ch 8

Why are Na⁺, K⁺, and Cl^– the only ions considered in the GHK equation when calculating resting membrane potential (V_m)?

• These ions are found in the highest concentrations inside the cell.

• These ions bind to receptors that increase the charge on the membrane.

• These are the ions to which cell membranes are permeable at rest.

• Only these ions have enough charge to influence V_m.

What would happen to the membrane potential if a resting cell suddenly became more permeable to Ca⁺⁺?

• hyperpolarize

• depolarize

• repolarize

• none

During an action potential, activation of voltage-gated sodium and potassium channels occurs at different rates. What is the effect of this difference on ion flow across an axon membrane?

• Initially, Na⁺ flows into the cell and then K⁺ flows out of the cell.

• Sodium ions flow out of the cell, then potassium ions flow out of the cell.

• K⁺ will flow into the cell first and then Na⁺ will flow out of the cell.

• First, sodium ions flow into the cell, and then potassium ions flow into the cell.

Which two properties determine how fast neurons conduct action potentials?

• Myelination and voltage-gated Na⁺ channel concentration

• The voltage-gated K⁺ ion channel concentration and axon diameter

• Axon diameter and the leak resistance of the membrane

• The leak resistance of the membrane and myelination

Which type of receptor would bind acetylcholine and be found in skeletal muscle?

• β-adrenergic

• Muscarinic cholinergic

• Nicotinic cholinergic

• NMDA receptors

Neurotransmitter is stored and released from

• cell bodies only.

• axon terminals and axon varicosities.

• axon terminals only.

• axon varicosities only.

Information coming into the central nervous system is transmitted along ________ neurons.

• efferent

• afferent

• sensory

• afferent and sensory

The afferent and efferent neurons together form the

• somatic motor division.

• central nervous system.

• peripheral nervous system

• autonomic division.

Autonomic motor neurons are subdivided into the

• sympathetic and parasympathetic branches

• visceral and enteric branches.

• somatic and enteric branches.

• visceral and somatic branches.

Interneurons are found

• in the CNS.

• only in brain

• only in spinal cord

• only in spinal nerves