GAS EXCHANGE Giacomo Leso

Gas Exchange In Lungs

During gas exchange in the lungs, oxygen diffuses from the alveoli to capillaries while carbon dioxide moves in the opposite direction. The blood flow between the heart and the lungs is the pulmonary circulation. The tissues of the rest of the body are supplied by circulation. Oxygen diffuses to the tissues and carbon dioxide diffuses into the capillaries.

Oxygen is carried in the blood bound to hemoglobin in the red blood cells. Carbon dioxide dissolves in the plasma, where most of it forms carbonic acid. Carbon dioxide also moves into red blood cells where it combines with hemoglobin.

Why do we need mucus and cilia? The bronchus in the lungs are lined with hair-like protections called cilia that move microbes up and out of the airways. Scattered throughout the cilia are goblet cells that secrete mucus which helps protect the lining of the bronchus and trap microorganisms. The purpose of mucus is to lubricate and protect the organs that it lines. (Mucus is supposed to be thin, clear, and watery. Cloudy, yellow, or green mucus are signs of an infection.)

How does smoke affects our respiratory system? The effects of smoking includes the introduction of tar particles into the respiratory system. This sticky substances not only stains the teeth and fingernails, but also leaves a residue on the delicate lung tissue. Carcinogen benzopyrene in tar is a cancer trigger. Although carbon monoxide is an odorless gas, it is fatal for inhalation because it replaces vital oxygen in the blood. Since it binds with hemoglobin faster and better than oxygen, the result is a reduced quantity of oxygen reaching important organs like the heart and brain.

Hydrogen cyanide is another toxic substance that enters the respiratory system through smoking. It damages the lung-clearance-system and facilitates the build up of hydrocarbons, nitrous oxides and oxidizing agents within the lungs. The reactive chemicals damage the blood vessels and the heart, leading towards heart disease and stroke. Tobacco also contains metals like cadmium and lead, which are carcinogenic in nature. Smoking facts reveal that all these inhalants cause damage to the trachea, larynx and lung function. Long term effects include narrowing of the lung airways, increased risk of lung infection, high blood pressure, blood prone to clotting, increased risk of stroke, damage to the immune system and reduced bone density.

Testing for CO ₂ Add equal parts of lime water and distilled water to the container. Bubble CO2 through the lime water solution until the precipitate is well established (20-30 seconds), and then remove the tube and discuss the precipitate. Continue to bubble CO2 through the solution until the precipitate just disappears. Fill the test tube about of the way full with the solution

Begin bubbling air through the remainder of the solution, using the glass tube from the generator. Boil the solution for a couple of minutes with the Bunsen burner. The precipitate with reappear almost at once, but it takes about minutes for the solution through which air is being bubbled to turn cloudy.

QUESTIONS: Why do we need cilia and mucus? What effects does smoke have on our respiratory system? Describe briefly how do we test for CO ₂.

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