21 steps of blood flow

Step 1

Superior and inferior venal cava

Step 2

Right atrium

Step 3

Tricuspid valve

Step 4

Right ventricle

Step 5

Pulmonary valve

Step 6

Pulmonary arteries

Step 7

Lungs gas exchange

Step 8

Pulmonary veins

Steps 9

Left atrium

Step 10

Bicuspid valve

Step 11

Left ventrical

Step 12

Aortic valve

Step 13

Aorta

Step 14

Arteries

Step 15

Arterioles

Step 16

Arteriol capillaries

Step 17

Gas exchange

Step 18

Venous capillaries

Step 19

Venules

Step 20

Veins

Step 21

Superior and inferior venacava