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 |