Neuroanatomy Overview

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Questions and Answers

What type of axon guidance cue triggers contact-mediated repulsion?

Eph receptors

Netrin

Semaphorins (correct)

Neurotrophic factors

Which of the following best describes the function of ephrins in axon guidance?

They do not interact with other cellular receptors.

They can trigger both attractive and repulsive signals. (correct)

They exclusively promote axon growth.

They are only involved in attracting axons.

How do chemotropic signals influence axon behavior?

By binding and activating specific receptors that alter the cytoskeleton. (correct)

By initiating apoptosis in non-target neurons.

By degrading the extracellular matrix.

By preventing synapse formation entirely.

What role does netrin play in axon guidance?

It acts as a chemoattractant for commissural axons. Signup and view all the answers

What happens when ephrins are proteolytically cleaved?

The signaling is terminated and growth is limited. Signup and view all the answers

Which receptor does the repulsive signal slit bind to during axon guidance?

Robo Signup and view all the answers

What is the consequence in the absence of neurotrophic factors for developing neurons?

They typically atrophy and may die. Signup and view all the answers

Which type of axon guidance cue is characterized as diffusible signals?

Netrin and slit Signup and view all the answers

What is the main purpose of the Whole-Cell Configuration in patch clamp techniques?

To measure currents from the entire cell for studying overall cellular properties. Signup and view all the answers

In which configuration does the pipette not disrupt the cell membrane during measurement?

Cell-Attached Configuration Signup and view all the answers

Which configuration is best suited for studying the intracellular regulation of ion channels?

Inside-Out Configuration Signup and view all the answers

What happens in the Outside-Out Configuration after isolating a patch of membrane?

The patch re-seals, exposing the extracellular side to the bath. Signup and view all the answers

Which patch clamp technique maintains the integrity of the cell membrane while measuring currents?

Perforated Patch Clamp Signup and view all the answers

What is the application of the Inside-Out Configuration during experiments?

Investigating ion channel regulation by intracellular factors. Signup and view all the answers

Which configuration utilizes suction to access the interior of the cell?

Whole-Cell Configuration Signup and view all the answers

What type of currents does the Cell-Attached Configuration specifically measure?

Currents through individual ion channels still embedded in the membrane. Signup and view all the answers

What is the primary reason for the negative resting membrane potential in neurons?

The efflux of potassium ions (K⁺) Signup and view all the answers

How is the intensity of a stimulus encoded by neurons?

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

What occurs when the membrane depolarizes to a certain threshold?

An action potential is generated Signup and view all the answers

Why do larger currents not produce larger action potentials?

Because action potentials follow an all-or-nothing principle Signup and view all the answers

What primarily creates ion concentration differences across the membrane?

Active transport by ion transporters Signup and view all the answers

Which ion's movement is most responsible for the resting membrane potential?

Potassium ions (K⁺) Signup and view all the answers

What leads to hyperpolarization of a cell's membrane potential?

Potassium ions exiting the cell Signup and view all the answers

What would cause the inside of a neuron to become more positive?

Increased Na⁺ influx Signup and view all the answers

What characterizes a chemical synapse compared to a faster synapse?

Greater synaptic plasticity Signup and view all the answers

Which sequence correctly describes the process of neurotransmitter release at the synapse?

Opening of calcium channels, release of NT, activation of postsynaptic receptors Signup and view all the answers

What role does synaptotagmin play in neurotransmitter release?

It binds calcium to initiate vesicle fusion Signup and view all the answers

What is a characteristic of short-term synaptic plasticity?

It is based on presynaptic changes and lasts for milliseconds to minutes Signup and view all the answers

What primarily causes facilitation in synaptic transmission?

Accumulation of calcium ions in the presynaptic terminal Signup and view all the answers

Which term describes long-term changes that strengthen synapses based on repeated activity?

Long-term potentiation Signup and view all the answers

What is the primary difference between small neurotransmitter vesicles and large dense-cored vesicles?

Size and content type Signup and view all the answers

What is the initial condition required for NMDA receptors to be activated?

Depolarization of the postsynaptic neuron Signup and view all the answers

What process primarily underlies learning and memory in the context of synaptic changes?

Long-term plasticity Signup and view all the answers

What is the role of calcium influx in the postsynaptic neuron during LTP?

It activates signaling pathways that strengthen synapses Signup and view all the answers

Which of the following is a consequence of long-term potentiation (LTP)?

Stronger synaptic responses from the same glutamate release Signup and view all the answers

What is a unique feature of LTP with regard to different synapses?

It occurs only in the pathway receiving high-frequency stimulation Signup and view all the answers

How does associativity play a role in LTP?

It allows weakly stimulated synapses to undergo LTP under certain conditions Signup and view all the answers

What structural change occurs in the postsynaptic neuron during LTP?

Formation of new dendritic spines Signup and view all the answers

What is the general importance of LTP in the brain?

It serves as a mechanism for information storage Signup and view all the answers

What happens to NMDA receptors during the baseline communication phase?

They are blocked by magnesium ions Signup and view all the answers

What initiates the wave of depolarization in an axon?

The influx of Na⁺ ions Signup and view all the answers

What is the primary purpose of the refractory period during action potential propagation?

