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14 Cards in this Set
- Front
- Back
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Definition of Tissue
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a collection of cells and their extracellular components that perform a common function
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Characteristics of Epithelium
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·tightly packed cells that are strongly connected
·very little extracellular space ·usually have a “free” surface (lumen or external environment) ·supported by connective tissue ·avascular (receive nourishment from vessels in the CT layer) ·polarized (cell surfaces are structurally and functionally distinct) ·continuously renewed |
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Major functions of epithelial tissue
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protection (i.e. covering or lining surfaces), absorption and secretion.
Some specialized epithelia are involved with sensory reception (neuroepithelia: receptors for smell, taste, hearing, and vision) and contractility (myoepithelia: cross between muscle and epithelial cell). |
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Surfaces of epithelial cells
what name is give to two of these surfaces to combine them into one domain? |
apical, lateral, basal
basolateral domain |
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What specialized features facilitate the functions of epithelia on the apical surface?
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Microvilli, Cilia, sterocilia
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How do microvilli help epithelia?
What is the structure of microvilli like? |
increase surface area for absorption, especially in instestines and kidneys,
Microvilli contain a core of actin filaments, anchored to base at terminal web (actin) that contracts to spread microvili apart. |
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How do cilia help with epithelia functions?
Where are they commonly found? What is their structure? |
motile, 10x larger than microvilli, found in resp tract (propel mucus) and uterine tubes (move ovum to uterus).
central core of 9+2 microtubules (axoneme)surrounded by cell membrane, anchored via attachment to basal bodies. |
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What do stereocilia do?
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are long microvilli (bad name) that are found in the male reproductive tract (absorptive function) and ear (function in sensory reception). Despite the name, they are not cilia and are not motile.
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What are the three types of junctions of epithelia and what are their functions?
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occluding junctions (act as barriers to
prevent the flow of material), adhering junctions (bind cells together providing structural support) and communicating junctions (allow intercellular communication). |
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What is an example of an occluding junction?
What are its functions? How is it formed? |
Tight junctions, seal off intercellular space from lumen/exterior, belt like, regulate material movement through space between cells. Formed by binding of transmembrane proteins of two cells. Number of fusion sites vary, alters permeability. Tight junctions form a complete band around the cell, defining diff surfaces.
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What are examples of Adhering junctions? lateral and basal
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Zonula adherens
Desmosomes Hemidesmosomes Focal adhesions |
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What is the function of zonula adherens
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Provide structural support by linking cytoskeletons, through transmembrane proteins (cadherins), anchor proteins and the actin in cytoskeleton. Form a complete band around cell.
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What is primary ciliary dyskinesia?
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structural abnormalities in cilia, causes abnormal movement, dynein arms commonly affected. Mucus clearance affected, sperm motility, and ovum movement
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What is function of Desmosomes and what is their structure?
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don't form complete band, inferior to ZA, two disc shaped plaques with transmembrane proteins between them (caderins), bind to intermediate filaments in cytoskeleton, very sturdy junction! found in epithel that are under lots of stress.
called spot weld junctions. |
