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Related Flashcards
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Cards In This Set
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Tissues - definition; function
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- Organized aggregation of cells or groups of cells- Function in a coordinated manner- Combine to form organs- Basic functional units for maintain body functions
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Types of tissues
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- Epithelium- Connective tissue- Muscle- Nervous tissue
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What is an epithelium?
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- Forms barrier between outside and inside- Derived from all 3 germ layers
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What are the three germ layers? (and examples)
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1. Ectoderm (skin epidermis, neuroepithelium)2. Mesoderm (endothelium, mesothelium)3. Endoderm (Intestinal epi, urothelium)
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4 Common Characteristics of Epithelial Cells
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1. Form avascular sheets - diff in # and shape of cells (depends on tissue function)2. Structurally and functionally polarized - a) apical, lateral and basal domains; b) some with structural specializations of free cell surface (apical)3. Held together by intercellular junctions and bound to connective tissue via basement membrane4. Capable of renewal and regeneration
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What are the functions of epithelia?
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PASTS1. Protection (skin, bladder)2. Absorption (intestines, kidneys)3. Secretion (stomach, pancreas, salivary glands)4. Transportation (endothelium, urothelium) - and regulate transport of small molecules from epi to other tissues5. Signal Reception (olf epi; taste buds; retina) - transduce ext stimuli to body
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Types of epithelium (8)
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A. Simplified squamous b. Simple cuboidalc. Simple squamousd. Stratified squamouse. Stratified cuboidalf. Stratified columnarg. Pseudostratifiedh. Transitional
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Simple Squamous Epithelium - one layer of cells; flattened / fried egg / tight junctions
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Simple Cuboidal Epithelium- Single layer o fcells- Width of cells about same as height- In diff small ducts in exocrine glands
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Simple Columnar- Single layer- Cells taller than wide- Often in lumen of intestines- Not always homogenous pop of cells
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Stratified Squamous Epithelium- Multiple layers of cells- Top / most epical layer = flattened- Keratinized and non-keratinized
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Keratinized vs. Non-keratinized
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Nonkeratinized - nucleated superficial squamous cells; lines esophagus, oral cavity and vagine
Keratinized - lines thick and thin skin |
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Stratified Cuboidal Epithelium- Multiple layers- Top Layer -- width about height- Termination of large intestine -- see change in epithelia but it's about apical layer
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Stratified Columnar Epithelium- Multiple layers- Height > Width- Salivary gland, rare tissue, only in largest exocrine
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Pseudostratified
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Initially looks stratified (mult layers) but then realize that all cells connect to basement membrane so it's simple - Mix of cells - all contact basement membrane
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