Reflex Arc Quiz: 15 Questions With Answers
Updated
A reflex arc is the simplest neural pathway: sensory receptor, afferent neuron, integration center, efferent neuron, effector. Stretch reflexes are monosynaptic; withdrawal reflexes are polysynaptic. Clinical testing reveals nervous system integrity.
This quiz tests your understanding of reflex arcs, the neural pathways that produce rapid, involuntary responses. It covers stretch reflexes, withdrawal reflexes, and how doctors use reflex testing to assess neurological function. Suitable for introductory neuroscience students.
Before starting, remember that a reflex arc has five components: receptor, afferent neuron, integration center, efferent neuron, and effector. The key distinction is between monosynaptic reflexes, like the knee jerk, and polysynaptic reflexes, like withdrawal, which involve interneurons.
The questions
What is the correct order of components in a reflex arc?
Which receptor initiates the stretch reflex?
In a monosynaptic stretch reflex, the afferent neuron synapses directly with which neuron?
The knee jerk (patellar) reflex is an example of which type?
A withdrawal reflex is always polysynaptic because it requires at least one...
During the withdrawal reflex, the crossed extensor reflex causes which response in the opposite limb?
Deep tendon reflex testing (e.g., striking patellar tendon) primarily assesses the integrity of which structure?
The Jendrassik maneuver (clasping hands and pulling) is thought to enhance a reflex by...
The Babinski sign (upgoing big toe) in adults indicates damage to which pathway?
Which structure carries sensory information into the spinal cord?
In a stretch reflex, the efferent neuron causes contraction of which muscle?
The withdrawal reflex is initiated by which type of stimulus?
Which of the following is a key difference between monosynaptic and polysynaptic reflexes?
Reflex arcs can function without input from the brain because the integration center is located in the...
In clinical testing, an absent or diminished deep tendon reflex suggests a lesion in which part of the reflex arc?
0 of 15 answered · 0 correct
Cheat sheet: key terms
| Reflex arc | Neural pathway from sensory receptor to effector, usually without brain involvement. |
|---|---|
| Muscle spindle | Stretch receptor in skeletal muscle that initiates the stretch reflex. |
| Monosynaptic reflex | One synapse between afferent sensory neuron and efferent motor neuron, e.g., knee jerk. |
| Polysynaptic reflex | One or more interneurons between afferent and efferent neurons, e.g., withdrawal reflex. |
| Withdrawal reflex | Protective flexor response to painful stimulus, often with crossed extensor reflex. |
| Deep tendon reflex | Clinical test of spinal reflex arc integrity using a reflex hammer. |
| Jendrassik maneuver | Facilitation technique thought to enhance reflexes, possibly via gamma motor neuron activity. |
| Babinski sign | Upgoing big toe in adults, indicating corticospinal tract lesion. |
Answers explained
Show all 15 answers
- What is the correct order of components in a reflex arc? receptor, afferent neuron, integration center, efferent neuron, effector. The sensory receptor detects the stimulus, the afferent neuron carries it to the CNS, the integration center processes it, the efferent neuron carries the response command, and the effector produces the reflex action.
- Which receptor initiates the stretch reflex? muscle spindle. Muscle spindles detect changes in muscle length and are the sensory receptors for the stretch reflex.
- In a monosynaptic stretch reflex, the afferent neuron synapses directly with which neuron? alpha motor neuron. The Ia afferent synapses directly on the alpha motor neuron that innervates the same muscle, causing contraction.
- The knee jerk (patellar) reflex is an example of which type? stretch reflex. Tapping the patellar tendon stretches the quadriceps, producing a rapid contraction via a monosynaptic stretch reflex.
- A withdrawal reflex is always polysynaptic because it requires at least one... interneuron. Interneurons are interposed between afferent and efferent neurons, allowing divergence to multiple motor pools and coordination.
- During the withdrawal reflex, the crossed extensor reflex causes which response in the opposite limb? extension. Extension of the opposite limb supports body weight when the stimulated limb withdraws from a painful stimulus.
- Deep tendon reflex testing (e.g., striking patellar tendon) primarily assesses the integrity of which structure? spinal reflex arc. Deep tendon reflexes test the spinal reflex arc, including sensory and motor components, without requiring higher brain centers.
- The Jendrassik maneuver (clasping hands and pulling) is thought to enhance a reflex by... increasing gamma motor neuron activity via descending pathways. The maneuver increases fusimotor drive to muscle spindles, making them more sensitive to stretch, though the exact mechanism is still debated.
- The Babinski sign (upgoing big toe) in adults indicates damage to which pathway? corticospinal tract. The Babinski sign is an upper motor neuron sign that appears when the corticospinal tract is damaged, releasing the reflex from cortical inhibition.
- Which structure carries sensory information into the spinal cord? dorsal root. The dorsal root contains afferent sensory fibers entering the spinal cord; it is not a white matter tract but the structure carrying fibers into the cord.
- In a stretch reflex, the efferent neuron causes contraction of which muscle? same muscle that was stretched. The stretch reflex produces contraction of the muscle that was stretched, via its alpha motor neurons.
- The withdrawal reflex is initiated by which type of stimulus? painful stimulus. Withdrawal reflexes are protective responses to noxious or painful stimuli.
- Which of the following is a key difference between monosynaptic and polysynaptic reflexes? polysynaptic reflexes involve one or more interneurons. Monosynaptic reflexes have a single synapse between afferent and efferent neurons, while polysynaptic reflexes include interneurons.
- Reflex arcs can function without input from the brain because the integration center is located in the... spinal cord or brainstem. Many reflex arcs have integration centers in the spinal cord or brainstem, allowing rapid responses without cortical processing.
- In clinical testing, an absent or diminished deep tendon reflex suggests a lesion in which part of the reflex arc? lower motor neuron or sensory afferent. Hyporeflexia or areflexia indicates interruption of the reflex arc at the lower motor neuron or sensory afferent level.
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