Lesson: Nervous Part 1 - 8.2 Questions

Question 1

Once an action potential starts at the axon hillock it cannot stop until it reaches the axon terminal. This is called the:

Answer 1

“All or None” response

Question 2

A membrane protein that has a channel that opens when a chemical, such as a neurotransmitter, binds to it is called a _______________.

Answer 2

A chemical (ligand) gated channel

Question 3

A membrane protein that has a channel that opens or closes when voltage is applied is called a _________________.

Answer 3

A voltage gated channel

Question 4

Chemical (ligand) and voltage gated channels are found.

Answer 4

In the plasma membrane of many types of cells, especially excitable (irritable) cells such as neurons and muscle cells.

Question 5

TRUE or FALSE? The first step of a nerve message most often occurs at the dendrite.

Answer 5

TRUE. A stimulus typically opens a chemical (ligand) gated channel and sodium ions flows into the neuron.

Question 6

TRUE or FALSE? All stimuli to the dendrites will cause an action potential.

Answer 6

FALSE. Threshold must be reached at the axon hillock to cause an action potential.

Question 7

TRUE or FALSE? An action potential is caused by the movement of both sodium and potassium ions.

Answer 7

TRUE. An action potential is due to depolarization followed by repolarization and only occurs where there are voltage gated channels.

Question 8

Depolarization followed by repolarization is called as _____________________.

Answer 8

Action potential

Question 9

A neuron is said to “fire” when it produces ______________________.

Answer 9

An action potential

Question 10

What happens at the axon hillock?

Answer 10

Actions potentials are started at the axon hillock.

Question 11

What type of gated channel is found in the plasma membrane of the axon hillock?

Answer 11

Voltage gated channels

Question 12

What type of gated channel is found in the plasma membrane of the axon hillock?

Answer 12

Chemical (ligand) gated channels

Question 13

What type of gated channels is found in the axons of neurons?

Answer 13

Voltage gated channels

Question 14

Positive sodium ions entering the cell is called:

Answer 14

Depolarization

Question 15

Location: In this lesson one would find chemical and voltage gated channels ________________.

Answer 15

In the plasma membranes of muscle and neurons.

Question 16

Location: The sodium/potassium pump is located?

Answer 16

In the plasma membranes of cells.

Question 17

What is the sodium/potassium pump?

Answer 17

A carrier protein, located in the plasma membrane that transports sodium out of the cell and potassium into the cell. This helps maintain the resting membrane potential.

Question 18

A resting membrane potential is when a neuron or muscle cell is:

Answer 18

Polarized. Charged up and ready to “fire”.

Question 19

Nerve signals on unmyelinated axons are slow due to:

Answer 19

Every voltage gated channel has to be opened one by one to keep the nerve signal going down the axon.

Question 20

Nerve signals on myelinated axons are very fast due to:

Answer 20

the neuron is insulated and this keeps enough sodium ions inside the cell to open voltage gated channels only at the nodes. It looks like the action potentials “jump” from node to node.

Question 21

What happens at a synapse?

Answer 21

One neuron sends a neurotransmitter to another neuron.

Question 22

Location: The synaptic cleft is located_______________

Answer 22

Between two neurons, between a neuron and a muscle cell, or between a neuron and a gland.

Question 23

Synaptic vesicles contain:

Answer 23

Neurotransmitters

Question 24

What is the active process that occurs when the synaptic vesicle releases its contents into the synaptic cleft?

Answer 24

Exocytosis.

Question 25

How does the neurotransmitter travel from the axon terminal to the postsynaptic neuron?

Answer 25

By diffusion.

Question 26

Location: The synaptic cleft is located_______________

Answer 26

Between two neurons, between a neuron and a muscle cell, or between a neuron and a gland.

Question 27

Synaptic vesicles contain:

Answer 27

Neurotransmitters

Question 28

What is the active process that occurs when the synaptic vesicle releases its contents into the synaptic cleft?

Answer 28

Exocytosis.

Question 29

How does the neurotransmitter travel from the axon terminal to the postsynaptic neuron?

Answer 29

By diffusion.

Question 30

Exocytosis requires _____________ to transport a substance to the plasma membrane to be released.

Answer 30

Vesicles

Question 31

TRUE or FALSE? Exocytosis is a passive process.

Answer 31

False. It is an active process requiring energy.

Question 32

LOCATION: Neurotransmitters diffuse across the synaptic cleft and bind to receptors on the postsynaptic membrane. These receptors are found on:

Answer 32

Chemical (ligand) gated channels

Question 33

The stimulus to start an action potential is due to what ion reaching threshold to open the voltage gated channels.

Answer 33

Sodium

Question 34

Exocytosis requires _____________ to transport a substance to the plasma membrane to be released.

Answer 34

Vesicles

Question 35

TRUE or FALSE? Exocytosis is a passive process.

Answer 35

False. It is an active process requiring energy.

Question 36

LOCATION: Neurotransmitters diffuse across the synaptic cleft and bind to receptors on the postsynaptic membrane. These receptors are found on:

Answer 36

Chemical (ligand) gated channels

Question 37

The stimulus to start an action potential is due to what ion reaching threshold to open the voltage gated channels.

Answer 37

Sodium

Question 38

In the nervous system lesson, what did we learn about sodium ions?

Answer 38

1. Sodium ions are higher in the ECF than ICF.

2. Sodium ions are responsible for causing local potentials and action potentials.

Question 39

In the nervous system lesson, what did we learn about potassium ions?

Answer 39

1. Potassium ions are higher in the ICF than ECF.

2. Potassium ions are responsible for repolarization.

Question 40

In the nervous system lesson, what did we learn about the use of calcium ions?

Answer 40

Calcium ions are “movers”. They cause the synaptic vesicles to move to the plasma membrane so that exocytosis can occur.

Question 41

What three structures are found at the synapse between two neurons?

Answer 41

1. axon terminals of the presynaptic neuron
2. synaptic cleft
3. dendrites of the postsynaptic neuron

Question 42

In nerve and muscle cells, ATP is needed to:

Answer 42

Power the Na+/K+ pumps to return sodium to the ECF and potassium to the ICF.

Question 43

TRUE or FALSE? Acetylcholine can travel through the chemical (ligand) gated channel and enter the muscle or postsynaptic cell.

Answer 43

FALSE. Acetylcholine never enters the gated channel it is too big. Acetylcholine is broken down and inactivated by the enzyme acetylcholinesterase in the synaptic cleft.

Question 44

What are the two benefits of a myelinated fiber?

Answer 44

Myelination of the axon:

1. Allows a faster conduction rate as compared to unmyelinated fibers.
2. Because the action potentials only occur at the nodes, there are fewer sodium/potassium pumps used so less energy is used.

Question 45

What enzyme breaks down acetylcholine to inactivate it?

Answer 45

Acetylcholinesterase inactivates acetylcholine in the synaptic cleft. This enzyme is released by the muscle sarcolemma.