What is the main organ of the circulatory system?

• small intestine

• bone

• lungs

• heart

The job of the heart is to . . .

• pump blood around the body.

• send food to the small intestines.

• break down food.

• give energy to the body.

The heart is about the size and shape of your . . .

• head

• fist

• hand

• foot

______________ are the smallest blood vessels.

• Arteries
• Veins
• Capillaries

______________ are the second largest blood vessel. 

• Arteries
• Veins
• Capillaries

Which system permits blood to circulate and transports nutrients around the body?

• Nervous
• Respiratory
• Circulatory
• Digestive

These cells, in the blood, carry oxygen and give the blood its color.

• white blood cells
• plasma
• platelets
• red blood cells

This type of vessel carries blood TO the heart:

• vein
• nerve
• muscle
• artery

When oxygen-rich blood is carried AWAY from the heart, it travels through an...

• artery
• neuron
• vein
• straw

The smallest type of blood vessel is the:

• nerve
• vein
• capillary
• artery