Communication between excitable cells

Question 1

What is present in a synapse for electrical transmission?

Answer 1

Gap junction

Question 2

What part of the neuron is where the decision is made as to whether an action potential occurs?

Answer 2

In the axon hillock

Question 3

How can you tell between the pre-synaptic and post-synaptic membrane?

Answer 3

Pre - synaptic has vesicles

Question 4

What is the shape of an action potential on a muscle cell and why?

Answer 4

Broad shape because it allows longer for the calcium to exit the sarcoplasmic reticulum

Question 5

List the events in synaptic transmission

Answer 5

1. Presynaptic action potential
2. Depolarisation of synaptic terminal
3. Opening of voltage - gated calcium ion channels
4. Calcium entry and function of vesicles with membrane
5. Transmitter release
6. Channel activation
7. Activation of Na and K channels

Question 6

What happens when there is low Ca and high Mg in a neuron?

Answer 6

Tiny action potentials are formed. Post - synaptic membrane is made up of minute end plate potential, triggering end plate potentials.

Question 7

Explain the ionic basis of excitatory post synaptic potential

Answer 7

If a cell becomes permeable to an ion then that ion moves down its electrochemical gradient and will drive Vm towards equilibrium potential. Acetlycholine opens channels and that allows sodium and potassium to flow simultaneously.

Question 8

What happens at an inhibitory post synaptic potential?

Answer 8

Membrane potential is -70mv. Chloride channels open and this hyperpolarises.