cell membranes and action potentials Flashcards
what are three forms of gated channels?
Ligand – gated
Voltage – gated
Gap Junctions!
What are the five functions of the cell membranes?
Generate signals in response to electrical & chemical
Facilitate communication between cells & their environment
allow control of the enclosed chemical environment
Form a continuous highly- selective permeability barrier
Allow recognition through presence of signalling molecules, adhesion proteins and allow immune surveillance
what is an action potential?
it is when excitable cells create an electrical signal via the movement of ions across the membrane
what is the membrane referred to if it is both hydrophilic and hydrophobic?
amphiphilic - amphipathic
what makes up a phospholipid membrane?
polar head (phosphate group), fatty acid tail, glycerol
what are the permitted modes of mobility in a lipid bilayer?
flip-flop
flexion
rotation
lateral diffusion
what is an integral protein?
Interact extensively w/ hydrophobic domains of lipid bilayer, can’t be removed by manipulation of pH and ionic strength
what is a peripheral protein?
Bound to surface, Electrostatic and hydrogen bond interactions, Removed by changes in pH or in ionic strength
what are the stages of an action potential?
initial stimulus - trigger of action potential
depolarisation - threshold level (-55 mV) reached, voltage-gated Na+ channels open which results in rapid depolarisation
depolarisation - Na+ inactivated and K+ channels open
hyperpolarisation - overshoot the repolarisation phase due to the movement of K+, until returns to resting membrane
refractory period
period of time in which the cell cannot generate an action potential
salutary conduction
action potential ‘jump’ from node to node
myelin sheaths act as a insulator to conduct APs, name a demyelination disease.
Multiple Sclerosis
what is the neuromuscular junction?
the synapse between a neurone and a skeletal muscle cell
release of a neurotransmitter (aCh)
activates receptors on the post-synaptic membrane (nicotinic receptors)
excitatory synapse
neurotransmitters open ligand gated channels permeable to Na+ and cations (naChR)
usually aCh or glutamate
inhibitory synapse
transmitters open ligand gated channels permeable to K+/Cl-
hyperpolarisation
GABA or glycine
