|The brain, heart, stomach, and lungs are examples of ____.
|The inner wall of the small intestine is covered with ____.
|Human cells organize into ____ and then into organs.
|The ____ are the two upper chambers of the heart.
|Arteries, veins, and capillaries are blood ____.
|Blood travels from your heart to your legs through ____.
|The various pigments that give skin and hair color are ____.
|Blood travels from your legs to your heart through ____.