Neuroanatomy Overview

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Questions and Answers

What does the Nernst equation predict?

The maximum voltage a neuron can achieve

The resistance of the neuron membrane

The equilibrium potential for each individual ion (correct)

The resting membrane potential based on multiple ions

Which equation is primarily used to calculate the resting membrane potential?

Nernst Equation

Ampere's Law

Goldman-Hodgkin-Katz (GHK) Equation (correct)

Ohm's Law

What factor determines how far an electrical signal can travel along a neuron before decaying?

Membrane potential

Space constant (λ) (correct)

Resting potential

Electrochemical gradient

What does the membrane time constant (τ) represent?

Time taken to charge the membrane to 63% of maximum voltage Signup and view all the answers

What influences whether multiple electrical signals result in an action potential?

The decay time of each postsynaptic potential (PSP) Signup and view all the answers

What does a long time constant (τ) indicate about postsynaptic potentials (PSPs)?

PSPs decay slowly and allow better temporal summation Signup and view all the answers

Which artery supplies blood to the anterior part of the brain?

a.cerebri anterior Signup and view all the answers

How is the time constant (τ) calculated?

Resistance multiplied by capacitance Signup and view all the answers

Which of the following elements is NOT considered in the Goldman-Hodgkin-Katz (GHK) Equation?

Membrane capacitance Signup and view all the answers

What is the primary role of the growth cone in a developing neuron?

To guide the direction of axon growth Signup and view all the answers

What cerebrospinal fluid pathway occurs after it flows from the lateral ventricles?

It enters the fourth ventricle Signup and view all the answers

What is contained within the ventricles of the brain?

Cerebrospinal fluid Signup and view all the answers

Which structures are responsible for the dynamic movement of the growth cone?

Filopodia Signup and view all the answers

What effects do attractive cues have on the growth cone?

They promote assembly in the direction of the cue Signup and view all the answers

How does repulsive signaling affect a growth cone?

It induces cytoskeletal disassembly Signup and view all the answers

Which of the following arteries is primarily responsible for supplying the posterior part of the brain?

a.cerebri posterior Signup and view all the answers

What is a characteristic of chemical synapses?

Minimal plasticity Signup and view all the answers

Which type of vesicles release neurotransmitters in response to high-frequency stimulation?

Large Dense-cored Vesicles (LDV) Signup and view all the answers

What role does calcium play in neurotransmitter release?

It binds to synaptotagmin to facilitate membrane fusion. Signup and view all the answers

What initiates the depolarization of a neuron?

Influx of Na⁺ ions Signup and view all the answers

What defines long-term plasticity in synaptic connections?

Alterations lasting more than hours due to pre and postsynaptic changes Signup and view all the answers

What is the primary effect of presynaptic facilitation?

Increased release of neurotransmitters Signup and view all the answers

During which phase do voltage-gated Na⁺ channels inactivate?

Repolarization Signup and view all the answers

Which protein complex is responsible for the fusion of synaptic vesicles with the plasma membrane?

SNARE complex Signup and view all the answers

What is the membrane potential at the threshold point for action potential generation?

-55 mV Signup and view all the answers

What occurs during the absolute refractory period?

Voltage-gated Na⁺ channels are inactivated. Signup and view all the answers

What is the consequence of synaptic depression?

Decreased neurotransmitter release due to lack of primed vesicles Signup and view all the answers

Which receptors are primarily involved in long-term potentiation (LTP) within the hippocampus?

AMPA and NMDA receptors Signup and view all the answers

Why does the membrane potential briefly become more negative than resting potential?

K⁺ channels are slow to close Signup and view all the answers

What is the main purpose of the refractory periods in action potentials?

To control the frequency of action potentials Signup and view all the answers

During which phase is a stronger-than-normal stimulus required to generate another action potential?

Relative refractory period Signup and view all the answers

What mechanism helps restore the resting membrane potential after hyperpolarization?

Activity of the sodium-potassium pump Signup and view all the answers

What is the primary function of oligodendrocytes in the CNS?

Produce myelin Signup and view all the answers

How do action potentials differ from receptor potentials?

Action potentials can travel over long distances Signup and view all the answers

What role do microglia play in the CNS?

They regulate synaptic pruning Signup and view all the answers

What factors influence the amplitude of synaptic potentials?

The strength of the synaptic connections Signup and view all the answers

What is the primary difference between excitatory and inhibitory synaptic potentials?

Inhibitory potentials move the membrane potential further away from threshold Signup and view all the answers

What is the role of nodes of Ranvier in neuronal function?

