Difference Between Inhalation and Exhalation

Breathing is a life process. The process of inspiration and expiration is vital to provide oxygen to tissues and remove carbon dioxide from the body. The process of breathing is the moving of air in and out of the lungs facilitating gas exchange with the internal environment by taking in oxygen and flushing out carbon dioxide. Gaseous exchange occurs in the alveoli through diffusion where the body’s circulatory system transports these gases to and from the cells, thereby enabling cellular respiration.

What Is Inhalation?

  • Occurs through active contraction of the muscles such as the diaphragm and is the action of breathing in
  • As part of the cycle of breathing, the process is autonomic and does not need conscious control
  • It begins with the contraction of muscles attached to the ribcage causing expansion in the chest cavity, where contraction of the diaphragm sets in resulting in the expansion of the intrapleural space and a rise in the negative pressure as per Boyle’s law

What Is Exhalation?

  • It is the act of exhaling air taken in and is passive
  • Here, the diaphragm relaxes, moving upwards into the chest cavity
  • The intercostal muscles between the ribs relax, causing the area of the chest cavity to reduce
  • Eventually, the area in the chest reduces and carbon dioxide-rich air is expelled out of the lungs and windpipe, ultimately out of the nose

Difference Between Inhalation and Exhalation

The table below shows the differences between inhalation and exhalation

Attributes Inhalation Exhalation
What it means Intake of air into the lungs Expelling air out of the lungs
Type Active process Passive process
Size of the chest in the process Increases, expands Decreases, reduces
Diaphragm – role Contracts, gets flattened by moving down Relaxes, moves up forming a dome-shape
Intercostal muscle – role Relaxation of internal intercostal muscles and contraction of external intercostal muscles Contraction of the internal intercostal muscles and relaxation of external intercostal muscles
Lungs – volume Rises to cause inflation Reduces causing deflation
Action it causes Supply of oxygen-rich air to the blood Carbon dioxide is expelled out
Air composition Inhaled air is a mix of oxygen and nitrogen Exhaled air is a mix of nitrogen and carbon dioxide
Air pressure Decrease Increase
Effect of intercostal muscles Ribcage moves upwards and outwards Ribcage moves downwards

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