Anatomy Physiology Epithelium tissue
Terms
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- Epithelial tissue
- covers body surfaces, lines body cavities, hollow organs, ducts; and form glands
- Connective tissue
- protects and supports the body and its organs-binds organs together stores energy and reserves as fat, provides immunity
- muscle tissue
- movement
- nervous tissue
- initiates and transmits nerve impulses to help coordinate body activities
- avascular
- blood vessels are located adjacent to connective tissue
- Function of Epithelial tissue
- protection, secretion, absorption, excretion, sensory reception, reproduction
- Simple Squamous
-
-thinness allows for active passive movement of substances
-allows diffusion of respiratory gases
-ex: lungs heart kidney - Simple Cuboidal
-
-produces body secretions; sweat and enzymes
-important in the secretion of substances (such as tears and saliva) and absorption - Simple non ciliated Columnar
-
contain micro-villi and goblet cells
-micro-villi are finger like projections that serve to increase surface area of plasma membrane causing greater absorption
-goblet cells modified columnar secrete mucous
-lines the inside of stomach and small intestines - Simple ciliated columnar
-
-protect underlying tissues
-specialized for absorption and secretion
-move mucous secreted by goblet cells
-respiratory track->move foreign particles toward throat were it could be swallowed or spit out - Transitional epithelium
-
-cell shape depends on whether relaxed or distended
-function is to help prevent rupture of an organ
-range in shape from flat squamous to columnar;as a result of distention expansion or movemnt in body part
ex: bladder - Stratified Squamous
-
-surface layer is flat while deeper layers vary from cuboidal to columnar
-bottom repeats by cell division
-new cells move outward and loose blood supply-dehydrated
-two forms keritinized and non keritinized
keratinized-tough layer of keratin deposited in surface cells(keratin is a protein that protects the skin from invasion by microbes, injury and also waterproofs)
ex: outer layer of skin
non-keratinized-remain moist
ex:mouth tongue - stratified cuboidal
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rare
main function is protection
ex: ducts of adult sweat glands - stratified columnar
-
uncommon
funtion is protection and secretion
ex:lines part of urethra - pseudo stratisfied columnar
-
-function as secretion
-covering and lining epithelium
-nuclei are at varying depths
-all cells are attatched to basement membrane
-some cells do not reach the surface
-the cells that reach the surface have cilia
ex:respiratory tract - glandular epithelium
-
-functions as secretion
-gland can consist of one cell or a group of highly specialized epithelial cells
-classified as endocryine or exocrine
exocrine-exits sweat mucous oil
-secrete products into ducts
-empty at the surface of covering and lining
endocrine- hormones ENter extracellular fluid and diffuse into blood
-ex: adrenaline