Definition of Inhalation

• Inhalation, also known as Inspiration, is a type of breathing that involves the inhalation of air. It is when the air is drawn into the lungs through the contraction of the diaphragm and respiratory muscles.
• Inhalation is an essential physical process. It is independent and occurs without any control or conciseness. But breathing can be controlled and interrupted within certain limits.
• Inhalation requires energy because it is an active process.
• It allows for the inhalation of oxygen that is carried into the lungs and then into the bloodstream.
• Inhalation causes an increase in volume in the lungs through the contraction of different respiratory muscles.
• Pleural fluid is a liquid that seals the lungs from the thoracic walls. It fills the space between the outer and thoracic walls, which is called the pleural space.
• This seal allows for the expansion of the thoracic cavity, which in turn ensures the expansion and expansion of the lungs.
• Two important muscles are involved in the process of inhalation: external intercostal and diaphragm.
• By contracting, the diaphragm becomes flatter and extends the thoracic cavity upwards. The diaphragm contracts while the external intercostal muscle contract and the inner intercostal muscle relax to raise the sternum and ribs, causing the thoracic cavity and to move outwards.
• These muscles contract to increase the volume of the thoracic cavity. The connection of the lungs to the cavity via the pleural sac eventually permits an increase in volume.
• Boyle’s Law states that the volume of the lungs increases, and the pressure inside the lungs also decreases.
• The pressure in the lungs is therefore less than that of the surrounding environment. This difference in pressure, or pressure gradient, allows air to flow through the respiratory passage into the lungs.
• Inhalation is when the air passes through the nose and into the lungs.
• The trachea is the beginning of the respiratory tree. It is then divided into several smaller branches.
• These branches carry the air through them and eventually reaches their alveoli. The exchange of gases occurs in the alveoli, where oxygen is dissolved into the blood vessels.
• Forcing inhalation occurs when exercise is completed. It occurs through the contraction of accessory muscles such as scalenes, sternocleidomastoid and pectoralis major, minor and serratus anterior, and latissimus Dorsi. These muscles all contribute to increasing the volume of the lungs.

Definition of Exhalation 

• Exhalation, also known as expiration, is a stage of breathing in which the air is pulled out of the lungs through relaxation of the respiratory muscles.
• The vital bodily process of exhalation is independent and occurs without any control or guidance. The process can be interrupted or controlled within certain limits.
• Expiration serves the main purpose of getting rid of carbon dioxide produced by cellular respiration.
• The volume of the lungs decreases when you exhale. This is due to relaxation of different respiratory muscles.
• Exhalation uses the same muscles as inspiration, but exhalation is different from inhalation.
• The diaphragm returns to its original position, pulling the thoracic cavity down to its former position.
• The external intercostal muscle relaxes while the internal intercostal muscle contracts, which causes the sternum and ribs to drop back, pulling the thoracic cavity inwards.
• These muscles relax, causing a decrease of the volume of the thoracic cavity as well as the volume of your lungs.
• A decrease in volume results in pressure inside the lungs that is higher than the environment.
• The respiratory passage draws out the air from the lungs.
• After the exchange of carbon dioxide and oxygen, the air in your lungs is formed by the diffusion of air through the blood vessels to the alveoli.
• After passing through the respiratory tree and the trachea and the pharynx, the air finally goes through the nasal passage and then out of the body.
• Because it allows for better gas exchange than inspiration, exhalation takes longer than inhalation.
• As with inhalation, the air that comes out of your lungs isn’t just carbon dioxide. It is also a mixture of gases, including methanol, isoprene and other alcohols.
• The respiratory centers in the Medulla Oblongata or Pons control exhalation, which is a passive process.
• Voluntary exhalation, which is an active process during exercise, is controlled by a more complicated neurological pathway.
• It is controlled by the motor cortex in the cerebral cortex, the brain’s same motor cortex that controls voluntary muscle movement.
• The cortex sends signals to the accessory muscles involved in forced expiration. Anterolateral abdominal, inner intercostals and innermost intercostals are some of the muscles that control forced expiration. They also help in the contraction of the lungs.

Key Differences between Inhalation and Exhalation (Inhalation vs Exhalation)