neuronal communicatos and exitable cells Flashcards
name 2 factors that affect the conduction velocity of an axon A insulation and size B myelination and velocity C myelination and diameter D insulation and diameter
OPTION C PLEASE
larger diamer, faster velocity as there is less resistance and have lower threshold
> salutatory conduction across the nodes of Ranvier
which phase of an action potential does TTX prevent? A depolaristion B repolarisation C refractory period D stimulus E hyperpolarisation
OPTION A PLEASE
the inital depolariation phase of actiOn potentiaL
> naturallu foun in pufferfish and blocks Na+ channels = respiratoty paralysis so prevents depolarisation
which of these best defines capacitance? A how fast current flows down an axon B p.d. across a membrane C ability for membrane to store charge D how fast current flows over time
OPTION C
which type of fibres conduct Action potential faster?
myelnated axon
nonmyelinated axon
myelinated for the winn > jumps across > good insulator > increases resitance > decreases conductance
which ion enters the cell during InhibotoryPSP A chloride B potassium C sodium D calcium
chloride
this reduced the charge leaidng cell to become more negative
potasssium LEAVES creating net negative
do all synapses use chemical neuroransmitters?
no! some use electrical synaptic transmission (gap junctions)
what does "FPM" stand for in fusion of vesicles with the presynaptic membrane? A fusion protein micromolecule B fusion protein macromolecule C fission protien molecule D fusion pairing molecule
OPTION B
> key protein in fusion of vesicles
>macro is large
> allows presynaptic vesicle to fuse with membrane
At rest, cell membranes are freely permeable to A Potassium and sodium ions B Potassium and chloride ions C Sodium and chloride ions D Potassium, sodium and chloride ions
OPTION B PLS
Cell membranes are readily permeable to potassium and chloride ions at rest.
They are poorly permeable to sodium ions at rest
Sometimes a membrane becomes hyperpolarised and therefore the membrane potential is moved further away from where it needs to be for an action potential. What is this known as?
A Excitatory post synaptic potential (EPSP)
B Inhibitory post synaptic potential (IPSP)
C Convergence of input
D Divergence of output
IPSP
> think about doing a drawing, the bump goes down so its furthur away from reachig a threshold
Which of these statements is INCORRECT regarding basic synaptic transmission?
A The action potential will reach the terminal, voltage gated calcium channels will open and calcium will enter the axon terminal
B Vesicle recycling happens by the “kiss and run” theory.
C Fusion protein macromolecules (FPM) assist the inward movement of the vesicle membrane.
D Fusion protein macromolecules (FPM) separate to allow neurotransmitter out.
E Clathrin molecules assist inward movement of the vesicle membrane.
OPTION C is false as FPM separates to allow neurotransmitter release
Clathrin+ Dyenin molecules assist the inward movement of the vesicle membrane.
what is nernst equation used for
if ion and concentration gradient are in opposite directions, we can use this to work it out for a SINGLE ion which way it would move
> GHK equations considers multiple ions
how is AchCholine recycled?
AchCholine esterase breaks it down and this is VITAL to prevent over-excitation
then it can be pumped by A.T back to vesicles in presnaptic terminal or brain/glial cells can uptake neurotransmitter
what ions can cause EPSP and IPSP
EPost synapticP = sodium influx so more postive
IPost SYnaptic P = chloride influx or Potassium efflux so membrane more negative
what is the ~resting membrane potential?
minus 70mV
what causes depolarisation A Calcium release B Sodium influx C Potassium efflux D Chloride influx
OPTION B
sodium INFLUX into cell
> they are voltage gated and only open ABOVE threshold
> faster acting than K+ (so K can have leakage//hyperpolarisation)
