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Surface Modifications of Epithelial Cells

by Thad Wilson, PhD
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    Epithelial and endothelial transport. How we’re going to get molecules both across a cell, across a vessel, and across a tissue? This is going to be very helpful for reabsorption, absorption, and then also delivery of substances from the blood to various tissues. The surface of epithelial tissue is very important. It has a number of modifications that have been made to it to increase its likelihood to do a good job. These apical membranes, and the apical membrane is the membrane closest to the tube. This oftentimes has been modified to include more surface area and how it is included more surface area is by projections, things like villi and microvilli, even having more invaginations associated with the membrane allows for a greater surface area within a given volume. The other way that there can be apical modifications is via cilia. These sometimes will be motive in nature, meaning that they will want to help something move along like the mucociliary elevator in the respiratory tract, or sometimes it is sensory in nature like what is in the renal epithelial tissue in the distal convoluted tubule next to the macula densa. The lateral aspects of epithelial tissue are as equally or maybe even more important. It’s hard to think about the junctions between cells as being important. They just seem like they are there to hold themselves together. But this can be an important process to move solutes through various tissues. They form something called tight junctions. Tight junctions can either be tight or tighter and they have high electrical resistances and help you establish gradients across the epithelial tissue. There are also leakier tight junctions and I know the wording is a little bit confusing here. They are called tight junctions, but some tight junctions are not as...

    About the Lecture

    The lecture Surface Modifications of Epithelial Cells by Thad Wilson, PhD is from the course Membrane Physiology.


    Included Quiz Questions

    1. Basolateral
    2. Apical
    3. Luminal
    4. At the base of microvilli
    5. Within tight junctions
    1. ...on the apical membrane of the enterocyte
    2. ...on the lateral surface of the entrocyte
    3. ...on the basal surface of the enterocyte
    4. ...near the desmosomes
    5. ...near the tight junctions
    1. ...have a higher electrical resistance and establish ionic gradients
    2. ...have a lower electrical resistance
    3. ...are isoosmotic
    4. contain actin
    5. contain gap junctions
    1. Help cells communicate with each other
    2. Provide stability between cells
    3. Provide ion exchange between cells
    4. Stabilize voltage between cells
    5. Allow ion exchange between cells
    1. Allow passage of water or solutes via a paracellular flow
    2. Allow passage of water or solutes via a transcellular flow
    3. Do not allow passage of water or solutes
    4. Allow passage of water via a transcellular flow
    5. Allow passage of solutes via a transcellular flow
    1. ...are polarized
    2. ...possess an equal distribution of ion channels
    3. ...possess more sodium ion channels on the basolateral membrane
    4. ... possess Na/K Atpases on the luminal side of the membrane
    5. ...are devoid of gap junctions
    1. Anchor the cells to one another
    2. Anchor the cell to the extracellular matrix
    3. Allow iso-osmotic passage of fluids
    4. Require energy for transport
    5. Are contained entirely in one cell
    1. The cell utilizes voltage differences between the apical and basolateral sides to transport solutes from the lumen to the blood
    2. The cell utilizes tight junctions between the apical and basolateral sides to transport solutes from the lumen to the blood
    3. The cell utilizes Na/K ATPases located the apical side to transport solutes from the lumen to the blood
    4. The cell utilizes sodium concentration differences between the apical and basolateral sides to transport solutes from the lumen to the blood
    5. The cell utilizes osmotic differences between the apical and basolateral sides to transport solutes from the lumen to the blood

    Author of lecture Surface Modifications of Epithelial Cells

     Thad Wilson, PhD

    Thad Wilson, PhD


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