Forces Acting Across Membranes Flashcards
4 main functions of membrane proteins
- receptors
- transporters
- enzymes
- maintenance of cell structure
protein content of different membranes
myelin - 18% proteins
plasma membrane - 50%
inner mitochondrial membrane - 75%
receptors
- integral membrane protein
- extracellular signal –> intracellular response
transporters
- channel proteins
2. carrier proteins (horseshoe shaped - larger molecules)
porin
protein channel that is always open and filled with water so that small water soluble molecules can pass through.
dystrophin protein
anchors cell membrane to intracellular cytoskeleton, is located on the inside of the cell membrane
- loss of these lead to DMD
5 mechs of movement btw compartments
- endo/exocytosis
- diffusion
- mediated transport
- osmosis
- filtration (not really related)
why don’t give patient water through IV?
once it has entered circulation, water will move into nearby tissue to regain equal concentration inside and out of vessel wall and cause the tissue to rupture.
It would be good if solutes can move out of the cell into the blood, but membrane is not permeable to those, and water moved in from the plasma to the cells instead.
normal plasma osmolarity and tonicity
285 milliosmoles/L
- since most of these are non penetrating, osmolarity and tonicity in the ECF is the same
molarity vs osmolarity vs tonicity
molarity: molecules/L
osmolarity: particles/L
tonicity: like osmolarity, but only non penetration particles
tonicity is the most important because it can actually determine the cell volume
an example of an isotonic solution commonly used
0.1% saline (150 mM)
will differentiate into 300 mM