BSC2085 ONLINE QUESTIONS CH12

Two organ systems are dedicated to internal coordination, communication between the other systems, and maintaining the overall homeostasis of the body. They are the \______________ system, which communicates by means of hormones, and the \____________ system which sends quick electrical and chemical messages from cell to cell.

endocrine; nervous

The nervous system plays an important role in maintaining homeostasis. List, in order, the basic steps that describe how the nervous system carries out this task.

1. Information is received
2. Information is processed
3. A command is issued

What are the two major anatomical subdivisions of the nervous system?

Central and peripheral nervous systems

The plural form of ganglion is \______.

ganglia

Which terms refers to the part of the PNS that carries signals from various receptors to the CNS?

Sensory division

Which two organ systems are primarily responsible for coordinating the other bodily systems so as to maintain homeostasis?

Nervous system
Endocrine system

Taken together, the sensory and motor subdivisions make up which of the following?

Peripheral nervous system

Sensory (afferent) neurons do which of the following?

Carry signals to spinal cord and brain

The brain and spinal cord are components of the \______ nervous system, while the nerves and ganglia are components of the \______ nervous system.

central, peripheral

Together, the sympathetic and parasympathetic nervous systems make up the entirety of which division of the nervous system?

Visceral motor

The knotlike swelling in a nerve where neuron cell bodies are found is called a(n)

ganglion

Another term for sensory division is \______ division.

afferent

The release of a neurotransmitter is an example of which physiological property exhibited by a neuron?

Secretion

The sensory and motor divisions of the peripheral nervous system are further split into which two subdivisions?

Somatic and visceral

Sensory, association and motor are the three classes of what?

Neurons

The autonomic nervous system is subdivided into the \______ division which tends to arouse the body for action and the \______ division which tends to have a calming effect.

sympathetic, parasympathetic

Motor, or \______ , neurons carry signals away from the CNS and they lead to effectors (muscle and gland cells).

efferent

List the fundamental physiological properties of neurons.

Excitability, conductivity, secretion

Which are usually found inside the cell body (or soma) of a mature neuron?

Mitochondria
Nucleus
Rough endoplasmic reticulum

Afferent neurons are \______ neurons.

sensory

\________ are the processes of a neuron that usually receive signals from other neurons.

dendrites

What are the effectors of motor neurons?

muscles and glands

Neurons are classified structurally according to the number of processes extending from the soma. Match each classification to its description.

Multipolar neurons matches One axon; multiple dendrites

Bipolar neurons matches One axon; one dendrite

Unipolar neurons matches A single process

Anaxonic neurons matches No axon; multiple dendrites

The \______ (the cell body of a neuron) gives rise to branch-like processes called \______, which are the primary sites for receiving signals from other neurons.

neurosoma, dendrites

The processes that branch from the somas of most neurons are called \______.

dendrites

Neurons that have one axon and one dendrite, such as olfactory cells, certain neurons of the retina, and sensory neurons of the inner ear, are classified as which of the following?

bipolar

Which term applies to the small swellings at the distal end of the axon of a neuron that contain synaptic vesicles?

Synaptic knobs

Neurons with a single process extending from the soma, such as the neurons that carry sensory signals to the spinal cord, are classified structurally as \______ neurons.

unipolar

Which term refers to the passage of proteins, organelles and other materials along an axon?

Axonal transport

Neurons with numerous dendrites and a single axon are structurally classified as which of the following?

multipolar

What is the approximate ratio of glial cells to neurons?

10:1

Which neuroglial cell is found in the peripheral nervous system?

Satellite cell

Which type of neuron has one single process that branches like a T into a peripheral fiber and a central fiber?

Unipolar

In the CNS, myelin is produced by glial cells called \_____.

oligodendrocytes

Which correctly describe axonal transport?

It involves transport of proteins within the axon (i.e. synaptic knob enzymes or proteins that maintain the axolemma).
It is bidirectional (retrograde and anterograde transport).

what is true of glial calls

They bind neurons together and provide a supportive scaffold.
They protect the neurons and help them function.

\______ cells protect the neurons and help them function.

Glial

Which types of glial cells are found in the central nervous system?

Microglia
Astrocytes
Oligodendrocytes
Ependymal cells

In the CNS, myelin is produced by glial cells called \_________

olgidendrocytes

Which type of glial cell produces the myelin sheath in the PNS?

Schwann cell

Which neuroglial cell is found in the peripheral nervous system?

Satellite cell

The myelin sheath is composed mostly of which of the following?

lipids

Which glial cell produces and helps circulate cerebrospinal fluid?

Ependymal cells

Which term refers to the outermost layer of myelin, containing the nucleus and cytoplasm of the Schwann cell?

Neurilemma

Between the nodes of Ranvier are myelin-covered segments of axon encircled by Schwann cells. Which term refers to these segments?

Internodes

Which type of glial cells in the central nervous system fight microorganisms and destroy foreign matter and dead nervous tissue?

Microglia

True or false: Unmyelinated nerve fibers (axons) in the PNS are enveloped in Schwann cells.

True: Reason:
Although the Schwann cell's plasma membrane does not spiral repeatedly around the axon as it does when forming a myelin sheath, it does fold once around each axon to form the neurilemma.

Which statements are true about Schwann cells?

They assist in the regeneration of damaged nerve fibers.
They form the myelin sheath in the PNS.
They form the neurilemma.

Which factors influence the speed of nerve signal conduction?

Presence of myelin
Diameter of axon

What is the primary function of the myelin sheath?

To increase the speed of signal conduction in the axon

True or false: Damaged nerve fibers in the CNS regenerate very fast whereas damaged nerve fibers in the PNS never regenerate.

