Nervous System Quiz
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Questions and Answers

What is the primary role of satellite cells within the peripheral nervous system (PNS)?

  • Synthesizing neurotransmitters for synaptic communication.
  • Forming the myelin sheath around axons for insulation.
  • Physically supporting the cell bodies of neurons. (correct)
  • Conducting action potentials to transmit signals.

What does the term 'membrane potential' refer to in the context of neurophysiology?

  • The difference in charge between the inside and outside of a neuron's cell membrane. (correct)
  • The physical thickness of the neuron's cell membrane.
  • The total number of ions present inside a neuron.
  • The rate at which action potentials propagate along an axon.

What is the typical resting membrane potential of a neuron, and what does the negative sign indicate?

  • -90 mV, indicating a very negative charge outside the membrane.
  • +70 mV, indicating a higher positive charge inside the membrane.
  • -70 mV, indicating a higher negative charge inside the membrane. (correct)
  • 0 mV, indicating no charge difference across the membrane.

Which of the following ionic distributions is characteristic of a neuron at rest?

<p>High concentration of Na+ outside the cell, high concentration of K+ inside the cell. (B)</p> Signup and view all the answers

How does the sodium-potassium pump contribute to maintaining the resting membrane potential?

<p>By transporting three sodium ions out of the cell for every two potassium ions into the cell. (C)</p> Signup and view all the answers

What distinguishes leakage channels in the neuron cell membrane from gated ion channels?

<p>Leakage channels are always open, allowing passive ion diffusion, while gated channels open or close in response to specific stimuli. (C)</p> Signup and view all the answers

What triggers mechanically-gated ion channels to open or close?

<p>Physical stimuli such as pressure, vibration, or stretching. (C)</p> Signup and view all the answers

Why is the sodium-potassium pump considered an 'electrogenic' pump?

<p>It helps to produce and maintain resting membrane potential by transporting unequal amounts of ions, creating a charge difference. (B)</p> Signup and view all the answers

What is the primary component contributing to the gray appearance of the gray matter in the spinal cord?

<p>Dark nuclei found within the cell bodies of neurons. (B)</p> Signup and view all the answers

Which of the following accurately describes the relationship between the meninges and the spinal cord, moving from the innermost to the outermost layer?

<p>Pia mater, arachnoid, dura mater. (D)</p> Signup and view all the answers

What is the primary function of the pia mater in relation to the spinal cord?

<p>To supply oxygen and nutrients to the spinal cord tissue. (D)</p> Signup and view all the answers

The epidural space is located between which two structures?

<p>Dura mater and vertebral foramen. (B)</p> Signup and view all the answers

A patient is diagnosed with a condition affecting the anterior gray horn of their spinal cord. Which of the following functions is MOST likely to be impaired?

<p>Motor control of skeletal muscles. (D)</p> Signup and view all the answers

Which of the following best describes the arrangement of spinal nerves in relation to the spinal cord?

<p>31 pairs of spinal nerves connect to the cord via dorsal and ventral roots. (B)</p> Signup and view all the answers

Cerebrospinal fluid (CSF) is found in which of the following spaces associated with the spinal cord?

<p>Subarachnoid space. (B)</p> Signup and view all the answers

A deep indentation observed on the anterior surface of the spinal cord would be the:

<p>Anterior median fissure. (C)</p> Signup and view all the answers

Which of the following scenarios accurately describes the effect of an inhibitory neurotransmitter on a postsynaptic neuron's membrane potential?

<p>Opening $K^+$ or $Cl^-$ gated channels, leading to hyperpolarization. (B)</p> Signup and view all the answers

A neuron releases a neurotransmitter that binds to receptors on a postsynaptic cell, resulting in an EPSP. Which ion channel is most likely to be directly affected by this neurotransmitter?

<p>Sodium ($Na^+$) channels (B)</p> Signup and view all the answers

A researcher is studying a synapse where the neurotransmitter consistently causes an EPSP in the postsynaptic neuron. Which of the following neurotransmitters is most likely being used at this synapse?

<p>Glutamate (C)</p> Signup and view all the answers

Which of the following neurotransmitters is known to be inhibitory in some synapses and excitatory in others, depending on the receptor subtypes present on the postsynaptic neuron?

<p>Acetylcholine (A)</p> Signup and view all the answers

Several EPSPs occur at a postsynaptic neuron, but the membrane potential only reaches -50mV. What prevents the membrane potential from reaching the threshold?

<p>The individual EPSPs are not strong enough to depolarize the membrane to threshold. (C)</p> Signup and view all the answers

A drug selectively blocks the reuptake of GABA from the synaptic cleft. What is the most likely effect of this drug on the postsynaptic neuron?

