Prepared by: Sabita k.c.

Submitted to: Anil Sir

Materials required: One plastic jug, Plastic tube, Plastic bags, and a rubber sheet.

Principal: Due to changes in pressure inside the lungs, the contraction of lungs takes place.

Procedure: Take two plastic bags. Make them in the shape of lungs and connect this plastic tube as shown in figure. Tie these plastic bags with plastic tightly so that you can make it air tight in the joints. Now take a white plastic jug and make a small hole in the jug. Now place your plastic lungs inside the jug as shown in the figure Cut a sheet a rubber bladder and close the mouth of jug with bladder. Tie the bladder tightly so that you can make the jug air tight. Now your model of lungs is ready. Observe the movement of lungs, pressing on the rubber bladder.

Conclusion: The air contains inside the plastic bags, comes outside through the plastic tube, when you press on the lubber sheet. It results to the contraction of lungs. When you leave to press on the rubber sheet, it results expansion of lungs. By similar process, we inhale and exhale oxygen through windpipe. Then movement of diaphragm acts as the function rubber sheet.

Respiration is a two-fold process whereby the interchange of gases takes place in the tissue which is called the “Internal respiration” and in the lungs “External respiration” takes place. The exchange of gases between the blood and lungs is called the external respiration and the one that takes place between the blood and the cells is called internal respiration.

The nose or nasal cavityThe pharynxThe larynxThe trachea or windpipeThe bronchiThe bronchiolesThe lungsDiaphragm and Intercostals muscles.

The process of breathing is generally divided into two phases, inspiration and expiration. In inspiration, air is moved into the lungs. In expiration, air is forced out of the lungs. The lungs themselves have no muscle tissue. Their movements are controlled by the rib cage and the diaphragm. During inspiration the muscles around the rib cage contract, lifting the ribs upward and outward, and lowering the dome of the diaphragm until it forms a nearly flat sheet. As a result of these changes, the chest cavity expands. Because the lungs are attached to the chest cavity, they also expand. With the enlargement of the lungs, air pressure inside the lungs falls below the pressure of the air outside the body, creating a partial vacuum, and air from outside the body rushes into the lungs.

Lung, either of a pair of elastic, spongy organs used in breathing and respiration. Lungs are present in all mammals, birds, and reptiles. Most amphibians and a few species of fish also have lungs.In humans the lungs occupy a large portion of the chest cavity from the collarbone down to the diaphragm, a dome-shaped sheet of muscle that walls off the chest cavity from the abdominal cavity. At birth the lungs are pink, but as a person ages, they become gray and mottled from tiny particles breathed in with the air. Generally, people who live in cities and industrial areas have darker lungs than those who live in the country.Air travels to the lungs through a series of air tubes and passages. It enters the body through the nostrils or the mouth, passing down the throat to the larynx, or voice box, and then to the trachea, or windpipe. In the chest cavity the trachea divides into two branches, called the right and left bronchi or bronchial tubes, that enter the lungs.In the adult human, each lung is 25 to 30 cm (10 to 12 in) long and roughly conical. The left lung is divided into two sections, or lobes: the superior and the inferior. The right lung is somewhat larger than the left lung and is divided into three lobes: the superior, middle, and inferior. The two lungs are separated by a structure called the mediastinum, which contains the heart, trachea, esophagus, and blood vessels. Both right and left lungs are covered by an external membrane called the pleura. The outer layer of the pleura forms the lining of the chest cavity.

In addition to the network of air tubes, the lungs also contain a vast network of blood vessels. Each alveolus is surrounded by many tiny capillaries, which receive blood from arteries and empty into veins. The arteries join to form the pulmonary arteries, and the veins join to form the pulmonary veins. These large blood vessels connect the lungs with the heart.

The lungs are subject to a number of disorders, with symptoms that may include difficulty in breathing, chest pain, coughing, and wheezing. Lung cancer, most commonly caused by smoking tobacco, is the deadliest lung disease, and each year it kills more Americans than any other kind of cancer. Smoking tobacco may also lead to emphysema, which is caused by wholesale destruction of alveoli. Other lung disorders include pneumonia, or inflammation of the lungs, which is usually caused by viruses or bacteria; pneumothorax, or collapse of the lung; pulmonary edema, or fluid in the lung; and pleural effusion, or fluid on the pleura. Pulmonary embolism occurs when a blood clot or other foreign substance lodges in the lungs and blocks the major pulmonary arteries.

Prepared by: Sabita k.c.

Helped by: Rajesh k.c.