nerve physiology formative assessment

What is the principal ion responsible for generating the resting membrane potential in neurons?

• Calcium

• Sodium

• Potassium

• Chloride

• Magnesium

The Nernst potential for an ion depends on which of the following?

• The membrane thickness

• Temperature and ion concentration gradient

• Resting potential

• Number of ion channels

• Enzyme concentration

The Goldman equation is used to determine:

• The resting membrane potential when the membrane is permeable to only one ion

• The action potential threshold

• The diffusion rate of gases

• The membrane potential when multiple ions are involved

• Osmotic pressure of a solution

Which ion channel opens first during the depolarization phase of an action potential?

• Potassium voltage-gated channel

• Calcium leak channel

• Sodium voltage-gated channel

• Chloride channel

• Non-specific cation channel

What causes repolarization during an action potential?

• Activation of calcium channels

• Opening of sodium channels

• Opening of potassium channels and efflux of K⁺

• Closing of chloride channels

• Influx of potassium

Saltatory conduction occurs only in:

• Smooth muscles

• Unmyelinated nerves

• Myelinated nerves

• Skeletal muscles

• Cardiac atrial tissue

The threshold potential is the level of membrane potential at which:

• The sodium-potassium pump activates

• All potassium channels close

• Voltage-gated sodium channels open explosively

• Calcium channels start calcium-induced calcium release

• There is maximum hyperpolarization

What effect does increased extracellular potassium concentration have on membrane potential?

• Hyperpolarization

• No effect

• Depolarization

• Enhances chloride influx

• Blocks sodium entry

During the plateau phase of some action potentials (e.g., cardiac), which ion primarily maintains depolarization?

• Chloride

• Potassium

• Calcium

• Magnesium

• Hydrogen

What is the role of the sodium-potassium pump in maintaining membrane potential?

• Depolarizes the membrane

• Repolarizes the membrane directly

• Restores ion concentration gradients by pumping Na⁺ out and K⁺ in

• Moves calcium into the cell

• Generates action potentials