To prevent the action potential from moving backward Signup and view all the answers

In myelinated axons, how does saltatory conduction affect action potential propagation?

It causes the action potential to jump between nodes Signup and view all the answers

What occurs during passive current flow in response to depolarization?

Local depolarization spreads to adjacent axon regions Signup and view all the answers

Active current flow is crucial for which of the following reasons?

It actively regenerates the action potential in response to depolarization Signup and view all the answers

How is a neurotransmitter synthesized after it has been used?

Enzymes synthesized in the soma convert it back to its precursor Signup and view all the answers

What role do calcium channels play during transmitter release?

They allow for the influx of calcium ions that trigger neurotransmitter release Signup and view all the answers

Which class of neurotransmitter is commonly located in vesicles within the axon?

Small molecule neurotransmitters Signup and view all the answers

Study Notes

Neuroanatomy

Be able to describe the nervous system's macroscopic anatomy, including major core areas and pathways.
Sagital Section: Shows brain structures including corpus callosum, telencephalon, diencephalon (thalamus & hypothalamus), brain stem, spinal cord, gyrus precentralis (motor functions), gyrus postcentralis (sensory functions), and cerebellum.
Brain Lobes: Frontal lobe, parietal lobe, occipital lobe, and temporal lobe.
Basal Ganglia: Structures within the brain, including the nucleus caudatus, putamen, and globus pallidus, crucial for motor control.
Limbic System: A set of brain structures involved in emotion and memory. This system comprises the amygdala, hippocampus, and cingulate gyrus
Brain Stem: Consists of the mesencephalon, pons, and medulla oblongata. Plays roles in autonomic functions.
Reticular Formation: A diffuse network of neurons in the brainstem involved, in consciousness and motor functions
Spinal Cord: Connects the brain to the rest of the body and plays a role in both sensory and motor functions.
Meninges: Protective membranes surrounding the brain and spinal cord. The layers are dura mater, arachnoid, and pia mater.

Blood Supply and Fluid Circulation

The internal carotid artery and vertebral arteries supply blood to the brain.
Cerebrospinal fluid circulates through ventricles in the brain and flows into the subarachnoid space.

Principles of Axon Growth and Synapse Formation

Neurons grow through a cell body, axon, and growth cone guided by chemical signals.
Attractive and repulsive cues influence growth cone movement and thus axon development and connections.

Types of Axon Guidance Cues

Contact-mediated repulsion: Repulsion due to direct contact between cells. Examples include semaphorins and plexins
Contact-mediated attraction: Attraction due to direct contact between cells. Examples include ephrins and Eph receptors
Chemoattraction: Attraction due to diffusible chemical signals. Example includes netrin.
Chemorepulsion: Repulsion due to diffusible chemical signals. Example includes slit.

Cellular Neurobiology

Trophic factors: Necessary for survival of neurons.

Function and Importance of Glial Cells and Neurons

Neurons: Transmit information throughout the body. Cell body, dendrites, and axons
Types: Bipolar, unipolar, pseudounipolar, multipolar.
Glial Cells: Support and protect neurons. Main types include Astrocytes, Oligodendrocytes, and Microglia

Passive Properties of Nerve Cells

Properties of Passive Current Flow: Fast, decays with distance, and depends on the length constant (λ) and time constant (τ).
Passive current: The movement of ions within the cytoplasm in response to local depolarization.
Cable theory: Describes how current flow spreads passively through the dendrite.

Active Properties of Nerve Cells and Ion Channels

Ion Channels: Specialized proteins that allow ions to pass through the cell membrane. Types include Na+ channels, K+ channels and gated channels.
Action potentials: Active electrochemical signaling that propagate along the axon. Threshold (-55 mV), Depolarization (+30 mV), Repolarization, and After-hyperpolarization are key stages.

Pharmacological Separation of Na+ and K+ Currents

Sodium-potassium pump: Maintains the resting membrane potential by pumping 3 sodium ions out and 2 potassium ions in.
Leak channels: Allow sodium and potassium to leak across the cell membrane.

Refractory Periods

Absolute refractory period: When the neuron cannot fire another action potential immediately after firing the current one.
Relative refractory period: A stronger-than-normal stimulus, is required to generate another action potential.

Synaptic Plasticity

Synaptic strength facilitation: Increases the synaptic strength of repetitive stimulation.
Synaptic depression: Decreases the synaptic strength with repetitive stimulation.

Types of Postsynaptic Receptors and Signal Transduction Mechanisms

Neurotransmitter release: Action potentials lead to calcium influx and the fusion of synaptic vesicles with the presynaptic membrane.
Ionotropic receptors: Ligand-gated ion channels that open/close directly in response to neurotransmitter binding. Example includes GABA and nAch receptors
Metabotropic receptors: G protein-coupled receptors that initiate a cascade of intracellular signaling events to affect later ion channels. Example includes glutamate and muscarinic ACh receptors

Storage of Neurotransmitters (NTs)

Small molecule neurotransmitters stored in small vesicles
Large molecule neurotransmitters are stored in large dense-core vesicles

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Description

Explore the macroscopic anatomy of the nervous system with a focus on brain structures, major areas, and neural pathways. This quiz covers essential components such as the brain lobes, basal ganglia, limbic system, brain stem, and spinal cord.