What is the difference between alveoli and capillaries

This results in a lower concentration of oxygen in the lungs than is found in the air outside the body. In the lungs, oxygen diffuses out of the alveoli and into the capillaries surrounding the alveoli. Oxygen about 98 percent binds reversibly to the respiratory pigment hemoglobin found in red blood cells.

These red blood cells carry oxygen to the tissues where oxygen dissociates from the hemoglobin, diffusing into the cells of the tissues. Since this pressure gradient exists, oxygen can diffuse down its pressure gradient, moving out of the alveoli and entering the blood of the capillaries where O 2 binds to hemoglobin. Due to this gradient, CO 2 diffuses down its pressure gradient, moving out of the capillaries and entering the alveoli.

Oxygen and carbon dioxide move independently of each other; they diffuse down their own pressure gradients. The primary function of the respiratory system Overview of the Respiratory System To sustain life, the body must produce sufficient energy. Energy is produced by burning molecules in food, which is done by the process of oxidation whereby food molecules are combined with Inhaled oxygen enters the lungs and reaches the alveoli.

The layers of cells lining the alveoli and the surrounding capillaries are each only one cell thick and are in very close contact with each other. Oxygen passes quickly through this air-blood barrier into the blood in the capillaries. Similarly, carbon dioxide passes from the blood into the alveoli and is then exhaled. Oxygenated blood travels from the lungs through the pulmonary veins and into the left side of the heart, which pumps the blood to the rest of the body see Function of the Heart Function of the Heart The heart and blood vessels constitute the cardiovascular circulatory system.

The heart pumps the blood to the lungs so it can pick up oxygen and then pumps oxygen-rich blood to the body Oxygen-deficient, carbon dioxide-rich blood returns to the right side of the heart through two large veins, the superior vena cava and the inferior vena cava. Then the blood is pumped through the pulmonary artery to the lungs, where it picks up oxygen and releases carbon dioxide. The function of the respiratory system is to add oxygen to the blood and remove carbon dioxide.

The microscopically thin walls of the alveoli allow inhaled oxygen to move quickly and easily from the lungs to the red blood cells in the surrounding capillaries. They inflate when a person inhales and deflate when a person exhales. During gas exchange oxygen moves from the lungs to the bloodstream. At the same time carbon dioxide passes from the blood to the lungs.

This happens in the lungs between the alveoli and a network of tiny blood vessels called capillaries, which are located in the walls of the alveoli. Here you see red blood cells traveling through the capillaries. The walls of the alveoli share a membrane with the capillaries. A hyperbaric chamber is a unit that can be sealed and expose a patient to either percent oxygen with increased pressure or a mixture of gases that includes a higher concentration of oxygen than normal atmospheric air, also at a higher partial pressure than the atmosphere.

There are two major types of chambers: monoplace and multiplace. Monoplace chambers are typically for one patient, and the staff tending to the patient observes the patient from outside of the chamber. Some facilities have special monoplace hyperbaric chambers that allow multiple patients to be treated at once, usually in a sitting or reclining position, to help ease feelings of isolation or claustrophobia.

Multiplace chambers are large enough for multiple patients to be treated at one time, and the staff attending these patients is present inside the chamber. In a multiplace chamber, patients are often treated with air via a mask or hood, and the chamber is pressurized. Hyperbaric chamber treatment is based on the behavior of gases. As you recall, gases move from a region of higher partial pressure to a region of lower partial pressure. In a hyperbaric chamber, the atmospheric pressure is increased, causing a greater amount of oxygen than normal to diffuse into the bloodstream of the patient.

Hyperbaric chamber therapy is used to treat a variety of medical problems, such as wound and graft healing, anaerobic bacterial infections, and carbon monoxide poisoning.

Hyperbaric chamber therapy can treat carbon monoxide poisoning, because the increased atmospheric pressure causes more oxygen to diffuse into the bloodstream. At this increased pressure and increased concentration of oxygen, carbon monoxide is displaced from hemoglobin.

Another example is the treatment of anaerobic bacterial infections, which are created by bacteria that cannot or prefer not to live in the presence of oxygen. An increase in blood and tissue levels of oxygen helps to kill the anaerobic bacteria that are responsible for the infection, as oxygen is toxic to anaerobic bacteria. For wounds and grafts, the chamber stimulates the healing process by increasing energy production needed for repair. Increasing oxygen transport allows cells to ramp up cellular respiration and thus ATP production, the energy needed to build new structures.

The greater the partial pressure of a gas, the more of that gas will dissolve in a liquid, as the gas moves toward equilibrium. Gas molecules move down a pressure gradient; in other words, gas moves from a region of high pressure to a region of low pressure. The partial pressure of oxygen is high in the alveoli and low in the blood of the pulmonary capillaries.

As a result, oxygen diffuses across the respiratory membrane from the alveoli into the blood. In contrast, the partial pressure of carbon dioxide is high in the pulmonary capillaries and low in the alveoli. Therefore, carbon dioxide diffuses across the respiratory membrane from the blood into the alveoli. The amount of oxygen and carbon dioxide that diffuses across the respiratory membrane is similar.

Ventilation is the process that moves air into and out of the alveoli, and perfusion affects the flow of blood in the capillaries. Both are important in gas exchange, as ventilation must be sufficient to create a high partial pressure of oxygen in the alveoli. If ventilation is insufficient and the partial pressure of oxygen drops in the alveolar air, the capillary is constricted and blood flow is redirected to alveoli with sufficient ventilation.

External respiration refers to gas exchange that occurs in the alveoli, whereas internal respiration refers to gas exchange that occurs in the tissue. Both are driven by partial pressure differences. Answer the question s below to see how well you understand the topics covered in the previous section. Skip to main content. Module 6: The Respiratory System. Search for:.