Your lungs

hOW YOUR LUNGS WORK

Parts of the Lungs. Human beings have two lungs--a left lung and a right lung--which fill up most of the chest cavity. A lung has a spongy texture and may be thought of as an elastic bag filled with millions of tiny air chambers called alveoli. If the walls of the alveoli could be spread out flat, they would cover about half a tennis court. The somewhat bullet-shaped ungs are suspended within the ribcage. They extend from just above the first rib down to the diaphragm, a muscular sheet that\par separates the chest cavity from the abdomen. A thin, tough membrane called the visceral pleura covers the outer surface of the lungs. The heart, large blood vessels, and esophagus (the tube connecting the mouth and stomach) lie between the two lungs. The lungs are designed to receive air, which enters the body through the mouth or nose. The air passes through the pharynx (back of the nose and mouth) and the larynx (voice box) and enters the bronchial tree--a system of tubes that leads to the alveoli. The largest of these tubes is the trachea (windpipe), which divides into two smaller tubes called bronchi. Each bronchus leads to one lung. Within the lung, the bronchus divides further into smaller and smaller tubes, much as a tree limb divides into branches and twigs. The final "twigs" are tiny tubes called bronchioles. The smallest bronchioles, called terminal bronchioles, lead to the respiratory units of the lung. The respiratory units are made up of many alveolar ducts. Each duct supplies about 20 alveoli. The very thin walls of each alveolus contain networks of extremely small blood vessels called pulmonary capillaries. Gas is exchanged between the blood in these capillaries and the gas in the alveoli. Three to five terminal bronchioles and the alveoli that they supply with air form a lobule. Many lobules unite to form the major subdivisions of the lung, called lobes. The left lung has two lobes, and the right lung has three. Each lobe has its own branches of bronchi and blood vessels, so a diseased lobe may be removed without sacrificing the usefulness of the other lobes. Blood reaches the lung through two routes. Almost all of the blood comes through the pulmonary circulation. This blood has already circulated through the body tissues, where it has given up oxygen and picked up carbon dioxide. A small amount of blood reaches the lungs through the bronchial circulation. This blood is rich in the oxygen and nutrients that the airway tissues--like all other body tissues--need.

hOW to KEEP YOUR LUNGS HEALTHY

IF YOU WANT TO KEEP YOUR LUNGS HEALTHY YOU SHOULD NOT SMOKE BECAUSE RIGHT NOW IF YOU DO NOT SMOKE YOUR LUNGS ARE HEALTHY AND THE COLOR OF THEM ARE PINK BUT OF YOU SMOKE YOUR LUNGS WILL TURN BLACK AND ULGY.

ABOUT YOUR LUNGS

LUNG is the breathing organ of mammals, birds, and reptiles. Most adult amphibians also have lungs. The main job of the lungs is to exchange gases. As blood flows through the lungs, it picks up oxygen from the air and releases carbon dioxide. The body needs oxygen to obtain energy from food, and it produces carbon dioxide as a waste product. This article discusses the human lungs, but the lungs of other animals function in a similar way.

(SOME OF THIS INFORMATION FROM "THE WORLD BOOK")

(I WOULD LIKE TO THANK WORLD BOOK BECAUSE A LOT OF THIS INFORMATION IS FROM THE WORLD BOOK :)

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