Reflexes are quick, involuntary responses that occur in response to a specific stimulus. Reflexes are important for our survival and help us to respond quickly to potentially dangerous situations. The reflex arc is the neural pathway responsible for generating reflexes.

Reflex Arc Definition

The brain network that mediates a reflex action is known as the reflex arc. There are sensory neurons, interneurons, and motor neurons involved. The sensory neuron receives a stimulus and sends a signal to the spinal cord or brain.

The interneuron is located in the spinal cord or brain and connects the sensory neuron to the motor neuron. The motor neuron sends a signal to the effector, which is the muscle or gland that carries out the reflex action.

Simple Reflex Arc

The simplest reflex arc involves only two neurons: a sensory neuron and a motor neuron. An example of a simple reflex arc is the knee-jerk reflex. In the knee-jerk reflex, tapping the patellar tendon just below the knee cap causes the quadriceps muscle to contract and the leg to kick forward.

Here is a step-by-step explanation of the knee-jerk reflex arc:

• A doctor taps the patellar tendon with a reflex hammer, which stretches the muscle spindle in the quadriceps muscle.
• The sensory neuron in the quadriceps muscle spindle is stimulated and sends a signal to the spinal cord.
• A spinal cord interneuron and a sensory neuron form a synaptic connection.
• The interneuron sends a signal to the motor neuron in the quadriceps muscle.
• The motor neuron sends a signal to the quadriceps muscle, causing it to contract and the leg to kick forward.

Reflex Arc Diagram

In this diagram, the sensory neuron is represented by the blue arrow, the interneuron is represented by the orange arrow, and the motor neuron is represented by the green arrow. The effector is represented by the red arrow. The stimulus is represented by the tapping of the patellar tendon, which activates the reflex arc.

The reflex arc is the neural pathway responsible for generating reflexes. There are sensory neurons, interneurons, and motor neurons involved. The simplest reflex arc involves only two neurons: a sensory neuron and a motor neuron. An example of a simple reflex arc is the knee-jerk reflex, which involves tapping the patellar tendon and causing the quadriceps muscle to contract.

Revision on reflex arc

Which of the following is a reflex arc’s potential pathways?

A) Sensory neuron to interneuron to motor neuron

B) Sensory neuron to motor neuron to interneuron

C) Motor neuron to the sensory neuron to the interneuron

D) Interneuron to motor neuron to sensory neuron

Answer: A) Sensory neuron to interneuron to motor neuron. This is the correct pathway for a reflex arc. The sensory neuron receives a stimulus and sends a signal to the spinal cord or brain. The interneuron is located in the spinal cord or brain and connects the sensory neuron to the motor neuron. The motor neuron sends a signal to the effector, which is the muscle or gland that carries out the reflex action.

Which kind of reflex arc is made up only of afferent and efferent neurons?

A) Monosynaptic reflex arc

B) Polysynaptic reflex arc

C) Cranial reflex arc

D) Spinal reflex arc

Answer: A) Monosynaptic reflex arc. A monosynaptic reflex arc consists of only two neurons, an afferent neuron and an efferent neuron. This type of reflex arc is the simplest and most rapid.

A reflex arc does not require which of the following?

A) Sensory receptor

B) Interneuron

C) Motor neuron

D) Conscious thought

Answer: D) Conscious thought. Reflexes are quick, involuntary responses that occur in response to a specific stimulus. Conscious thought is not required for a reflex arc to occur.

What is the correct simple spinal reflex arc, out of the following?

A) Sensory neuron to interneuron to motor neuron to effector

B) Sensory neuron to effector to motor neuron to interneuron

C) Motor neuron to interneuron to sensory neuron to effector

D) Sensory neuron to motor neuron to effector

Answer: D) Sensory neuron to motor neuron to effector. This simple spinal reflex arc is correct. An example of this type of reflex arc is the knee-jerk reflex. In the knee-jerk reflex, tapping the patellar tendon just below the knee cap causes the quadriceps muscle to contract and the leg to kick forward.

Reflex arc work sheet

Reflex arc work sheet answers