Coronary heart disease can lead to the build-up of fatty deposits (atheroma) inside the coronary arteries, restricting blood flow to the heart muscle cells.
Table 1 shows how the percentage occlusion (blockage) of a patient's coronary artery affects the blood flow rate to the downstream cardiac muscle.
Table 1
| Coronary artery occlusion (%) | Blood flow rate (cm3/min\text{cm}^3\text{/min}cm3/min) |
|---|---|
| 0 | 240 |
| 20 | 192 |
| 50 | 96 |
| 70 | 44 |
| 90 | 12 |
Describe the trend shown in Table 1 between the coronary artery occlusion and the blood flow rate.
Calculate the percentage decrease in the blood flow rate when the artery's occlusion increases from 0% to 50%. Show your working.
Assuming the change in blood flow rate is linear between an occlusion of 50% and 70%, estimate the blood flow rate when the coronary artery is 60% occluded. Show your working.
44 exam-style questions on AQA GCSE Biology 2.2 Animal tissues, organs and organ systems, covering 2.2.1 The human digestive system, 2.2.2 The heart and blood vessels, 2.2.3 Blood, 2.2.4 Coronary heart disease: a non-communicable disease, 2.2.5 Health issues, 2.2.6 The effect of lifestyle on some non-communicable diseases, and 2.2.7 Cancer. Each one has a worked solution and a mark scheme showing where the marks go.