Notes Integumentary System

Notes Integumentary System - Biol 121 Anatomy Physiology...

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Biol 121 Anatomy & Physiology LECTURE NOTES The Integumentary System *Protein Synthesis – Notes are included in the Unit One notes. I. Integumentary system the skin and its derivatives (sweat and oil glands, hairs and nails). A. Function 1. Protection - provides a chemical and physical barrier 2. Excretion - limited amounts of nitrogen containing wastes released in sweat. 3. Body temperature regulation - sweating, control of superficial blood flow 4. Cutaneous sensation - skin has rich supply of sensory receptors (part of the nervous system) that respond to changes in the environment. 5. Metabolic Functions - Vitamin D activation, keratinocyte enzymes destroy cancer causing chemicals that penetrate the epidermis, manufacture proteins. 6. Blood reservoir - vast vascular supply of skin holds large volumes of blood that can be redistributed when the need arises. B. Skin 1. Surface area of 15-20 sq. ft. 2. Weight 9-11 pounds, 7% of body weight 5. Composed of two regions: a) Epidermis - epithelial, outer covering. b) Dermis - fibrous connective tissue, deep to the epidermis (Hypodermis - adipose and areolar CT below the dermis that anchors skin to the underlying tissues) C. Epidermis 1. Keratinized stratified squamous epithelium consisting of four distinct cell types and four or five distinct layers. 2. Cells include: a) Keratinocytes - produce keratin the fibrous protein the give skin its protective and waterproof characteristics
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b) Melanocytes - produce melanin, the brown pigment giving skin its color. Branching processes of these cells deliver pigment to surrounding cells. Melanin accumulates on the "sunny" side of the cell. c) Merkel cells - sensory function for touch d) Langerhans' cells - macrophages that help activate immune system. D. Layers of the epidermis: 1. Stratum basale (basal layer) Deepest layer, attached to underlying dermis along a wavy border. single row of columnar keratinocytes setting on basement membrane rapid cell division, push toward surface 2. Stratum Spinosum (spiny layer - cells become spiny only when histologically prepared) several spiny cell layers, mitotically active with basale collectively called stratum germinativum or growing layer
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Notes Integumentary System - Biol 121 Anatomy Physiology...

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