Tissue notes

Tissue notes - Tissues Wednesday, January 28, 2009 12:49 PM...

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Tissues Wednesday, January 28, 2009 12:49 PM 1. Tissue:collection of specialized cells + cell products with a common/related function  o Histology=study of tissues  Objective= examine 4 main types of Tissue found in body o Epithelial  o Connective  o Muscle  o Neural (these two will analyze later)    I. Epithelial Tissue A sheet of cells that covers a body surface or lines a body cavity  Mostly cellular in makeup Many subtypes, classified by physical properties Two types:  1. Epithelia: covers surfaces , line passageways of the body  2. Glandular Epithelium/Glands, fashions glands and generate  important secretions  Purpose=form boundaries between different environments Functions:  Protective Brain Control Permeability Provide Sensation Produce specialized secretions  Characteristics:   Composed mostly of cells (little extracellular material)  Contain upper free exposed surface (apical surface) and a  lower  attachment to a common base (basement membrane) and lower end of  cells called basal surface. This is called Polarity : the cell region near apical  surface differ in structure/function than basal surface Have microvilli: small  extensions of plasma membrane to  increase surface area for absorption/secretion. Some have larger  extensions called cilia.
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  IV. Supported by Connective Tissue by reticular lamina and Basal lamina  that make up Basal Membrane  V. Avascular (no blood vessels go through them) but innervated VI. Regeneration: due to hostile external environment , reproduce rapidly  through cell division  Classifications:  By shape: Squamous-flat/squished  Cuboidal-square Columnar-Rectangular  By layering: Simple- 1 layerd Stratified- 2 or more clear layers  Pseudostratified: no distinct layering  Simple Epithelia-       absorption, secretion, filtration, very thin, NOT  protective  Simple Squamous- Description: flattened cells with disc-shaped  central nuclei and sparse cytoplasm; the simplest of the epithelia,  Function: allows passage of materials by diffusion and filtration in  sites where protection is not important; secretes lubricating 
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substances in serosae membranes, Location:kidney glomeruli, air  sacs of lungs  i. Endothelium-"inner covering" provides a slick, friction- reducing lining in lymphatic vessels and in all hollow organs of  the cardiovascular, capillaries  consist exclusively of  endothelium and to allow things inside these tubes to pass  through frictionless  i. Mesothelium- epithelium found in serous membranes lining  the ventral body cavity and covering its organs ( it's like a little  protective ball in a way, mesothelium is contributing to this ball-
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This note was uploaded on 09/16/2009 for the course BIOL 252 taught by Professor Johnson during the Spring '07 term at UNC.

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Tissue notes - Tissues Wednesday, January 28, 2009 12:49 PM...

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