Neuroscience Chapter 12 Flashcards

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Questions and Answers

Label the figure with the items provided.

Labeling items

Label the different types of neuronal pools in the figure.

Labeling neuronal pools

Label the glial cells of the CNS.

Labeling glial cells

Identify the functional classification of the neurons in the figure, based on the direction the nerve impulse is traveling relative to the CNS.

Functional classification of neurons Signup and view all the answers

Identify the components of a typical neuron.

Components of a neuron Signup and view all the answers

Label the features of a myelinated axon.

Labeling myelinated axon features Signup and view all the answers

Label the structures that establish and maintain the resting membrane potential in neurons.

Structures for resting membrane potential Signup and view all the answers

Link the definitions to the correct action potential periods.

Refractory period = A time when there is a decrease in the sensitivity of the plasma membrane to further stimulation. Absolute refractory period = The time when there is complete insensitivity of the plasma membrane to another stimulus. Relative refractory period = The time when a stronger-than-threshold stimulus is needed to initiate another action potential. Signup and view all the answers

Label the parts of the typical myelinated neuron.

Labeling parts of myelinated neuron Signup and view all the answers

Normally, sodium and potassium leakage channels differ because ___________________.

sodium ions diffuse through leakage channels into the cell, but potassium ions diffuse through leakage channels out of the cell. Signup and view all the answers

Graded potentials are produced within the _______________________ segment of a neuron.

receptive Signup and view all the answers

Graded potentials result from the opening of ________________.

ligand-gated channels Signup and view all the answers

An inhibitory postsynaptic potential results from the opening of____________________.

potassium and/or chloride channels Signup and view all the answers

Identify (click on) the appropriate graph which represents an excitatory postsynaptic potential.

Graph for excitatory postsynaptic potential Signup and view all the answers

Indicate the summative effect that brings the initial segment closest to threshold.

Two EPSPs in proximity to each other Signup and view all the answers

Reducing the time between signals sent from the same presynaptic terminal increases the strength of the graded potential. This is an example of ________________ summation.

temporal Signup and view all the answers

Substances that cause facilitation of a neuron ____________________________.

cause the neuron to fire that may not fire under the same circumstances in the absence of the facilitator. Signup and view all the answers

Assume in a laboratory you were able to isolate a neuron and remove the Acetylcholine receptors from the postsynaptic membrane. The substance _________________ would no longer cause facilitation of this neuron.

nicotine Signup and view all the answers

If two synapses fired simultaneously, which synaptic combination brings the initial segment closest to threshold based on spatial summation? Click on the appropriate synapses.

Proper synaptic combination Signup and view all the answers

When voltage-gated sodium channels are open, sodium flows _ the neuron making the inside of the cell more ___.

into; positive Signup and view all the answers

The following information best describes the _____________ phase of an action potential: A membrane potential reading of +10 mV, Inactivated voltage-gated sodium channels, Open voltage-gated potassium channels.

repolarization Signup and view all the answers

Label each phase of the action potential as identified by the highlighted region of each graph.

Labeling phases of action potential Signup and view all the answers

Action potentials occur ____________________________.

in the unmyelinated regions of an axon. Signup and view all the answers

Demyelinating diseases cause a(n) ______________ in the conduction velocity of action potentials.

decrease Signup and view all the answers

If demyelination occurs, why don't action potentials occur at regions of the axon that were previously myelinated?

These regions lack the appropriate concentration of voltage-gated sodium channels. Signup and view all the answers

At the synaptic knob, voltage-gated ______________ channels open, thereby stimulating the synaptic vesicles to release their neurotransmitters by exocytosis.

calcium Signup and view all the answers

If acetylcholinesterase became mutated and nonfunctional, what would be the immediate result?

acetylcholine would build up in the synaptic cleft. Signup and view all the answers

If a drug was developed that interfered with the proper functioning of the microtubules found within the axons of neurons, how would you expect this to impact axonal transport processes?

Both anterograde and retrograde transport processes would cease. Signup and view all the answers

The enzyme choline acetyltransferase catalyzes the reaction between acetyl-CoA and choline, resulting in the formation of the neurotransmitter acetylcholine. What direction describes the axonal transport route taken by this virus?

