Lecture 4 Exam Part 4

Front 1

What is the term for the time between threshold and repolarization?

Back 1

Absolute refractory period

Front 2

What is the term for the time where an action potential is below the resting membrane potential?

Back 2

Relative refractory period

Front 3

True/False: You can generate another action potential during the absolute refractory period.

Back 3

False: You cannot stimulate another action potential while it's above threshold.

Front 4

True/False: You can generate another action potential during the relative refractory period.

Back 4

True: It would have to be depolarized more though, because you are in hyperpolarization.

Front 5

What is the difference between local potentials and action potentials?

Back 5

Local: Graded

Action: Non graded (all or none)

Local: Decremental

Action: Nondecremental

Local: Reversible

Action: Irreversible

Front 6

Why can we not generate an action potential out near the soma and dendrites?

Back 6

There are not enough voltage gated channels available

Front 7

During and action potential, when the sodium ions come in what do they do to the membrane?

Back 7

They will depolarize that part of the membrane, and if they depolarizes it enough, they will generate another action potential next door.

Front 8

Why can't we generate another action potential next door in the opposite direction?

Back 8

The previous action potential has not reset yet (still in absolute refractory period), so it cannot generate another action potential (not quite hyperpolarized).

Front 9

What type of neuron are action potentials on when they regenerate new action potentials right on to the next one?

Back 9

Unmyelinated neuron

Front 10

True/False: You cannot generate a new action potential on a myelinated area.

Back 10

True: The only place you can generate an action potential is on the nodes of rambeugh.

Front 11

True/False: The nodes of rambeugh have to be exactly the right distance apart.

Back 11

True: If the nodes are too far the signal will fade and will not bring the synapse to threshold, thus killing it.

Front 12

What is the term for the idea that the action potentials jump (leap) from one area on down to the next in a myelinated neuron?

Back 12

Saltatory conduction

Front 13

What is the name for the area where the end of an axon meets the synaptic cleft at a synapse?

Back 13

Presynaptic membrane

Front 14

What is the name for the gap area that separates the presynaptic membrane from a postsynaptic membrane at a synapse?

Back 14

Synaptic cleft

Front 15

What is the name for the area where an axon terminal forms a synapse with another neuron?

Back 15

Postsynaptic membrane

Front 16

What major category of synapses occurs when the signal is moved across the gap by chemicals (neurotransmitters)?

Back 16

Chemical synapses

Front 17

True/False: Chemical synapses are two way signaling waves.

Back 17

False: They are one way signaling, because there is no mechanism in which action potentials can go backwards across a synapse.

Front 18

True/False: Electrical synapses are two way signaling wave (bi directional).

Back 18

True

Front 19

What is found in a chemical synapse that bridge the gap to form a tunnel, allowing ions to move back and forth from?

Back 19

Proteins

Front 20

Are electrical synapses slow or fast?

Back 20

Fast

Front 21

What occurs once an action potential sweeps down into the membrane at the synapse?

Back 21

1. Voltage gated calcium channels open up

2. Calcium enters into the end of the axon

3. Neurotransmitters fuse and release their contents (AcH) into the synaptic membrane

4. AcH diffuses across the synapse and binds to ligand/chemically gated channels

5. These receptors will either let sodium in or potassium out

Front 22

True/False: In a chemical synapse there is a possibility that the action potential can stop if there is not enough stimulation (depolarization) as it moves on, whereas in an electrical synapse the action potential continues on through without stopping.

Back 22

True

Front 23

What is the term for any neurotransmitter that causes a depolarization (gets the membrane closer to threshold)?

Back 23

Excitatory

Front 24

What is the term for any neurotransmitter that hyperpolarizes the membrane (makes it harder to generate a new action potential)?

Back 24

Inhibitory

Front 25

What type of neurotransmitter causes a depolarization using a vesicle filled with AcH?

Back 25

Cholenergic neuron

Front 26

What type of neurotransmitter causes a depolarization using a vesicle filled with norepinephrine?

Back 26

Adrenergic neuron

Front 27

What are the steps involved in a cholinergic synapse?

Back 27

1. Arrival of nerve signal at synaptic knob opens voltage gated channels

2. Calcium enters knob and triggers exocytosis of synaptic vesicles (releases AcH)

3. Empty vesicles drop back into cytoplasm to be refilled with AcH while synaptic vesicles move to active sites to release their AcH

4. AcH diffuses across synaptic cleft and binds to ligand gated channels on the postsynaptic neuron (allowing channels to open to let sodium enter the cell and potassium leave the cell)

5. As sodium enters the cell it depolarizes it producing local potential (postsynaptic potential), and if strong enough it will open voltage gated channels in trigger zone to cause a postsynaptic neuron to fire

Front 28

What are the steps involved in an adrenergic synapse?

Back 28

1. NE receptor is bound to a G protein

2. NE receptor causes G protein to disassociate

3. G protein binds to adenylate cyclase, activates it, and induces it to convert ATP into cAMP

4. cAMP can either produce an internal chemical that binds to s ligand gated ion channel from the inside of the membrane, opening the channel and depolarizing the cell, or it can activate preexisting cytoplasmic enzymes which can lead to diverse metabolic changes (liver to break down glycogen into glucose and release into blood), or induce genetic transcription so that the cell produces new cytoplasmic enzymes, which can lead to diverse metabolic effects

Front 29

How can a neurotransmitter excite one cell and inhibit another?

Back 29

Dependent on the type of receptor

Front 30

What are the four classifications of neurotransmitters?

Back 30

1. AcH (cholinergic neuron)

2. Amino acid

3. Monoamines (modified amino acids)

4. Neuropeptide

Front 31

What neurotransmitter group last the longest, are made in the soma and then transported down by axoplasmic transport, and is then stored as granules instead of vesicles?

Back 31

Neuropeptides

Front 32

How does the signal at the synapse stop (four different processes)?

Back 32

1. Stop sending action potentials down

2. Diffusion of the neurotransmitter out of the synapse

3. Destruction (break down of neurotransmitter in the synapse)

4. Reuptake (moving enzyme back into the synapse where it can be removed from the synapse and be reused or broken down)