15 Key Difference Inhalation And Exhalation (With Table)

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The two important structures in the processes of inhalation and exhalation are diaphragm and intercostalsmuscles.  The diaphragm is a sheet of muscles that separate the chest (thoracic) cavity from the rest of the body while intercostals muscles are found between the ribs and they control movement of rib. The diaphragm and intercostals muscles are constantly relaxing and contracting, thus causing the chest cavity to increase and decrease. The lung is protected by layers of tissue referred to as the visceral pleura and parietal pleura, the intrapleural space contains a small amount of fluid that protects the tissue by reducing friction.

Inhalation Process

Inhalation also known as inspiration, as part of the cycle of breathing, it occurs when air or other gases enter the lungs (respiratory system). This process is very vital for all human and animal life. The thoracic cavity or chest cavity, always has a slight, negative pressure which helps in keeping the airways of the lungs open. during the process of inhalation, the lung volume expands as a result of the contraction of the diaphragm and intercostal muscles (the muscles that are connected to the rib cage), thus expanding the thoracic cavity. due to this increase in volume, the pressure is decreased.

The decrease of pressure in the thoracic cavity relative to the environment makes the cavity pressure less than the atmospheric pressure. This pressure gradient between the atmosphere and the thoracic cavity allows air to push into the lungs and inhalation occurs. The resulting increase in volume is largely attributed to an increase in alveolar space because the bronchioles and bronchi are stiff structures that do not change in size.

During inhalation process, the chest wall expands out and away from the lungs. the lungs are elastic; therefore, when air fills the lungs, the elastic recoil within the tissues of the lungs exerts pressure back towards the interior of the lungs. These outward and inward forces complete to inflate and deflate the lung with every breath. Inhalation is an active process as it involves the contraction of muscles.

What You Need To Know About Inhalation

  • Inhalation also known as inspiration, is a process of taking in air (oxygen) into the lungs through the nostrils
  • During the Inhalation process, the diaphragm flattens by moving down
  • During inhalation, the external intercostal muscles contract while internal intercostal muscles relax
  • During inhalation process, the lungs become inflated (increase in size)
  • During the inhalation process the size of the chest cavity increases
  • Air full of oxygen is taken into the blood via lungs during inhalation
  • Rib cage moves forward and outward due to the effect of intercostal muscles during inhalation
  • During Inhalation, the inhaled air is a mixture of oxygen and nitrogen
  • During the inhalation process, air pressure inside the lungs reduces due to the increase of volume in the chest cavity
  • During inhalation, muscular contractions are involved and therefore, the process can be classified as an active process
  • The size of the lungs increase during inhalation
  • The accessory muscles involved during forced inhalation include:scalenes, sternocleidomastoid, pectoralis major and minor, serratus anterior and latissimus dorsi

Exhalation Process

In humans and animals, the main reason for exhalation is to get rid of carbon dioxide from the body. Exhalation also known as expiration is a process of taking air (CO2) out of the lungs through the nostrils.

During the process of exhalation, air is taken in through the lungs; the diffusion in the alveoli allows for the exchange of oxygen into the pulmonary capillaries and the removal of carbon dioxide and other gases from the pulmonary capillaries to be exhaled. In order for the lungs to expel the air, the diaphragm and the muscles attached to the rib cage relax causing the chest cavity to decrease in size. This eventually creates a high pressure in the lungs due to the reduction of volume and thus the resultant pressure difference causes air to move out from the lungs through the nostril to the external environment. There is no contraction of muscles during exhalation; it is considered a passive process.

What You Need To Know About Exhalation

  • Exhalation also known as expiration is a process of taking air (CO2) out of the lungs through the nostrils
  • During exhalation process while during exhalation process, the diaphragm relaxes and turns into a dome-shaped by moving up
  • During exhalation the external intercostals muscles relax while the internal intercostals muscles contract
  • During the exhalation process, the lungs become deflated (reduce in size)
  • The chest cavity decreases in size during the process inhalation
  • Exhalation takes air full of carbon II oxide out of blood.
  • Ribcage moves downward and inward due to the effect of intercostal muscle during exhalation
  • During exhalation, exhaled air is a mixture of carbon dioxide and nitrogen
  • During exhalation, air pressure inside the lungs increases due to the increase of volume in the chest cavity
  • During exhalation no muscular contractions involved, the process can be classified as a passive process
  • The size of the lungs decrease during exhalation
  • The accessory muscles muscles involved during forced exhalation are anterolateral abdominal, internal intercostals and innermost intercostals

Difference Between Inhalation And Exhalation

Elements for Comparison Inhalation Exhalation
Definition Inhalation also known as inspiration is a process of taking in air (oxygen) into the lungs through the nostrils. Exhalation also known as expiration is a process of taking air (CO2) out of the lungs through the nostrils.
Behavior of Diaphragm During the process, the diaphragm flattens by moving down. The diaphragm relaxes during the process and turns into a dome-shaped by moving up.
Behavior of Intercostal Muscles External intercostal muscles contract while internal intercostal muscles relax. External intercostals muscles relax while the internal intercostals muscles contract.
Size (volume) of the Lungs During the process the lungs become inflated (increase in size). During the process the lungs become deflated (reduce in size).
Chest Cavity size During the process the size of the chest cavity increases. The chest cavity decreases in size during the process.
Air Air full of oxygen is taken into the blood via lungs. Air full of carbon dioxide is taken out of blood.
Behavior of Rib cage Rib cage moves forward and outward due to the effect of intercostal muscles. Rib cage moves downward and inward due to the effect of intercostal muscle.
Composition of Air The inhaled air is a mixture of oxygen and nitrogen. The exhaled air is a mixture of carbon dioxide and nitrogen.
Air Pressure Air pressure inside the lungs reduces due to the increase of volume in the chest cavity. Air pressure inside the lungs increases due to the increase of volume in the chest cavity.
Classification of the process Because muscular contractions are involved then the process can be classified as an active process. Since there are no muscular contractions involved, the process can be classified as a passive process.