Neuroscience Chapter 5 Quiz

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Questions and Answers

What is the primary role of kinesin in axoplasmic transport?

It moves substances from the cell body to the terminal buttons. (correct)

It regulates the shape of the neuron.

It generates electrical impulses within the neuron.

It moves substances from terminal buttons to the cell body.

Which part of the neuron is primarily associated with integrating signals?

Axon hillock (correct)

Terminal buttons

Dendrites

Cell nucleus

How do neurotransmitters interact with the postsynaptic neuron?

They bind to receptors and then diffuse away. (correct)

They trigger action potentials directly.

They are absorbed by the postsynaptic neuron.

They enter the postsynaptic neuron.

What is an example of retrograde axoplasmic transport?

Dynein transporting signals from the terminal buttons to the cell body. Signup and view all the answers

What structural component of the neuron contributes to its shape?

Cytoskeleton Signup and view all the answers

Which type of transport is primarily responsible for moving proteins produced in the cell body to the terminal buttons?

Anterograde transport Signup and view all the answers

What happens to dendritic spines over time?

They can change rapidly or remain stable. Signup and view all the answers

What is the function of channel proteins in the neuron's cell membrane?

To allow selective passage of certain molecules. Signup and view all the answers

What triggers the action potential in a neuron?

Threshold of excitation Signup and view all the answers

What force is responsible for the movement of molecules from regions of high concentration to low concentration?

Diffusion Signup and view all the answers

What type of ion is represented by Na+?

Cation Signup and view all the answers

Which ion is predominantly found in the extracellular fluid?

Chloride ion (Cl-) Signup and view all the answers

What balances the diffusion of potassium ions (K+) outside the axon?

Electrostatic pressure pulling K+ inside Signup and view all the answers

What is true about the A- ion in relation to the neuronal membrane?

It cannot pass through the membrane Signup and view all the answers

How does electrostatic pressure affect cations and anions in the neuron?

It attracts cations away from regions with excess cations Signup and view all the answers

Which statement correctly describes the concentration of K+ ions in the axon?

They are concentrated inside the axon Signup and view all the answers

What characterizes a bipolar neuron?

It has one dendrite and one axon. Signup and view all the answers

Which type of neuron is primarily responsible for transmitting sensory information?

Bipolar neurons Signup and view all the answers

What is a primary role of motor neurons?

To control the contraction of muscles. Signup and view all the answers

How do local interneurons differ from relay interneurons?

Local interneurons form circuits with nearby neurons. Signup and view all the answers

What structural components are essential for synapse function?

Presynaptic membrane, synaptic cleft, and postsynaptic membrane. Signup and view all the answers

What initiates the release of neurotransmitters from synaptic vesicles?

Electrical activity in the presynaptic neuron. Signup and view all the answers

What is the function of postsynaptic receptors?

To capture and react to neurotransmitters. Signup and view all the answers

Which of the following best describes multipolar interneurons?

They have no axon. Signup and view all the answers

What role do sodium-potassium pumps play in the neuron?

They maintain the concentration gradient by pumping Na+ out and K+ in. Signup and view all the answers

Which statement correctly explains the movement of Na+ ions across the neuronal membrane?

Both diffusion and electrostatic pressure push Na+ inward. Signup and view all the answers

What is a significant characteristic of voltage-dependent ion channels?

They can be opened by changes in membrane potential. Signup and view all the answers

What effect does the influx of Na+ ions have on the membrane potential during an action potential?

It leads to a rapid increase in membrane potential. Signup and view all the answers

How does the sodium-potassium pump affect the concentration of K+ ions inside the neuron?

It increases the intracellular concentration of K+ ions. Signup and view all the answers

What is the primary reason why Na+ ions are more concentrated outside the axon?

Sodium-potassium pumps actively transport Na+ ions out of the axon. Signup and view all the answers

What occurs when the membrane potential reaches the threshold of excitation?

Sodium channels open, allowing Na+ to rush into the axon. Signup and view all the answers

What percentage of a neuron's metabolic resources is used by sodium-potassium transporters?

40% Signup and view all the answers

What distinguishes action potentials from postsynaptic potentials?

Action potentials are all-or-none and not decremental. Signup and view all the answers

What is spatial summation in neural integration?

The integration of PSPs from different locations on the cell body. Signup and view all the answers

How are postsynaptic potentials terminated?

By reuptake and enzymatic deactivation. Signup and view all the answers

What is presynaptic inhibition?

Decreased neurotransmitter release due to axoaxonic synapse activity. Signup and view all the answers

Which type of synapse occurs between two terminal buttons?

Axoaxonic synapse. Signup and view all the answers

What role do gap junctions play at dendrodendritic synapses?

They facilitate electrical connections without neurotransmitter involvement. Signup and view all the answers

Which of the following describes temporal summation?

