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4 Tissue Types
- Epithelial- inner and outer surfaces
- Connective- connects parts of body together, encloses and protects organs
- Nervous- nerve cells and supporting (glial)
- Muscle- skeletal, cardiac, and smooth
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Epithelial cells
- line inner and outer surfaces
- ex: skin, inner lining of blood vessels, lining of digestive tract
- "gate keeper" controls what goes in and out of layer
- Tight junctions bind them together to keep things out
- Polarity: exposed to exterior (apical) and interior (basal)
- 4 Layers: (1 = simple, multiple = stratified) 3 shapes, pseudostratified= looks stratified but not, and transitional- simple as tissue stretches
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Squamous Simple Epithelial Cell
- found where materials cross a membrane
- flat with disk shaped nucleus
- allows passage of materials by diffusion where protection isn't important
- ex: kidney, air sacs of lungs, lining of heart, blood vessels and capillaries
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Squamous Stratified Epithelial Cells
- found where mechanical abrasion occurs
- protects underlying tissues in areas subject to abrasion
- keratinized
- thick layers with an cuboidal or columnar base
- ex: lining of esophagus, mouth, epidermis of skin
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Cuboidal Simple Epithelial Cells
- single layer of cubelike cells with large nucleus
- secretion and absorption
- ex: kidney tubules, ovary, ducts
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Columnar Simple
- single layer of tall cells with round nuclei
- absorption, secretion of mucous, enzymes
- some contain cilia or mucous secreting (goblet cells)
- ex: non ciliated: gallbladder, excretory duct, ciliated: uterus, small bronchi
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Pseudostratified Ephithelial Cells
- single layer of cells with differing heights at different levels
- for secretion of mucous and cilia
- ex: male sperm ducts, trachea, respiratory tract
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Transitional Ephithelial Cells
- looks like stratified squamous and cuboidal, surface cells
- dome shaped
- stretchy to permit distension of urinary organ by urine
- lines ureter, bladder, and urethra
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