Involuntary action

NCERT sorts the actions of our muscles into three kinds:

• Voluntary actions are decided first, like writing or moving a chair. The fore-brain, the thinking part of the brain, decides them.
• Reflex actions are sudden responses, like the change in the size of the pupil.
• Involuntary actions sit in between. We do not think about them, and we cannot easily control them even if we try.

The mid-brain and hind-brain run many of these actions. Blood pressure, salivation and vomiting are run by the medulla, a part of the hind-brain. The cerebellum, also in the hind-brain, keeps voluntary actions precise and keeps our balance.

A small example

Sort three actions. Writing your name is voluntary. Your pupil shrinking in bright light is a reflex. Your mouth watering at the sight of food you like is involuntary.

Where marks go

Question 11 of CBSE's 2026-27 Science sample paper, option A, carries 2 marks. It asks three things. Which parts of the brain run actions we cannot control? What are they called? What are two examples? The board's Science marking scheme for 2026-27 answers all three. The parts are the mid-brain and hind-brain. The actions are called involuntary actions. The examples are any two of blood pressure, salivation and vomiting.

So an answer that stops at the name leaves two parts out. The question has an internal choice. Its other option is on how the sensitive plant responds to touch, which is not a tropism.

About the author

Deepti Sardana

Founder Member & Academic Lead

An IIT alumna (M.Sc., M.Phil.) with over 25 years in teaching, child psychology and learning assessment. As Academic Lead at EduBrahma, she leads the method TRUtesting uses to find where and why a child loses marks.

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