Forces acting across Membranes 1 Flashcards
Distribution of water between ECF and ICF
1/3 ECF 2/3 ICF
Distribution of water between Plasma and ISF
25% plasma 75% ISF
Channel that water freely passes through
Aquaporins
What passes freely through all compartments? (2)
Gas and Water
Which compartment has the highest K+ conc.
ICF
Which compartment has the highest Na+ and Cl- conc.
ECF
How are ISF and Plasma different?
Plasma has proteins so higher protein conc.
Define varying permeability of membranes
Permeability can increase and decrease at times
Why are membranes flexible?
The fatty acids. However if stretched too much, they may rupture.
Integral protein structure
Spans the length of the entire membrane
Peripheral protein structure
Spans only the phosphate head
What are membrane receptors?
Attach from ECF to ICF to allow communication of signals
What are membrane transporters?
Integral proteins which allow movement of molecules through a valve-like mechanism (typically for larger molecules (glucose))
What are membrane channels?
A type of transporter that can be gated or open (like aquaporins)
What are an enzymes role in membrane proteins?
Catalyse reactions on the membrane, on either the outside or inside. Typically convert signals from receptors into a cellular response
Structural proteins role in the membrane?
Attach to the cytoskeleton and the ECM to hold the membrane in place and maintain cell shape. Allow 2 cell membranes to stay adjacent to provide a temporary binding site.
Glycoproteins role in cell membrane
Cell signalling, cell-cell recognition (recognises self/foreign cell)
What drives movement of particles/molecules in a cell
Concentration gradient
What is an electrical gradient
The difference in charge across a membrane
What is endocytosis?
Macromolecules invaginate a cell membrane to form a vesicle which enters the cell and transport the macromolecules to their final destination
What is exocytosis?
A vesicle fuses with the cell membrane, releasing its components to the ECF
What is a G protein?
Peripheral proteins found on the inner membrane, responsible for translocate messages for receptor proteins to other proteins on the membrane - e.g. enzymes or ion channels
