Arteries
Carries blood from heart to the rest of the body.

Capillaries
Arteries branch out and the smallest branches of arteries are called capillaries. They connect arteries and veins. They transfer oxygen to tissues

Veins
Leads blood back to the heart. They carry deoxygenated blood back to the heart.

Heart rate is the number of heartbeats per unit of time, usually as beats per minute. Your pulse starts in your heart, with your heart beat. Every heart beat causes a pulse in your arteries, similar to the ripple a stone makes when it is thrown in a pond. Your heart rate is the number of times your heart beats in one minute.Your heart rate increases if you do excersise, or do something that makes your heart beat faster.

Energy is one of the most important. Energy helps in our daily activities so it is useful for the body.

The difference between respiration and breathing is that, breathing is the process of inhaling and exhaling that you do unconsciously and respiration is when your body breaks down the oxygen. Respiration is a chemical process and breathing is physical.