<p>Increased inhibition due to prolonged GABA presence. (C)</p> Signup and view all the answers

A researcher discovers a new gasotransmitter that causes depolarization of the postsynaptic membrane. Which of the following mechanisms is the most likely explanation for this effect?

<p>Opening of $Na^+$ channels. (C)</p> Signup and view all the answers

What distinguishes biogenic amines from amino acid neurotransmitters?

<p>Biogenic amines are modified amino acids, while amino acid neurotransmitters are used directly. (B)</p> Signup and view all the answers

During the depolarization phase of an action potential, what is the state of the sodium-potassium (Na/K) pumps and the ion channels?

<p>Na/K pumps are off, Na+ gated channels are open, K+ gated channels are closed. (C)</p> Signup and view all the answers

Which event primarily characterizes the repolarization phase of an action potential?

<p>Efflux of potassium ions ($K^+$) out of the cell. (D)</p> Signup and view all the answers

What best describes the state of a neuron at rest?

<p>Sodium ($Na^+$) and potassium ($K^+$) gated ion channels are closed and the Na/K pumps are operating. (B)</p> Signup and view all the answers

During the absolute refractory period, why is it impossible for a new action potential to be initiated?

<p>Sodium channels ($Na^+$) are inactivated, preventing further depolarization. (B)</p> Signup and view all the answers

What defines the relative refractory period?

<p>Only a stimulus stronger than usual can trigger a new action potential. (C)</p> Signup and view all the answers

How do the absolute and relative refractory periods differ in terms of the stimulus required to initiate a new action potential?

<p>The absolute refractory period cannot be triggered by any stimulus, while the relative refractory period requires a suprathreshold stimulus. (B)</p> Signup and view all the answers

An experimental drug completely blocks potassium channels ($K^+$) in a neuron. How would this affect the action potential?

<p>The repolarization phase would be significantly prolonged or absent. (C)</p> Signup and view all the answers

If a neuron is stimulated during its relative refractory period, what change in ion channel activity is most likely to occur?

<p>Reopening of sodium channels ($Na^+$). (A)</p> Signup and view all the answers

Which of the following accurately describes the sequence of events in a reflex arc?

<p>Stimulus → Receptor → Control center → Motor neuron → Effector (C)</p> Signup and view all the answers

During a medical examination, a doctor taps the patellar tendon to elicit the knee-jerk reflex. What is the primary purpose of this reflex?

<p>To evaluate the integrity of the spinal cord and associated nerves. (C)</p> Signup and view all the answers

If a person steps on a sharp object, the flexor reflex causes them to withdraw their foot. What is the immediate purpose of the crossed extensor reflex in this situation?

<p>To maintain balance by extending the opposite limb. (B)</p> Signup and view all the answers

Which of the following scenarios best illustrates the tendon reflex?

<p>A weightlifter drops a heavy weight, relaxing their muscles to prevent tendon damage. (A)</p> Signup and view all the answers

If the medulla oblongata were damaged, which of the following functions would be most immediately compromised?

<p>Regulation of heartbeat and breathing (B)</p> Signup and view all the answers

What is the primary function of the pons in the context of neural communication?

<p>Linking the spinal cord with the brain and different parts of the brain (D)</p> Signup and view all the answers

A patient has suffered damage to their vasomotor center. Which of the following symptoms would you expect to observe?

<p>Inability to regulate blood pressure effectively (D)</p> Signup and view all the answers

Which of the following reflexes are controlled by the brain rather than the spinal cord?

<p>Cranial reflexes (A)</p> Signup and view all the answers

Which of the following best describes the primary function of the reticular activating system (RAS)?

<p>Alerting the cerebral cortex to sensory signals, thereby influencing wakefulness and consciousness. (B)</p> Signup and view all the answers

Damage to the cerebellum would most likely result in:

<p>Difficulty in maintaining balance and coordinating movements. (D)</p> Signup and view all the answers

Which of the following functions is NOT directly associated with the hypothalamus?

<p>Relaying sensory information, except for smell, to the cerebral cortex. (A)</p> Signup and view all the answers

What would be the impact of a lesion in the pneumotaxic area of the pons?

<p>Impaired control of respiration. (D)</p> Signup and view all the answers

Which structure serves as a crucial link between the endocrine system and nervous system?

<p>Hypothalamus (A)</p> Signup and view all the answers

A patient reports a complete loss of sensation on their left side. Which area of the brain is most likely affected, assuming a typical neurological presentation?

<p>Right cerebral hemisphere (C)</p> Signup and view all the answers

If a person is having difficulty interpreting pain and temperature sensations, which area of the diencephalon is MOST likely involved?

<p>Thalamus (D)</p> Signup and view all the answers

What is the primary function of the midbrain?

