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69 Cards in this Set
- Front
- Back
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Tissues
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similar cells performing similar functions
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classification of Tissues
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epithelium, connective tissue, muscle, and neural
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Epithelium characteristics
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very little intercellular space
form cohesive layers on the surface or lining of organs avascular regenerative capacity selective permeability cells exhibit polarity |
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epithelium functions
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secretion and absorption
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Classification of Epithelium based on the shape of the cells
squamous cuboidal columnar |
flat and long
cube, about the same amount of cytoplasm above and below the nucleus, very round nucleus have more cytoplasm about the nucleus than below it, oval nucleus |
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Classification of Epithelium based on the number of layers
simple stratified |
1 layer
more than 1 layer |
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Basement Membrane
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really composed of two layers, at the basal portion of the cell, seperates the epithelium from the connective tissue
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basement membrane: Basal Lamina
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right underneath the BM, produced by epithelial cells, functions in attachment of epithelial cells, maintains tissue archetecture during regeneration, divides tissue compartments, special function in kidney filtration
MAIN constituents: collagen (type IV), laminins, enactin, proteoglycans, fibronectin |
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basement membrane: reticular lamina
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below the basal lamina, produced by connective tissue cells inderneath, mainly type III collagen
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Cell adhesion molecules (CAMs) and intercellular junctions
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CAMs are cell suface molecules that mediate intercellular contact, intercellular junctions stabilize the contact between cells and also function in intercellular communication
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CAMs: Calcium-dependent: cadherins, selectins
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loss of cadherins associated with invasive cell behavior of tumor cells
selectins bind to carbs and participate in cell "homing" behavior |
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CAMs: Calcium-independent: immunoglobulin superfamily, integrins
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Ig superfamily involved in immune reactions
integrins involved in cell-matrix interactions such as linking cells to the BM. Integrin-matrix interactions are important during embryogenesis and cell migratoin, because cell layers are moving across each other, and there needs to be recognition of the two different layers |
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Cell junctions
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CAMs function as transmembrane liners that link adjacent cell CAMs as well as intracellular proteins
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Occluding (tight) junctoins (zona occludens)
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prevent diffusion of molecules between adjacent cell
mainly located between cells with secretory or absorptive function, found by the apical side of the cell transmembrane proteins (occluding, claudin) arranged in interwing strands that "stich" cells together at intervals. Ig superfamily moleculares also involved in transmembrane linking bacteria, viruses, and parasites can destroy these jcns clostridium perfringens:enterotoxin binds to claudin Hejobactor pylori: bind to occluding jcn proteins and cause peptic ulcers dust mites: fecal matter destroys occluding junctions in respiratory epithelim |
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Anchoring (attachment) junctions
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attach cells to each other or extracellular matrix
may be focal (macula), sheet-like (fascia), or wrap around the whole cell (zonular) main types: zonula adherins (terminal bar) desmosome (macula adherins) hemidesmosome |
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desmosome (macula adherens)
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focal adherins
between cells, provide mechanical stability in epithelium exposed to tensile and shearing forces intermediate keratin filaments insert into intracellular plaques. plaques of adjacent cells attached by extracellular transmembrane linkers, keratin is usually the intermediate filament in epithelium |
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Zona adherins
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wrap around the cell
link intracellular actin networks of adjacent cells. Most common towards apex of columnar cells (intestine), where they form a "belt" around the cells visible at the LM level as the terminal bar intercellular linkers |
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hemidesmosome
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half a desmosome
attach cells to asal lamina keratin filaments insert in intracellular plaque. transmembrane proteins attach plaque to extracellular proteins of basal lamina |
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gap junctions
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function in intercellular communication
pore-like channels formed by integral proteins calld connexions span b/w adj cells and allow selective diffusion of molecules between cells common in embryonic tussyes, i nadult tissue found mainly in cardiac and SM where they mediate electrical couple of cells |
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Specializations of cell membrane: Apical
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microvilli: core of actin filaments insert in terminal web of actin filaments jst beneath PM, actually part of the cellular membrane, inc surface area of cell for absorp
Steroeocilia: long microvilli Cilia: |
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Specializations of cell membrane: Lateral
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intercellular interdigitations: located b/w cells, regulate passage of substances through an epithelium
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Specializations of cell membrane:: Basal Infoldings
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characteristic of ion-transporting/ion-pumping cells, infoldings of the PM, inbetween the infoldings are lots of mito
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Main types of epithelia:
Simple Squamos |
lining all blood vessels (endothelial), air interface in lung, kidney loop of henle, visceral covering of organs (mesothelium)
flat squamous cells, found where things pass |
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Main types of epithelia:
Simple Cuboidal |
ducts, kidney tubules
look at the shape of the nucleus and the amounnt of cytoplasm abouve and below the nucleus a duct system |
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Main types of epithelia:
Simple Columnar |
GI tract, female reproductive tract
individual microvilli are only visible at EM level |
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Main types of epithelia:
pseudostratified columnar |
respiratory tract, male reproductive tract
it is ciliated, simple epithelial because all the cells touch the basal lamina the nuclei are all at different levels, there are white gaps between the columnar at goblet cells |
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Main types of epithelia:
Stratified Squamous |
the top layer is squamous the bottom layers are not
Keritinized: skin, masticator mucosa of oral cavity - accumulate more and more at the top of the cell nonkeritinized: esophagus, lining muscosa of oral cavity, vagina - a mucous membrane |
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Main types of epithelia:
Stratified Cuboidal |
usually about 2 cell layers
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Main types of epithelia:
Stratified Columnar |
usually about 2 cell layers
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Main types of epithelia:
Stratified Transitional (uroepithelium) |
allows for distension, has special membrane plaques that can fold or unfold, found in the urinary bladder, uterus, and parts of the urethra
specialized for distension surface has plaques, and where is is distended it looks like simple squamous, but when it is contracted cells have a rounded/domed shaped cells on the surface |
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Glands: Endocrine
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no ducts, secrete into blood, and are not part of the surface epithelium