Retrograde transport Signup and view all the answers

Indicate the direction of axonal transport by aligning the proper label with each arrow.

Direction of axonal transport Signup and view all the answers

Depolarization of a cell membrane occurs because

more sodium ions diffuse into the cell than potassium ions diffuse out of it. Signup and view all the answers

Depolarization is initiated by a stimulus that makes the membrane potential

more positive. Signup and view all the answers

Activation gates in the cell membrane for voltage-gated sodium ion channels open into the

extracellular fluid. Signup and view all the answers

At resting membrane potential, voltage-gated potassium ion channels are open.

False Signup and view all the answers

The cell membrane immediately adjacent to an action potential depolarizes because of

local currents. Signup and view all the answers

What is produced when depolarization of a cell membrane reaches threshold?

a new action potential is produced. Signup and view all the answers

The absolute refractory period assures that action potential propagation is

only in one direction. Signup and view all the answers

The inside of the cell membrane becomes negative at the time of an action potential.

False Signup and view all the answers

If neurotransmitter from Neuron A causes Neuron B to hyperpolarize, this is an example of an

inhibitory postsynaptic potential. Signup and view all the answers

Scorpion agitoxin is a neurotoxin that blocks the activity of voltage-gated potassium channels. In the presence of agitoxin, which will occur during an action potential?

The neuron will remain depolarized and unable to repolarize. Signup and view all the answers

Nerve growth factors that stimulate outgrowth of severed axons are secreted by

neurolemmocytes. Signup and view all the answers

Which part of a neuron contains calcium pumps and channels?

synaptic bulbs. Signup and view all the answers

The _ nervous system transmits information from receptors to the CNS, while the _ nervous system transmits information from the CNS to the rest of the body.

sensory; motor. Signup and view all the answers

What type of neuronal circuit caused this single reaction from the multiple stimuli you experienced?

converging circuit. Signup and view all the answers

What type of cells produce the myelin sheath in the central nervous system (CNS)?

oligodendrocytes. Signup and view all the answers

When threshold is reached, depolarization occurs with the same amplitude of potential change. This is known as

the all-or-none principle. Signup and view all the answers

The _______ is a period when a membrane cannot respond to another stimulus (no matter how strong).

absolute refractory period. Signup and view all the answers

What is the correct order for the events of neurotransmitter release from the synaptic terminal?

1 = Exocytosis of neurotransmitter into synaptic cleft 2 = Extracellular Ca2+ enters terminal and binds to sensor protein in the cytoplasm 3 = Action potential reaches axon terminal 4 = Ca2+-protein complex stimulates fusion of the docked synaptic vesicle with the plasma membrane 5 = Voltage-gated Ca2+ channels open Signup and view all the answers

The fundamental physiological properties that enable nerve cells to communicate with other cells are

all of these choices are correct. Signup and view all the answers

Pain receptors in the skin send signals to the CNS for processing. These pain receptors are an example of ____________ neurons.

afferent. Signup and view all the answers

Neurons that carry signals from the CNS to skeletal muscle for contraction would be classified as _____________ neurons.

efferent. Signup and view all the answers

When a neurotransmitter binds a protein channel, it opens and lets sodium diffuse down its concentration gradient. This is an example of a

chemically gated sodium channel. Signup and view all the answers

When sodium enters the neuron via chemically gated sodium channels, the membrane will depolarize. Therefore, the membrane potential will become more

positive. Signup and view all the answers

On a graph of an action potential, the small depolarizations that lead to threshold are from

excitatory postsynaptic potentials (EPSPs). Signup and view all the answers

If extracellular calcium was absent, which would likely be true?

