Spinal reflexes
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Questions and Answers

What is the best definition of a reflex? A. A voluntary response that occurs with conscious effort B. An automatic response to a stimulus that requires brain involvement C. A rapid, automatic, and predictable response to a specific stimulus without conscious effort D. A response to a stimulus that varies based on the individual's conscious control

  • A voluntary response that occurs with conscious effort
  • An automatic response to a stimulus that requires brain involvement
  • A rapid, automatic, and predictable response to a specific stimulus without conscious effort (correct)
  • A response to a stimulus that varies based on the individual's conscious control

    • Which structure in the spinal cord contains cell bodies of efferent motor neurons that supply skeletal muscles?

  • Dorsal horn
  • Ventral horn (correct)
  • Dorsal root ganglion
  • Central canal

    • What is the primary function of the spinal cord in reflex activity?

  • To serve as a relay for conscious brain activity
  • To store sensory information
  • To link afferent input and efferent output in a reflex without involving the brain (correct)
  • To initiate voluntary motor control

    • Which of the following statements is correct regarding monosynaptic and polysynaptic reflexes?

    <p>Monosynaptic reflexes involve only one synapse and are simpler than polysynaptic reflexes.</p> Signup and view all the answers

    Where do afferent neurons terminate within the spinal cord?

    <p>Dorsal horn</p> Signup and view all the answers

    Where do afferent sensory fibers enter the spinal cord?

    <p>Through the dorsal root</p> Signup and view all the answers

    Where are the cell bodies of afferent sensory neurons located?

    <p>In the dorsal root ganglion (DRG)</p> Signup and view all the answers

    What type of motor neuron innervates skeletal muscle fibers?

    <p>α motor neurons</p> Signup and view all the answers

    How many pairs of spinal nerves are there in total?

    <p>31</p> Signup and view all the answers

    Which statement is correct regarding the dorsal and ventral roots of the spinal nerves?

    <p>The dorsal root carries sensory signals, and the ventral root carries motor signals.</p> Signup and view all the answers

    Which motor neuron type specifically innervates intrafusal fibers within muscle spindles?

    <p>γ motor neurons</p> Signup and view all the answers

    Which of the following best describes the role of α motor neurons in the reflex arc?

    <p>They directly innervate extrafusal skeletal muscle fibers, causing muscle contraction.</p> Signup and view all the answers

    In the context of a withdrawal reflex, such as pulling a hand away from a hot surface, which sequence of events is correct?

    <p>Sensory neurons carry the signal to the dorsal root → interneurons in the dorsal horn process the signal → α motor neurons in the ventral horn activate flexor muscles.</p> Signup and view all the answers

    During a stretch reflex, which specific components are involved in maintaining muscle tone? (Select one)

    <p>The muscle spindle and γ motor neurons, which work to adjust spindle length and sensitivity.</p> Signup and view all the answers

    Which of the following statements about spinal nerve roots is accurate?

    <p>The dorsal root contains afferent fibers that terminate in the dorsal horn, whereas the ventral root contains efferent fibers originating in the ventral horn.</p> Signup and view all the answers

    What is the primary function of γ motor neurons during a muscle stretch reflex?

    <p>To adjust the sensitivity of the muscle spindle, keeping it taut during muscle contraction</p> Signup and view all the answers

    In which scenario would polysynaptic reflexes, as opposed to monosynaptic reflexes, be more advantageous?

    <p>When coordinated movement of multiple muscle groups is required, such as in a withdrawal reflex involving both sides of the body</p> Signup and view all the answers

    Which reflex mechanism provides the most effective protection against muscle damage during excessive load?

    <p>The Golgi tendon reflex, which inhibits excessive contraction by activating inhibitory interneurons</p> Signup and view all the answers

    Which of the following best describes the role of spinal cord reflexes in response to painful stimuli?

    <p>They initiate rapid withdrawal responses that involve both sensory and motor pathways.</p> Signup and view all the answers

    Which reflex mechanism is primarily responsible for preventing muscle damage due to overstretching?

    <p>The Golgi tendon reflex, which inhibits excessive contraction to protect tendons</p> Signup and view all the answers

    The spinal cord reflex involved in emptying pelvic organs, such as bladder contraction, is an example of which type of reflex?

