Introduction to structure of the lungs
The lungs are the respiratory organs present in all air breathing animals. In humans a pair of lungs are located in the chest region on either side of the heart. The lungs helps the human body to take in the oxygen and to release carbon dioxide. The lungs of the humans are filled with about 90% air and 10% tissue.
In humans they are divided into lobes. The right human lung has three lobes and the upper and middle lobe of the right lungs are separated by a transverse fissure. The middle and the lower lobes of the right lungs are separated by a oblique fissure.
The left human lung contains only two lobes, the right lobe and a left lobe and these are lobes are separated by a gap called oblique fissure.
The left lung in humans is little bit smaller than the right lung. The space present between the right and left human lung is known as mediastinum. Lungs are cone shaped organs with a apex and the base. The apex of lungs is rounded and the base is broader than apex and concave in shape. The lung is porous with a spongy texture and is highly elastic in nature. The surface of the lung is smooth and appears shiny.
The air inhaled through the nostrils passes through the trachea and enters into the bronchi. The bronchi are the two tubes that carries air to the lungs. The bronchi further splits into smaller branches called bronchioles.
Bronchioles further divide again in to tiny structures to form respiratory bronchioles which will lead to the alveolar ducts. These finally leads to the minute air sacs called alveoli the unit structure of the lungs. Alveoli are the basic functional units of lungs and are lined with the simple squamous epithelial cells. Alveoli covers the area about 60-70m.
Alveoli are the microscopic structure of the lungs or units where the oxygen is exchanged for carbon dioxide from the bloodstream. The lungs are guarded by the fluid cushioning system known as the pleura which also separates the lung from the chest cavity.
The diaphragm is a muscle that is found below the lungs. During inspiration (breathin in of air) the diaphragm contracts which allows the chest cavity to expand the lungs gets filled with air. Muscles between the ribs are known as intercostals muscles. They work in along with the diaphragm for pulling down the rib cage away from chest cavity so that lungs are filled with air.
Abdominal muscles also helps with the function of lungs. When a person breathes due to its physical activity the muscles of abdomen push against the diaphragm to increase speed of exhalation. The lungs also depends on the muscles that are present in neck region and collarbone.