Chapter 4 - Chapter 4 Skin and Body Membranes I....

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Chapter 4 – Skin and Body Membranes I. Classification of Body Membranes A. Epithelial Membranes 1) Cutaneous Membrane – “skin” - Superficial epidermis – a keratinizing stratified squamous epithelium - Underlying dermis – mostly dense (fibrous) connective tissue - * exposed to air and is a dry membrane 2) Mucous Membrane – mucosa – epithelium resting on loose connective tissue called lamina propria – this tissue lines all body cavities that open to the exterior – ex – respiratory, digestive, urinary and reproductive tracts. - Often adapted for absorption and secretion - Many, but not all, secrete mucus 2) Serous Membrane o A layer of simple squamous epithelium resting on a thin layer of areolar connective tissue - ** Line body cavities that ace closed to the exterior - Occurs in pairs – Parietal layer – lines the ventral cavity and Visceral layer - covers the outside of the organs in that cavity.
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- ** these 2 layers are separated by a fluid called serous fluid – this allows movement and reduces friction between the layers - Peritoneum – serous tissue in the abdominal cavity - Pleura – around the lung - Pericardium – around the heart B. Connective Tissue Membranes Synovial Membranes – composed of connective tissue and no epithelial cells o Line the fibrous capsules surrounding joints o Provide a smooth surface and secretes a lubricating fluid. o Also line small sacs called bursae and tube like tendon sheaths . Both help cushion organs during muscle activity. II. Integumentary System (skin) – serves many functions – but mainly protection . A. Basic Skin Functions - Integument – “covering” - ** keeps water and other precious molecules in the body - also keeps water and other things out - This is the reason we can swim without getting water logged. 1) Protection
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2) d) From ultraviolet radiation (sunlight) e) From bacteria 3) Regulating heat loss from the body surface. Because of rich capillary network and sweat glands. 4) Rids body of wastes – urea, salts, H 2 O 5) Manufactures proteins and synthesizes Vitamin D 6) Contains sensory receptors – detect touch, pressure, temperature, and pain receptors B. Structure of the Skin - Two Kinds of Tissue: 1) Epidermis 2) Dermis 1) Epidermis – Composed of 5 zones or layers called strata - from inside – 1) stratum basale 2) spinosum 3) granulosum 4) lucidum 5) corneum - ** epidermis is avascular – without its own blood supply - most of the cells are keritinocytes – they produce keratin – fibrous proteins that make skin tough.
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a) Stratum basale – bottom layer – closest to nutrients - Constantly undergoing cell division – Produces millions of new cells daily. Daughter cells are pushed upward. -
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Chapter 4 - Chapter 4 Skin and Body Membranes I....

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