What occurs at the alveoli and pulmonary capillaries?
Alveoli are the smallest airways and the functional units of the lungs. At the alveolar level, gas exchange takes place.Capillaries are the smallest blood vessels. Their walls are only one cell layer thick.Alveoli are surrounded by numerous capillaries. The walls of these two structures are in very close proximity.The heart pumps venous blood that is low in oxygen and high in carbon dioxide to the pulmonary capillaries.The air that we breathe is high in oxygen and low in carbon dioxide.Partial pressure of oxygen:Alveolar air = 100 mmHgVenous blood = 40 to 50 mmHgPartial pressure of carbon dioxide:Alveolar air = 35 mmHgVenous blood = 50 mmHgThe differences in concentrations of oxygen and carbon dioxide between the venous blood and alveolar air aids in the transfer of these gasses.The gasses diffuse from an area of high concentration to an area of low concentration i.e. the transfer happens along the concentration gradient.Thus, oxygen diffuses from alveoli into the capillaries while carbon dioxide diffuses from the capillaries into alveoli.Once the oxygen diffuses into the capillaries, it binds to the hemoglobin in the red blood cells (RBC). Each hemoglobin molecule binds to 4 oxygen atoms.The oxygenated blood then returns to the left-side of the heart from where it is pumped to the rest of the body.The process looks fairly simple but the oxygen and carbon dioxide molecules travel through various layers of cell/tissue/fluid between the alveoli and the capillaries. Any pathological changes in these layers will affect the efficiency of the entire process.Image: Khan Academy
How does oxygen and carbon dioxide diffusion occur in the lungs?
Q: How does oxygen and carbon dioxide diffusion occur in the lungs?A: Google to the rescue:Source: Exchanging Oxygen and Carbon Dioxide - Lung and Airway Disorders - Merck Manuals Consumer VersionThe primary function of the respiratory system is to exchange oxygen and carbon dioxide. 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. This barrier between air and blood averages about 1 micron (1/10,000 of a centimeter, or 0.000039 inch) in thickness. 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 Biology of the Heart : Function of the Heart). 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.Gas Exchange Between Alveoli and CapillariesTo support the exchange of oxygen and carbon dioxide, about 5 to 8 liters (about 1.3 to 2.1 gallons) of air per minute are brought in and out of the lungs, and about three tenths of a liter of oxygen is transferred from the alveoli to the blood each minute, even when the person is at rest. At the same time, a similar volume of carbon dioxide moves from the blood to the alveoli and is exhaled. During exercise, it is possible to breathe in and out more than 100 liters (about 26 gallons) of air per minute and extract 3 liters (a little less than 1 gallon) of oxygen from this air per minute. The rate at which oxygen is used by the body is one measure of the rate of energy expended by the body. Breathing in and out is accomplished by respiratory muscles.
What are the functions of alveoli? How do they carry out this function?
The alveoli provide one of the most important functions our bodies perform. They're the gateway through which oxygen enters our bloodstream and the primary way in which some of the waste products of metabolism (carbon dioxide) exit the body.Structure in brief :-Alveoli are tiny balloon shaped structures and are the smallest passageway in the respiratory system. The alveoli are only one cell thick, allowing the relatively easy passage of oxygen and carbon dioxide (CO2) between the alveoli and blood vessels called capillaries.In the lungs, air is diverted into smaller and smaller microscopic branches called respiratory bronchioles, which connect to the alveolar ducts. At the end of each duct are approximately 100 alveolar sacs, each containing 20 to 30 alveoli that are 200 to 300 µm in diameter.Each alveolar membrane is one cell thick and is in direct contact with capillaries that are also one cell thick.There are about 600 million alveoli in the lungs, with a total surface area of about 75 m2.Mechanism of gas exchangeAs Alveoli are the endpoint of the respiratory system which starts when we inhale air into the mouth or nose. The oxygen-rich air travels down the trachea and then into one of the two lungs via the right or left bronchus. From there, the air is directed through smaller and smaller passages, called bronchiloes, past the alveolar duct, until it finally enters an individual alveolus.How do alveoli adapted to carry out this functionThe large alveolar surface area, combined with the thin membranes, allows gases to diffuse easily across the alveolar walls.The diameter of the capillaries surrounding the alveoli is so small that only one red blood cell can pass through at a time.This slows down the blood cells, so that gases have more time to diffuse through the capillaries.It also forces the red blood cells close to the walls of the capillaries, decreasing the diffusion distance.Hope this helps :)Thanks for the A2A John.
Why do the lungs and the small intestines need a large surface area? What are the tasks they perform?
the surface area in your lugs are covered with alveolar or small capillary like structures that allow blood to absorb oxygen and give off carbon dioxide. the more surface area for these structures to cover allows more absorbency of oxygen and dissipation of carbon dioxide. typically lungs contain more alveolar than minimum because of their delicate nature. they can easily be affected by chemicals, pollution, and small particulates. the small intestine needs a large amount of surface area because they are the only stage in our digestive system that actually absorbs nutrients. the more surface area the greater absorption of nutrients and more efficient our digestion will be. hope this helps!
Which is the site of gaseous exchange in lungs?
alveoli
What is external respiration? Where does it occur?
External respiration is the processes by which external air is drawn into the body in order to supply the lungs with oxygen, and air is expelled from the lungs in order to remove carbon dioxide from to body.External respiration or pulmonary gas exchange takes place in the lungs, between the external surroundings and the blood capillaries of the lungs. External respiration removes carbon dioxide from the blood and refills the blood with oxygen. The exchange of gas is taken due to a pressure gradient.The gases circulate from the air into the capillary blood of lungs owing to the difference in the partial pressures of the two gases. Exchange of CO2 with oxygen cannot occur if the pressures of the gases are the same. The pressure of a gas is a function of the concentration of that gas in the mixture. The movement of gas occurs from its high concentration area to the area of its low concentration. As the oxygen concentration is higher in the air than in the blood, it diffuses into the blood.
Tour through the Respiratory System fill-in-the-blanks?
1. When air comes into your ____ it gets ____ by tiny hairs and it is ___ by the mucus in your nose. 2. Air can also get into your body through your ___, but it is not filtered as much as it is when it enters your nose. 3. The air heads down your ____(throat) and your ___ (windpipe), which is help open by "_________". 4. Your trachea splits up into ___ bbrronchi tubes, which in turn split up to form _________. 5. Broncholes split and become smaller and smaller until they finally end with small air sacs called _____. 6. Alveoli are surrounded by tiny blood vessels called ______. The walls of the alveoli and capillaries are so thin that the oxygen or carbon dioxide can _________________. 7. To make all of this happen, a special muscle called the ______ is involved. The lungs expand and contract in response to ______ inside of the chest cavity, caused by movement of the diaphragm.