    <p>Visceral reflex</p> Signup and view all the answers

    Which spinal reflex is essential for maintaining balance and coordination during activities like walking and running?

    <p>Crossed-extensor reflex, which supports balance when shifting weight</p> Signup and view all the answers

    Which of the following is a learned reflex coordinated by the spinal cord?

    <p>Somersaults in sports</p> Signup and view all the answers

    The spinal reflexes that contribute to standing, walking, and running work primarily through:

    <p>Spinal cord reflex circuits that allow for coordinated, automatic movements</p> Signup and view all the answers

    Why are spinal cord reflexes essential for coordinating trunk and limb movements in daily activities?

    <p>They allow the body to maintain posture, balance, and coordinated movement without constant brain involvement.</p> Signup and view all the answers

    Reflex responses are a form of integrated neural activity that occurs in which two parts of the nervous system?

    <p>The central nervous system and the peripheral nervous system</p> Signup and view all the answers

    Which of the following is not one of the three main components of a reflex arc?

    <p>Cortical processing center</p> Signup and view all the answers

    In a basic reflex arc, what is the role of the peripheral sensory receptor?

    <p>To detect a stimulus and initiate the reflex signal</p> Signup and view all the answers

    What is the role of the integration area in the CNS within a reflex arc?

    <p>To process sensory input and coordinate an appropriate motor response</p> Signup and view all the answers

    Which component of the reflex arc directly causes the response in the effector organ?

    <p>Efferent motor nerve</p> Signup and view all the answers

    Which of the following describes a reflex in the autonomic nervous system?

    <p>Heart rate adjustment in response to blood pressure changes</p> Signup and view all the answers

    Which of the following best describes the role of sensory neurons in a reflex arc?

    <p>To carry information from peripheral receptors to the CNS for processing</p> Signup and view all the answers

    A somatic reflex differs from an autonomic reflex in that:

    <p>Somatic reflexes target skeletal muscles, while autonomic reflexes target organs and glands.</p> Signup and view all the answers

    Which of the following is the correct order of components in a typical reflex arc?

    <p>Receptor, sensory neuron, integration center, motor neuron, effector</p> Signup and view all the answers

    What is the role of a sensory receptor in the reflex arc?

    <p>To respond to specific stimuli and initiate a nerve impulse</p> Signup and view all the answers

    Which type of sensory receptor provides information about the position of body parts, such as muscles and joints?

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

    What type of receptor would detect changes in temperature or pressure from the external environment?

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

    Which of the following best describes the role of an interneuron in a reflex arc?

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

    In a reflex arc, what is the main function of the motor neuron?

    <p>To transmit signals from the CNS to the effector organ</p> Signup and view all the answers

    Which of the following receptors is responsible for detecting changes within internal organs, such as stretching or pain?

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

    The role of the integration center in a reflex arc is to: A. Send signals to the receptor B. Directly stimulate the effector organ C. Process incoming sensory information and generate a response D. Detect changes in the external environment

    <p>Process incoming sensory information and generate a response</p> Signup and view all the answers

    Where are exteroceptors most likely located, given their role in detecting external stimuli?

    <p>In the skin and mucous membranes</p> Signup and view all the answers

    In a reflex arc, the area responsible for receiving, processing, and integrating sensory information is located in:

    <p>The central nervous system (CNS)</p> Signup and view all the answers

    Which part of the CNS is typically involved in the integration process during a reflex action?

    <p>Brain or spinal cord</p> Signup and view all the answers

    What is the primary role of interneurons in the CNS?

    <p>To distribute sensory information and coordinate motor commands</p> Signup and view all the answers

    Interneurons in the CNS can influence other neurons by having which types of effects?

    <p>Both excitatory and inhibitory</p> Signup and view all the answers

    The integration center in the CNS issues appropriate commands to effectors based on:

    <p>The integration of incoming sensory information</p> Signup and view all the answers

    Which of the following accurately describes the function of interneurons in a reflex arc?

    <p>They distribute sensory information and coordinate motor responses.</p> Signup and view all the answers

    What type of neurons in the CNS is crucial for coordinating reflex responses through integration?

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

    Which of the following statements about the integration area in the CNS is incorrect?

