Reflex Action — Interactive Diagram
See how your body pulls your hand away from a hot object before you even think about it.
TL;DR: See how your body pulls your hand away from a hot object before you even think about it.
Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated
Reflex Action: See how your body pulls your hand away from a hot object before you even think about it.
Why it matters: The reflex arc (receptor → sensory neuron → spinal cord → motor neuron → muscle) shows how the nervous system protects us instantly — a key diagram.
Reflex Action — Step by Step
- STIMULUS: your hand touches a hot object. Heat RECEPTORS in the skin detect the danger.
- The signal races along a SENSORY NEURON to the SPINAL CORD — it does not wait to reach the brain.
- The spinal cord instantly sends a signal back along a MOTOR NEURON to the arm muscle — you pull your hand away. Fast and automatic!
Quick Notes — the Exam Crux
- A reflex action is a quick, automatic response to a stimulus, not under conscious control.
- The pathway it follows is called the reflex arc.
- Order: receptor (skin) → sensory neuron → spinal cord (relay) → motor neuron → effector (muscle).
- It is processed by the spinal cord, which makes it faster than a brain-routed response.
- The brain is informed afterwards, which is why you feel the pain a moment later.
- Examples: pulling the hand off a hot object, the knee-jerk, blinking, sneezing.
Remember It (Memory Trick)
Reflex arc: Receptor → Sensory neuron → Spinal cord → Motor neuron → Muscle. The brain is bypassed for speed — "the spinal cord decides, the brain finds out later."
Real-Life Example
Touch a hot tawa by accident and your hand jerks back before you even feel the pain — the spinal cord fires the response instantly to protect you.
Test Yourself
Which part of the nervous system controls a reflex action?
The spinal cord.
Why is a reflex action faster than a normal voluntary action?
It is processed directly by the spinal cord, bypassing the brain.
Write the correct order of a reflex arc.
Receptor → sensory neuron → spinal cord → motor neuron → effector (muscle).
📖 Read the full explanation of Reflex Action →
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