How is the majority of carbon dioxide transported?
Third, the majority of carbon dioxide molecules (85 percent) are carried as part of the bicarbonate buffer system. In this system, carbon dioxide diffuses into the red blood cells. Carbonic acid is an unstable, intermediate molecule that immediately dissociates into bicarbonate ions (HCO3−) and hydrogen (H+) ions.
Carbon dioxide is transported in the blood from the tissue to the lungs in three ways:1 (i) dissolved in solution; (ii) buffered with water as carbonic acid; (iii) bound to proteins, particularly haemoglobin. Approximately 75% of carbon dioxide is transport in the red blood cell and 25% in the plasma.
- Oxygen enters the blood from the lungs and carbon dioxide is expelled out of the blood into the lungs. The blood serves to transport both gases. Oxygen is carried to the cells. Carbon dioxide is carried away from the cells.
- Oxygen is transported in the blood in two ways: A small amount of O 2 (1.5 percent) is carried in the plasma as a dissolved gas. Most oxygen (98.5 percent) carried in the blood is bound to the protein hemoglobin in red blood cells. A fully saturated oxyhemoglobin (HbO 2) has four O 2 molecules attached.
- Respiratory failure also can occur if your lungs can't properly remove carbon dioxide (a waste gas) from your blood. Too much carbon dioxide in your blood can harm your body's organs. Both of these problems—a low oxygen level and a high carbon dioxide level in the blood—can occur at the same time.
Hemoglobin: The protein inside red blood cells (a) that carries oxygen to cells and carbon dioxide to the lungs is hemoglobin (b). Hemoglobin is made up of four symmetrical subunits and four heme groups. Iron associated with the heme binds oxygen.
- Functionally, the respiratory system is separated into a conducting zone and respiratory zone. The conducting zone consists of the nose, pharynx, larynx, trachea, bronchi, and bronchioles. These structures form a continuous passageway for air to move in and out of the lungs.
- Oxygen is absorbed by the blood capillaries from the lungs alveoli by diffusion while carbon-dioxide is absorbed by the lungs alveoli from blood capillaries by diffusion. Transport of oxygen and carbon-dioxide occurs with the help of respiratory pigment called hemoglobin.
- Some of the carbon dioxide is transported dissolved in the plasma. Some carbon dioxide is transported as carbaminohemoglobin. However, most carbon dioxide is transported as bicarbonate. As blood flows through the tissues, carbon dioxide diffuses into red blood cells, where it is converted into bicarbonate.
Updated: 21st September 2018