Untitled Quiz

Questions and Answers

The all-or-none phenomenon as applied to nerve conduction states that the whole nerve cell must be stimulated for conduction to take place.

False

Reflexes are rapid, automatic responses to stimuli.

True

Efferent nerve fibers may be described as motor nerve fibers.

True

Cell bodies of sensory neurons may be located in ganglia lying outside the central nervous system.

True Signup and view all the answers

Myelination of the nerve fibers in the central nervous system is the job of the oligodendrocyte.

True Signup and view all the answers

During depolarization, the inside of the neuron's membrane becomes less negative.

True Signup and view all the answers

Neurons in the CNS are organized into functional groups.

True Signup and view all the answers

Strong stimuli cause the amplitude of action potentials generated to increase.

False Signup and view all the answers

The oligodendrocytes can myelinate several axons.

True Signup and view all the answers

Enkephalins and endorphins are peptides that act like morphine.

True Signup and view all the answers

In myelinated axons, the voltage-regulated sodium channels are concentrated at the nodes of Ranvier.

True Signup and view all the answers

A postsynaptic potential is a graded potential that is the result of a neurotransmitter released into the synapse between two neurons.

True Signup and view all the answers

Large-diameter nerve fibers conduct impulses much faster than small-diameter fibers.

True Signup and view all the answers

The nodes of Ranvier are found only on myelinated, peripheral neuron processes.

False Signup and view all the answers

Unipolar neurons have axons structurally divided into peripheral and central processes.

True Signup and view all the answers

A stimulus traveling toward a synapse appears to open calcium ion channels at the presynaptic end, which in turn promotes fusion of synaptic vesicles to the axonal membrane.

True Signup and view all the answers

If bacteria invaded the CNS tissue, microglia would migrate to the area to engulf and destroy them.

True Signup and view all the answers

The overlapping functions of the nervous system are sensory input, integration, and motor output.

True Signup and view all the answers

The autonomic nervous system is under voluntary control; whereas, the somatic nervous system is involuntary.

False Signup and view all the answers

Axon diameter and degree of myelination determine nerve impulse conduction velocity.

True Signup and view all the answers

The action potential is caused by permeability changes in the plasma membrane.

True Signup and view all the answers

Some neurotransmitters can be either excitatory or inhibitory depending upon the receptor.

True Signup and view all the answers

Which of the following is not a function of astrocytes?

Provide the defense for the CNS Signup and view all the answers

Which of the choices below describes the ANS?

Motor fibers that conduct nerve impulses from the CNS to smooth muscle, cardiac muscle, and glands Signup and view all the answers

What are ciliated CNS neuroglia that play an active role in moving the cerebrospinal fluid called?

Ependymal cells Signup and view all the answers

What does the central nervous system use to determine the strength of a stimulus?

Frequency of action potentials Signup and view all the answers

Bipolar neurons are commonly ______.

Found in the retina of the eye Signup and view all the answers

Which of the following is an excitatory neurotransmitter secreted by motor neurons innervating skeletal muscle?

Acetylcholine Signup and view all the answers

Which of the following describes the nervous system integrative function?

Analyzes sensory information, stores information, makes decisions Signup and view all the answers

The period after an initial stimulus when a neuron is not sensitive to another stimulus is the ______.

Absolute refractory period Signup and view all the answers

Which of the following is not characteristic of neurons?

They are mitotic. Signup and view all the answers

The part of a neuron that conducts impulses away from its cell body is called a(n) ______.

Axon Signup and view all the answers

Which ion channel opens in response to a change in membrane potential and participates in the generation and conduction of action potentials?

Voltage-gated channel Signup and view all the answers

An impulse from one nerve cell is communicated to another nerve cell via the ______.

Synapse Signup and view all the answers

What is the role of acetylcholinesterase?

Destroy ACh a brief period after its release by the axon endings Signup and view all the answers

Which of the following is not a function of the autonomic nervous system?

Innervation of skeletal muscle Signup and view all the answers

Collections of nerve cell bodies outside the central nervous system are called ______.

Ganglia Signup and view all the answers

The term central nervous system refers to the ______.

Brain and spinal cord Signup and view all the answers

The substance released at axon terminals to propagate a nervous impulse is called a(n) ______.

Neurotransmitter Signup and view all the answers

A neuron that has as its primary function the job of connecting other neurons is called a(n) ______.

Association neuron Signup and view all the answers

Saltatory conduction is made possible by ______.

The myelin sheath Signup and view all the answers

Which of the following is not a chemical class of neurotransmitters?

Nucleic acid Signup and view all the answers

Which of the following is false or incorrect?

A nerve impulse occurs if the excitatory and inhibitory effects are equal. Signup and view all the answers

Select the correct statement regarding synapses.

The synaptic cleft prevents an impulse from being transmitted directly from one neuron to another. Signup and view all the answers

Which of the following correctly describes a graded potential?

Amplitude of various sizes Signup and view all the answers

Neuroglia that control the chemical environment around neurons by buffering potassium and recapturing neurotransmitters are ______.

Astrocytes Signup and view all the answers

Schwann cells are functionally similar to ______.

Oligodendrocytes Signup and view all the answers

Immediately after an action potential has peaked, which cellular gates open?

Potassium Signup and view all the answers

Nerve cell adhesion molecules (N-CAMs) ______.

Are crucial for the development of neural connections Signup and view all the answers

An inhibitory postsynaptic potential (IPSP) is associated with ______.

Hyperpolarization Signup and view all the answers

Which of the following will occur when an excitatory postsynaptic potential (EPSP) is being generated on the dendritic membrane?

