• Question: How is carbon dioxide removed from blood before it is exhaled?

    Asked by khughes08 to Hermine, Katy, Laura, Nathalie, Paula on 16 Jun 2010 in Categories: .
    • Photo: Nathalie Pettorelli

      Nathalie Pettorelli answered on 14 Jun 2010:

      http://www.scholarshipsinindia.com/answer/removing_of_CO2_from_blood.html
      Better explained than what I could ever write 😉

    • Photo: Paula Salgado

      Paula Salgado answered on 14 Jun 2010:

      When carbon dioxide diffuses into the blood plasma and then into the red blood cells, most of it eacts with water

      H2O + CO2 H2CO3

      H2CO3, dissociates to form hydrogen ions and hydrogencarbonate ions in a dynamic equilibrium:

      H2CO3 H+ + HCO3-

      Negatively charged HCO3- ions diffuse from the cytoplasm of red blood cells to the plasma, increasing the pH of the blood.

      Hydrogen ions, H+, then react with haemoglobin charged with oxygen, releasing it to reduce the acidity of the blood.

      Hb.4O2 + H+ -> HHb+ + 4O2

      Carbon dioxide is a waste product of respiration and its concentration is high in the respiring cell and so it is here that haemoglobin releases oxygen.

      Once it releases the oxygen in respiring cells, the haemoglobin is strongly attracted to carbon dioxide molecules. Carbon dioxide is removed to reduce its concentration in the cell and is transported to the lungs were its concentration is lower.

      In the lungs, the opposite reaction occurs, with red blood cells releasing carbon dioxide and haemoglobin absorbing oxygen.

      This process is continuous since the oxygen concentration is always higher than the carbon dioxide concentration in the lungs and the carbon dioxide concentration is always higher than the oxygen concentration in the respiring cells.

      Hope that wasn’t too long or complicated! It’s not a simple process, sorry 😉

    • Photo: Katy Mee

      Katy Mee answered on 15 Jun 2010:

      If my Dad wasn’t retired, I’d ask him – he was a doctor! But he is so i asked Google instead:

      http://wiki.answers.com/Q/How_is_carbon_dioxide_removed_from_the_blood_stream

      …..plus Paula’s answer is way more detailed than i could give!

    • Photo: Hermine Schnetler

      Hermine Schnetler answered on 15 Jun 2010:

      When you breath in the air flows into thousands of tiny little tubes in your lungs. These tubes are surrounded by lots of equally tiny little blood vessels. Seperating these tubes of blood and air are really thin walls. Now, these walls are “semi-permeable,” which means small molecules like gases can pass through them, but big things, like blood cells cannot. When you breath in the air that comes into your lungs has lots of oxygen and not much carbon dioxide. But your blood, which has been all the way around your body, is the other way round: it has lots of carbon dioxide and not much oxygen. So we get an exchange of gases across these thin walls. All the oxygen leaves the oxygen-rich air, and all the carbon dioxide goes the other way, leaving the blood and entering the air. When you breath out, you get rid of all this carbon dioxide, and the blood keeps flowing round your body delivering the new oxygen to other places.

    • Photo: Laura Dixon

      Laura Dixon answered on 16 Jun 2010:

      There’s an ‘exchange’ of gases in your lungs – oxygen get transferred into the blood stream and CO2 is removed and transferred to your lungs.

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