Membrane Potentials Part 2 Flashcards
What can change the magnitude of rmp?
- difference of ion concetration between ecf and icf
- difference in membrane permeability to different ions
Voltage gated:
electrical events (change of membrane potential)
Ligand Gated:
chemical events (NT open or close channels)
Stretch Sensitive
mechanical events (vibrate or membrane is stretched)
Ay rest what is more permeable to the membrane?
K+ due to leake channels
What determines what ion is dominating?
relative permeability
Summary of RMP
- Na+/K+ pump sets up a concentration gradient and generates a small negative potential with the 3 Na+ out and 2 K+ in
-At first more K+ leaks in due to more channels but then Na+ leak permability kicks in and RMP becomes -70
-The steady state resting neuron leak of K+ and Na+ are balanced
What has to be established before a graded potential occurs?
a concentration gradient
Where do graded potentials occur
presynaptic axon terminal, and postsynaptic dendrite
What is a graded potential?
there are thousands of synapses on one post synaptic cell and each synapse produces a small post synaptic signal, these signals are GP
True or False: gp’s don’t summate
false; they do
What distance and what do they rely on (GPs)
short distance and rely on local flow of ion currents
Are graded potentials proportional to the size of the stimulus
yes
Why does the amplitude of the GP decrease with distance from the stimulus site?
because charges leak back out through the membrane (mostly K+)
True or false: Gps can be depolarizing or hyperpolarizing
true
