chapter 10,11 & 12

________ account for roughly half of the volume of the nervous system.

Neuroglia

Classify neurons based on their function. (Module 11.3B)

Neurons are classified functionally as sensory, interneurons, or motor neurons.

Classify neurons based on their structure. (Module 11.3A)

Neurons are classified structurally as anaxonic, bipolar, unipolar, or multipolar.

The spinal cord consists of five regions and ________ segments.

31

Describe the all-or-none principle. (Module 11.10B)

All stimuli that bring the membrane to threshold will generate identical action potentials.

Which event occurs at the axon terminal?

Calcium ions enter the cytoplasm and trigger exocytosis of the neurotransmitter.

___ monitor the internal environment.

Interoceptors

The posterior horns of the spinal cord contain mainly

sensory nuclei.

Define gray matter in the spinal cord.

It contains the cell bodies of neurons, neuroglia, and unmyelinated axons, and it surrounds the narrow central canal.

What is the significance of the cauda equina? (Module 12.2E)

It is made up of extensions of the posterior and anterior roots of spinal segments L2 to S5. It forms as the vertebral column continues to elongate after growth of the spinal cord ceases at about age 4.

In saltatory propagation, a local current produces a(n) _________

graded depolarization

The brachial plexus gives rise to all of the following nerves except the

phrenic

Many medications introduced into the bloodstream cannot directly affect the neurons of the CNS because

the astrocytes isolate the CNS by forming a blood-brain barrier.

A characteristic of graded potentials is __________.

the effect spreads passively through local currents

Regions of the CNS with an abundance of myelinated axons constitute the ________ matter.

white

Which neurotransmitter is the most studied?

ACh

________ monitor the position and movement of skeletal muscles and joints.

Proprioceptors

Opening of sodium channels in the axon membrane causes

depolarization and increased positive charge inside the membrane.

The subdural space lies between the

dura mater and the arachnoid mater.

Name the neuroglia of the CNS. (Module 11.4A)

ependymal cells, microglia, astrocytes, oligodendrocytes

Regions of the CNS where neuron cell bodies dominate constitute the ________ matter.

grey

The anterior horns of the spinal cord contain mainly

somatic motor nuclei.

Where is spinal CSF located? (Module 12.3A)

subarachnoid space

Cerebrospinal fluid flows within the

subarachnoid space.

List the major nerves of the sacral plexus. (Module 12.10B)

superior and inferior gluteal, posterior femoral cutaneous, sciatic, and pudendal nerves

Define resting membrane potential

Resting membrane potential is the membrane potential of an unstimulated cell.

Which glial cells are found only in the PNS?

Schwann cells

What is the resting membrane potential for most neurons?

-70 mV

Define spinal reflex. (Module 12.1C)

A spinal reflex is an automatic response to a stimulus that is controlled in the spinal cord and can function without input from the brain.

Describe a synapse. (Module 11.2B)

A synapse is where one neuron communicates with another cell

A typical spinal cord has how many pairs of spinal nerves, and where does the spinal cord end? (Module 12.2A)

31 pairs; lumbar vertebra 1 or 2

After age ________ the vertebral column continues to elongate, but the spinal cord itself does not.

4

Describe a dermatome. (Module 12.5B)

A dermatome is the bilateral sensory region monitored by a single pair of spinal nerves.

What is a reflex? (Module 12.1B)

A reflex is a rapid, automatic response triggered by specific stimuli.

Define action potential. (Module 11.10A)

An action potential is the propagated change in membrane potential of an excitable cell

Describe depolarization, repolarization, and hyperpolarization. (Module 11.9B)

Depolarization is a shift in membrane potential toward a more positive value; repolarization is the return of the membrane potential to resting; and hyperpolarization is a shift in membrane potential toward a more negative value.

Compare the absolute refractory period with the relative refractory period. (Module 11.10C)

During the absolute refractory period the membrane cannot respond to further stimulation. During the relative refractory period the membrane can respond only to a larger-than-normal stimulus.

________ line the brain ventricles and spinal canal.

Ependymal cells Satellite cells

____ provide information about the external environment.

Exteroceptors

Choose the correct statement regarding synapses.

Gap junctions at an electrical synapse interlock the presynaptic and postsynaptic membranes.

