Neurophysiology: Action Potentials and Stimuli

Why are action potentials not decremental in nature?

Because the action potential is initiated at one end of the neuron and propagates towards the other end
Because the action potential is initiated at the middle of the cell and propagates towards the ends
Because the action potential can propagate in either direction along the membrane
Because the action potential depends on the positive feedback cycle of a new group of Na+ channels (correct)

What is the main reason action potentials can only propagate in one direction along a membrane?

Because the action potential is initiated near the middle of the skeletal muscle cells and propagates towards the two ends
Because the velocity of propagation depends on the fiber diameter and whether the fiber is myelinated
Because the action potential is initiated at one end of the neuron and propagates towards the other end
Because the membrane area that has just undergone an action potential is refractory and cannot immediately undergo another (correct)

What is the relationship between the velocity of action potential propagation and the fiber diameter?

The smaller the fiber diameter, the faster the action potential propagates
The velocity of action potential propagation depends only on whether the fiber is myelinated, not on the fiber diameter
The larger the fiber diameter, the faster the action potential propagates (correct)
The fiber diameter has no effect on the velocity of action potential propagation

Under what condition can action potentials propagate in either direction along an excitable membrane?

If the membrane through which the action potential must travel is not refractory (C) Signup and view all the answers

Where are action potentials typically initiated in most neurons?

At one end of the neuron and propagate towards the other end (A) Signup and view all the answers

What happens to the action potential when it reaches the end of an axon?

It is unable to propagate further and the propagation ceases (B) Signup and view all the answers

What is the term used to describe the stimuli that cause subthreshold potentials?

Subthreshold stimuli (D) Signup and view all the answers

According to the all-or-none law, what is true about action potentials?

Action potentials either occur maximally or they do not occur at all (A) Signup and view all the answers

What happens during the absolute refractory period of an action potential?

The voltage-gated Na+ channels are already open or in an inactivated state (C) Signup and view all the answers

What is the effect of anesthetics on nerve cells?

Anesthetics suppress the formation and transmission of nerve impulses (C) Signup and view all the answers

What is the relationship between the amplitude of an action potential and the stimulus intensity?

The amplitude of the action potential is constant above the threshold level (D) Signup and view all the answers

What is the purpose of the refractory period in the generation of action potentials?

To prevent the generation of a second action potential during the action potential (D) Signup and view all the answers

What is the primary reason that voltage-gated Na+ channels open before voltage-gated K+ channels during membrane depolarization?

Voltage-gated Na+ channels have a faster response time to changes in membrane potential compared to voltage-gated K+ channels. (D) Signup and view all the answers

What is the primary function of the inactivation gate in voltage-gated Na+ channels?

To limit the influx of Na+ ions through the channel after it has opened. (B) Signup and view all the answers

Which of the following is a key difference between voltage-gated Na+ and K+ channels during the action potential?

Voltage-gated Na+ channels open faster, but close slower than voltage-gated K+ channels. (B) Signup and view all the answers

What is the purpose of the refractory period during an action potential?

To prevent the cell from generating multiple action potentials in rapid succession. (C) Signup and view all the answers

What is the significance of the 'all-or-none' law in the context of action potentials?

It suggests that the action potential is an all-or-nothing event, with no intermediate or partial responses possible. (D) Signup and view all the answers

What is the relationship between subthreshold potentials and the generation of an action potential?

Subthreshold potentials can summate to eventually reach the threshold potential and trigger an action potential. (D) Signup and view all the answers