HW 11: Overview of Nervous System

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

Axon terminals

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

Axonal transport

Axon collateral

Branch that originates from an axon

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

Central and peripheral nervous systems

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

Cholinergic

Axoplasm

Cytoplasm of the axon

The soma of a neuron gives rise to branch-like processes called what? They are the primary sites for receiving signals from other neurons.

Dendrites

List the fundamental physiological properties of neurons.

Excitability, conductivity, secretion

This picture illustrates neural transmission at which type of synapse?

Excitatory cholinergic synapse

Satellite cells

In the PNS; surround somas of neurons in ganglia, provide electrical insulation, and regulate the chemical environment of neurons

Choose all that are names for the cell body of a neuron.

Neurosoma, Soma

Stimulation of the postsynaptic neuron will end when nerve signals stop arriving at the presynaptic axon terminal or when which of the following occurs?

Neurotransmitter is removed from postsynaptic receptors.

Which glial cell insulates nerve fibers from extracellular fluids and speeds up signal conduction in the brain?

Oligodendrocyte

Which type of glial cell is indicated by the arrow labeled A?

Oligodendrocytes

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

Peripheral nervous system

Axolemma

Plasma membrane of the axon

Neural integration is based on the combining together of which of the following?

Postsynaptic potentials

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

Potassium

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

Potential energy

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

Schwann cell

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

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

Secretion

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

True

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

True

Which lists the structural categories of neurons?

Unipolar, bipolar, anaxonic, and multipolar

An axon lacking a myelin sheath is said to be what?

Unmyelinated

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

Visceral motor

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

absolute

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

central, peripheral

Which process of a neuron is specialized for rapid conduction of nerve signals to structures relatively far away from the neuron cell body?

Axon

Schwann cells

In the PNS; form neurilemma around all PNS fibers and myelin around most of them; aid in regeneration of damaged nerve fibers.

Which best describes an electrical potential?

A form of potential energy that can produce current

Choose all of the following statements that are true about signal conduction along unmyelinated fibers.

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

Choose all the ways neuromodulators alter synaptic transmission.

- Altering the breakdown and/or reuptake of neurotransmitter - Adjusting the sensitivity of postsynaptic neurons to neurotransmitters - Increasing the release of neurotransmitters by presynaptic neurons

Choose all that would cause postsynaptic stimulation to end.

- Cessation of signals in the presynaptic nerve fiber - Reuptake of neurotransmitter into the presynaptic knob - Enzymatic degradation of neurotransmitter in the synaptic cleft - Diffusion of neurotransmitter from the synaptic cleft into extracellular fluid

Choose all that are characteristics of local potentials.

- Decremental - Graded

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

- Ependymal cells - Oligodendrocytes - Astrocytes - Microglia

Which correctly describe axonal transport?

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

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

- Nervous system - Endocrine system

Choose all that are properties of action potentials.

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

Choose all the factors that influence the speed of nerve signal conduction.

- Presence of myelin - Diameter of axon

Choose the three functional classes of neurons.

- Sensory neurons - Motor neurons - Interneurons

Choose all statements that are true about Schwann cells?

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

Choose all statements that are true regarding postsynaptic potentials?

- They include EPSPs and IPSPs. - They are changes in the membrane potential of the postsynaptic terminal of a chemical synapse. - They are caused by neurotransmitters.

Starting with a signal reaching the distal end of the presynaptic axon, indicate the correct order of events that occur during transmission at a cholinergic excitatory synapse.

1. Opening of calcium gates in synaptic knob as nerve signal arrives 2. Exocytosis of ACh; diffusion across synaptic cleft 3. Binding of ACh to receptors on postsynaptic neuron 4. Opening of sodium gates on post-synaptic membrane allowing influx of sodium 5. Depolarization of postsynaptic plasma membrane

What is the approximate ratio of glial cells to neurons?

10:1

Axon hillock

A mound located on one side of the soma from which the axon originates

Which best describes signal conduction in unmyelinated axons?

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

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

Acetylcholine

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

False

True or false: The more synapses a neuron has, the lesser its information-processing capability.

False

______ cells protect the neurons and help them function.

Glial

Ependymal cells

In the CNS; line cavities of the brain and spinal cord; secrete and circulate CSF

Microglia

In the CNS; phagocytize microorganisms, foreign matter, and dead nervous tissue

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.

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

Lipids

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

Local potentials

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

Multipolar

The picture shows the most common structural type of neuron. It contains one axon and multiple dendrites, and it is classified as what type of neuron.

Multipolar

Which term describes the ability of neurons to process information, store and recall it, and make decisions?

Neural integration

Which alter synaptic transmission by adjusting the sensitivity of postsynaptic neurons to neurotransmitters or by affecting the breakdown and/or removal of a neurotransmitter?

Neuromodulators

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

Neurons

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

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

Somatic and visceral

Which division inhibits digestion?

Sympathetic

At its distal end, an axon has an extensive complex of fine branches called what?

Terminal arborization

The processes of a neuron that usually receive signals from other neurons are called _____.

dendrites

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

dendrites

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 myelin sheath is a spiral layer of ______ around a nerve fiber.

insulation

The refractory period in which it is possible to trigger a new action potential, but only with an unusually strong stimulus is the ______ refractory period.

relative

The neurons indicated by a letter "A" are structurally classified as ______ neurons. The neurons indicated by a letter "B" are structurally classified as ______ neurons.

multipolar, bipolar

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

oligodendrocytes

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

postsynaptic

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

presynaptic