Which of the following changes occur in diaphragm and intercostal muscles when expiration of air takes place?a)External intercostal muscles relax anddiaphragm contractsb)External intercostal muscles contract and diaphragm relaxesc)External intercostal muscles and diaphragm relaxd)External intercostal muscles and diaphragm contractCorrect answer is option 'D'. Can you explain this answer?

Question

Answer

During expiration pressure inside lungs should be higher as compared to external atmosphere ,
so as air (co2) move from higher pressure side to lower pressure side
Hence to decrease volume and increase pressure inside lungs external intercoastal muscle and diaphragm should be contract
as ,we know pressure is inversely related to volume

Answer

During Inspiration the ext. intercoastal muscles and diaphragm expands creating pressure diff for air to get in.
During expiration, ext. intercoastal muscles and diaphragm contracts forcing the air out of the lungs.
hence,op D

Answer

The correct answer is option 'D' - External intercostal muscles and diaphragm contract.

When expiration of air takes place, the diaphragm and intercostal muscles undergo specific changes to facilitate the expulsion of air from the lungs.

1. Role of Diaphragm:
The diaphragm is a dome-shaped muscle located at the bottom of the thoracic cavity. It separates the thoracic cavity from the abdominal cavity. During expiration, the diaphragm undergoes relaxation and moves upwards towards the thoracic cavity, decreasing the volume of the thoracic cavity.

2. Role of External Intercostal Muscles:
The external intercostal muscles are located between the ribs. They play a crucial role in respiration by assisting in the expansion of the rib cage during inhalation. During expiration, the external intercostal muscles relax, allowing the rib cage to move downward and inward, reducing the volume of the thoracic cavity.

3. Contraction of External Intercostal Muscles:
Contrary to the relaxation during expiration, the external intercostal muscles contract during inhalation. This contraction helps elevate the rib cage, increasing the volume of the thoracic cavity. It allows the lungs to expand and fill with air.

4. Contraction of Diaphragm:
During expiration, the diaphragm contracts. This contraction causes the diaphragm to flatten and move downwards towards the abdominal cavity, increasing the pressure within the thoracic cavity. The increased pressure aids in the expulsion of air from the lungs.

Overall, the contraction of the external intercostal muscles and the diaphragm during expiration leads to a decrease in the volume of the thoracic cavity. This decrease in volume increases the pressure within the lungs, causing the expulsion of air.

Answer

When the external intercostal muscles and diaphragm relax, the ribs move downward and inward and diaphragm becomes convex (dome shaped), thus decreasing the volume of thoracic avity and increasing the pressure inside as compared to the atmospheric pressure outside. This will cause the air to move out (expiration).

Similar NEET Doubts

Which of the following changes occur in diaphragm and intercostal muscles when expiration of air takes place?

Which of the following changes occur in diaphragm and intercostal muscles when expiration of air takes place?

Which of the following changes occur in diaphragm and intercostal muscles when expiration of air takes place?

Read the following statements (A – D).(

Which of the following statements about the mechanism of ventilation/breathing is incorrect?

Top Courses for NEETView all

Biology Class 11

Daily Test for NEET Preparation

NEET Mock Test Series 2025

Topic-wise MCQ Tests for NEET

Physics Class 11

Top Courses for NEET

Top Courses for NEET

Suggested Free Tests

Related Content

About NEET

NEET Preparation Material

How to Prepare for NEET Exam?

NCERT Based Study Material

NEET Mock Tests

Other Popular Exams

Company