Nerves and Action Potentials

The term central nervous system refers to the:

• autonomic and peripheral nervous systems

• brain, spinal cord, and cranial nerves

• brain and cranial nerves

• spinal cord and spinal nerves

• brain and spinal cord

The Schwann cell forms a myelin sheath around the:

• dendrites

• cell body

• nucleus

• axon

• nodes of Ranvier

The neuron processes that normally receive incoming stimuli are called:

• axons

• dendrites

• neurolemmas

• Schwann cells

• satellite cells

Impulse conduction is fastest in neurons that are:

• myelinated

• unmyelinated

• sensory

• motor

• cerebral

The ability to respond to a stimulus is termed:

• polarized

• irritability

• depolarized

• conductivity

• all-or-none response

The gap between two communicating neurons is termed:

• synaptic cleft

• cell body

• effector

• Schwann cell

• node of Ranvier

An action potential is caused by an influx of these ions into the cell:

• potassium

• sodium

• calcium

• magnesium

• both potassium and sodium

Which of the following is the correct sequence in a typical reflex arc?

• effector, afferent neuron, integration center, efferent neuron, receptor

• receptor, afferent neuron, integration center, efferent neuron, effector

• effector, efferent neuron, integration center, afferent neuron, receptor

• receptor, efferent neuron, integration center, afferent neuron, effector

• receptor, afferent neuron, efferent neuron, integration center, effector

The substance that is released at axonal endings to propagate a nervous impulse is called:

• an ion

• nerve glue

• a neurotransmitter

• the sodium-potassium pump

• an action potential

Which one of the following is the correct sequence of events:

1. the membrane becomes depolarized
2. sodium channels open and sodium ions diffuse in
3. the membrane become repolarized
4. potassium channels open and potassium ions diffuse inward while sodium is actively transported out of the cell

• 3,2,4,1

• 2,1,4,3

• 2,1,3,4

• 1,2,4,3

• 4,1,3,2