The two types of cells of the nervous system are

The space between neurons is a

The nervous system

Neurons that convey impulses from the CNS to muscles or glands are

Sensory receptors

Three general functions of the nervous system are

Masses of myelinated nerve fibers appear

A neuron may have

_________ support the axon from within.

Every neuron has

Which of the following is unique to neurons?

_____comprises much of the cell membrane of Schwann cells.

A myelinated nerve fiber is ___.

An unmyelinated nerve fiber is ___.

Gray matter is made of ____neurons.

White matter is made of ___neurons.

Myelin is rich in ___________.

Which of the following is(are) a type of neuroglia?

Which cells produce myelin in the brain and spinal cord?

A reason that the CNS and PNS differ in their ability to regenerate after injury is that

Most of the neurons in the brain and spinal cord are

Which of the following cells is only found in the PNS?

Clusters of neuron cell bodies are called _____.

Which of the following neuroglia is not part of the CNS?

Synaptic knobs are at the ends of

Presynaptic neurons release neurotransmitters by ______________.

When an action potential passes over the surface of a synaptic knob, the contents of the vesicles are released in response to the presence of

If a neuron receives a series of stimuli whose effect is excitatory but subthreshold, the neuron is more excitable to incoming stimulation than before and is said to be

A stimulus great enough to change the membrane potential and propagate an action potential is said to have reached _________.

When a nerve fiber is polarized, the concentration of potassium is higher on the ___, and the concentration of sodium is higher on the ___.

Saltatory conduction is ___than conduction on an unmyelinated fiber.

The most rapid nerve impulses are conducted on fibers that are

Which of the following ions cross cell membranes most readily?

If a resting potential becomes more negative, the membrane is

Which of the following molecules is responsible for "runner's high," a good feeling that accompanies long-distance running?

An excitatory postsynaptic potential lasts for about

The neurotransmitter that controls skeletal muscle contraction is

The neurotransmitter that Viagra affects is

Drugs that increase the actions of norepinephrine and/or serotonin by keeping them in synapses longer are most likely used to treat

The types of neurons that are organized into neuronal pools are

Multiple sclerosis is caused by an abnormal response of the

An immune response that triggers inflammation of the spinal cord and brain, leaving scars is

The neurotransmitter most likely produced when a person uses a drug that creates a sense of well-being is

A drug that activates a receptor is working as an ___.

The cytoplasmic extensions that, together with the cell body, provide the main receptive surfaces for neurons are