What is the function of diaphragm in human respiratory system? Where is it present in human body?
What is the function of diaphragm in human respiratory system? Where is it present in human body?
Official answer
The diaphragm is a dome-shaped muscular sheet located at the base of the chest cavity, separating the thoracic cavity (containing the lungs and heart) from the abdominal cavity. Its function is to help change the volume of the chest cavity during breathing: as described in the chapter, 'when we breathe in, we lift our ribs and flatten our diaphragm, and the chest cavity becomes larger as a result. Because of this, air is sucked into the lungs and fills the expanded alveoli.' When we breathe out, the diaphragm relaxes and returns to its dome shape, reducing the volume of the chest cavity and pushing air out of the lungs.
Marking scheme
- 1.1 mark for correctly stating the function — flattening to increase chest cavity volume during inhalation, aiding air intake, and relaxing during exhalation
- 2.1 mark for correctly stating the location — at the base of the chest cavity, separating thoracic and abdominal cavities
Quick oral answer
The diaphragm is a muscular sheet at the base of the chest cavity that flattens during inhalation to enlarge the chest cavity and draw air in, and relaxes during exhalation to push air out.
Common mistakes
- 1.Saying only 'it helps in breathing' without explaining the volume-pressure mechanism
- 2.Placing the diaphragm's location incorrectly, e.g., inside the lungs, instead of at the base of the chest cavity separating it from the abdomen
- 3.Forgetting to mention both inhalation (flattening) and exhalation (relaxing back to dome shape)
Analysis and explanation
This is a 2-mark 'function and location' question, so both parts must be answered precisely and grounded in the chapter's description of breathing mechanics.
Location: The diaphragm lies at the floor of the chest (thoracic) cavity, forming the boundary between the thoracic cavity above (which houses the lungs) and the abdominal cavity below.
Function: During inhalation, the ribs are lifted and the diaphragm flattens, which enlarges the chest cavity. This larger cavity creates a pressure difference that causes air to be 'sucked into the lungs' filling the expanded alveoli. During exhalation, the diaphragm relaxes back into its dome shape, the chest cavity volume decreases, and air is pushed out of the lungs. Thus, the diaphragm, working together with the rib muscles, drives the mechanical process of breathing by altering the volume (and hence pressure) of the chest cavity.
Interesting facts
The lungs always retain a residual volume of air even after breathing out, which gives sufficient time for oxygen absorption and carbon dioxide release across the alveoli.
Question details
Q10 of 39 questions
- Board
- CBSE
- Class
- Class 10
- Subject
- Science
- Year
- 2026
- Section
- Section A
- Marks
- 2
- Type
- Very Short Answer
- Chapter
- Life Processes
- Topic
- Respiration — Human Respiratory System
- Bloom's level
- Understand
- Syllabus topic
- Mechanism of breathing
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Frequently asked questions
How many marks does this question carry in CBSE Class 10 Science 2026?
This question carries 2 marks in the CBSE Class 10 Science 2026 examination.
Which chapter does this question come from in Science?
This question is from the chapter "Life Processes" in the CBSE Class 10 Science syllabus.
What topic does this question cover in Science?
This question covers the topic "Respiration — Human Respiratory System" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2026 paper?
This is a Very Short Answer question from Section A in the CBSE Class 10 Science 2026 paper.