7 The Respiratory System

THE RESPIRATORY SYSTEM

WHAT IS RESPIRATION? Whether you know it or not, you are breathing right now... To do so, you need us— Your LUNGS! When you breathe in, you take in oxygen from the air. Oxygen is a gas that your body needs in order to live.

The cells of the body need oxygen to break down food and use energy. As this happens, wastes like carbon dioxide gas are formed. When you breathe out, you get rid of carbon dioxide. This process of using oxygen is called respiration. Your lungs and other body parts allow you to breathe. Together, these body parts make up the respiratory system!

THE RESPIRATORY SYSTEM Several organs and muscles make up the respiratory system. The nose and mouth connect to a large tube called the trachea, or windpipe. The trachea begins at the back of the mouth, runs down the neck into the upper chest, and splits into two smaller tubes... ...called bronchi. Each of these tubes leads to the lungs.

Muscles and bones also play an important role in respiration. The chest wall includes bones that form a protective cage around the chest cavity, muscles associated with these bones, and the abdominal muscles. The diaphragm is a dome-shaped sheet of muscle that separates the chest area from the abdomen. Without these bones and muscles, you would not be able to take a single breath!

INHALATION AND EXHALATION Breathing consists of two acts: breathing in, or inhalation... ...and breathing out, or exhalation. When you inhale, the diaphragm and the muscles of the chest wall contract. This action lifts the ribs and makes the chest cavity longer and wider, causing the lungs to expand and draw in air. The lower parts of each lung contain elastic fibers in the walls of the airways. When you inhale and the lungs expand, these elastic tissues stretch- -like an inflating balloon.