    <p>It relies only on excitatory interneurons.</p> Signup and view all the answers

    What is the main function of spinal reflexes in the somatic nervous system?

    <p>Involuntary control of the skeletal muscles</p> Signup and view all the answers

    In spinal reflexes, where is the area for integration typically located?

    <p>In the spinal cord</p> Signup and view all the answers

    Which statement is true about spinal reflexes? A. They can only function independently of higher CNS centers. B. They are only under voluntary control. C. They can be influenced and modified by higher centers in the CNS. D. They bypass the spinal cord entirely.

    <p>They can be influenced and modified by higher centers in the CNS.</p> Signup and view all the answers

    Which of the following is an example of a monosynaptic reflex?

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

    What distinguishes a monosynaptic reflex from a polysynaptic reflex?

    <p>A monosynaptic reflex includes a single synapse between sensory and motor neurons.</p> Signup and view all the answers

    Which of the following is characteristic of a polysynaptic reflex?

    <p>It includes one or more interneurons in the reflex pathway.</p> Signup and view all the answers

    Which type of reflex is typically faster due to fewer synapses?

    <p>Monosynaptic reflex</p> Signup and view all the answers

    Which of the following is an example of a monosynaptic reflex?

    <p>Stretch (myotactic) reflex</p> Signup and view all the answers

    In the stretch reflex, which component serves as the sensory receptor?

    <p>Muscle spindles</p> Signup and view all the answers

    What is the main function of the stretch reflex?

    <p>To oppose sudden changes in muscle length</p> Signup and view all the answers

    Which of the following describes the reflex response when a stretch reflex is triggered?

    <p>Brief contraction of the stretched muscle</p> Signup and view all the answers

    The area for integration in the stretch reflex is located in the: A. Cerebral cortex B. Spinal cord C. Brainstem D. Autonomic ganglia

    <p>Spinal cord</p> Signup and view all the answers

    In a stretch reflex, which of the following acts as the effector?

    <p>The skeletal muscle that was stretched</p> Signup and view all the answers

    Which of the following is necessary for proper control of muscle function?

    <p>Constant feedback of sensory information from the muscle to the spinal cord</p> Signup and view all the answers

    Which type of muscle sensory receptor provides information about the length of a muscle and the rate of change in length?

    <p>Muscle spindles</p> Signup and view all the answers

    What is the primary function of Golgi tendon organs in muscle control?

    <p>Monitoring tension in the muscle and rate of change of tension</p> Signup and view all the answers

    Muscle spindles and Golgi tendon organs are examples of: A. Exteroceptors B. Thermoreceptors C. Proprioceptors D. Chemoreceptors

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

    Which sensory receptor primarily responds to changes in muscle length?

    <p>Muscle spindles</p> Signup and view all the answers

    Golgi tendon organs respond to:

    <p>Muscle tension and rate of tension change</p> Signup and view all the answers

    What type of feedback do muscle spindles provide to the spinal cord?

    <p>Feedback about muscle length and rate of change of length</p> Signup and view all the answers

    What is the role of proprioceptors in the muscular system?

    <p>To provide feedback about muscle length, tension, and changes in these variables</p> Signup and view all the answers

    What happens to muscle tone when extrafusal fibers are stretched?

    <p>Muscle tone increases</p> Signup and view all the answers

    Which type of afferent nerve fiber is primarily responsible for conveying information from muscle spindles?

    <p>1a fibers</p> Signup and view all the answers

    What effect does compressing the extrafusal fibers have on muscle tone?

    <p>Muscle tone decreases</p> Signup and view all the answers

    Which of the following fibers innervates the intrafusal fibers of muscle spindles?

    <p>Gamma fibers</p> Signup and view all the answers

    The resting length of a muscle is influenced by which of the following factors? A. The action potential frequency in motor neurons B. The amount of tension generated in extrafusal fibers C. The state of afferent nerve fibers only D. The contraction of the intrafusal fibers alone

    <p>The amount of tension generated in extrafusal fibers</p> Signup and view all the answers

    Alpha motor neurons are primarily responsible for:

    <p>Innervating extrafusal muscle fibers</p> Signup and view all the answers

    What is the role of motor end plates?

    <p>To transmit signals from motor neurons to muscle fibers</p> Signup and view all the answers

    Which of the following statements is true regarding muscle tone?