<p>Regulation of auditory and visual reflexes. (A)</p> Signup and view all the answers

Flashcards

Satellite cells

Cells in the PNS that support neuron cell bodies physically.

Membrane potential

The charge difference (in mV) across a neuron's membrane.

Resting membrane potential

The charge difference when a neuron is not firing, typically -70 mV.

Resting ion distribution

Ionic concentrations of Na+, K+, and POPs in a resting neuron.

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Sodium-potassium pump

A protein pump that moves Na+ out and K+ into the cell using ATP.

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Leakage channels

Channels allowing passive diffusion of Na+ and K+ ions through the membrane.

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Gated ion channels

Channels that open or close in response to specific stimuli.

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Mechanically-gated channels

Gated channels that respond to physical pressure or stretching.

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Action Potential

A rapid change in membrane potential that propagates along a neuron.

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Depolarization

The phase where Na+ ions enter the cell, leading to a positive membrane potential change.

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Repolarization

The phase where K+ ions exit the cell, restoring the negative membrane potential.

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Absolute Refractory Period

The interval where a new action potential cannot be initiated, no matter the stimulus strength.

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Relative Refractory Period

The interval where only a strong stimulus can trigger a new action potential.

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Na+ Gated Ion Channels

Channels that open during depolarization, allowing sodium ions to enter the neuron.

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K+ Gated Ion Channels

Channels that open during repolarization, allowing potassium ions to exit the neuron.

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Neurotransmitters

Chemical messengers that transmit signals across synapses between neurons.

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Excitatory neurotransmitters

Neurotransmitters that increase the likelihood of an action potential by raising membrane potential.

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Inhibitory neurotransmitters

Neurotransmitters that decrease the likelihood of an action potential by lowering membrane potential.

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Amino acids (neurotransmitters)

A class of neurotransmitters including glutamate and GABA that can be excitatory or inhibitory.

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Excitatory Postsynaptic Potential (EPSP)

A slight increase in postsynaptic neuron membrane potential caused by excitatory neurotransmitters.

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Postsynaptic neuron

Neuron receiving signals across the synapse, affected by neurotransmitter release.

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Facilitation

The effect of EPSPs in making it easier for a postsynaptic neuron to reach threshold and fire an action potential.

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Biogenic amines

Modified amino acids that act as neurotransmitters, can be excitatory or inhibitory depending on the synapse.

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Gray Matter

A butterfly-shaped region in the spinal cord with cell bodies and dark nuclei.

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Anterior Gray Horn

Part of gray matter containing cell bodies of somatic motor neurons.

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Lateral Gray Horn

Region of gray matter with cell bodies of preganglionic sympathetic neurons.

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Posterior Gray Horn

Contains cell bodies of association neurons in the gray matter.

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Central Canal

A narrow passage through the spinal cord containing cerebrospinal fluid (CSF).

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Pia Mater

The delicate innermost layer of connective tissue covering the spinal cord.

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Dura Mater

The tough outer layer of membranes surrounding the spinal cord.

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Epidural Space

The space between the dura mater and the vertebrae, filled with adipose tissue.

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Control Center

The part of the CNS that receives action potentials from receptors and sends them to motor neurons.

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Motor Neuron

A neuron that carries action potentials from the CNS to an effector.

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Effector

The structure that carries out the response to a stimulus, usually muscles or glands.

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Spinal Reflex

A reflex with the spinal cord as the control center.

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Stretch Reflex

A reflex where stretching a muscle causes it to contract.

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Flexor Reflex

A withdrawal response from pain, involving flexing of the body part.

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Medulla Oblongata

The part of the brainstem responsible for vital functions like heartbeat and breathing.

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Pons

Connects the spinal cord to the brain and relays signals between brain regions.

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Midbrain

Connects the pons to the diencephalon and regulates auditory and visual reflexes.

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Reticular Formation

A network of gray matter in the brainstem involved in muscle tone and consciousness.

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Cerebellum

The 'little brain' that coordinates skeletal muscle contractions and balance.

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Thalamus

Relay station for all sensory impulses (except smell) to the cerebral cortex.

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Hypothalamus

Regulates homeostasis, autonomic nervous system, and endocrine functions.

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Cerebrum

Largest brain part, divided into right and left hemispheres, involved in complex functions.

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Reticular Activating System (RAS)

Sensory portion of the reticular formation, responsible for alertness and consciousness.

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Study Notes

Nervous System Introduction

  • The nervous system is one of two systems responsible for maintaining homeostasis in the body. The other is the endocrine system.
  • Homeostasis is maintained through electrical communication between neurons and other body cells through action potentials.
  • Nervous system activity is categorized into three types:
  • Sensory activities: detect stimuli, send signals to the brain or spinal cord (sensory/afferent neurons).
  • Motor activities: send signals from the brain/spinal cord to effectors, which create responses (motor/efferent neurons).
  • Integrative activities: connect sensory and motor neurons and involve analysis and decision-making (association/interneurons neurons).

