The lungs are located in the thoracic cavity and they are protected by twelve pairs of ribs that join at the sternum. When air is breathed into the lungs oxygen penetrates the red blood cells and is carried around the body. Expiration of the lungs allows the body to emit carbon dioxide. Each individual has two lungs, the right and the left, which is divided by the mediastinum. Each lung has an apex, base, tip, costal surface and medial surface. The right lung is larger than the left as the heart takes up more area left of the midline. The lungs are split into lobes which are caused by large fissures, the right lung has three lobes and the left lung has two lobes.
Surrounding the lungs is the pleural cavity. The pleural space has two coverings, the visceral pleura and the parietal pleura. A collapsed lung is generated by air entering the pleural space.
…show more content…
The anterior and lateral walls of the trachea are made of cartilage and the posterior wall is made up of elastic ligament. The trachea is circular and is covered with columnar epithelium. The air then passes through the two main bronchi supplied to each lung and then on into the bronchioles ending up in the small alveoli which are little sacs.
Gas exchange takes place by a process called diffusion which is when the gases move from a high concentration to a low concentration. Diffusion takes place through the alveoli and the blood. The cell wall is only one cell thick so allows diffusion to take place. During inspiration the chest inflates and this is caused by the intercostals muscles and the diaphragm contracting. Expiration is exactly the opposite process as the intercostal muscles and diaphragm reclines, the chest reduces in