Question

The inhalation and exhalation are two characteristics of the respiratory function.

Write an essay in which you clarify the concept of ventilation versus respiration, and explain the characteristics of inspiration and expiration in terms of involved organs and the forces triggering them. (Don’t exceed 800 words.)

The knowledge of muscles and pressures involved in the respiration is fundamental to write this essay.

Answer 1

ventilation versus respiration :

Living beings require oxygen for the process of oxidation of glucose (food) so that energy is released. Also the carbon dioxide is produced during the oxidation process which is a waste product and needs to be removed from body. Oxygen is obtained from the atmosphere and carbon dioxide is released to the atmosphere with the help of respiratory system.

The respiratory system completes the above mentioned function in two stages or processes namely respiration and ventilation. These both processes occur simultaneously in the human body.

Ventilation: It is essentially the exchange of air between human body (lungs) and the atmosphere. Ventilation comprises of two phases known as inhalation and exhalation. Inhalation is the process of intake of atmospheric air in lungs. Exhalation is the discharge of carbon dioxide and unused air into atmosphere. These both processes take place with the help of movement of diaphragm and rib cage muscles which changes pressure in lungs. The exchange of air happens due to the Boyles law which states the relationship between pressure and volume.

Respiration: It is essentially the exchange of oxygen and carbon dioxide between blood and different tissues. In internal respiration the oxygen and carbon dioxide is exchanged between blood and cells through blood capillary walls. In external respiration the the oxygen and carbon dioxide is exchanged between blood and alveoli tissues present in the lungs. The mechanism followed for exchange of gases in respiration is diffusion. Diffusion is caused due to the difference in concentrations of gases across semi permeable membranes.

Characteristics of inspiration and expiration and the forces triggering :

Pulmonary ventilation comprises two major steps: inspiration and expiration. Inspiration is the process that causes air to enter the lungs, and expiration is the process that causes air to leave the lungs . A respiratory cycle is one sequence of inspiration and expiration. In general, two muscle groups are used during normal inspiration: the diaphragm and the external intercostal muscles. Additional muscles can be used if a bigger breath is required. When the diaphragm contracts, it moves inferiorly toward the abdominal cavity, creating a larger thoracic cavity and more space for the lungs. Contraction of the external intercostal muscles moves the ribs upward and outward, causing the rib cage to expand, which increases the volume of the thoracic cavity. Due to the adhesive force of the pleural fluid, the expansion of the thoracic cavity forces the lungs to stretch and expand as well. This increase in volume leads to a decrease in intra-alveolar pressure, creating a pressure lower than atmospheric pressure. As a result, a pressure gradient is created that drives air into the lungs.

The process of normal expiration is passive, meaning that energy is not required to push air out of the lungs. Instead, the elasticity of the lung tissue causes the lung to recoil, as the diaphragm and intercostal muscles relax following inspiration. In turn, the thoracic cavity and lungs decrease in volume, causing an increase in interpulmonary pressure. The interpulmonary pressure rises above atmospheric pressure, creating a pressure gradient that causes air to leave the lungs.

In contrast, forced breathing, also known as hyperpnea, is a mode of breathing that can occur during exercise or actions that require the active manipulation of breathing, such as singing. During forced breathing, inspiration and expiration both occur due to muscle contractions. In addition to the contraction of the diaphragm and intercostal muscles, other accessory muscles must also contract. During forced inspiration, muscles of the neck, including the scalenes, contract and lift the thoracic wall, increasing lung volume. During forced expiration, accessory muscles of the abdomen, including the obliques, contract, forcing abdominal organs upward against the diaphragm. This helps to push the diaphragm further into the thorax, pushing more air out. In addition, accessory muscles (primarily the internal intercostals) help to compress the rib cage, which also reduces the volume of the thoracic cavity.