haemoglobin in red blood cells. The haemoglobin is now called oxyhaemoglobin. Oxygen is transported to every cell in the body for aerobic respiration. Carbon dioxide and water are produced by the cells as waste products of aerobic respiration. They are carried in the blood to the lungs where they pass into the alveoli and travel through the airways to be exhaled.
CO2 exhaled
Alveolus of the lung
Oxygen inhaled
Red blood cells containing oxyhaemoglobin
Deoxygenated blood
Capillaries
Oxygenated blood
Diffusion Movement of molecules from an area of high concentration to an area of low concentration.
Cell
Respiration
Fig. 6 This diagram shows how gas exchange takes place between the lungs and the blood during aerobic respiration.
11.3 Inhalation and exhalation
We inhale, or breathe in, to provide our bodies with oxygen. As we learned in Chapter 8: Cell Processes, oxygen is essential for aerobic respiration. We exhale, or breathe out, to remove carbon dioxide and water vapour.
Air is sucked in through the nose or mouth.
The intercostal
muscles contract, causing the
ribs to move up and out.
Air is pushed out of the lungs.
The intercostal muscles relax and the ribs move back in.
The diaphragm contracts and moves down.
The diaphragm relaxes and moves up. Fig. 7 Inhalation and exhalation 119