_____ monitor the digestive, respiratory, cardiovascular, urinary, and reproductive systems.

Interoceptors

Of the spinal meninges, the middle one is the ________ mater.

arachnoid

Define membrane potential. (Module 11.6A)

Membrane potential is the unequal charge distribution between the inner and outer surfaces of the plasma membrane.

Compare presynaptic and postsynaptic cells. (Module 11.2C)

Presynaptic cells are usually neurons and postsynaptic cells can be a neuron or another type of cell, such as skeletal muscle fiber or a gland cell.

Identify the neuroglia of the PNS. (Module 11.5A)

Schwann cells and satellite cells

Describe the direction of sensory input and motor commands relative to the spinal cord. (Module 12.1A)

Sensory input travels toward the spinal cord and motor commands travel away from the spinal cord

Which is correct regarding the spinal cord?

The adult spinal cord ends between vertebrae L1 and L2.

What is the first step in Wallerian degeneration?

The axon and myelin degenerate and fragment.

Describe the brachial plexus. (Module 12.9A)

The brachial plexus is a network of nerves formed by branches of spinal nerve segments C5-T1.

Describe the lumbar plexus and sacral plexus. (Module 12.10A)

The lumbar plexus is a nerve network formed by axons from the anterior rami of spinal nerve segments T12-L4; the sacral plexus is a nerve network formed by axons from the anterior rami of spinal nerve segments L4-S4.

Which of the following would occur in a resting membrane after a stimulus is applied?

The opening of sodium channels will cause depolarization

What is the relationship between myelin and the propagation speed of action potentials? (Module 11.11B)

The presence of myelin increases the propagation speed of action potentials.

Which ramus carries sensory information from the limbs? (Module 12.6A)

anterior ramus

Contrast the white matter and gray matter in the CNS. (Module 11.4D)

White matter of the CNS is dominated by myelinated axons. Gray matter of the CNS is dominated by neuron cell bodies, dendrites, and unmyelinated axons.

Which glial cell protects the CNS from chemicals and hormones circulating in the blood? (Module 11.4C)

astrocytes

Which part(s) of the neuron can conduct an action potential?

axon and telodendria

The axon is connected to the cell body at the

axon hillock

In which part of a neuron does Wallerian degeneration occur? (Module 11.5B)

axons of PNS neurons

Name the effectors of the ANS. (Module 11.1C)

cardiac muscle, smooth muscle, glands, and adipose tissue

In the spinal cord, white matter is separated into ascending and descending tracts organized as

columns

The epidural space contains

connective tissue and blood vessels

In a typical undisturbed cell, the extracellular fluid (ECF) contains high concentrations of sodium ions and chloride ions, whereas the cytosol contains __________.

high concentrations of potassium ions and negatively charged proteins

What is the function of the posterior ramus?

innervates the muscles, joints, and skin of the back

Which of the following are not types of neuroglia?

interneurons

The most common neurons in the CNS, including the motor neurons that control skeletal muscles, are __________.

multipolar neurons

The white matter of the spinal cord is mainly

myelinated axons

The gray horns of the spinal cord contain mainly

neuron cell bodies.

The basic functional unit of the nervous system is the

neuron.

Which neurotransmitter is located in most neuromuscular and neuroglandular junctions of the sympathetic division of the ANS?

norepinephrine

Continuous propagation __________.

occurs along unmyelinated axons

The myelin sheath that covers many CNS axons is formed by

oligodendrocytes

The layer of the meninges in direct contact with the spinal cord is the

pia mater

What structure contains the cell bodies of sensory neurons?

posterior root ganglion

The separation of plus and negative charges across the membrane creates a ________ difference, or voltage.

potential

List the components of a reflex arc. (Module 12.12B)

receptor, sensory neuron, motor neuron, effector, and sometimes interneurons may be involved

Which division of the PNS brings information to the CNS? (Module 11.1B)

sensory

If the posterior root of a spinal nerve is severed,

sensory input would be blocked.

Compared to the vertebral column, the spinal cord is

shorter.

Which of the following activities or sensations is not monitored by interoceptors?

sight

The ________ nervous system controls the skeletal muscles.

somatic

The minimum stimulus required to trigger an action potential is known as the

threshold.

Neurotransmitter for release is stored in synaptic

vesicles