Intro To Nervous System II

Question 1

How does action potential propagate down a neuron

Answer 1

1. Localized change in membrane potential as voltage gated Na channels open. The beginning of the axon becomes depolarized
   2.Localized change causes more voltage gated Na channels to open. Depolarization spreads down the axon. At the same time, repolarization happens at the start of the axon due to voltage gated K channels opening
   3.Action potential travels down the length of the axon

Question 2

What is the ‘all or none’ response

Answer 2

The action potential happens or it doesn’t. It never partly happens

Question 3

What happens to the action potential when voltage gated sodium channels are blocked? What does that result in?

Answer 3

No rapid depolarization - no action potential!
Paralysis - this is the basis of some anesthetics (e.g.novocaine)

Question 4

What happens to the action potential when voltage gated potassium channels are blocked? What does that result in?

Answer 4

No rapid repolarization - no action potential
Excitable convulsions (depolarization still happens)

Question 5

What are the Nodes of Ranvier and what do they do?

Answer 5

Breaks in the myeling sheath surrounding an axon that increases the speed of transmission

Question 6

Why are Nodes of Ranvier important?

Answer 6

They allow for saltatory conduction which means that the action potential jumps.

Question 7

What ion stimulates secretion of neurotransmitters?

Answer 7

Calcium

Question 8

What type of channel opens to allow an influx of calcium into the neuron terminal

Answer 8

voltage gated calcium ion channels

Question 9

What happens if the calcium channels didn’t work?

Answer 9

No neurotransmitter would be released

Question 10

Two opposing actions can happen to the postsynaptic neuron - what are they called?

Answer 10

Excitatory Post Synaptic potential
Inhibitory post synaptic potential

Question 11

what ions/ion channels are at work with excitatory postsynaptic potential?

Answer 11

-These postsynaptic cells have NT receptors that open gated sodium channel and lead to depolarization
-Action potential of postsynaptic neuron becomes morelikely

Question 12

what ions/channels are at work with inhibitory postsynaptic potential?

Answer 12

-These postsynaptic cells have NT receptors that open potassium and chloride channels which leads to hyperpolarization
-Action potential of postsynaptic neuron becomes lesslikely

Question 13

What is summation?

Answer 13

The process of EPSPs and IPSPs being added together

Question 14

What do neuromodulators do?

Answer 14

Substances that block the response to a neurotransmitter or block the release of a neurotransmitter

Question 15

What is an example of a neuromodulator

Answer 15

Endorphins work with receptors and block the transmission of pain

Question 16

What are some examples of neurotransmitters and their function

Answer 16

Dopamine-voluntary movement, learning, feelings of pleasure
Serotonin- sleep, arousal levels, emotion

Question 17

Describe different neurological disorders and which neurotransmitter is affected

Answer 17

Clinical Depression-inexplicable sadness-deficient in norepinephrine and serotonin
Parkinson’s disease- Hand tremors, muscle rigidity- deficient in dopamine
Alzheimer’s disease- memory loss- deficient in acetylcholine

Question 18

Describe some examples of drugs that impact the actions of neurotransmitters

Answer 18

Nicotine activates acetylcholine receptors and elevates dopamine. Increased pleasure and alertness
Antidepressants inhibits reuptake of serotonin and/or norepinephrine
Valium- enhances GABA receptor binding