Vesicles containing neurotransmitter would not merge with the plasma membrane. Signup and view all the answers

An excitatory postsynaptic potential (EPSP) causes

the postsynaptic neuron's membrane potential to become more positive. Signup and view all the answers

An inhibitory postsynaptic potential (IPSP)

will make it more difficult for the postsynaptic neuron to reach threshold. Signup and view all the answers

An axon with a large diameter transmits an impulse ____ than an axon with a smaller diameter.

faster. Signup and view all the answers

Which of the following characteristics of action potentials can vary?

the frequency of action potentials. Signup and view all the answers

Neuronal pools are composed of

interneurons. Signup and view all the answers

Ependymal cells help produce

cerebrospinal fluid. Signup and view all the answers

Which glial cell acts as a phagocyte?

microglial cell. Signup and view all the answers

Which glial cell is starlike in shape and helps form the blood-brain barrier?

astrocytes. Signup and view all the answers

Neurolemmocytes produce myelin in the _____ nervous system.

peripheral. Signup and view all the answers

The symptoms of MS can come and go. This is because

the oligodendrocytes are constantly renewing the myelin sheathes, so they are able to temporarily repair some of the damage. Signup and view all the answers

Triggers of acute episodes of MS include

all listed choices. Signup and view all the answers

Most researchers believe MS results from a combination of genetic and environmental factors. One peculiar observation regarding the environment is the fact that the incidence increases as one gets further from the equator.

True Signup and view all the answers

Study Notes

Neuron Structure and Function

Neurons are composed of various components such as dendrites, axons, and synaptic knobs.
Myelinated axons have specialized features allowing for faster impulse propagation due to saltatory conduction.
Glial cells in the CNS include astrocytes, oligodendrocytes, microglial cells, and ependymal cells, each serving unique roles such as forming the blood-brain barrier and producing cerebrospinal fluid.

Action Potential and Membrane Potential

Action potentials are all-or-none events; they reach a consistent amplitude once the threshold is reached.
Depolarization occurs when sodium ions flow into the neuron, making the membrane potential more positive.
The absolute refractory period ensures that action potentials propagate in one direction and prevents immediate repeating signals.

Graded Potentials and Synaptic Transmission

Graded potentials occur at the receptive segments and result from the opening of ligand-gated channels, varying in amplitude and duration.
Excitatory postsynaptic potentials (EPSPs) make the membrane potential more positive, while inhibitory postsynaptic potentials (IPSPs) make it harder to reach the threshold.
The interaction of multiple synapses can lead to summation effects; temporal summation increases potential strength by sending signals more frequently.

Neurotransmitter Release and Action

The release of neurotransmitters involves calcium channels opening, allowing calcium ions to enter the synaptic knob, triggering exocytosis of vesicles containing neurotransmitters.
Acetylcholinesterase breaks down acetylcholine, preventing excessive stimulation of postsynaptic neurons.
Disorders affecting microtubules can disrupt axonal transport, affecting neuronal function and neurotransmitter release.

Ion Channels and Membrane Dynamics

Voltage-gated sodium channels open when the neuron is depolarized; sodium influx amplifies the membrane potential change.
Potassium channels play a role in repolarization during the action potential after peak depolarization.
A resting membrane potential of -70 mV indicates a negative interior compared to the exterior, maintained by leakage channels for sodium and potassium.

Neuronal Circuits and Classification

Neurons can be classified based on the direction of impulses: afferent neurons transmit signals to the CNS, while efferent neurons carry signals away from the CNS.
Converging circuits process multiple inputs to produce a singular output response, such as reflex actions.

Pathophysiology and Myelin

Myelin is essential for efficient nerve impulse transmission, produced by oligodendrocytes in the CNS and neurolemmocytes in the peripheral nervous system.
Conditions like Multiple Sclerosis arise from loss of myelin, related to environmental factors impacting disease presentation.
Scorpion agitoxin blocks potassium channels, disrupting repolarization and preventing normal action potential cycling.

Additional Important Concepts

Large diameter axons transmit impulses faster due to less resistance to ion flow.
The frequency of action potentials can vary depending on the stimulus strength rather than the action potential's peak amplitude.
Neuronal pools consist of interneurons, facilitating communication within the nervous system.

Studying That Suits You

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Description

Test your knowledge of neuroscience concepts with these flashcards from Chapter 12. You'll label various figures related to neuronal pools, glial cells, and functional classifications of neurons. Ideal for students seeking to deepen their understanding of the central nervous system.