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Questions and Answers

What is the primary function of dendrites in a neuron?

  • To insulate the axons and increase impulse speed
  • To propagate electrical impulses to the axon terminal
  • To create synaptic contacts with effector cells
  • To receive information from other neurons (correct)
  • Which part of the neuron is responsible for generating the nerve impulse?

  • Myelin sheath
  • Axon terminal
  • Dendrites
  • Cell body (soma) (correct)
  • What role does the myelin sheath play in neuron function?

  • It speeds up the transmission of electrical impulses (correct)
  • It stores neurotransmitters
  • It generates electrical impulses
  • It transmits signals to other neurons
  • Where are synaptic contacts made in a neuron?

    <p>Axon terminal</p> Signup and view all the answers

    What defines the cluster of neuron axons in the nervous system?

    <p>Nerves</p> Signup and view all the answers

    In the context of neuron functionality, what does the term 'integration' refer to?

    <p>To produce a single output response from multiple inputs</p> Signup and view all the answers

    What is the primary chemical agent released at the axon terminal?

    <p>Neurotransmitter</p> Signup and view all the answers

    Which of the following statements is true regarding electrical impulses in neurons?

    <p>They propagate from the cell body to the axon terminal</p> Signup and view all the answers

    What type of sensory function detects changes in muscle stretch?

    <p>Stretch receptors</p> Signup and view all the answers

    In a simple reflex arc, what is the role of the interneuron?

    <p>To connect sensory and motor neurons</p> Signup and view all the answers

    What is the primary function of a sensory receptor in the reflex arc?

    <p>To detect environmental changes</p> Signup and view all the answers

    Which of the following is a characteristic of the stretch reflex?

    <p>It causes a muscle contraction in response to stretching</p> Signup and view all the answers

    What symptom is associated with damage to the spinal nerve at L4?

    <p>Absence of stretch reflexes</p> Signup and view all the answers

    How does reflex testing provide diagnostic information about neuronal damage?

    <p>It helps locate lesions in the spinal cord or brain.</p> Signup and view all the answers

    Which condition reflects hyperactive reflexes as a symptom?

    <p>Compressive injury to the upper motor neuron</p> Signup and view all the answers

    What is indicated by flaccid paralysis in the leg?

    <p>Damage to the spinal nerve</p> Signup and view all the answers

    What initiates the action potentials in a simple reflex response?

    <p>The sensory receptor detecting a stimulus</p> Signup and view all the answers

    In a clinical case, what would be a common reason for referred pain?

    <p>Corresponding sensory nerves being activated</p> Signup and view all the answers

    What type of receptors monitor blood pressure in the body?

    <p>Baroreceptors</p> Signup and view all the answers

    If a patient exhibits no voluntary movement in the leg and also shows increased muscle tone, what type of injury is most likely?

    <p>Upper motor neuron injury</p> Signup and view all the answers

    Which step in the reflex arc follows the detection of stimuli by sensory receptors?

    <p>Interneuron relay</p> Signup and view all the answers

    What can be inferred if a patient has stretch reflexes rated +4?

    <p>Possible upper motor neuron compression</p> Signup and view all the answers

    What implication does a painful skin eruption caused by shingles have regarding nerve function?

    <p>It indicates sensory nerves corresponding to affected skin</p> Signup and view all the answers

    How does the body respond to increased muscle tone in the context of motor neuron compression?

    <p>By enhancing reflexes due to loss of inhibition</p> Signup and view all the answers

    What triggers the release of a neurotransmitter at the axon terminal?

    <p>The arrival of the action potential</p> Signup and view all the answers

    How does myelin influence the conduction speed in axons?

    <p>It creates a vacuum-like tunnel for swift travel</p> Signup and view all the answers

    Which is NOT a component of the Central Nervous System (CNS)?

    <p>Peripheral nerves</p> Signup and view all the answers

    What happens to a neurotransmitter after it binds to receptors on the other neuron?

    <p>It creates another action potential</p> Signup and view all the answers

    Which statement best describes the Peripheral Nervous System (PNS)?

    <p>It consists of spinal nerves that branch from the spinal cord</p> Signup and view all the answers

    What is the role of sodium channels in an unmyelinated axon?

    <p>To propagate the action potential across the entire length</p> Signup and view all the answers

    What is the primary type of communication at the synapse?

    <p>Chemical communication</p> Signup and view all the answers

    Which divisions make up the autonomic nervous system?

    <p>Sympathetic and parasympathetic</p> Signup and view all the answers

    How can drug binding to plasma proteins affect drug efficacy in the kidneys?

