Forces Acting Across The Membrane Flashcards
What is the structure of the cell membrane?
Selectively permeable barrier consisting of a phospholipid bilayer, containing proteins and glycoproteins.
What are the 4 classes of membrane proteins?
Receptors
Enzymes
Transporters
Peripheral Proteins
What is the difference between channel proteins and carrier proteins?
Channel proteins create a continuous pore, whereas carrier proteins change arrangement to be either ‘open’ to ECF or ICF.
Carrier proteins can typically transport larger molecules than channel proteins.
What is the electrochemical gradient?
The sum of the electrical and chemical gradients.
Determines the direction of passive movement of ions.
What is endocytosis?
Invagination of cell membrane to enclose desired contents into vesicle which eventually enters cell.
What is exocytosis?
Vesicle fuses with cell membrane, and becomes incorporated into it. Contents are released outside of cell.
What are the criteria for molecules to diffuse through the lipid bilayer?
Must be:
Small
Uncharged
Lipophilic
What are ligand gated channels?
Channels which open or close depending on a molecule (e.g. neurotransmitter) binding to the protein
What are voltage gated channels?
Channels which open or close based on alterations of the membrane electrical potential.
What is osmotic pressure?
The pressure required to oppose the change in volume which will occur via osmosis due to concentration differences.
What is the difference between osmolality and tonicity?
Osmolarity only describes the number of particles in solution- Does not give indication of their nature.
Tonicity describes the number of non- penetrating particles in solution.
What is the osmolarity of normal human plasma?
300 mosmol/L
What is the tonicity of normal human plasma?
300mosmol/L
What is meant by the term hypotonic?
Contains less non penetrating particles (Lesser tonicity)
What is meant by the term hypertonic?
Contains more non penetrating particles (Greater tonicity)
