Skip to content
Know.itKnow.it
Create an animated lesson
On request

Read the answer free. Creating a lesson uses your daily or stored credits; review the language and settings before starting.

What is a reflex action?

Class 10 ScienceNCERT chapter: Control and Coordinationइसे हिंदी में पढ़ें

Exam-ready answer

A reflex action is a sudden, involuntary and rapid response of the body to a stimulus, controlled by the spinal cord without conscious thought from the brain. It protects the body from harm. Example: withdrawing your hand immediately after touching a hot object.

Explanation

A reflex action is a quick, automatic response to a stimulus that does not involve conscious thinking. It is involuntary, meaning you cannot stop it by will. The brain is not directly involved in generating the response, although it is informed later.

The pathway taken by nerve impulses in a reflex action is called a reflex arc. It involves: receptor (detects stimulus) → sensory neuron → spinal cord (relay neuron) → motor neuron → effector (muscle or gland). This short route makes the response very fast.

Common examples include withdrawing your hand from a hot object, blinking when something approaches the eye, sneezing, coughing, and the knee-jerk response when the tendon below the knee is tapped. Reflex actions protect the body from injury.

Points to remember

  1. Reflex action: sudden, involuntary, rapid response to a stimulus.
  2. Reflex arc: receptor → sensory neuron → spinal cord → motor neuron → effector.
  3. Spinal cord acts as the coordinating centre; brain is not directly involved in the immediate response.
  4. Examples: hand withdrawal from hot object, blinking, sneezing, coughing, knee jerk.
  5. Function: protects the body from harm by producing a quick response.

Exam tip

Draw a labelled diagram of the reflex arc showing receptor, sensory neuron, spinal cord, motor neuron, and effector. Write the definition clearly and give at least one example.

Questions students also ask

What is the difference between a reflex action and walking?
Reflex action is involuntary and controlled by the spinal cord, while walking is a voluntary action controlled by the brain. Reflex actions are immediate and protective, whereas walking is a conscious, learned activity.
Why do reflex actions occur so quickly?
Reflex actions occur quickly because the nerve impulse travels through a short pathway called the reflex arc, which bypasses the brain. The spinal cord directly sends the response to the effector, saving time.
Is the brain involved in reflex action?
The brain is not directly involved in generating the immediate response, but it receives information about the reflex after it has occurred. The spinal cord coordinates the reflex action.

Chapter labels help you find the topic in your textbook. Check your own edition: chapter names and order can change. These are Know.it explanations, not official NCERT solutions.