Chapter 11

Question 1

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Single point disturbances:

Answer 1

Graded potentials occur at a specific location on the neuron’s membrane.

Question 2

Decremental:

Answer 2

Graded potentials weaken as they spread away from the point of stimulation.

Question 3

Variable strength

Answer 3

The strength of a graded potential depends on the strength of the stimulus.

Question 4

Excitatory or inhibitory

Answer 4

Depending on the type of channel opened, graded potentials can either depolarize (excitatory) or hyperpolarize (inhibitory) the membrane.

Question 5

When will an action potential be reached?

Answer 5

If the membrane reaches threshold, which is going from -70 mV to -60mV

Question 6

What does threshold trigger?

Answer 6

the opening of voltage-gated sodium and potassium channels.

Question 7

what is Refractory Period

Answer 7

A period of time following an action potential during which it is difficult or impossible to generate another action potential.

Question 8

WHat is the absolute refractory period?

Answer 8

It is impossible to generate another action potential during this time.

Question 9

Relative refractory period

Answer 9

A stronger than usual stimulus is required to generate another action potential during this tim

Question 9

Schwann cells

Answer 9

In the peripheral nervous system, myelin is formed by Schwann cells.

Question 10

Channels in the receiving zone

Answer 10

Primarily ligand-gated channels (respond to neurotransmitters)

Question 11

Channels in the trigger zone

Answer 11

Voltage-gated sodium and potassium channels (initiate action potentials)

Question 12

Channels in the propagating zone

Answer 12

Voltage-gated sodium and potassium channels (propagate action potentials).

Question 13

Channels in the output zone

Answer 13

Voltage-gated calcium channels (trigger neurotransmitter release).

Question 14

Where do graded potentials occur?

Answer 14

Local changes in membrane potential at the receiving zone of a neuron, caused by the opening of ligand-gated ion channels.

Question 15

Phaeses of the ap

Answer 15

Depolarization: Rapid influx of sodium ions through voltage-gated sodium channels.
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Repolarization: Outflow of potassium ions through voltage-gated potassium channels.
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Hyperpolarization: Slight overshoot of potassium outflow, making the membrane potential more negative than resting.
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Return to Rest: Resting membrane potential restored by leak channels and the Na+/K+ pump

Question 16

Significance of Double Gates on Na+ Channels

Answer 16

Voltage-gated sodium channels have two gates: an activation gate and an inactivation gate.
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This allows for the absolute refractory period, preventing backward propagation of action potentials and ensuring unidirectional signal transmission.