All cells of the body constantly need oxygen. The respiratory (breathing) system supplies the body with oxygen, which is found in the atmospheric air. The air we breathe contains 21 percent oxygen. When a person inhales, air fills the lungs and oxygen enters the blood. Oxygenated blood flows to the heart, which pumps the blood, distributing it to all parts of the body. In the lungs, carbon dioxide is removed from the blood and eliminated from the body when you exhale. This process is called respiratory (breathing) activity.
Our body uses only one quarter of the oxygen received during inhalation. Exhaled air contains 16 percent
oxygen sufficient to provide oxygen to the victim during artificial ventilation.
The respiratory organs include the airways and lungs (Figure 5-1). Air passes through the nasal and oral cavities, entering the trachea. A piece of tissue called the epiglottis covers the trachea during swallowing, preventing food and liquid from entering the lungs.
From the trachea, air enters the lungs through two tubes called bronchi. The bronchi become smaller branches, like the branches of a tree (Fig. 5-2A). These processes end in millions of tiny air sacs called alveoli. Due to the thin walls of the alveoli and capillaries, oxygen enters the blood and carbon dioxide is removed from it.
Air enters the lungs when you inhale and leaves the lungs when you exhale.
When a person inhales, the pectoral muscles and diaphragm expand the chest and draw air into the lungs. When you exhale, the pectoral muscles and diaphragm relax, allowing air to escape from the lungs. An adult consumes about one and a half liters of air with one breath. The average person at rest takes from 10 to 20 breaths per minute. The breathing process is controlled by the nervous system.
To ensure proper breathing, the functioning of the circulatory, respiratory, nervous and musculoskeletal systems is required. Any injury or disease that impairs the functions of these systems can cause respiratory problems. For example, when the heartbeat stops, the victim stops breathing. Injury or disease to a specific part of the brain can lead to breathing problems or stoppage. Damage to the muscles or bones of the chest and back makes breathing difficult or painful. All these situations can cause acute respiratory failure.
When breathing stops, the body no longer receives oxygen and cannot continue to function normally. After several minutes of oxygen starvation, disturbances in the functioning of the body's systems occur. The person loses consciousness within a minute and eventually the heart muscle stops contracting, after which the crisis spreads to other life support systems. In the absence of oxygen, the body's cells begin to die within four to six minutes.
4-6 minutes: Possible brain damage
6-10 minutes: definite brain damage
More than 10 minutes: permanent brain damage
Time is of the essence in emergency situations. If the brain does not receive oxygen within a few minutes of stopping breathing, permanent brain damage or death occurs.
Some tissues, such as the brain, are very sensitive to oxygen deprivation. If the brain does not receive oxygen within a few minutes, it will become damaged or die.