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Glands: Exocrine
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secrete onto surface epithelium, exocrine cells may occur within (are part of the surface epithelium) an epithelium (goblet cells) or may be below an epithelium and secrete into ducts that connect a surface eopithelim
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Secretory Cells
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protein (serous), muscous produce the secretory product (mucous or protein)
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secretory units
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unicellular (goblet mucus cells) acinar (serous acinus - arranged in clusters and stain basic, tubular (usually mucous)
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Ducts
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may be simple or compund
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modes of secretion:
merocrine (eccrine) apocrine holocrine |
exocytosis the product
apical portion of the cell is lost into the secretion (mammary and sebacous glands) whole cell is shed |
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Functions of epithelial
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protection
absorption secretion selective barrier transport of substances sensory reception |
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pathology
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cells may respond to environmental stimuli by changes in growth, differentiation, and rates of cell division, change in cell morphology
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hyperplasia
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increased cell division and hypertrophy may be normal or abnormal procceses and can revert back to normal state after stimulus is removed
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hypoplasia
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refers to incomplete development of tissues or agenesis
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atrophy
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tissue mass lost due to decreased cell volume or number. tissue may be replaced by connective tissue, if you change circumstances the cell can go back to regular state
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metaplasia
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change in cell differentiation that is an adaptive response to environment, involves changes in stem cell populatoin. common in epithelia and can revert back to normal state once stimulus is removed
protective adaptive response complete change from one cell type to another |
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Main types of epithelia:
Simple Squamos |
lining all blood vessels (endothelial), air interface in lung, kidney loop of henle, visceral covering of organs (mesothelium)
flat squamous cells, found where things pass |
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Main types of epithelia:
Simple Cuboidal |
ducts, kidney tubules
look at the shape of the nucleus and the amounnt of cytoplasm abouve and below the nucleus a duct system |
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Main types of epithelia:
Simple Columnar |
GI tract, female reproductive tract
individual microvilli are only visible at EM level |
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Main types of epithelia:
pseudostratified columnar |
respiratory tract, male reproductive tract
it is ciliated, simple epithelial because all the cells touch the basal lamina the nuclei are all at different levels, there are white gaps between the columnar at goblet cells |
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Main types of epithelia:
Stratified Squamous |
the top layer is squamous the bottom layers are not
Keritinized: skin, masticator mucosa of oral cavity - accumulate more and more at the top of the cell nonkeritinized: esophagus, lining muscosa of oral cavity, vagina - a mucous membrane |
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Main types of epithelia:
Stratified Cuboidal |
usually about 2 cell layers
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Main types of epithelia:
Stratified Columnar |
usually about 2 cell layers
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Main types of epithelia:
Stratified Transitional (uroepithelium) |
allows for distension, has special membrane plaques that can fold or unfold, found in the urinary bladder, uterus, and parts of the urethra
specialized for distension surface has plaques, and where is is distended it looks like simple squamous, but when it is contracted cells have a rounded/domed shaped cells on the surface |
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Glands: Endocrine
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no ducts, secrete into blood, and are not part of the surface epithelium
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Glands: Exocrine
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secrete onto surface epithelium, exocrine cells may occur within (are part of the surface epithelium) an epithelium (goblet cells) or may be below an epithelium and secrete into ducts that connect a surface eopithelim
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Specializations of cell membrane: Lateral
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intercellular interdigitations: located b/w cells, regulate passage of substances through an epithelium
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Specializations of cell membrane:: Basal Infoldings
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characteristic of ion-transporting/ion-pumping cells, infoldings of the PM, inbetween the infoldings are lots of mito
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Secretory Cells
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protein (serous), muscous produce the secretory product (mucous or protein)
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secretory units
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unicellular (goblet mucus cells) acinar (serous acinus - arranged in clusters and stain basic, tubular (usually mucous)
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Ducts
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may be simple or compund
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modes of secretion:
merocrine (eccrine) apocrine holocrine |
exocytosis the product
apical portion of the cell is lost into the secretion (mammary and sebacous glands) whole cell is shed |
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Functions of epithelial
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protection
absorption secretion selective barrier transport of substances sensory reception |
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pathology
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cells may respond to environmental stimuli by changes in growth, differentiation, and rates of cell division, change in cell morphology
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hyperplasia
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increased cell division and hypertrophy may be normal or abnormal procceses and can revert back to normal state after stimulus is removed
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hypoplasia
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refers to incomplete development of tissues or agenesis
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atrophy
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tissue mass lost due to decreased cell volume or number. tissue may be replaced by connective tissue, if you change circumstances the cell can go back to regular state
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metaplasia
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change in cell differentiation that is an adaptive response to environment, involves changes in stem cell populatoin. common in epithelia and can revert back to normal state once stimulus is removed
protective adaptive response complete change from one cell type to another |
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celluar atypia and dysplasia
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atypia usually represents a high cellular turnover where cells dont mature completely before next divsion. results in atypical cells with high nuclear to cytoplasmic ration, dysplasia is persistant atypia which is not a regenerative response, it often results from metaplasia
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neoplasia
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autonomous abnormal proliferation and growth
benign vs. malignantwell differentiated vs. poorly differentiated localized vs. invasive |
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Epithelial tumors:
Papilloma |
benign, surface cell origin
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Epithelial tumors: adenoma
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benign, glandular origin
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Epithelial tumors: adenocarcinoma
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malignant, glandular origin
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