Smart Book Assignment Extra Credit chapter 12

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

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

1. Information received by sensory receptors is transmitted to the CNS. 2. Information is processed and an appropriate response is determined. 3. A command is issued to effectors such as muscles or glands.

What is the approximate ratio of glial cells to neurons?

10:1

Which best describes an electrical potential?

A form of potential energy that can produce current

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

Select all that are categories of neurotransmitters based on chemical composition.

Acetylcholine Monoamines Amino acids Neuropeptides

Choose all the ways neuromodulators alter synaptic transmission.

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

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

Axon

Name the area of the neuron indicated by the arrow labeled A.

Axon collateral

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

Tetanic stimulation at a synapse is due to accumulation of which of the following in the synaptic terminal?

Calcium

Sensory (afferent) neurons do which of the following?

Carry signals to spinal cord and brain

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

Which fundamental physiological property of neurons allows them to send signals quickly over long distances?

Conductivity

Choose all that are types of long-term memory?

Declarative Procedural

Choose all that are characteristics of local potentials.

Decremental Graded

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

Dendrites

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

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

Endocrine system Nervous system

Long-term potentiation may be involved in long-term memory. Choose all of the following that are molecular changes that occur in long-term potentiation.

Entrance of calcium into the dendrite Binding of glutamate to NMDA receptors The release of nitric oxide which triggers more glutamate release

Choose all that would cause postsynaptic stimulation to end.

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

This picture illustrates neural transmission at which type of synapse?

Excitatory cholinergic synapse

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

False

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

False

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

Gap junctions

______ cells protect the neurons and help them function.

Glial

Short-term memory allows you to remember things for up to how long?

Hours

Which type of memory is important as you read (e.g. remembering the previous words in a sentence)?

Immediate

In a synapse, where are synaptic vesicles located?

In the axon terminal

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 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

Which type of memory can store the most information?

Long-term

Declarative and procedural memory are two types of what?

Long-term memory

Which may be the basis for learning and long-term memory at the neuronal level?

Long-term potentiation

The ability of synapses to change is called synaptic plasticity. Which term refers to the neuronal pathways formed during learning?

Memory traces

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

Multipolar

The neuron has a rounded cell body and a short axon. The dendrites are branched like a tree with fine endings labeled, dendritic spines. Two multipolar neurons are shown with two types of dendrites and axon terminals.

Multipolar

The pathway of neurons within a neural pool is called its what?

Neural circuit

This picture illustrates that when a stimulus strength (weight) and stretch increase at a sensory fiber, the firing frequency of the neurons increase. Which term refers to the conversion of stimulus information into a meaningful pattern of action potentials?

Neural coding

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

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.

Choose all that are properties of action potentials.

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

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

Oligodendrocytes

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

Oligodendrocytes Ependymal cells Astrocytes Microglia

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

Peripheral nervous system

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

Synapses in a certain pathway can be modified to allow signals to travel more easily across "trained" synapses. Which term refers to the process of making transmission easier?

Potentiation

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

Presence of myelin Diameter of axon

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

Immediate memory, which is the ability to hold something in mind for a few seconds, might be based on activity in which type of neural circuit?

Reverberating

Choose all that are the principal types of neural circuits.

Reverberating circuit Converging circuit Parallel after-discharge circuit Diverging circuit

Which neuroglial cell is found in the peripheral nervous system?

Satellite cell

Identify the type of cell indicated by the arrow labeled A.

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

Afferent neurons are what type of neurons?

Sensory

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

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

Soma Neurosoma

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

Somatic and visceral

Membrane potential ranges from negative 80 to 40 and time are plotted on an increasing scale. The curve starts at negative 70 millivolts and rises in a wave-like pattern to 55 millivolts. The wave-like patterns represent stimuli. After that, the curve rises steeply to 30 millivolts and falls steeply (Action potential) to negative 55 millivolts and further below 70 millivolts before it levels out finally at negative 70 millivolts. A horizontal line starting at negative 70 millivolts is labeled, resting membrane potential and a horizontal line starting at negative 55 millivolts are labeled, threshold.

Summation

Which division inhibits digestion?

Sympathetic

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

Synaptic cleft

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

Terminal arborization

What type of stimulation is caused by rapid, repetitive signals arriving at a synaptic knob, causing progressively larger quantities of calcium to accumulate and leading to synaptic facilitation?

Tetanic

Choose all the statements that 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.

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 that are characteristics of neural pools.

They consist of complex patterns of interneurons. They may be concerned with a particular body function.

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.

Why would the synapses of a memory trace undergo synaptic potentiation?

To allow easier signal transmission along pathway

What is the role of neural pools in the CNS?

To process information

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

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

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

How long can long-term memory last?

Up to a lifetime

Looking up a new phone number and then dialing it from memory utilizes which type of memory?

Working memory

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

The nervous system must interpret quantitative and qualitative information about its environment, thus it converts information to a meaningful pattern of action potentials. This process is called neural

coding

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 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

Synapses are not fixed for life. In response to experience, they can be modified to make transmission easier or harder. The ability of synapses to change is called synaptic

plasticity

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

There are two ways in which EPSPs can add up to produce enough activity to make a postsynaptic cell fire. They are temporal and spatial

summation

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