    <p>Muscle tone decreases when the muscle is compressed and increases when stretched.</p> Signup and view all the answers

    What happens to the firing rate of 1a afferent fibers when a muscle is stretched?

    <p>The firing rate increases</p> Signup and view all the answers

    In response to a decrease in muscle length, what is the expected change in the firing rate of muscle spindle afferent fibers?

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

    When extrafusal fibers are compressed, what effect does this have on the firing rate of the 1a afferent fibers?

    <p>It decreases</p> Signup and view all the answers

    The change in firing rate of alpha motor neurons during muscle contraction is primarily responsible for:

    <p>Adjusting the muscle tone and maintaining posture</p> Signup and view all the answers

    Which of the following best describes the relationship between muscle spindle activation and motor neuron firing?

    <p>Increased spindle activity results in increased alpha motor neuron firing</p> Signup and view all the answers

    The change in firing of gamma motor neurons primarily affects: A. The contraction of extrafusal fibers B. The tension in intrafusal fibers and the sensitivity of muscle spindles C. The activity of sensory neurons in the dorsal root ganglia D. The overall muscle mass

    <p>The tension in intrafusal fibers and the sensitivity of muscle spindles</p> Signup and view all the answers

    During a reflex action, what is the expected change in firing rate of sensory neurons when a painful stimulus is applied?

    <p>Increase in firing rate</p> Signup and view all the answers

    What impact does sustained muscle contraction have on the firing patterns of motor neurons?

    <p>Firing patterns may increase initially but decrease over time due to fatigue</p> Signup and view all the answers

    What is the primary function of muscle spindles in relation to muscle tone?

    <p>To regulate resting muscle tension</p> Signup and view all the answers

    Which of the following statements about the stretch reflex is true?

    <p>It is a monosynaptic reflex involving a brief stretch leading to a brief contraction.</p> Signup and view all the answers

    How do muscle spindles contribute to the maintenance of muscle tone?

    <p>By preventing over-lengthening of muscles during contraction</p> Signup and view all the answers

    What happens to muscle tone if the activity of gamma motor neurons is decreased?

    <p>Muscle tone decreases</p> Signup and view all the answers

    Which part of the central nervous system receives sensory information from muscle spindles during a stretch reflex?

    <p>Spinal cord</p> Signup and view all the answers

    What is the consequence of excessive muscle tone?

    <p>Muscles cannot rest and recover adequately</p> Signup and view all the answers

    What is the role of γ-motoneurons in muscle tone regulation?

    <p>They keep muscle spindles under proper tension during relaxation</p> Signup and view all the answers

    What is the mechanism by which muscle tone is produced?

    <p>Continuous feedback from muscle spindles to the brain</p> Signup and view all the answers

    Muscle spindles send information about changes in muscle length to which part of the brain?

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

    Which of the following best describes muscle tone?

    <p>The residual tension in muscles even when at rest</p> Signup and view all the answers

    What happens to muscle tone when the reflex arc controlling it is interrupted?

    <p>Muscle tone is lost immediately.</p> Signup and view all the answers

    What is the primary function of the Golgi tendon organ?

    <p>To detect muscle tension</p> Signup and view all the answers

    Where are Golgi tendon organs located?

    <p>Inside muscle tendons</p> Signup and view all the answers

    Which type of sensory nerve is primarily involved in transmitting signals from the Golgi tendon organ to the spinal cord?

    <p>Type Ib sensory nerves</p> Signup and view all the answers

    What happens to motor neurons when muscle tension increases and signals are transmitted by the Golgi tendon organ?

    <p>They are inhibited to prevent excessive muscle tension.</p> Signup and view all the answers

    How many muscle fibers are typically connected to a single Golgi tendon organ?

    <p>10-15 muscle fibers</p> Signup and view all the answers

    What role do Golgi tendon organs play in joint stiffness?

    <p>They control the force within muscles, affecting joint stiffness.</p> Signup and view all the answers

    Which statement best describes the action of Golgi tendon organs in response to increased muscle tension?

    <p>They inhibit the activity of motor neurons to prevent injury.</p> Signup and view all the answers

    What is the primary purpose of the feedback mechanism provided by Golgi tendon organs?

