major features of coronary circulation

The circumflex branch

lies in the coronary sulcus and distributes oxygenated blood to the walls of the left ventricle and left atrium.

The left coronary artery

passes inferior to the left auricle and divides into the anterior interventricular and circumflex branches.

key point

The right and left coronary arteries deliver blood to the heart; the coronary veins drain blood from the heart into the coronary sinus.

The right coronary artery

supplies small branches (atrial branches) to the right atrium. It continues inferior to the right auricle and ultimately divides into the posterior interventricular and marginal branches.

collateral circulation

the alternate routes for blood to reach a particular organ or tissue.

Coronary Circulation

-occurs because nutrients are not able to diffuse quickly enough from blood to the heart wall. -For this reason, the myocardium has its own network of blood vessels, the coronary (cardiac) circulation

Why does the myocardium contain many anastomoses?

-so that heart muscle may recieve sufficient oxygen even if one of its coronary arteries is partially blocked. -anastomoses provide detours for arterial blood if a main route becomes obstructed. -because anastomoses connect branches of a given coronary artery or extend between branches of different coronary arteries.

anastomoses

-the connections between two or more arteries when they both supply the same part of the body with blood.

reperfusion

-the reestablishment of blood flow. -this my occur when a blockage of a coronary artery deprives the heart muscle of oxygen. -This surprising effect is due to the formation of oxygen free radicals from the reintroduced oxygen.

Two coronary arteries

-the right and left coronary arteries, branch from the ascending aorta and supply oxygenated blood to the myocardium

The principal tributaries carrying blood into the coronary sinus are the following:

1. Great cardiac vein -in the anterior interventricular sulcus, which drains the areas of the heart supplied by the left coronary artery (left and right ventricles and left atrium) 2. Middle cardiac vein -in the posterior interventricular sulcus, which drains the areas supplied by the posterior interventricular branch of the right coronary artery (left and right ventricles) 3. Small cardiac vein -in the coronary sulcus, which drains the right atrium and right ventricle 4. Anterior cardiac veins -which drain the right ventricle and open directly into the right atrium

coronary sinus

A wide venous channel on the back of the heart that collects the blood from the coronary circulation and returns it to the right atrium.

from coronary arteries to coronary veins

After blood passes through the arteries of the coronary circulation, it flows into capillaries, where it delivers oxygen and nutrients to the heart muscle and collects carbon dioxide and waste, and then moves into coronary veins.

Coronary Veins

Most of the deoxygenated blood from the myocardium drains into a large vascular sinus in the coronary sulcus on the posterior surface of the heart, called the coronary sinus.

Which coronary blood vessel delivers oxygenated blood to the walls of the left atrium and left ventricle?

The circumflex artery delivers oxygenated blood to the left atrium and left ventricle.

coronary arteries and relaxed muscle:

When the heart relaxes, the high pressure of blood in the aorta propels blood through the coronary arteries, into capillaries, and then into coronary veins.

coronary arteries and muscle contraction:

While the heart is contracting, little blood flows in the coronary arteries because they are squeezed shut.

The marginal branch

beyond the coronary sulcus runs along the right margin of the heart and transports oxygenated blood to the myocardium of the right ventricle.

The posterior interventricular branch

follows the posterior interventricular sulcus and supplies the walls of the two ventricles with oxygenated blood.

The anterior interventricular branch or left anterior descending (LAD) artery

is in the anterior interventricular sulcus and supplies oxygenated blood to the walls of both ventricles.

Coronary arteries

-branch from the ascending aorta and encircle the heart like a crown.