Physiology: Cell Flashcards
What are the factors effecting solute diffusion across the cell ?
7
1) concentration gradient
2) membrane permeability
3) electrochemical gradient due to charges ions
4) molecular weight ( light ions -faster)
5) diffusion distance
6) membrane SA and SA:V
7) temperature
What conditions are necessary for osmosis ?
3
- solute concentration gradient
- membrane permeable to water and not the solute
- aquaporins
What’s osmolarity ?
1
Total number of dissolved particles per litre of solvent
what’s 1 osmole ? (2)
Mr/number of freely moving ions and particles the molecule can dissociate to in a solution.
“The standard unit of osmotic pressure. The osmole is equal to the molecular weight of the dissolved substance expressed in grams divided by the number of particles or IONS into which each molecule of the substance dissociates in solution,”
ie =low osmolality- too much fluid = oedema
what is tonicity ? (1)
actual affect of a solution on living cells
what’s osmotic pressure ? (1)
the pressure needed to oppose / prevent water molecules moving .
what’s facilitated diffusion ? (2)
- passive diffusion of molecules through membrane down their concentration gradients
- using carrier proteins
what’s primary active transport ? (1)
- molecules are actively moved against their concentration gradients using ATP
what’s secondary active transport ? (2)
example ?(2)
- an examples would be a symport pump which pumps Na+ down its electrochemical gradient , releasing energy
- this energy is then used to pump glucose INTO the cell against its concentration gradient .
- passive movement of one substance down its electrochemical gradient used to transport another substance AGAINST its concentration gradient .
what is an : isotonic solution ? hypertonic? Hypotonic? terms for the States ? (6)
a) isotonic solution =both cell/ plasma have the same osmolarity / equal water potential
b) Hypertonic =higher water potential on the inside to water diffuses out = crenation
c) Hypotonic= low water potential on the inside so water diffuses in =lysis
what are the three types endocytosis ?
1) receptor mediated endocytosis
2) phagocytosis
3) pinocytosis
How does receptor-mediated endocytosis work?
6
1-ligand binds to the receptor
2-the receptors are on Clathrin Coated pit
3-the receptor/ligand molecules sink into a cell in a vesicle surrounded by Clathrin molecules
4-clathrin molecules leave and go back to the membrane
5-vesicle fuses with endosome ( another vesicle) and the ligands are separated from the receptor
6-then the ligand vesicle fuses with lysosome which then breaks down ligand to smaller molecules and is used in various regions around the cell
what’s phagocytosis ? (1)
-Phagocytosis is the process by which a cell uses its plasma membrane to engulf a large particle, giving rise to an internal compartment called the phagosome.
what’s pinocytosis ? (1)
-the ingestion of liquid into a cell by the budding of small vesicles from the cell membrane.
what’s exocytosis ? (1)
Exocytosis is the process of moving materials from within a cell to the exterior of the cell.
requires ATP
