neurophysiology 1&2

Question 1

This type of signaling generates an action potential that propagates down the axon of a neuron.

Answer 1

Electrical signaling

Question 2

This type of signaling is transferred via neurotransmitters from neuron to neuron or neuron to a target cell (pre- and post-synaptic cells). Can be excitatory or inhibitory.

Answer 2

Chemical signaling

Question 3

What type of channel is responsible for creating action potentials, and where is it located?

Answer 3

A voltage-gated channel, which is located at the axon hillock of a neuron.

Question 4

What type of channel is responsible for creating post-synaptic potentials, and where is it located?

Answer 4

A ligand-gated channel (ligand = a neurotransmitter), which is located on the post-synaptic membrane of the receiving cell (on dendrites of neurons or receptors of target cells).

Question 5

What type of polarization is associated with an excitatory change in a neuron, and how does it change the membrane potential? What does this changes induce?

Answer 5

Depolarization: Na+ ions flow IN, and the membrane potential becomes less negative. Induces action-potential firing @ axon hillock.

Question 6

What type of polarization is associated with an inhibitory change in a neuron, and how does it change the membrane potential? What does this change induce?

Answer 6

Hyperpolarization: K+ ions flow OUT, and Cl- ions flow IN, and the membrane potential becomes more negative. Induces the inhibition of action-potential firing @ axon hillock.

Question 7

What is spatial summation?

Answer 7

Post-synaptic membranes closest to the axon hillock will have the greatest impact on inducing action-potential firing when stumuli are received.

Question 8

What is temporal summation?

Answer 8

Post-synaptic membranes that receive stimuli simultaneously will have the greatest impact on inducing action-potential firing at the axon hillock.

Question 9

How does myelination increase the speed of an action potential down an axon? (2)

Answer 9

1. Decreases the leakage of ions
2. Formation of “Nodes of Ranvier” –> only the desired voltage-gated channels are uncovered by the myelin sheath –> “saltatory conduction” occurs (electrical signals of the AP “jump” from node to node.