A myocardial infarction (heart attack) occurs when blood flow through the coronary arteries is severely restricted, reducing the supply of oxygen and glucose to cardiomyocytes (cardiac muscle cells).
Explain why a reduction in the transport of oxygen to cardiomyocytes impairs their ability to contract rhythmically and eventually causes cell death.
Cardiac tissue is serviced by an extensive network of capillaries. Describe two structural features of capillaries and explain how each feature minimises diffusion distance to maximise the exchange of substances between blood and cardiomyocytes.
55 exam-style questions on Edexcel IGCSE Biology Transport. Each one has a worked solution and a mark scheme showing where the marks go.