INTEGUMENTARY SYSTEM SKIN & BODY MEMBRANES

MEMBRANES: An overview Defined:Defined: –Superficial layer of epithelial cells –underlying layer of supportive connective tissue Structure: Thin, sheet-like structureStructure: Thin, sheet-like structure

Membranes: Functions Functions:Functions: –Cover and protect the body surface, internal organs –Line the body cavities, inner surface of hollow organs –Anchor organs to each other or to bones –Secrete lubricating fluids that reduce friction during organ movements

Two Types of Body Membranes 1) Connective Tissue Membranes1) Connective Tissue Membranes 2) Epithelial Membranes2) Epithelial Membranes –Serous membranes –Mucous membrane –Cutaneous membrane (skin)

Connective: Synovial Membrane StructureStructure –No epithelial layer – connective only –Smooth & slick

Connective: Synovial Membrane Function:Function: –Lines capsules b/w joints that move –Lines bursa sacs –Secrete synovial fluid –Reduce friction b/w opposing bones

Epithelial: Serous Membranes Found only on surfaces within closed cavitiesFound only on surfaces within closed cavities 2-layer structure:2-layer structure: –Epithelial – thin layer of simple, squamous epithelium –Connective – thin, glue-like basement membrane that holds and supports

Serous Membranes: Function Function: Protection/reduce friction for organsFunction: Protection/reduce friction for organs Two Types (1 continuous layer):Two Types (1 continuous layer): 1. Visceral: covers the surface of the organ 2. Parietal: lines the walls of the body cavity Thoracic Cavity/Lungs=PleuraThoracic Cavity/Lungs=Pleura Abdominal Cavity=PeritoneumAbdominal Cavity=Peritoneum –What is pleurisy? –What is peritonitis?

Epithelial: Mucous Membrane Secretes Mucus: moistens, lubricates, protects Lines body surfaces opening directly to exterior (respiratory, digestive, reproductive & urinary tracts) Structure: - Epithelium varies depending on location, function

Epithelial: Mucous Membranes

Epithelial: Cutaneous Membrane = Skin= Skin

Epithelial: Cutaneous Membrane (SKIN) FUNCTIONSFUNCTIONS –Protection against microbes, UV rays, harmful chemicals, cuts & tears –Temperature regulations –Sense organ activity: touch, pressure, pain, temperature –Metabolic functions: synthesis of vitamin D

Skin: Structure Structure: 2 Layers:Structure: 2 Layers: 1. Epithelial: Epidermis outermost & thinnestoutermost & thinnest cells are very tightly packedcells are very tightly packed 2. Connective: Dermis deep & thickdeep & thick primarily connective tissueprimarily connective tissue loosely packedloosely packed Hypodermis (adipose tissue)Hypodermis (adipose tissue) –Deep to the skin/dermis –Layer of insulation

Epidermis Outermost: Stratum corneumOutermost: Stratum corneum –Dry, dead, –keratin filled (waterproof, tough) Statum germinativum / basaleStatum germinativum / basale –Cells undergoing mitosis, move up –“Pigment layer”

Stratum corneum: Dead squamous cells Stratum corneum: Dead squamous cells Stratum Germanitivum/Basale: dividing columnar cells Stratum Spinosum: cuboidal cells, desmosomes hold together >> spiny Stratum Spinosum: cuboidal cells, desmosomes hold together >> spiny Stratum granulosum: Granules with lipids and keratin – forms waterproof layer Stratum granulosum: Granules with lipids and keratin – forms waterproof layer Stratum lucidum: oils from lysosome disintegration Stratum lucidum: oils from lysosome disintegration

Epidermis Specialized cells within epidermis:Specialized cells within epidermis: –Melanocytes Melanin: pigment, inc. w/sun (protection)Melanin: pigment, inc. w/sun (protection) –Keratinocytes Keratin: tough, waterproof material; abrasion resistance for cellsKeratin: tough, waterproof material; abrasion resistance for cells –Langerhans cells Immune response against microbes invading the skinImmune response against microbes invading the skin