During the movement of the inspiration, the increase in the volume of the chest box in three dimensions and a secondary increase in the volume of the lung (pulmonary exposure) occur.
EXPIRATION
At the end of the inspiration, through the relaxation of the inspirational muscles (diaphragm and intercostal muscles) takes place the recoil of elastic fibers from the alveolar walls with the expulsion of air from the lungs.
GAS EXCHANGE
The main function of the respiratory system is to eliminate
carbon dioxide (CO2
) from the systemic venous blood that arrives
to the lungs and add oxygen (O2
) thereof.
Gaseous exchanges in the respiratory system refer to
diffusion of oxygen and carbon dioxide in the lung and in
peripheral tissues.
The diffusion of oxygen and carbon dioxide between the alveolus and
capillary is performed through the alveolo-capillary membrane, under the
action of partial pressure gradients of gases in the air and
plasma and are favored by the peculiarities of alveolocapillary membrane.
INTRODUCTION
The respiratory system includes the airways and lungs. These organs ensure the exchange of respiratory gases between the body and the environment.
The airways are tube-shaped organs through which air passes during breathing. Some of the airways are outside the lungs (extrapulmonary airways) and some are inside the lungs (intrapulmonary airways or bronchial tree).
Extrapulmonary airways are located in the head, neck and chest, being represented by nasal fossa, pharynx, larynx, trachea and main bronchi.
PULMONARY VENTILATION
It is the process of alternating air circulation between the environment and the alveoli of the lungs, thus leading to the penetration of oxygen-rich air to the alveoli and the removal of carbon dioxide to the outside.
Ventilation is carried out by movements of the chest under the influence of respiratory muscles, the lungs have only a passive role.
Cyclic variations in thoracopulmonary volume induce pressure differences between atmospheric and intrapulmonary air.
There are two movements of the opposite sense: inspiratory and expiratory.
VOLUMES AND RESPIRATORY CAPACITIES
- Volume current-500 ml (volume of air inspired and exhaled during normal breathing)
- Spare-inning volume-1500 ml (extra volume of air that can be inspired above the current volume)
- Spare exhaler volume-1500 ml (additional air volume that can be expired following a forced exhalation, after the expiration of the current volume)
- Residual volume-1500 ml (volume of air remaining in the lungs and after forced breathing)
- Inspiratory capacity-2000 ml (sum of current volume and back-up volume, representing the amount of air a person can breathe at normal expiratory level until maximum lung distension)
- Functional residual capacity-3000 ml (sum of the back-up expiratory volume and the residual volume, representing the remaining air capacity in the lungs at the end of a normal exhalation)
- Total lung capacity
- Vital capacity
THE LUNGS
The lungs are in the chest and are trapped by it through the pleura. Each lung has a pleura made up of two overlapping sheets, glued together by a film of fluid, which increases the adhesion of the lungs to the chest. The lungs are formed from lung tissue and the bronchial tree.
Lung tissue is spongy, with many blood vessels and includes pulmonary subdivisions: lobes, segments, lobules and lung acins made up of numerous pulmonary alveoli. The walls of the alveoli are thin, lined with a liquid and surrounded by networks of blood vessels to allow blood to oxygenate. The bronchial tree consists of branches of the main bronchi, from which its name comes. The first, wider branches are called bronchi, and the deeper, narrower branches are called bronchioles.