False; Reason:
Damaged nerve fibers in the CNS cannot regenerate at all, but since the CNS is enclosed in bone, it suffers less trauma than the PNS. Regeneration in the PNS is facilitated by Schwann cells. It may be a slow and not always perfect process.

Which term refers to the thick outermost coil of a Schwann cell?

Neurilemma

Which best describes an electrical potential?

A form of potential energy that can produce current

An axon lacking a myelin sheath is said to be \______.

unmyelinated

Which is true about a neuron with a large diameter, myelinated axon as compared to a neuron with a small diameter, unmyelinated axon?

Signal conduction will be faster

Which term refers to the flow of charged particles from one point to another?

current

Which type of glial cell aids in regeneration of damaged peripheral nerve fibers by forming a regeneration tube to help reestablish the former connection?

Schwann cells

An electrical potential is a form of what type of energy?

Potential energy

Which is most likely to be the resting membrane potential of a neuron?

-70 mV

Which of the following contributes to the development of the resting membrane potential in neurons?

K+ is more concentrated in the ICF than in the ECF.

Which best describes an electrical current?

The movement of charged particles like ions

Why is sodium more concentrated in the ECF than in the ICF of most neurons?

Sodium is actively pumped out of the cell by transporter proteins.

Which are characteristics of local potentials?

Decremental
Graded

A negative membrane potential indicates which of the following?

The inside of the membrane is negatively charged relative to the outside.

True or false: Action potentials occur only where there are voltage-gated ion channels.

true

Which term refers to the upward change in membrane potential during an action potential?

Depolarization

Which ion has the greatest influence on the resting membrane potential of most neurons?

Potassium

Match each point in the action potential to the corresponding description of voltage-gated sodium and potassium channel activity.

-Resting membrane potential matches Both types of voltage-gated channels are closed.
-Depolarization begins matches Voltage-gated Na+ channels open; voltage-gated K+ channels open more slowly
-Repolarization begins matches Voltage-gated Na+ channels inactivate; voltage-gated K+ channels remain open longer

Which of the following statements are true about sodium?

The resting plasma membrane is much less permeable to Na+ than to K+.
Na+ is about 12 times as concentrated in the ECF as in the ICF.

Which term refers to decremental changes in electrical potential along a dendrite or the soma?

Local potentials

The refractory period in which no stimulus of any strength will trigger a new action potential is the \______ refractory period.

absolute

Which are properties of action potentials?

All or none
Self-propagating
Nondecremental (signal maintains amplitude)

Place these events into the order in which they occur during a single action potential.

1. Local potential depolarizes membrane
2. Threshold reached
3. Deploration spike
4. Repolarization
5. Hyperpolarization

Which best describes signal conduction in unmyelinated axons?

A wave of depolarization opens more voltage-gated channels immediately distal to the action potential.

During which part of the action potential do most voltage-gated sodium channels open?

Depolarization

Where does saltatory conduction occur?

From node to node in myelinated fibers

Which term refers to the period of time after a nerve cell has responded to a stimulus in which it cannot be excited by a threshold stimulus?

Refractory period

True or false: Action potentials occur only where there are voltage-gated ion channels.

true

Saltatory conduction means \______.

"leaping"

This picture illustrates signal conduction along myelinated fibers. Which statements are true about this type of conduction?

Ions can be exchanged with the ECF only at the nodes of Ranvier.
There are few voltage-gated ion channels at the myelin-covered internodes and multiple channels at the nodes of Ranvier.
Action potentials occur only at the nodes of Ranvier.

At a synapse, the neuron that responds to the neurotransmitter is the \______ neuron.

postsynaptic

Which are properties of action potentials?

Nondecremental (signal maintains amplitude)
Self-propagating
All or none

In electrical synapses, electrical signals move quickly from cell to cell through which of the following?

Gap junctions

At a synapse, the neuron that releases neurotransmitter is the \______ neuron.

presynaptic

In a chemical synapse, synaptic vesicles full of neurotransmitter are docked at release sites on the membrane of the presynaptic neuron, while neurotransmitter receptors are found on the membrane of the \_________ neuron.

postsynaptic

This picture illustrates signal conduction along unmyelinated fibers. Indicate which of the following statements are true about this type of conduction.

A zone of depolarization excites voltage-gated channels immediately distal to the action potential.
Unmyelinated fibers have voltage-gated channels along their entire length.

Select the four categories of neurotransmitters based on chemical composition.

Amino acids
Monoamines
Neuropeptides
Acetylcholine

True or false: Electrical synapses are able to integrate information and make decisions more rapidly than chemical signals.

False

Which neurotransmitters are classified as amino acids?

Glutamate
GABA

In a synapse, where are synaptic vesicles located?

In the axon terminal

Which statements characterize neurotransmitters?

They are released in response to stimulation.
They bind to receptors and alter the physiology of the postsynaptic cell.
They are synthesized by presynaptic neurons.

Which group of neurotransmitters are synthesized from amino acids by removal of the -COOH group?

Monoamines

Which neurotransmitters are classified as neuropeptides?

Cholecystokinin
Endorphins

The neurotransmitters glutamate and GABA are examples of which of the following?

Amino acids

A cholinergic synapse uses which of the following as its neurotransmitter?

Acetylcholine

Which term refers to the microscopic physical gap between the presynaptic and postsynaptic neurons at a chemical synapse?

Synaptic cleft

Which neurotransmitters are classified as monoamines?

Epinephrine
Serotonin

Some neurotransmitters can have either excitatory or inhibitory effects depending on which of the following?

The type of receptors on the postsynaptic cell

At a GABA-ergic synapse, the postsynaptic receptor for the GABA neurotransmitter is which type of channel?

Chloride

Which term refers to a synapse that releases acetylcholine from the presynaptic axon terminal?

Cholinergic