Enhance the propagation of action potentials Signup and view all the answers

What type of cells interact bidirectionally with oligodendrocyte precursor cells?

Oligodendrocytes and microglia Signup and view all the answers

What is the significance of dynamic regulation of myelin production?

To fine-tune neural circuit functionality Signup and view all the answers

What initially activates the postsynaptic neuron when glutamate is released by the presynaptic neuron?

Only AMPA receptors Signup and view all the answers

What triggers the removal of the magnesium block on NMDA receptors?

Simultaneous high activity in both presynaptic and postsynaptic neurons Signup and view all the answers

After LTP has occurred, what is the effect on postsynaptic responses?

Increases response to the same amount of glutamate Signup and view all the answers

What role does calcium play in the process of LTP?

It activates signaling pathways for synaptic changes Signup and view all the answers

What is the concept of associativity in the context of LTP?

Weakly stimulated synapses can undergo LTP if active simultaneously with strong stimulation Signup and view all the answers

What structural change occurs in the postsynaptic neuron as a result of calcium signaling during LTP?

Insertion of more AMPA receptors Signup and view all the answers

How does LTP contribute to learning and memory?

It strengthens the likelihood of future synaptic firing Signup and view all the answers

Which statement accurately describes the effect of tetanus on synaptic pathways?

Only the tetanized pathway experiences LTP 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.
The brain is divided into sections, such as the telencephalon, diencephalon, brain stem, and spinal cord.
The corpus callosum is a large bundle of nerve fibers connecting the two hemispheres of the brain.
The thalamus is a major relay center for sensory information, with the hypothalamus regulating homeostasis.
The brain stem controls basic life functions and relays information between the brain and spinal cord.
The spinal cord is a major pathway for sensory and motor information.
Different regions of the brain have specific functions, such as gyrus precentralis for motor functions, and gyrus postcentralis for sensory functions.
Broca's area (in the frontal lobe) and Wernicke's area (in the temporal lobe) are crucial for language processing.
There are association areas in the brain that integrate information from different sensory modalities.
The cerebellum plays a role in coordination, balance and motor control.
The basal ganglia are involved in motor control, posture and coordination.
The limbic system is involved in emotion and memory.

Cerebral Cortex - Division into Lobes

The cerebral cortex is divided into four lobes: frontal, parietal, temporal, and occipital.
The frontal lobe is located at the front of the brain and is involved in higher-level cognitive functions such as planning, decision-making, and voluntary movements.
The parietal lobe is located behind the frontal lobe and is involved in processing sensory information from the body, including touch, temperature, and pain.
The temporal lobe is located on the sides of the brain and is involved in processing auditory information and language.
The occipital lobe is located at the back of the brain and is involved in processing visual information.

The Basal Ganglia

The basal ganglia is a group of subcortical nuclei that play a critical role in motor control, habit learning, and procedural memory.
Major components of the basal ganglia include the caudate nucleus, putamen, and globus pallidus.
The basal ganglia are involved in the initiation and execution of movement, as well as the control of posture and muscle tone.
The basal ganglia work by sending signals through circuits to the thalamus and the cortex.

The Anatomy of Emotions

The limbic system plays a vital role in emotion and memory.
Amygdala, hippocampus, and hypothalamus are key structures involved.

The Brainstem

The brainstem consists of the midbrain, pons, and medulla oblongata.
The brainstem is responsible for regulating essential bodily functions.
It serves as a vital relay station for sensory and motor signals.

The Reticular Formation

The reticular formation is a network of neurons within the brainstem, influencing consciousness and alertness.
It has ascending and descending pathways that impact various functions.
The ascending part is associated with awareness and wakefulness, the descending part with motor control.

The Spinal Cord

The spinal cord serves as a communication pathway between the brain and the peripheral nervous system.
It contains sensory and motor neurons.
White and gray matter are present.
Contains tracts that relay information, either sensory or motor.

The Meninges

There are three layers: Dura mater, Arachnoid mater, and Pia mater.
The meninges protect the brain and spinal cord.
The ventricles are fluid-filled cavities and are apart of the ventricular system.
The ventricular system contains cerebrospinal fluid (CSF) that cushions and protects the brain.

Axon Growth and Synapse Formation

Axon growth is guided by attractive and repulsive cues.
Axon guidance is mediated by different molecules, including those that bind to receptors.
The growth cone changes its shape to respond to signals.
The cytoskeleton remodels to adjust to signals in different directions.

Types of Axon Guidance Cues

Contact-mediated and diffusible cues guide the growth cone in a specific direction.
Sempahorins bind to plexins and cause repulsion.
Ephrins bind to Eph receptors to either attract or repel growth.
Neurtins bind to DCC receptors to cause attraction.
Slit binds to Robo receptors leading to repulsion.

