<Tr> <Th> Arteries (down) </Th> <Th> Veins (up) </Th> </Tr> <Tr> <Td> Abdominal aorta </Td> <Td> Vena cava </Td> </Tr> <Tr> <Td> Renal artery (Note 1) </Td> <Td> Renal vein </Td> </Tr> <Tr> <Td> Segmental arteries (Note 2) </Td> <Td>--</Td> </Tr>

How many parts of the kidney are there