The cardiovascular and circulatory systems are very important to the human body. It is your body's delivery system for the circulation of blood. It is made up of blood, blood vessels and the heart.
Blood moving away from the heart delivers oxygen and nutrients to every part of your body through arteries. The arteries carry blood away from your heart to smaller and smaller blood vessels called capillaries.
Capillaries connect the ends of the smallest arteries (arterioles) with the beginnings of the smallest veins (venules) to send the blood back to your heart through the veins.
Blood moving back to the heart picks up waste products so that your body can get rid of them. Veins carry the blood back to the heart and it does this against gravity. So there has to be enough pressure generated from the heart in order to get the blood to your fingers and toes, and then back up to the heart again. That's a lot of pressure. Too much or too little pressure can be detrimental to your health.
Your Heart is about the size of your clenched fist. And your heart is a muscle. The muscle fibers in the heart are different than the muscle fibers on your legs or that line your organs and blood vessels. This type of muscle fiber is called "cardiac muscle." These muscle fibers branch out and (anastomose) form a continuous network. At intervals, there are prominent bands or intercalated disks that cross the fibers. The special fibers in the heart are called Purkinje fibers. The Purkinje Fibers form the impulse-conducting system of the heart.