The respiratory system is composed of two mutually interdependent processes of the physical movement of air in and out of the lungs, and the exchange of oxygen for carbon dioxide. Words like respiration, breathing, ventilation and oxygenation are used interchangeably when trying to describe the physical from the functional parts of the system. The two can function separately but rely on each other to keep the cells of your body functioning.
Breathing
Breathing is a part of your respiratory system that describes the physical movement of air in and out of the lungs. Movement is accomplished by the contraction of the diaphragm creating a pressure less than atmospheric pressure resulting in an in-rush of air through the nose, a tube called the trachea, into the lungs and stopping at tiny little air sacs called alveoli. According to The Franklin Institute, the average adult has more than 600 million of these spongy sacs that are surrounded by small vessels called capillaries. At the peak of a breath, the diaphragm relaxes, causing an out-rush of air from a higher than atmospheric pressure in the chest out through the same pathway to the atmosphere. This function is also referred to as ventilation.
External Respiration
Respiration is the part of the respiratory system that is functional movement of oxygen from the air you breathe in exchange for carbon dioxide at the alveolar level. Exchange of gases like oxygen and carbon dioxide rely on the physical movement of air, however, it is the principles of diffusion that cause the exchange. According to Cartage, diffusion is the movement of gases from a higher concentration to a lower concentration. During inhalation, the concentration of oxygen is higher than that in the capillary blood, resulting in diffusion of oxygen from the alveolar sac, across the membrane and attach to the red blood cells. Conversely, the capillary blood is higher in carbon dioxide that the alveolar air, causing a diffusion from the blood, across the membrane and into the sac to be exhaled.
Cellular Respiration
Cellular respiration is an internal process where each of the cells of your body exchanges oxygen with carbon dioxide. The oxygen is used for a metabolic process to generate energy. According to biologist John Kimball's online textbook, cellular respiration is the oxidation of fuels, such as glucose, into cellular fuel called adenosine triphosphate, or ATP, and producing the byproducts of carbon dioxide and water. The principles of diffusion apply; the blood reaching the capillaries of your body tissues is oxygen rich, causing diffusion from the blood stream to the cells in exchange for the high concentration of cellular carbon dioxide from the cell to the blood to be taken to the lungs to exhale. This function is also referred to as oxygenation.
Breathing Without Respiration
The physical movement of air into the lungs can occur without the functional movement of gases, such as in the case of pulmonary embolism. Pulmonary embolism, or PE, occurs when clots in the body break loose and migrate into the lungs, causing blockage of the pulmonary blood vessels. Blockage of vessels prohibits oxygen rich blood cells from reaching the capillaries to exchange gases. Other causes of pulmonary vessel blockage include lung masses pushing on vessel walls, and a condition called chronic obstructive pulmonary disorder, or COPD, that causes scarring of the alveolar sacs.
Respiration Without Breathing
The functional movement of gases can also occur without the physical movement of air in and out of the lungs. The principle of diffusion occurs within the body at any level there is a higher concentration of molecules on one side of a membrane than the other. According to the American Heart Association, layperson CPR has been shown to be effective without providing respirations initially because of the remaining amount oxygen levels still in the blood. Chest compressions allow the still oxygen-rich blood to reach the capillaries and cause gas exchange.