Parts of the Nervous System

  • Nerves: bundles of sensory and motor neurons.
  • Ganglia: bundles of neuron cell bodies in the PNS
  • Nuclei: bundles of neuron cell bodies in the CNS

Divisions of the Nervous System

  • The autonomic nervous system controls involuntary functions.
  • The sympathetic division activates the "fight or flight" response (increases heart rate, blood pressure, breathing rate, and blood glucose levels).
  • The parasympathetic division activates the "feed and breed" response (decreases stress preparation and stimulates digestive and reproductive systems).
  • The somatic nervous system is responsible for voluntary movements and receives sensory input from the skin, muscles, and special sense organs.

Neuron Structure and Function

  • Neurons are long-lived, high-metabolic cells requiring a constant supply of oxygen and glucose.
  • The function of a neuron is to generate and conduct electrical signals, called action potentials.
  • Neurons consist of:
  • Dendrites: short, branched processes that receive signals.
  • Cell body (soma): contains the nucleus and organelles.
  • Axon: a long, slender process that transmits signals away from the cell body.
  • Axon hillock: cone-shaped region where the axon originates from the cell body.
  • Axon terminal (axon collateral): branches at the distal end.
  • Synaptic end bulbs (synaptic boutons): the rounded structures at the terminals containing neurotransmitters
  • Myelin sheath: insulates some axons, increasing signal conduction speed
  • Neuroglia: support, nourish, protect neurons in the CNS and PNS.
  • Types of Neuroglia in the CNS include: Astrocytes, Oligodendrocytes, Microglia, and Ependymal cells.
  • Types of Neuroglia in the PNS include: neurolemmocytes (Schwann cells) and satellite cells

Neurophysiology

  • Membrane potential: difference in electrical charge across a neuron's cell membrane.
  • Resting membrane potential: electrical charge difference when the neuron is not transmitting signals (typically -70mV).
  • Ion distribution: the relative amounts and locations of ions (sodium, potassium, and proteins) across the membrane.
  • Sodium-potassium pump: actively transports sodium out and potassium in.
  • Gated ion channels: open or close in response to certain stimuli (mechanically gated, chemically gated, voltage gated, light-gated).
  • Action potential: a sequence of rapid changes in membrane potential (depolarization, repolarization, possible hyperpolarization).
  • Depolarization: membrane potential moves toward zero
  • Repolarization: membrane potential returns to resting potential.
  • Hyperpolarization: membrane potential moves away from zero (more negative than resting value).
  • Refractory periods: time intervals where another action potential cannot be initiated immediately.
  • Absolute refractory period: no new action potential is possible.
  • Relative refractory period: only a stronger stimulus can trigger a new action potential.

Synapses and Neurotransmitters

  • Synapse: junction between two excitable cells allowing the transmission of information.
  • Chemical synapse: slower than electrical synapses, uses neurotransmitters to transmit signals.
  • Neurotransmitters: chemical messengers that transmit information across synapses between cells (neurons or muscle cells).
  • EPSPs (excitatory postsynaptic potentials): increase the likelihood of an action potential.
  • IPSPs (inhibitory postsynaptic potentials): decrease the likelihood of an action potential.
  • Neurotransmitter classes: amino acids (glutamate, aspartate, GABA, glycine), biogenic amines (norepinephrine, epinephrine, dopamine, serotonin, acetylcholine), gases (nitric oxide, carbon monoxide).

Reflexes

  • Reflex: an automatic response to a stimulus.
  • Reflex arc components: sensory receptor, sensory neuron, control center, motor neuron, effector.
  • Spinal reflexes: control centers in the spinal cord.
  • Cranial reflexes: control centers in the brain.

The Human Brain

  • The brain consists of the brainstem, cerebellum, diencephalon, and cerebrum.
  • Brainstem: medulla oblongata, pons, midbrain, reticular formation.
  • Cerebellum: coordination of skeletal muscle movement, balance and posture.
  • Diencephalon: thalamus (sensory relay station), hypothalamus (maintains homeostasis).
  • Cerebrum: four lobes (frontal, parietal, occipital, temporal). Sensory and motor areas, association areas.
  • Cerebrospinal fluid (CSF): protects the brain and spinal cord, circulates within the meninges.
  • Blood-brain barrier (BBB): regulates the passage of substances between the blood and the cerebrospinal fluid, protecting the brain from toxins.

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Test your understanding of the nervous system, covering satellite cells, membrane potential, ion channels, and spinal cord anatomy. Questions focus on neuron physiology and structure. Evaluate your knowledge of neurobiology.

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