Question

The correct sequence of events when someone’s hand touches a hot object (reflex action):

• A. Sensory neuron → Motor neuron → Relay neuron → Effector muscle
• B. Relay neuron → Sensory neuron → Motor neuron → Effector muscle
• C. Sensory neuron → Relay neuron → Motor neuron → Effector muscle in arm
• D. Motor neuron → Sensory neuron → Relay neuron → Effector muscle

Answer 1

The Correct Option is C

Step 1: Understand reflex action
A reflex action is an immediate and automatic response to a stimulus, which does not involve the conscious part of the brain. It helps protect the body from harm, like quickly pulling your hand away from a hot object.

Step 2: Identify the pathway involved (reflex arc)
When a person touches a hot object, the following sequence of events occurs:
1. The sensory neuron detects the stimulus (heat) from the skin receptors and sends a signal to the spinal cord.
2. In the spinal cord, the signal is passed to a relay neuron (interneuron).
3. The relay neuron then passes the message to a motor neuron.
4. The motor neuron sends the command to the effector muscle in the arm, causing it to contract and move the hand away.

Step 3: Final Answer
Sensory neuron → Relay neuron → Motor neuron → Effector muscle in arm