A single type of channel will open, permitting simultaneous flow of sodium and potassium. Signup and view all the answers

When a sensory neuron is excited by some form of energy, the resulting graded potential is called a(n) ______.

Generator potential Signup and view all the answers

Which of the following is not true of graded potentials?

They increase amplitude as they move away from the stimulus point. Signup and view all the answers

Which of the following is true about the movement of ions across excitable living membranes?

Sodium gates in the membrane can open in response to electrical potential changes. Signup and view all the answers

A second nerve impulse cannot be generated until ______.

The membrane potential has been reestablished Signup and view all the answers

In what way does the interior surface of a cell membrane of a resting (nonconducting) neuron differ from the external environment?

Negatively charged and contains less sodium Signup and view all the answers

If a motor neuron in the body were stimulated by an electrode placed about midpoint along the length of the axon ______.

The impulse would spread bidirectionally Signup and view all the answers

Which of the following neurotransmitters inhibits pain and is mimicked by morphine, heroin, and methadone?

Endorphin Signup and view all the answers

Which of the following describes the excitatory postsynaptic potential?

Short distance depolarization Signup and view all the answers

That part of the nervous system that is voluntary and conducts impulses from the CNS to the skeletal muscles is the ______ nervous system.

somatic Signup and view all the answers

Neuroglia found in the CNS that bind axons and blood vessels to each other are called ______.

astrocytes Signup and view all the answers

A chemical messenger that does not directly cause ESPSs or IPSPs but does affect the strength of synaptic transmission is a ______.

neuromodulator Signup and view all the answers

The synapse more common in embryonic nervous tissue than in adults is the ______.

electrical synapse Signup and view all the answers

When information is delivered within the CNS simultaneously by different parts of the neural pathway, the process is called ______ processing.

parallel Signup and view all the answers

Potentials that are short-lived, local changes in membrane potential that can be either depolarized or hyperpolarized are called ______ potentials.

graded Signup and view all the answers

When one or more presynaptic neurons fire in rapid order it produces a much greater depolarization of the postsynaptic membrane than would result from a single EPSP; this event is called ______ summation.

temporal Signup and view all the answers

Study Notes

Nervous System Function and Structure

All-or-none phenomenon: Not required for nerve cell conduction; partial stimulation can still lead to conduction.
Reflexes: Rapid, automatic responses to stimuli crucial for quick reactions.
Efferent nerve fibers: Described as motor fibers, they transmit signals away from the CNS.
Sensory neuron cell bodies: Often located in ganglia outside the central nervous system, aiding sensory processing.
Oligodendrocytes: Responsible for myelination of nerve fibers in the central nervous system, enhancing signal conduction.

Action Potentials and Membrane Dynamics

Depolarization: Inside of a neuron's membrane becomes less negative, critical for action potentials.
Action potential amplitude: Remains constant; stronger stimuli do not increase amplitude but can increase frequency.
Voltage-regulated sodium channels: Concentrated at nodes of Ranvier, facilitating rapid signal transmission in myelinated axons.

Neurotransmitters and Synapses

Enkephalins and endorphins: Peptides that act like morphine, modulating pain and emotions.
Synaptic communication: Impulses from one neuron to another occur across synapses, utilizing neurotransmitters.
Inhibitory and excitatory signals: Some neurotransmitters can function either way, depending on the receptor.

Nerve Conduction and Impulse Generation

Large-diameter fibers: Conduct impulses faster than small-diameter fibers due to reduced resistance.
Saltatory conduction: Made possible by the myelin sheath, allowing for leapfrogging of action potentials between nodes.

Neuroglia and Cellular Support

Astrocytes: Play a key role in maintaining chemical homeostasis and support for neurons.
Microglia: Act as immune responders in the CNS, migrating to engulf pathogens.

Types of Neurons and Their Functions

Unipolar neurons: Have axons divided into peripheral and central processes, commonly found in sensory pathways.
Association neurons: Connect other neurons, facilitating complex reflexes and cognitive processing.

Neural Integration and Signal Processing

Integrative function: Involves analyzing sensory information, storing it, and making decisions based on stimuli input.
Graded potentials: Local changes in membrane potential that vary in amplitude and can be depolarized or hyperpolarized.

Other Key Concepts

Absolute refractory period: Period after an action potential where a neuron cannot respond to another stimulus.
Calcium ion channels: Open at the presynaptic end during the arrival of an impulse, promoting synaptic vesicle release.
Sodium channels: Open in response to changes in membrane potential, aiding in action potential generation.
Neuromodulators: Chemicals that affect synaptic transmission strength without directly causing postsynaptic potentials.
Temporarily summation: Occurs when multiple presynaptic signals enhance postsynaptic depolarization effectively.

Common Misconceptions

Involuntary vs. voluntary: The autonomic nervous system is involuntary, while the somatic nervous system is under voluntary control.
Neurons and mitosis: Neurons do not undergo mitosis, preserving their structural integrity for long-term functions.

Neurotransmitter Types and Characteristics

Acetylcholine: An excitatory neurotransmitter, critical for muscle contraction.
Electrical synapses: More prevalent during embryonic development, facilitating rapid communication.

Recognizing Neural Structures

Ganglia: Collections of nerve cell bodies outside of the CNS, essential for peripheral processing.
CNS Components: Includes the brain and spinal cord, which serve as the primary control centers for the nervous system.

Summary of Nerve Types

Bipolar neurons: Found in the retina of the eye, crucial for transmitting visual information.

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