    <p>To protect muscles from excessive tension</p> Signup and view all the answers

    If Golgi tendon organ activity is diminished, what effect would that have on muscle control?

    <p>Increased risk of muscle damage from excessive tension</p> Signup and view all the answers

    What is the primary function of the Golgi tendon organ (GTO)?

    <p>To detect muscle tension and prevent excessive force</p> Signup and view all the answers

    What happens first in the sequence of events during the knee jerk reflex?

    <p>Brief stretch of the quadriceps</p> Signup and view all the answers

    Which type of sensory fibers are activated in response to the stretch of the muscle spindles in the quadriceps?

    <p>Type Ia sensory afferent fibers</p> Signup and view all the answers

    The knee jerk response is primarily an example of which type of reflex?

    <p>Monosynaptic reflex</p> Signup and view all the answers

    What role does the α-motoneuron play in the knee jerk reflex?

    <p>It stimulates the contraction of the quadriceps muscle.</p> Signup and view all the answers

    Why is the knee jerk reflex considered informative about the integrity of the central nervous system (CNS)?

    <p>It reflects proper function of spinal reflex pathways.</p> Signup and view all the answers

    What happens to the activity in the α-motoneuron supplying the quadriceps when the quadriceps is stretched? A. Activity decreases. B. Activity remains unchanged. C. Activity increases. D. Activity fluctuates unpredictably.

    <p>Activity increases.</p> Signup and view all the answers

    What sensory receptors are primarily responsible for detecting the stretch in the quadriceps during the knee jerk reflex?

    <p>Muscle spindles</p> Signup and view all the answers

    In the context of the knee jerk reflex, what does the term 'monosynaptic' refer to?

    <p>The direct connection between the sensory neuron and the motor neuron.</p> Signup and view all the answers

    What is the primary purpose of testing stretch reflexes (tendon jerks) during a neurological examination?

    <p>To evaluate the integrity of reflex pathways</p> Signup and view all the answers

    Which grade of tendon reflex indicates a very brisk response, often with clonus?

    <p>Grade 4</p> Signup and view all the answers

    Hyporeflexia is characterized by which of the following?

    <p>Diminished reflex responses</p> Signup and view all the answers

    Which of the following conditions is associated with hyporeflexia?

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

    What does an absent stretch reflex (areflexia) indicate?

    <p>Loss of tendon reflexes due to lesions in the reflex arc</p> Signup and view all the answers

    Which of the following could be a potential cause of areflexia?

    <p>Root lesion or peripheral neuropathy</p> Signup and view all the answers

    In grading tendon reflexes, what does Grade 1 indicate?

    <p>Minimal response</p> Signup and view all the answers

    A condition characterized by degeneration of skeletal muscle and associated with hyporeflexia is known as:

    <p>Muscular dystrophy</p> Signup and view all the answers

    In a neurological assessment, if a patient exhibits a brisk reflex response (Grade 3), what does this indicate?

    <p>An abnormal reflex response</p> Signup and view all the answers

    What condition typically leads to hyperreflexia?

    <p>Damage to motor pathways from brain to spinal cord</p> Signup and view all the answers

    Which muscle reflex is primarily tested through the knee jerk response?

    <p>The protagonist muscle responsible for knee extension</p> Signup and view all the answers

    What is the role of reciprocal innervation during a muscle contraction?

    <p>To allow opposing muscles to relax</p> Signup and view all the answers

    What is a common consequence of an upper motor neuron lesion?

    <p>Exaggerated stretch reflex responses</p> Signup and view all the answers

    In the context of muscle reflexes, what does the term 'antagonist' refer to?

    <p>A muscle that opposes the action of the protagonist muscle</p> Signup and view all the answers

    How many synapses are typically involved in a polysynaptic reflex?

    <p>Two to hundreds</p> Signup and view all the answers

    What is a key feature of polysynaptic reflexes compared to monosynaptic reflexes?

    <p>They produce more complex responses.</p> Signup and view all the answers

    What is the primary function of the withdrawal reflex?

    <p>To protect against painful stimuli</p> Signup and view all the answers

    In a polysynaptic reflex, how do interneurons contribute to the response?

    <p>They connect sensory afferent fibers to multiple motor neurons.</p> Signup and view all the answers

    Which of the following is an example of a polysynaptic reflex?

