Nerve Impulse

​Action Potentials

​Nerve Impulse

A nerve impulse is a series of action potentials that occur along an axon of a neuron

​

When a neuron is stimulated enough to start an impulse it causes​ a signal to be sent

Multiple Choice

A series of action potentials is called __________

• a reaction

• an impulse

• a stimulus

• an effector

​Polarized

• When a neuron is at rest (resting potential) this is called polarized ​

• ​The axon of the neuron when polarized will have a postive charge on the outside of the membrane and a negative charge on the inside of the membrane​

• More Sodium (Na⁺) ​ions will be outside and more Potassium (K⁺) ions will be inside

Multiple Choice

A resting potential in an axon is called _______

• rest

• polarized

• repolarized

• depolarized

Multiple Choice

A polarized membrane will have a positive charge on the outside and a negative charge on the inside.

• True

• False

​Depolarized

• When a stimulus is received this opens the sodium ion channels at the start of the axon this depolarizes this area of the axon

• ​Depolarization causes the sodium ions to move into the axon and the charges switch because there are now more positive charges on the inside than the outside

Multiple Choice

When a stimulus is received, this causes which channels to open?

• chlorine

• sodium

• potassium

Multiple Choice

When sodium ions rush INTO the axon through the sodium channels this causes the membrane in this section to become _________.

• polarized

• depolarized

• repolarized

• hyperpolarized

Multiple Choice

The net charge on the outside of a depolarized membrane is ______ and the net charge on the inside of a depolarized membrane is _________.

• neutral, negative

• negative, positive

• positive, negative

• neutral, positive

​Repolarized

• When sodium ions rush in this causes the potassium ion channels in the same area to open and the potassium ions move out of the axon this repolarizes this area of the axon

• ​Repolarization causes the potassium ions to move out of the axon and the charges switch because there are now more positive charges on the outside than the inside

Multiple Select

What happens when sodium ions rush in and cause depolarization of the membrane?

• potassium ion channels close

• potassium ion channels open

• sodium ion channels open

• sodium ion channels close

Multiple Choice

When the potassium ions start moving out of the membrane in the area that was depolarized this causes this section of the membrane to become ________.

• polarized

• depolarized

• repolarized

• hyperpolarized

​Hyperpolarization

• potassium ion channels remain open for longer than sodium ion channels so more potassium ions have moved out than there were sodium ions to begin with.

• This causes the outside of the axon to become more positive than it is during polarization​

Multiple Choice

Immediately after repolarization, more potassium ions have moved outside this is called ________.

• polarization

• depolarization

• repolarization

• hyperpolarization

Multiple Choice

Which ion channels stay open longer allowing more ions to move across?

• chlorine

• potassium

• sodium

​Sodium Potassium Pump

• In order to move the sodium and potassium ions back across the membrane

  • sodium to the outside

  • potassium to the inside

• a pump must be used (active transport) ATP must be used to move them against their concentration gradient.

  ​

Multiple Choice

To get the membrane potential back to rest (polarization), sodium and potassium have to get moved back to where they started. How do they get there?

• sodium and potassium ion channels

• sodium-potassium pump

• diffusion

Multiple Choice

The sodium-potassium pump requires ATP, energy, this is what type of transport?

• passive

• active

• energy required

• osmosis

Reorder

Reorder the following

• polarized

• depolarized

• repolarized

• hyperpolarized

• sodium-potassium pump

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

Match

Match the following

• polarized

• depolarized

• repolarized

• hyperpolarized

• sodium-potassium pump

membrane is at rest; positive charge outside and negative charge inside

sodium ions have moved into the axon; membrane is - on the outside and + on the inside

potassium ions have moved out of the axon; membrane is + on the outside and - on the inside

potassium ions have moved out of the axon causing the outside of the membrane to be even more +

active transport moves sodium and potassium back across the membrane against concentration gradient

• membrane is at rest; positive charge outside and negative charge inside

• sodium ions have moved into the axon; membrane is - on the outside and + on the inside

• potassium ions have moved out of the axon; membrane is + on the outside and - on the inside

• potassium ions have moved out of the axon causing the outside of the membrane to be even more +

• active transport moves sodium and potassium back across the membrane against concentration gradient

Multiple Choice

Action potentials and the nerve impulse overall can move

• in only one direction

• in either direction

• back and forth

Reorder

Reorder the following structures in the order a signal would go on a neuron

• dendrite

• cell body

• axon

• axon terminal

• synapse

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

1. Polarized membrane is at -70mV​

Threshold for an impulse to be sent is -55mv

2. depolarization - sodium channels open and sodium ions rush into the axon

3. at +30 mv sodium ion channels close and potassium ion channels open

4. repolarization - potassium ions rush out of the axon

5. hyperpolarization - potassium ion channels remain open and cause more potassium ions to move out

6. sodium-potassium pump- actively moves sodium ions back out and potassium ions back into the axon​

​

​6 1

​

1. Back to a Polarized membrane at -70mV​

​

​

Multiple Choice

What has to happen to bring the graph from 4 to 5?

• depolarization

• hyperpolarization

• sodium-potassium pump

• threshold

Match

Match the term with the number indicated on the graph.

• depolarization

• hyperpolarization

• repolarization

• polarization

2

4

3

5

• 2

• 4

• 3

• 5

Reorder

Reorder the following

• sodium ion channels open

• sodium ions rush into the axon

• sodium channels close and potassium channels open

• potassium ions rush out

• sodium ions are pumped out oand potassium ions are pumped into the axon

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5