Physiology: membrane, homeostasis and fluid balance Flashcards
What is the Gibbs-Donan effect?
The Gibbs-Donnan effect occurs when a membrane separating two solutions can be permeated by some but not all of the molecules in solution. This effect accounts for the small differences in the ionic compositions of the plasma and the interstitial fuid
Name a mechanism for regulating cell volume after cell swelling due to hypotonic ECF
regulatory volume decrease response transports osmotucally active particles out of the cells to restore cell volume, therefore, when exposed to hypotonic ECF, the cell will swell and shortly after, when the mechanism is activated, the volume will decrease back to normal.
What are tight-, gap-, and adherence junctions and which cells have them?
Tight junctions: connection of 2 adjacent cells that serve transport purposes- a. they restrict movement of membrane lipids (fence function) and b. they are important for water transport around the cell rather than through the cell; TJs separate membrane into the apical and the basolateral domains important for vectorial transport
Gap junctions: channels of low electrical resistance that connect 2 adjacent cells. gap junctions are important for communications. the most important unit in the GJ is the connexon. it is a protein that is made of 6 integral units (connexins). the connexons 2 adjacent cells are linked together, forming a channel and enabling electrical coupling.
Adherence junctions: adhering junction, desmosomes, and hemidesmosomes provide mechanical adhesion by linking together the cytoskeleton of adjacent cells
(adhering junction and desmosome) or to the underlying connective tissue (hemidesmosome).
All found in epithelial cells,
GJ also in neurons
what is Dyenin?
a motor protein found at the core of the motile stereocelium in epithelial cells. especially in the respiratory tract, where they
serve to transport mucus and inhaled particulates out of the lung.
