Between 10 and 20 per cent of the Western adult population has high blood pressure. The sensation of pins and needles is caused by an impairment of blood circulation.

Look at diagram of blood flow through the heart - Figure 10.9 on page 97 ... vessels listed in Table 1 and shown in Figure 5.3. Functional anatomy of circulatory and respiratory system is important.

This furry creature is a water vole. Like all mammals, it has a circulation system that's made up of two circuits. Its heart pumps oxygen rich blood around its body and back again. And also pumps ...