resting/changing membrane potentials

Question 1

Define membrane potential.

Answer 1

electrical potential difference that exists across a plasma membrane always expressed as the potentials inside the cell relative tot eh extracellular solution

Question 2

How would you measure membrane potentials?

Answer 2

microelectrode

Question 3

What units is membrane potential?

Answer 3

millivolts

Question 4

What is the resting membrane potential of cardiac myocytes?

Answer 4

-80 mv

Question 5

What is the resting membrane potential of skeletal myocytes?

Answer 5

-90 mv

Question 6

What is the resting membrane potential of smooth muscle?

Answer 6

-50 mv

Question 7

What is the resting membrane potential of neurons?

Answer 7

-70mv

Question 8

Why does resting membrane potential vary in different cell types?

Answer 8

different ratio and selection of ion channels and transporters

Question 9

How is resting membrane potential set up?

Answer 9

na-k atpase sets up gradient 
k+ gates open 
k+  out chemical gradient 
k+ in electrical gradient
set approx -90mv

Question 10

Why is resting membrane potential -70 mv and not -90mv?

Answer 10

leakage of ions through na an ca voltage sensitive gates

Question 11

What is equilibrium potential?

Answer 11

when the net flow of an on through channels is 0. The chemical and electrical gradients are equal and opposite

Question 12

What is depolarisation?

Answer 12

decrease in size of membrane potential from its normal value
less negative
na/ca channels open

Question 13

What is hyperpolarisation?

Answer 13

increase in size of membrane potential from its normal value
more negative
open K /Cl channels

Question 14

What changes membrane potential?

Answer 14

change in plasma membrane permeability to a particular ion

Question 15

How does synaptic potential result form ligand gated channels?

Answer 15

ACh to nicotinic ACh receptor
ion channel opens
Na/K in
membrane potential towards 0mv

Question 16

Name three ways ion channels are regulated.

Answer 16

ligand
mechanical
voltage

Question 17

What is responsible for fast synaptic transmission?

Answer 17

nictonic ACh

ion channel itself

Question 18

Excitatory synapse which ions involved?

Answer 18

na and ca

Question 19

inhibitory synapse which ions involved, what type of ion channels, what neurotransmitters?

Answer 19

cl and K
NT = glycine and GABA
g-protein receptors/ligand gated