Neurons, Glia and Nervous Systems

The threshold of a neuron is the

• membrane voltage at which an axon potential will be suppressed.

• amount of inhibitory neurotransmitter required to inhibit an action potential.

• membrane voltage at which the membrane potential develops into an action potential.

• amount of excitatory neurotransmitter required to elicit an action potential.

An action potential can vary in strength depending on the stimulus.

• True

• False

Which of the following statements about the knee-jerk reflex is false?

• Chemoreceptors in the skin sense a physician's hammer tap.

• It is a monosynaptic reflex.

• It causes the leg extensor muscle to contract.

• The afferent nerve travels from the receptor to the spinal cord.

A resting membrane potential (RMP) is due to

• a relaxed muscle.

• The influx of only negatively charged ions into the cell.

• unequal distribution of ions across the cell membrane.

• equal distribution of ions across the cell membrane.

Which of the following statements about neurotransmitters is true?

• triglycerides and their derivatives, fatty acids function as neurotransmitters.

• Neurotransmitters have different effects in different tissues.

• Each neurotransmitter has a single type of receptor.

• Gases, such as nitric oxide, can act as neurotransmitters.

Which of the following statements about glia cells is false?

• They support neurons.

• They are more numerous than neurons.

• They transmit electrical signals.

• They include microglia and macroglia.

The peripheral nervous system (PNS) includes the spinal cord but not the brain

• True

• False

The extensions of postsynaptic neurons that provide the main receptive surface for presynaptic
neurons are the

• glia.

• dendrites.

• nuclei.

• somas.

• axons

The substance that wraps around the axon of many neurons and provides for increased conduction
speed is

• acetylcholine

• histamine

• microglia

• myelin

• a bipolar cell

The long extension from the cell body of a neuron that provides the pathway for an action potential
to the synapse is the

• presynaptic membrane.

• nerve net.

• Schwann cell.

• dendrite.

• axon.