Reflex Arc Components and Steps Quiz
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Questions and Answers

What is the term for the phenomenon where a receptor adapts to a sustained stimulus by decreasing its response?

  • Adaptation (correct)
  • Refractory period
  • Saturation
  • Sensory overload
  • Which type of receptors are always active and provide continuous information about stimulus?

  • Tonic receptors (correct)
  • Adapting receptors
  • Phasic receptors
  • Dynamic receptors
  • In which receptor type does a decrease in stimulus intensity lead to a decrease in action potential frequency?

  • Adapting receptors
  • Phasic receptors (correct)
  • Dynamic receptors
  • Tonic receptors
  • What is the term for the region of skin monitored by a sensory neuron, with greater receptor density leading to greater acuity?

    <p>Receptive field</p> Signup and view all the answers

    Which phenomenon involves the most intensely activated pathway inhibiting less excited pathways at the peripheries, leading to localization and contrast sharpening?

    <p>Lateral inhibition</p> Signup and view all the answers

    Which of the following statements about receptor potentials is correct?

    <p>Receptor potentials are generated by sensory transduction, which alters the receptor's permeability.</p> Signup and view all the answers

    Which component of the reflex arc is responsible for integrating and processing information received from sensory receptors?

    <p>Integrating center (CNS)</p> Signup and view all the answers

    Which of the following is NOT a step in a simple reflex arc?

    <p>Repolarization of the receptor potential</p> Signup and view all the answers

    What is the primary function of the afferent division in a reflex arc?

    <p>To detect and respond to stimuli from the environment</p> Signup and view all the answers

    How is the strength of a stimulus encoded in the reflex arc?

    <p>Both a and b</p> Signup and view all the answers

    Study Notes

    Reflex Arc

    • Consists of 5 components: sensory receptor, afferent pathway, integrating center (CNS), efferent pathway, and effector organ (muscle or gland)
    • Steps in a simple reflex arc:
      • Activation of a receptor by a stimulus
      • Activation of a sensory neuron: stimulation of dendrites produces graded polarization
      • Information processing in the CNS
      • Activation of a motor neuron: interneuron stimulates motor neurons that carry APs to periphery
      • Response of a peripheral effector: motor neuron(s) release neurotransmitters at axon terminals, stimulating effector to respond

    Afferent Division

    • Consists of sensory receptors at peripheral endings of afferent neurons
    • Respond to stimuli from external or internal environment
    • Exist in various energy forms (modalities)
    • Bring about graded potentials (receptor potentials) in receptor
    • Receptor potential: sensory transduction process by which a stimulus is converted into an electrical signal

    Coding of Stimulus Strength

    • Stimulus intensity (strength) distinguished by:
      • Frequency of APs generated in afferent neuron
      • Number of receptors and afferent neurons activated within an area
    • Stronger stimuli affect larger areas, and more receptors respond

    Adaptation

    • Decrease in receptor sensitivity with sustained stimulus strength
    • Receptor “adapts” to stimulus by no longer responding to it to the same degree
    • Decrease in AP frequency

    Types of Receptors

    • Tonic receptors:
      • Always active
      • Do not adapt or adapt slowly to sustained stimulus
      • Provide continuous information about stimulus
      • AP frequency reflects level of stimulation
    • Phasic receptors:
      • Normally inactive
      • Adapt rapidly to sustained stimulus
      • Become active for a short time
      • Exhibit an off response when stimulus is removed

    Acuity and Perception

    • Receptive field: region of skin surface monitored by a sensory neuron
    • Greater receptor density = smaller receptive field = greater acuity (discriminative ability)
    • Lateral inhibition:
      • Each activated signal pathway inhibits pathways next to it
      • Stimulates inhibitory interneurons that pass laterally between ascending fibers
      • Most strongly activated pathway in center of stimulus area inhibits less excited pathways at the peripheries
    • Facilitates localization and sharpens contrast between wanted and unwanted information

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    Description

    Test your knowledge on the 5 components of a reflex arc - sensory receptor, afferent and efferent pathways, integrating center in the CNS, and effector organ. Also, quiz yourself on the steps involved in a simple reflex arc from activation of a receptor to response by the effector organ.

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