​ (a)   is the liquid part of blood.

• Plasma
• Red blood cells
• White blood cells
• Platelets

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

Veins have special ________________ to stop blood from flowing backward.

• gravity
• valves
• arteries
• ventricles

The cells in the blood that help fight germs and illnesses are the...

• red blood cells
• platelets
• white blood cells
• axons

The circulatory system works with the ___________ system to provide our body with oxygen.

• respiratory
• digestive
• muscular
• skeletal

The main function of the circulatory system is 

• To give the body structure and support
• Excrete waste
• transport blood, nutrients, and gases throughout the body
• to transport messages from the body to the brain

The heart has ___ chambers.

• 1
• 2
• 3
• 4