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Biology > Action Potential > Flashcards

Action Potential Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is the function of dendrites?

A

They receive information from other neurons or from the environment.

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2
Q

What are the functions of the cell body?

A

It controls the cell’s metabolic activities and it integrates input from other neurons.

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3
Q

What is the function of an axon?

A

It conducts the nerve impulse away from the cell body.

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4
Q

What is the function of axon endings?

A

They release chemicals called neurotransmitters that affect the activity of nearby neurons or an effector (muscle or gland).

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5
Q

What is used to transmit a message from neutron to neuron?

A

Action potential

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6
Q

What are the three types of neurons?

A

Sensory neurons, interneurons, motor neurons

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7
Q

What are the three basic mechanisms of membrane transport?

A

Simple diffusion, facilitated diffusion, active transport

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8
Q

What is an ion channel?

A

It is a cell membrane transport protein that allows a specific ion to cross the membrane.

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9
Q

What is an action potential?

A

It is the movement of ions through the membrane, changing the voltage across the membrane.

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10
Q

What is the voltage?

A

It is a difference in charge between the inside and outside of the membrane.

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11
Q

Are the ion channels involved in an action potential always open?

A

No, they are gated

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12
Q

How can a gated channel be opened?

A

A gated channel is closed until a signal opens it. Some gated channels are opened by changes in voltage while others are opened in the presence of a specific chemical such as a neurotransmitter.

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13
Q

What are the three membrane proteins that can be find along the axon of a neuron?

A
  1. Voltage-gated sodium (Na+) channels
  2. Voltage-gated-Potassium (K+) channels
  3. Sodium-Potassium pumps
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14
Q

What does the sodium-potassium pump do?

A

It actively moves Na+ out of the cell and K+ in the cell (the neuron), creating a resting membrane potential. For very three sodium ions out, two potassiums are let in. When the pump is active, the gated channels are closed, preventing the diffusion of the ions.

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15
Q

What is the consequence of using the sodium-potassium pump?

A

It creates a concentration gradient between the inside and the outside of the neuron.

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16
Q

What do the voltage-gated channels do?

A

They allow Na+ and K+ to move through facilitated diffusion across the membrane.

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17
Q

What is a resting neuron?

A

It is when the plasma membrane is charged, with the inside negative relative to the outside.

18
Q

Why do neurons have a more negative charge inside compared to outside when they are at rest?

A

Because of the sodium-potassium pump.

19
Q

When a neuron is at rest where are the potassium and the sodium?

A

The sodium is outside the cell and the potassium is inside.

20
Q

How can a neuron be described when it is at rest?

A

We say that the neuron is polarized.

21
Q

What kind of stimulus is needed to open the gated channels?

A

An “electrical” stimulus is needed.

22
Q

What is the other name for action potentials?

A

Nerve impulses

23
Q

When does an action potential occur?

A

When a neuron sends information down an axon.

24
Q

What is the detailed definition of action potential?

A

An action potential is an electrochemical signal involving the flow of sodium ions (Na+) and potassium ions (K+) across the cell membrane through ion channels in a precise sequence.

25
Q

Describe depolarization.

A

-An increase in membrane potential (toward zero)
-Inside of the membrane becomes less negative than the resting potential
-Increases the probability of producing a nerve impulse.

26
Q

Describe hyperpolarization

A

-A decrease in membrane potential (away from zero)
-Inside of the membrane becomes more negative than the resting potential
- Reduces the probability of producing a nerve impulse

27
Q

What is a threshold stimulus?

A

The minimum stimulus needed to achieve an action potential.

28
Q

What happens when a neuron is stimulated?

A

There is a sudden reversal of charge across the membrane because the sodium gates open and sodium ions enter the cell . The neuron becomes more positive inside.

29
Q

Is the action potential always the same if it occurs?

A

According to the all or non principle, if a stimulus reaches threshold, the action potential is always the same. Action potentials occur maximally or not at all (a stronger stimulus will not cause a larger impulse).

30
Q

When is a threshold reached?

A

A threshold is reached at -20mV above the resting potential.

31
Q

What is the resting potential?

A

-70mV

32
Q

What is the first step of action potential?

A

The sodium gates open and Na+ ions rush in the cell, causing the cell to depolorize.

33
Q

What is the second step in action potential?

A

Potassium gates open and K+ ions exit the cell, causing the action potential to decrease (goes back to original state)

34
Q

What is the third step in action potential?

A

Reestablishing the resting potential via the sodium-potassium pump

35
Q

Does the force of the stimulus changes something in the transmission of the signals?

A

Yes, it does not cause a larger impulse, but it creates more impulses. Also, more neurons can start firing.

36
Q

What are axons insulated with?

A

Myelin sheath

37
Q

What forms the myelin sheath?

A

Glial cells

38
Q

What does the myelin sheath do?

A

It increases the rate of conduction of a nerve impulse and facilitates nerve repair.

39
Q

What are Schwann cells?

A

A type of glial cells

40
Q

Can neurons from the PNS and the CNS be repaired?

A

Neurons from the PNS can, but neurons from CNS can’t.

41
Q

How do Schwann cells help with nerve repair?

A

When an axon in the PNS is damaged, the Schwann cells clean up the dead axon and guide a new growing axon.

Biology (4 decks)

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