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Tissues. Cells Tissues Organs Organ systems Organisms. Tissues. Groups of cells with a common structure and function—similar cells work together at one job. Epithelial Tissues. Introductory Questions. What is the function of epithelial tissue? List some locations in which it is found.
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Cells Tissues Organs Organ systems Organisms
Tissues • Groups of cells with a common structure and function—similar cells work together at one job.
Introductory Questions • What is the function of epithelial tissue? • List some locations in which it is found.
Epithelial Overview • General definition • Structure • Function • Types Simple • Squamous, cuboidal, columnar Stratified • Squamous, columnar, transitional
Epithelial Tissues • Structure Tightly-packed cells Little material between cells Cover or line organs or body cavities Has free side Basement layer—non-living and separates epithelial from underlying connective tissue
Epithelial – Structure • Classified by: • 1) Number of layers • Simple – single layer • Stratified – multiple layers
Epithelial – Structure Classified by: 2) Shape of cells Squamous – fried egg, tiles Cuboidal – cube Columnar - brick
Epithelial Tissues • Function Protective—Barrier to: -water loss -microbes -mechanical injury --Secretion --Absorption --Sensory reception --Movement -Cilia
Types of Epithelial Cells • 1) Simple A) Squamous Single layer Flat cells Passage ways such as lungs, arteries, mesentary Places of diffusion, filtration & secretion—alveoli, capillaries, lymph vessels
Types of Epithelial—Simple • B) Cuboidal • Single layer • Cube-shaped • Covers and lines • Forms tubes/glands • Pancreas, kidney, salivary glands
Types of Epithelial—Simple • C) Columnar • Single Layer – nuclei often on same level • Tall, elongated cells • Lining tissues • Digestive, uterine • Secretion – goblet cells secrete protective mucus
Types of Epithelial • 2) Stratified • A) Squamous • Layered • Often keratinized (protein hardens—water stays inside & chemicals & microorg. kept out) – outermost skin, areas of high stress • Non-keratinized -Mouth, rectum, vagina, esophagous
Types of Epithelial—Stratified • B) Transitional • Many cells thick • Elastic • Bladder, ureters • Appearance • Stretched or relaxed
Types of Epithelial—Stratified • C) Columnar, pseudo- stratified • Appears layered due to nuclei on multiple layers • Often ciliated • Moves product • Respiratory tract • Fallopian tubes • Goblet cells secrete mucus & cilia sweeps away.
The ink of tattoos must be injected below the basement membrane.
It takes about 27 days for the outer layer of skin to shed and be replaced; that works out to 1.5 pounds of skin cells per year. Where does all the dead skin you shed go?