Properties of Lung Tissue

Physical Factors Influencing Pulmonary Ventilation

As we have seen, the lungs are stretched during inspiration and recoil passively during expiration. The inspiratory muscles consume energy to enlarge the thorax. Energy is also used to overcome various factors that hinder air passage and pulmonary ventilation. These factors are listed below.

Changes in volume

Lung Volumes

There are several lung volumes and capacities that are useful to understand respiratory physiology and they are briefly described below.

Tidal Volume

Is the amount of air that moves into the lungs with each inspiration (or the amount that moves out of the lungs with each expiration). 

Location, Relation and Structure - Part 2

The Thoracic cage

The thoracic cage is formed by the vertebral column behind, the ribs and intercostal spaces on either side laterally and the sternum and costal cartilages anteriorly in front. Above, it communicates with the root of the neck through the ‘thoracic inlet’; and below, it is separated from the abdominal cavity by the diaphragm. 

                                                                      (The thorax)

Location, Relation and Structure

The Thoracic Cavity

The structure and functions of the major organs of the respiratory system are described below:

(Right median saggital section of the head showing the upper portion of the respiratory tract) 

The structures of the nose are divided into the external nose and the internal nasal cavity.

The surface features of the external nose include the root (area between the eyebrows), bridge, and dorsum nasi (anterior margin). The external openings of the nose, the nostrils or nares, are bounded laterally by the flared alae.

The internal nasal cavity lies in and posterior to the external nose. The nasal cavity is divided by a midline nasal septum, The nasal cavity continues posteriorly with the nasal portion of the pharynx through the posterior nasal apertures. It is lined by the mucosa which secretes mucus. The roof of the cavity has olfactory (smell) receptors.

Anatomy of Respiratory System

                                         

                                                 A human being can survive without food for as much as several weeks and without water for several days, but the body cannot survive without air even for three to six minutes.  A constant supply of oxygen to the tissues of the body (especially to the heart and brain) is essential to maintain life. To supply this air, respiration continues to occur from the moment a new born infant takes its first breath until the death of the individual.