Neural Conduction

Question 1

What ions are important in the action potential? When the cell is at rest, which ions are most highly concentrated inside of the cell, and which ones are most highly concentrated outside of the cell?

Answer 1

Sodium, Na+. Potassium, K+. Chloride Cl-. Calcium, Ca2+

K+ is greater inside. Na+, Cl- is greater outside.

Question 2

Understand the forces working on the ions (electrical gradient and concentration gradient).

Answer 2

Electrical gradient- different charge inside vs outside. Ions flow to areas of opposite charge.
Concentration gradient- different levels of ions inside vs outside. Ions flow from areas of high to low concentration.

Question 3

What is a voltage-gated channel? Where are they?

Answer 3

Opens when the cell reaches a certain voltage allows ions in or out. It is located on the axon, mostly the nodes

Question 4

Understand the steps of the action potential, and how one leads to the next. How is an action potential started and propagated? What ion enters first? Thru what type of channel does it enter? What forces drive it inside? Why does that channel close? What channel opens next? What ion moves thru that? What forces drive that ion? Etc etc.

Answer 4

Sodium inside a cell diffuses to the next node of ranvier, causes the node to be -50mV then the sodium channel opens and sodium rushes in. Potassium channels open when sodium channels close. Potassium rushes out of cell. When it reaches -70, its resting and going to start over again.

Question 5

Whats an action potential do?

Answer 5

sends signals across the synapse

Question 6

When sodium rushes in……

Answer 6

it become depolarized

Question 7

When potassium rushes out…….

Answer 7

it becomes hyper polarized

Question 8

What voltage is resting potential?

Answer 8

-70 mV

Question 9

Whats threshold?

Answer 9

depolarization that must be achieved to trigger action potential

Question 10

Depolarized is…..

Answer 10

less negative than -70

Question 11

Hyperpolarized is….

Answer 11

more negative than -70

Question 12

Cell membrane is

Answer 12

always polarized

Question 13

How could we depolarize the cell?

Answer 13

Add sodium

Question 14

How could we hyperpolarize the cell?

Answer 14

Remove potassium.

Question 15

What is the sodium/potassium pump? What does it do? What purpose does it serve?

Answer 15

For every 3 Sodium out, 2 potassium’s in.

Needed for maintaining rest potential and for recovery from an action potential

Question 16

Removal of neurotransmitter?

Answer 16

Absorption by glia, enzymatic degradation, reuptake by presynaptic terminal

Question 17

What is the purpose of myelin? What happens at the nodes of Ranvier? What is saltatory conduction?
What does it mean that an action potential is “all or none”?

Answer 17

Action potentials are generated in an “all-or-none” fashion. That is, in most (but not all) neurons, subthreshold depolarizations have no effect, but once the threshold is crossed, an action potential is generated

Question 18

What is the difference between ionotropic and metabotropic receptors?

Answer 18

Ionotropic: Neurotransmitter binds to receptor and opens ion channel
Metabotropic: do not have channels. Neurotransmitter binds outside and that activates a G protein inside. The G protein can activate a second messenger which can find an ion channel and open it up. Takes longer than ionotropic, affects can be longer lasting

Question 19

Know the common neurotransmitters.

Answer 19

Dopamine (Reward), Serotonin (Sleep), Norepinepherine (Adrenaline)

Question 20

What is the most common excitatory neurotransmitter?

Answer 20

Most common excitatory NT: Glutamate

Question 21

What is the most common inhibitory neurotransmitter?

Answer 21

Most common inhibitory NT: GABA

Question 22

Where are neurotransmitters made?

Answer 22

Somas or teminals. The bigger ones are made in the somas.

Question 23

What neurotransmitters share a pathway of synthesis?

Answer 23

Dopamine, Norephinephrine, epinephrine

Question 24

What are the initial precursors for dopamine, norepinepherine, and epinepherine?

Answer 24

norephinpherine-epinepherine: Phenylalenine, tyrosine and dopa.

Question 25

What are the initial precursors for serotonin ?

Answer 25

Tryptophan and 5-hydrozytryptophan

Question 26

What are the initial precursors for acetylcholine?

Answer 26

Acetyl coenzyme A and Choline

Question 27

What happens to neurotransmitters when they are released, and how are they cleared from a synapse?

Answer 27

Absorption by glia, enzymatic degration and reuptake by presynaptic terminal.

Question 28

Can a neuron release more than 1 neurotransmitter? Can you think of an example of this?

Answer 28

Yes, the motorneurons in the spinal cord.

Question 29

For dopamine and serotonin: what are they involved in?

Answer 29

Drugs

Question 30

Whats a Agonist?

Answer 30

A drug that mimics or increases the effects of a neurotransmitter
Many antidepressants are serotonin agonists

Question 31

Whats a Antagonist?

Answer 31

Drug that blocks the effects of a neurotransmitter

Many antipsychotics are dopamine antagonists