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collections of specialized cells and cell products that perform a limited number of functions
tissues
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four types of basic tissues:
- - epithelial tissue
- - connective tissue
- - muscle tissue
- - neural tissue
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type of tissue that covers exposed surfaces, lines internal passageways and chambers
epithelial tissue
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type of tissue that fills internal spaces, provides structural support for other tissues, and stores energy reserves.
connective tissue
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type of tissue which is specialized for contraction, includes skeletal muscles of the body, muscle of the heart and muscular walls of the hollow organs
muscle tissue
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type of tissue that carries information from one part of the body to another in the form of electrical impluses
neural tissue
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structures that produce fluid secretions
glands
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several important factors of the epithelia:
- -cellularity
- -polarity
- -attachment
- -avascularity
- -regeneration
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avascularity
absense of blood vessels
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the presence of structural and functional differences between the exposed and attached surfaces
polarity
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apical cells
exposed surface cells
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basal cells
attached surface cells
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a complex structure produced by the basal surface of the epithelium and the underlying connective tissues
basement membrane
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epithelial cells that are damaged or lost at the exposed surface are continuously replaced through stem cell divisions
regeneration
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four functions of epithelial tissue:
- - physical protection
- - control permeability
- - provide sensation
- - produce specialized secreations
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-two plasma membranes are tightly bound together by interlocking membrane proteins
-prevent the passage of water and solutes between the cells
tight junction
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forms a narrow passageway that lets small molecules and ions pass from cell to cell
gap junctions
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-CAMs and proteoglycans link the opposing plasma membranes
-very strong and can resist stretching and twisting (hold cells tightly together)
desmosomes
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the 8 classifications of epithelium:
- - simple squamous
- - simple cuboidal
- - simple columnar
- - stratified squamous
- - stratified cuboidal
- - stratified columnar
- - pseudostratified ciliated columnar
- - transitional
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-one layer of flat cells
-most delicate
- protection, secretion, absorption, diffusion
-located in alveoli (lungs), lining of the heart and blood vessels
simple squamous
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- cells form a series of layers
- generally located where mechanical stresses are severe
- surface of skin, lining of mouth, esophagus, anus
stratified squamous
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