While the circulatory system is busy providing oxygen and nourishment to every cell of the body, let's not forget that the heart, which works hardest of all, needs nourishment, too. Coronary circulation refers to the movement of blood through the tissues of the heart. The circulation of blood through the heart is just one part of the overall circulatory system.
Serious heart damage may occur if the heart tissue does not receive a normal supply of food and oxygen. The heart tissue receives nourishment through the capillaries located in the heart.
Systemic circulation supplies nourishment to all the tissue located throughout our body, with the exception of the heart and lungs because they have their own systems. Systemic circulation is a major part of the overall circulatory system.
The blood vessels are responsible for the delivery of oxygen and nutrients to the tissue. Oxygen-rich blood enters the blood vessels through the heart's main artery called the aorta. The forceful contraction of the heart's left ventricle forces the blood into the aorta which then branches into many smaller arteries, which run throughout the body. The inside layer of an artery is very smooth allowing the blood to flow quickly. The outside layer of an artery is very strong allowing the blood to flow forcefully. The oxygen-rich blood enters the capillaries where the oxygen and nutrients are released. The carbon dioxide is collected and the de-oxygenated blood flows into the veins. All the veins unite together to form two main veins called the superior vena cava and the inferior vena cava which open into the right auricle of the heart where pulmonary circulation will allow the exchange of gases in the lungs.
During systemic circulation, blood passes through the kidneys. This phase of systemic circulation is known as renal portal circulation. During this phase, the veins from the posterior part of the body collect the blood by way of renal portal veins and pass it into the kidney, and then the kidneys filter much of the waste from the blood before sending it into the heart. Blood also passes through the liver during systemic circulation. This phase is known as hepatic portal circulation. During this phase, the blood from the small intestine collects in the portal vein, which passes through the liver where it again breaks into capillaries. The liver filters sugars from the blood; storing them for later use. The capillaries reunite to form the hepatic vein and join the inferior vena cava.