections Other skin disorders • Decubitus ulcers – bedsores • Urticaria – hives (often caused by allergic reaction) • Scleroderma – autoimmune disease affecting blood vessels and connective tissues • Psoriasis – plaques that remain on the skin for a long time • Eczema – inflammation, caused by an underlying disease Skin Cancers • • • • Squamous Cell Carcinoma Basal Cell Carcinoma Melanoma Kaposi’s Sarcoma