    <p>Withdrawal of hand from a hot plate</p> Signup and view all the answers

    Olysynaptic reflexes often involve which of the following structures?

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

    What is the primary role of interneurons in polysynaptic reflex pathways?

    <p>To modulate and integrate sensory input</p> Signup and view all the answers

    Which of the following statements is true regarding polysynaptic reflexes?

    <p>They can involve multiple muscle groups.</p> Signup and view all the answers

    Oligosynaptic reflexes can be influenced by which of the following?

    <p>Higher centers in the CNS</p> Signup and view all the answers

    What type of sensory fibers primarily mediate the flexor withdrawal reflex?

    <p>Aδ fibers</p> Signup and view all the answers

    In the flexor withdrawal reflex, sensory pathways first synapse on which type of neurons?

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

    What is the primary action of the flexor withdrawal reflex when touching a hot surface?

    <p>The hand is pulled up and away from the heat source.</p> Signup and view all the answers

    Which muscle group contracts during the flexor withdrawal reflex when a painful stimulus is detected?

    <p>Flexor muscles</p> Signup and view all the answers

    What is inhibited during the flexor withdrawal reflex to facilitate the movement away from the painful stimulus?

    <p>Extensor muscles</p> Signup and view all the answers

    What is the role of nociceptors in the flexor withdrawal reflex?

    <p>To convey information about pain</p> Signup and view all the answers

    What would happen if the integrative centers in the spinal cord were damaged during the flexor withdrawal reflex?

    <p>The reflex would be absent or diminished.</p> Signup and view all the answers

    During the flexor withdrawal reflex, which part of the body is primarily moved to avoid the painful stimulus?

    <p>The arm</p> Signup and view all the answers

    What occurs in the opposite limb during the crossed extensor reflex when the flexor reflex is triggered?

    <p>The opposite limb extends</p> Signup and view all the answers

    How quickly does the crossed extensor reflex occur after the initial stimulus?

    <p>0.2 to 0.5 seconds</p> Signup and view all the answers

    What happens to the extensor muscles of the opposite limb when the flexor reflex is activated?

    <p>They are excited</p> Signup and view all the answers

    When one foot is lifted away from a sharp object, what reflex action is responsible for preparing the opposite leg to bear weight?

    <p>Crossed extensor reflex</p> Signup and view all the answers

    Which of the following best describes the relationship between the flexor reflex and the crossed extensor reflex?

    <p>The crossed extensor reflex complements the flexor reflex to maintain balance.</p> Signup and view all the answers

    What is the sensory feedback mechanism responsible for the activation of the crossed extensor reflex?

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

    If the crossed extensor reflex is impaired, what might occur when stepping on a sharp object?

    <p>The person may fall due to lack of support from the opposite leg</p> Signup and view all the answers

    What structure allows for temporary override of spinal reflexes?

    <p>Higher brain centers</p> Signup and view all the answers

    What mechanism does the brain use to manage a pin prick sensation during a blood draw?

    <p>Sending IPSPs to the bicep motoneurons and EPSPs to the tricep</p> Signup and view all the answers

    Which type of reflex is modified through learning and practice?

    <p>Acquired/conditioned reflex</p> Signup and view all the answers

    What is an example of an acquired reflex associated with sports activities?

    <p>Catching a ball</p> Signup and view all the answers

    How does performing a skill repeatedly affect neural synaptic patterns?

    <p>It generates new synaptic patterns that substitute for natural reflexes.</p> Signup and view all the answers

    What ability does overriding basic postural reflexes provide?

    <p>Perform complex movements consciously</p> Signup and view all the answers

    What type of signals does the brain send to motoneurons while overriding a reflex during actions like bladder contraction?

    <p>Both IPSPs and EPSPs</p> Signup and view all the answers

    Why might individuals learn to inhibit basic reflexes during activities?

    <p>To perform activities that require conscious control</p> Signup and view all the answers

    What is the primary characteristic of conditioned reflexes compared to unconditioned reflexes?

    <p>Conditioned reflexes are learned and can be modified.</p> Signup and view all the answers

    What role do interneurons play in polysynaptic reflexes?

    <p>They facilitate communication between sensory and motor pathways.</p> Signup and view all the answers

    Which reflex allows for a quick withdrawal from a painful stimulus?

