VBP 301: Action Potential & Resting Membrane Potential

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What is the primary function of excitable tissues?

To generate and transmit electrochemical impulses along the membrane (correct)
To facilitate the exchange of nutrients and waste products
To maintain a constant membrane potential across all cell membranes
To regulate ionic distribution across the membrane

What is the typical range of the resting membrane potential?

-50 to -70 mV
-20 to -40 mV
-100 to -120 mV
-70 to -90 mV (correct)

What is the main factor that determines the resting membrane potential?

Ionic distribution across the membrane
Membrane permeability
Na+/K+ pump activity
All of the above (correct)

What is the polarity of the resting membrane potential?

The outer surface of the membrane is positively charged, and the inner surface is negatively charged (C) Signup and view all the answers

What is the typical value of the resting membrane potential for skeletal muscle fibers?

-70 to -90 mV (A) Signup and view all the answers

What is the term for the potential difference that exists across all cell membranes?

Resting membrane potential (D) Signup and view all the answers

What is the main factor contributing to the Resting Membrane Potential (RMP) of a cell?

Potassium efflux (B) Signup and view all the answers

What is the term for the potential level across the membrane that will exactly prevent net diffusion of an ion?

Nernst potential (A) Signup and view all the answers

What is the name of the equation used to calculate the equilibrium potential that develops when the membrane is permeable to several ions?

Goldman Equation (A) Signup and view all the answers

What is the net effect of the Na/K pump on the membrane potential?

It causes a negative charge inside the membrane (B) Signup and view all the answers

What is the term for the rapid transient changes in the membrane potential that spread rapidly along the nerve fiber membrane?

Action potential (A) Signup and view all the answers

What is the direction of the change in polarisation during the sharp upstroke of an action potential?

Depolarisation (A) Signup and view all the answers

What is the main reason for the development of an electrochemical equilibrium across the membrane?

All of the above (D) Signup and view all the answers

What is the characteristic of an action potential that makes it an 'all or none' phenomenon?

The potential is graded, but once the threshold is reached, it cannot be reversed (C) Signup and view all the answers

What is the duration of an action potential?

1 msec (D) Signup and view all the answers

What is the term for the sharp upstroke and downstroke of an action potential?

Spike potential (B) Signup and view all the answers

What is the potential reached during the initial sharp downstroke of an action potential?

Resting level (B) Signup and view all the answers

In myelinated nerves, which of the following is responsible for faster propagation of action potentials?

Local currents flowing from one node to another (A) Signup and view all the answers

What is the primary function of the inactivation gate in the Na+ channel?

To prevent the reopening of the Na+ channel until the resting membrane potential is reached (A) Signup and view all the answers

What is the primary function of the Na-K pump in nerve cells?

To re-establish the resting membrane potential after an action potential (C) Signup and view all the answers

What is the main reason for the absolute refractory period?

The closure of the inactivation gate (A) Signup and view all the answers

Which of the following phases of the cardiac muscle action potential is characterized by a rapid influx of sodium ions?

Phase 0: depolarisation (A) Signup and view all the answers

What is the primary difference between skeletal muscle action potentials and smooth muscle action potentials?

Skeletal muscle action potentials require an action potential for contraction, while smooth muscle action potentials do not (A) Signup and view all the answers

What is the role of the local current flow in the propagation of an action potential?

To initiate the opening of voltage-gated Na channels in the adjacent membrane (A) Signup and view all the answers

What is the effect of a myelin sheath on the propagation velocity of an action potential?

It increases the propagation velocity (A) Signup and view all the answers

What is the term for the process by which an action potential 'jumps' from one node of Ranvier to the next in myelinated nerves?

Saltatory conduction (B) Signup and view all the answers

What is the term for the process by which the membrane potential becomes more negative due to an efflux of potassium ions or an influx of chloride ions?

Hyperpolarisation (C) Signup and view all the answers

What is the purpose of the nodes of Ranvier in myelinated nerve fibers?

To allow the generation of action potentials (C) Signup and view all the answers

What is the primary mechanism of saltatory conduction?

The jumping of action potentials from node to node (D) Signup and view all the answers

What is the main difference between the absolute and relative refractory periods?

The ability of the nerve membrane to be excited again (B) Signup and view all the answers

What is the effect of a large axon diameter on the conduction velocity of an action potential?

It increases the conduction velocity (D) Signup and view all the answers

What is the role of the voltage-gated Na+ channels in the propagation of an action potential?

To generate an action potential at the next node (A) Signup and view all the answers

What is the purpose of the myelin sheath in the human body?

To maximize the propagation velocity of action potentials (D) Signup and view all the answers