Summation of postsynaptic potentials occurring in rapid succession. Signup and view all the answers

What happens during the reuptake of neurotransmitters?

Transporter molecules remove neurotransmitters from the synaptic cleft. Signup and view all the answers

What mechanism allows for faster conduction of action potentials in myelinated axons?

Saltatory conduction Signup and view all the answers

What is the consequence of sodium channels being concentrated at the nodes of Ranvier?

Decreased energy consumption by the axon Signup and view all the answers

Which feature of cerebral neurons is NOT accounted for in the Hodgkin-Huxley model?

Active conduction of action potentials in dendrites Signup and view all the answers

What is the primary role of small synaptic vesicles in terminal buttons?

Contain molecules of a neurotransmitter Signup and view all the answers

How does myelination affect the sodium balance in an axon?

It decreases the amount of sodium that must be pumped out Signup and view all the answers

What kind of conduction do non-myelinated axons primarily utilize?

Continuous conduction Signup and view all the answers

How does the firing rate of an axon change in response to varying light intensities?

The axon fires more action potentials for brighter light Signup and view all the answers

In what way do some cerebral neurons differ from typical action potential behavior?

They may not display action potentials at all Signup and view all the answers

Study Notes

Neurons and the Nervous System

The nervous system is composed of neurons and glial cells.
Neurons are specialized cells for receiving, conducting, and transmitting electrochemical signals.
Glial cells provide support and contribute to information processing.
The neuron doctrine proposes that information is transmitted from one neuron to the next across synapses.
Neurons are 80-90 billion in the adult human brain and roughly equal numbers to glial cells.
External features of neurons include dendrites, cell body, axon, and axon terminals.

Anatomy of Neurons

Dendrites: Receive information from other neurons across synapses.
Cell body (soma): Contains the cell nucleus and processes the received information to determine if there is a need to send a signal.
Axon: A long, thin tube that leaves the cell body and serves as a conduction zone. It is covered by a myelin sheath.
Myelin sheath: Insulating substance that speeds the conduction of electrical signals.
Axon terminals (terminal buttons): Transmit signals across synapses to other cells.
Nodes of Ranvier: Gaps between sections of myelin in the axon.

Classifications of Neurons

Multipolar neuron: Many dendrites and a single axon (most common type).
Unipolar neuron: Only 1 process extending from the cell body, branching into input and output zones.
Bipolar neuron: 1 dendrite and 1 axon, common in sensory systems (e.g., vision).
Multipolar interneuron: Short axon or no axon, connecting circuits of neurons within a brain region.

Synapses

Synapses consist of a presynaptic membrane, synaptic cleft, and postsynaptic membrane.
Presynaptic membrane (axon terminal): Contains synaptic vesicles with neurotransmitters.
Synaptic cleft: A gap between presynaptic and postsynaptic neurons.
Postsynaptic membrane: Contains receptors for neurotransmitters.

Synaptic Transmission

Electrical activity in the axon causes vesicles to fuse with the presynaptic membrane and release neurotransmitters into the synaptic cleft.
Neurotransmitters bind to receptors on the postsynaptic membrane, causing changes in membrane potential.

Types of Neurotransmitters

Neurotransmitters are molecules that transmit signals across synapses. Examples are not provided.

Neuron Classifications by Function

Sensory neurons: Gather information from the environment (light, sound, touch etc).
Motor neurons: Control the contraction of muscles (facilitate movements).
Interneurons: Connect circuits of neurons in different parts of the CNS or within a region.

Action Potentials

Action potentials are bursts of rapid depolarization and hyperpolarization.
They begin at the axon initial segment and travel down the axon.
This process is all-or-none (always the same size), but rate of firing varies with the intensity of the stimulus.

Membrane Potential

Membrane potential is the difference in charge across the membrane.
Resting potential is -70 mV.
Action potentials are caused by changes in the movement of ions (sodium, potassium, chloride) across the membrane, driven by diffusion and electrostatic pressure.

Axoplasmic Transport

Anterograde transport: Movement of substances from cell body to axon terminals.
Retrograde transport: Movement of substances from axon terminals to cell body.

Glial Cells

Astrocytes are the largest glial cells. They form functional networks and control blood flow.
Microglia respond to damage and remove debris.
Oligodendrocytes myelinate axons in the CNS and Schwann cells myelinate axons in the PNS.

Neurotransmission: Direct and Indirect

Direct method: neurotransmitter directly opens ion channels.
Indirect method: neurotransmitter activates a second messenger system to open ion channels.

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Description

Test your knowledge on the intricate functions of neurons with this quiz covering axoplasmic transport, neurotransmitter interaction, and the role of ions in neuronal activity. Dive deep into the cellular components and the mechanisms that underpin signal integration and action potentials within the nervous system.