    <p>It prevents filtration of bound drugs in the glomerulus.</p> Signup and view all the answers

    What does the bioavailability of a drug determine?

    <p>The proportion of the drug that reaches the systemic circulation.</p> Signup and view all the answers

    Which of the following is a consequence of developing drug tolerance?

    <p>The body adapts to the drug, requiring higher doses for the same effect.</p> Signup and view all the answers

    Why are pharmacokinetics crucial in evaluating a drug's usefulness?

    <p>They help understand if the drug reaches its target site effectively.</p> Signup and view all the answers

    What happens if a drug is broken down by low pH in the stomach?

    <p>The drug becomes ineffective before reaching the target site.</p> Signup and view all the answers

    What is a key factor in determining the concentration of a drug at its target site?

    <p>The drug's interaction with plasma protein binding.</p> Signup and view all the answers

    Which of the following describes how pharmacokinetics and pharmacodynamics work together?

    <p>Both must be considered to achieve the intended therapeutic effect.</p> Signup and view all the answers

    What effect does increasing the dose and frequency of a medication have over time?

    <p>It compensates for the body's adaptation to the drug.</p> Signup and view all the answers

    Study Notes

    Introduction to the Nervous System

    • Neurons transmit electrochemical messages called nerve impulses to other neurons and effectors (muscles or glands).
    • Key parts of a neuron:
      • Cell body (soma): Contains nucleus and produces proteins.
      • Dendrites: Input area; branched projections that receive information.
      • Axons: Integration area; long fibers that propagate electrical impulses (action potentials) from cell body to axon terminal.
      • Axon terminal: Output area; nerve endings that make synaptic contacts and release neurotransmitters.
      • Myelin sheath: Insulating cover that enhances the speed of impulse transmission.
    • A single neuron integrates multiple inputs (inhibitory/excitatory) to produce one output (action potential).

    Neurotransmission Process

    • Electrical communication at the axon terminal converts to chemical communication via neurotransmitter release.
    • Neurotransmitters bind to receptors on adjacent neurons, creating new action potentials.
    • Deactivation of neurotransmitters occurs when they are reabsorbed by the axon terminal.

    Myelin and Conduction Speed

    • Myelin sheath allows action potentials to jump between sodium channels, promoting rapid electrical conduction.
    • Unmyelinated axons require channels to open sequentially, which slows conduction.

    Divisions of the Nervous System

    • Central Nervous System (CNS): Comprises the brain and spinal cord; brain has external grey matter (cell bodies) and internal white matter (axons); spinal cord has internal grey matter and external white matter.
    • Peripheral Nervous System (PNS): Comprises spinal nerves (31 pairs) that connect spinal cord to body segments; includes sensory and motor functions.
    • Sensory (afferent) Functions: Includes somatic sensory (touch, taste, smell, hearing, vision) and autonomic sensory functions (chemoreceptors, stretch receptors, baroreceptors).

    Reflex Arc Components

    • Components of a reflex arc:
      • Stimulus detection by sensory receptors.
      • Sensory information relayed to the CNS via sensory neurons.
      • Action potentials transferred to motor neurons via interneurons.
      • Effectors respond to stimuli.
    • Example: In a stretch reflex, a muscle stretch is detected, leading to a contraction response (e.g., knee-jerk response).

    Diagnostic Use of Reflex Testing

    • Reflex testing helps identify damage in the CNS or PNS by observing the presence or absence of reflexes.
    • Deficits and symptoms can provide clues about affected nerves based on the vertebral level of spinal nerve injury.

    Patient Comparison for Motor Neuron Damage

    • Patient A: No stretch reflex, absent voluntary movement, flaccid paralysis - indicates damage at the spinal nerve (L4).
    • Patient B: Hyperactive stretch reflex, absent voluntary movement, spastic paralysis - indicates upper motor neuron compression.

    Pharmacokinetics and Drug Effectiveness

    • Pharmacokinetic processes affect drug action duration, bioavailability, concentration at target sites, and potency.
    • Effective drug treatment relies on both pharmacokinetics and pharmacodynamics to ensure the drug reaches its target and remains effective.
    • Additionally, long-term medication use can lead to drug tolerance, requiring dose adjustments for therapeutic effect.

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    Description

    This quiz covers the introduction to the nervous system, focusing on the parts of a generalized neuron and their functions including input, output, and integration. Perfect for students of HUBS1416 at the University of Newcastle. Test your understanding of this fundamental concept in human bioscience.

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