BIOL121 Lecture 3: Tissues and Membranes
26 Jul 2018
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Document Summary
Tissue = group of similar cells for a specific function. Primary tissue types: epithelial tissue, connective tissues, muscle tissues, neural (nerve) tissues. Functions: protection, lining, covering, absorption, filtration, excretion, secretion. Characteristics: cells are very tightly packed together, little extracellular material (matrix, avascular, grow rapidly, high turnover (labile) Shape: squamous flat, cuboidal, columnar. Number of layers: single layer, simple, many layers, stratified, pseudostratified, single layer but uneven. Microvilli ^ increased surface area on the cell membrane: ^ increased absorption, e. g. Cilia to beat/contract in unison: sweeps substances across the cell surface, e. g. Keratin waterproofs the cell: restrict water loss from the body, e. g. Functions: supports and binds other tissues, provides insulation and protection. Classified according to physical properties: ct proper (loose, dense regular, dense irregular, elastic adipose, reticular, e. g. Areolar connective tissue: fat, tendons, ligaments, fluid ct, e. g. All connective tissues (except fluid ct) have the same basic construction: background matrix, protein fibres, e. g.
