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Epithelium Tissue
Question | Answer |
---|---|
Simple Squamous Epithelium | Function: 1. passage of materials by diffusion/filtration 2. secretes lubricating substances in serosae Location: 1. renal corpuscles 2. alveoli of lungs 3. lining of heart, blood, lymphatic vessels 4. lining of ventral body cavity (s |
Simple Columnar Epithelium | Function: 1. absorption 2. secretion of mucus, enzymes 3. ciliated type propels mucus or reproductive cells Location 1. ciliated: small bronchi, uterine tubes, uterus 2. nonciliated: digestive tract, gallbladder, some ducts |
Simple Cuboidal Epithelium | Function: 1. secretion and absorption Location: 1. kidney tubules 2. ovary surface 3. secretory portions of small glands |
Pseudostratified Columnar Epithelium | Function: 1. secretion of mucus 2. propulsion of mucus by cilia Location: 1. ciliated: trachea and most of upper respiratory tract 2. nonciliated: ducts of large glands, male reproductive tubes |
Stratified Squamous Epithelium | Function: 1. protect underlying tissues in abrasive areas Location: 1. Keratinized: epidermis of skin 2. Non-keratinized: lining of mucous membranes = esophagus, mouth, anus, vagina, urethrea |
Stratified Cuboidal Epithelium | Function: 1. protection Location: 1. Ducts of: mammary glands, salivary glands, largest sweat glands |
Stratified Columnar Epithelium | Function: 1. protection and secretion Location: 1. male urethra and large ducts of some glands |
Transitional Epithelium | Function: 1. permits distention of urinary organs by contained urine Location: 1. epithelium of urinary bladder 2. ureters 3. proximal urethra |
Endocrine glands | Ductless glands that secrete directly into surrounding tissue fluid and blood |
Exocrine glands | The products (sweat, mucus, oil, etc.) travel in ducts to epithelial surface |
Goblet cell | - Produce mucin: mucin + water --> mucus - unicellular exocrine gland - protect and lubricate many body surfaces |
Multicellular exocrine glands | - can have simple or compound ducts - can be tubular, alveolar, or tubuloalveolar |
Tight junctions | - prevent certain molecules from passing between epithelial cells - apical region of most epithelial tissue types - beltlike junction extends around periphery of each cell - degree of leakiness depends on the functions of the cells |
Adhesive belt junctions | - just below tight junctions in epithelial tissue - transmembrane linker proteins attach to actin microfilaments of cytoskeleton and bind adjacent cells - reinforce the tight junctions |
Desmosomes | - scattered along abutting sides of adjacent cells - cytoplasmic side of each plasma membrane has plaque, which are joined by linker proteins - intermediate filaments extend across cytoplasm and anchor to opposite side of the cell |
Gap Junctions | - passageway between 2 adjacent cells - let small molecules move directly between neighboring cells - cells are connected by hollow cylinders of protein - function in intercellular communication |
Basal Lamina | - non-cellular supporting sheet between epithelium and underlying CT - made up of proteins secreted by epithelial cells - acts as selective filter - acts as scaffolding along which regenerating epithelial cells can migrate |
Microvilli | - fingerlike extensions of plasma membrane of apical epithelial cells - occurs in almost every moist epithelium of the body - maximized surface area across which small molecules enter and leave - act as stiff knobs to resist abrasion |
Cilia | - whiplike, highly motile extensions of apical surface membranes of some cells - contain a core of microtubules held together by cross-linking and radial proteins - produces a propulsive power stroke, followed by a nonpropulsive recovery stroke |
Flagellum | - very long, single cilium - only human cells with these are sperm cells |