    <p>Polysynaptic reflex</p> Signup and view all the answers

    What happens when muscle spindles detect an increase in muscle length?

    <p>Muscle tone increases as the stretch reflex is activated.</p> Signup and view all the answers

    What characterizes an acquired reflex compared to an unconditioned reflex?

    <p>Acquired reflexes are learned through experience and practice.</p> Signup and view all the answers

    During a stretch reflex, what occurs to the alpha motor neurons when muscle spindles are activated?

    <p>They are excited.</p> Signup and view all the answers

    Which statement best reflects the role of muscle spindles in muscle tone regulation?

    <p>Muscle spindles maintain muscle tone by providing feedback to the CNS about muscle length and tension.</p> Signup and view all the answers

    In the flexor withdrawal reflex, which muscle group is activated and which is inhibited?

    <p>Flexors activated, extensors inhibited.</p> Signup and view all the answers

    Which sensory fibers are primarily responsible for conveying pain signals in the flexor withdrawal reflex?

    <p>Aδ fibers</p> Signup and view all the answers

    What is the main purpose of the crossed extensor reflex?

    <p>To maintain balance when one limb is withdrawn.</p> Signup and view all the answers

    Study Notes

    Hyperreflexia

    • Exaggerated stretch reflex response
    • Occurs due to damage to motor pathways from brain to spinal cord
    • Can occur after stroke or brain tumor
    • Damage to motor areas of cerebral cortex (e.g., loss of inhibitory inputs from higher areas to some motor neurons)
    • Causes Upper motor neuron lesion (UMNL)
    • Certain stretch reflexes become exaggerated (e.g., elbow)

    Reciprocal Innervation

    • Occurs in somatic reflexes involving limb movement (e.g., knee jerk response, knee extends and leg kicks forward)
    • When antagonist muscle contracts (protagonist), opposing muscles (antagonist) must relax
    • Stretch reflexes in antagonist muscle must be inhibited
    • Achieved by reciprocal innervation
    • Example of reciprocal innervation is knee-jerk reflex, with the semitendinosus acting as antagonist muscle
    • Connection between neurons involved in stretch reflexes (e.g., knee jerk) show reciprocal innervation

    Spinal Reflexes

    • Higher brain centers can override spinal reflexes.
    • Interneurons within the spinal cord are important for communication between sensory and motor pathways.
    • Acquired/conditioned reflexes are learned through practice and modify basic reflex responses.
    • Catching a ball is an example of an acquired reflex in sports.
    • Repeated skill performance can generate new synaptic patterns in the CNS.
    • Overriding basic postural reflexes allows for conscious control of movement.
    • The brain sends both excitatory (EPSPs) and inhibitory (IPSPs) signals to motoneurons when overriding a reflex.
    • Inhibiting basic postural reflexes allows for conscious control of complex movements.
    • Acquired reflexes make skills more efficient and automatic.
    • Conditioned reflexes are learned and can be modified.
    • Polysynaptic reflexes involve multiple synapses and allow for quick withdrawal from painful stimuli.
    • Crossed extensor reflex helps maintain balance when one limb is withdrawn.
    • Muscle spindles are activated during a stretch reflex, exciting alpha motor neurons.
    • Aδ fibers are primarily responsible for conveying pain signals in the flexor withdrawal reflex.
    • Muscle tone increases when muscle spindles detect increased muscle length.
    • Acquired reflexes are learned through experience and practice.
    • Muscle spindles provide feedback to the CNS about muscle length and tension, maintaining muscle tone.
    • Testing for stretch, crossed extensor, and withdrawal reflexes can assess the integrity of the spinal cord and peripheral nerves.
    • The flexor withdrawal reflex activates flexor muscles and inhibits extensor muscles.

    Reflex Types

    • Unconditioned reflexes are innate, automatic responses.
    • Monosynaptic reflexes involve one synapse, such as the stretch reflex.
    • Conditioned reflexes are learned through experience and association, such as Pavlov's dogs.
    • Involuntary reflexes are not under conscious control.

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    Description

    This quiz explores the concept of reflexes, focusing on their definitions and characteristics in biological systems. Test your knowledge about the automatic responses to stimuli and the role of the nervous system in these reactions.

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