Types of Neurons

Bipolar neurons (two extensions), unipolar neurons (one extension), and multipolar neurons (multiple extensions).
Unipolar and pseudounipolar neurons are common in peripheral sensory systems.
Motor neurons are a common example of multipolar neurons.

Glial Cells

Glial cells maintain homeostasis in the nervous system.
Astrocytes support neurons metabolically and maintain the chemical environment.
Microglia are immune cells that help defend against pathogens.
Oligodendrocytes and Schwann cells produce myelin sheaths.

Passive Properties of Nerve Cells

Passive properties of nerve cells are due to the cell's membrane structure.
They include properties like capacitance, resistance and membrane time constant.
Signal passively spreads along the membrane to the next channels.
Spatial summation is an effect of passive channels

Active Properties of Nerve Cells and Ion Channels

Ion channels determine the flow of ions in the cell to make it more or less passive.
Non-gated channels are always open and maintain resting potential.
Gated channels in the membrane open in response to stimuli affecting the neuron's membrane potential. These channels include voltage-gated, ligand-gated, mechanically-gated and other types.

Steps of an Action Potential

Membrane depolarization happens as sodium channels open, which increases the inside positivity.
A stimulus reaches the threshold potential, which starts an action potential.
During depolarization, voltage-gated sodium channels open and sodium ions rush into the neuron, increasing in positivity.
Repolarization happens when sodium channels close and potassium channels open allowing potassium ions to rush out.
Afterhyperpolarization occurs when potassium continues to leave the neuron.
The sodium-potassium pump restores the original resting potential.

Refractory Periods

Absolute refractory period: Neuron cannot fire another action potential.
Relative refractory period: Neuron can fire another action potential, but it needs a stronger stimulus.

Synaptic Transmission

Action potential depolarizes the axon terminal.
Voltage-gated calcium channels open.
Calcium influx triggers neurotransmitter release.
Neurotransmitters diffuse across the synaptic cleft.
Neurotransmitters bind to receptors on the postsynaptic neuron or other neurons to generate synaptic potential.

Synaptic Plasticity

Short-term plasticity: Includes modifications in release, such as facilitation and depression.
Long-term plasticity: synaptic changes that can influence synaptic strength, and include important neural mechanisms like LTP.

Neurotransmitters

Small molecule transmitters (acetylcholine, amino acids, biogenic amines, purines)
Peptide transmitters (endorphins, substance P, somatostatin)

Postsynaptic Receptors

The binding of a neurotransmitter to a receptor triggers ion channels to open or close.
Ligand-gated ion channels alter the membrane potential directly.
G protein-coupled receptors (GPCRs) initiate a cascade of intracellular signaling events.

Signal Transduction in Postsynaptic Receptors

Different postsynaptic receptors generate different types of signals that trigger different intracellular responses.
Ligand gated channels are directly connected to ion channels modifying the membrane voltage.
G-protein coupled receptors (GPCRs) use a second messenger system that triggers a cascade of changes to modify ion currents or other intracellular processes.

Types of Postsynaptic Receptors

Ionotropic receptors (ligand-gated ion channels): Fast and direct effects, like generating EPSPs or IPSPs directly.
Metabotropic receptors (GPCRs): Slower and more complex effects, which can cause a cascade of intracellular signaling events.

Chemical Synapse Mechanisms

Action potential arrives at the axon terminal.
Calcium channels open, and calcium enters the terminal.
Neurotransmitter vesicles fuse with the membrane and release neurotransmitters into the synaptic cleft.
Neurotransmitters bind to receptors on the postsynaptic membrane.
Postsynaptic response occurs.
Neurotransmitters are removed from the cleft.

Neural Recording Techniques

Techniques like patch clamp and intracellular recording allow researchers to measure ion channel activity and membrane potential.
Patch-clamp technique measures currents flowing through ion channels or cells.
Techniques allow for an in-depth investigation of the electrical and other properties of cells.

Advantages of Patch Clamp

Provides high resolution to study single channel activity.
Enables detailed investigation of ionic channels.
Allows study of specific ion channels and their behavior.
Allows study of channel activity from living cells more reliably.

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Description

This quiz explores the macroscopic anatomy of the nervous system, detailing major sections such as the telencephalon, diencephalon, brain stem, and spinal cord. It also covers critical functions of specific brain regions and their roles in sensory and motor processing. Test your knowledge on the anatomical pathways and functional areas of the brain.