Two processes maintain the concentration gradients between the blood and the alveolar air to ensure that diffusion of both oxygen and carbon dioxide can occur: firstly circulation of the blood brings a constant supply of high carbon dioxide, deoxygenated blood to the alveoli. Secondly the diaphragm (above) and intercostal muscles constantly increase and decrease the volume of the lungs to cause ventilation to occur, this is turn ensures a supply of high oxygen, low carbon dioxide air to the alveoli. The muscles cause the lungs to increase and decrease in volume by contractions. You can clearly see the striations in the diaphragm muscle tissue above. The striations help the muscle tissue to contract and relax.
Obtain evidence for theories—epidemiological studies have contributed to our understanding of the causes of lung cancer. (1.8)
Applications and Skills:
Causes and consequences of lung cancer.
Causes and consequences of emphysema.
External and internal intercostal muscles, and diaphragm and abdominal muscles as examples of antagonistic muscle action.
Monitoring of ventilation in humans at rest and after mild and vigorous exercise. (Practical 6)
PLEASE NOTE THIS IS DESIGNED FOR THE OLD SYLLABUS AND SO THE SPECIFICATION IS NOT THE SAME. REFER TO THE ABOVE SPECIFICATION FOR WHAT YOU NEED TO KNOW!