INTERNATIONAL UNIVERSITY

Circulatory Routes(Pulmonary, systemic and Coronary circulations)

Dr. Sam Nang

The pulmonary circulation

• The principal divisions of the circulatory blood flow are the pulmonary and systemic circulations.

• The pulmonary circulation includes blood vessels that transport blood to the lungs for gas exchange and then back to the heart.

The pulmonary circulation It consists of:• the right ventricle that ejects the blood.• the pulmonary trunk with its pulmonary

valve,• the pulmonary arteries that transport

deoxygenated blood to the lungs, • the pulmonary capillaries within each lung, • the pulmonary veins that transport

oxygenated blood back to the heart, and• the left atrium that receives the blood from

the pulmonary veins.

The systemic circulation• The systemic circulation involves all of the

vessels of the body that are not part of the pulmonary circulation.

• It includes the right atrium, the left ventricle, the aorta with its aortic valve. all of the branches of the aorta, all capillaries other than those in the lungs involved with gas exchange, and all veins other than

the pulmonary veins.

Path of Blood

• Heart (L. ventricle) → Aorta → Arteries → Arterioles → Capillaries → Venules → Veins → Vena cava → Heart (R. atrium)

The systemic circulation

• The right atrium receives all of the venous return of oxygen depleted blood from the systemic veins.

Coronary Circulation • The wall of the heart has its own supply

of blood vessels to meet its vital needs. • The myocardium is supplied with blood

by the right and left coronary arteries .• These two vessels arise from the

ascending part of the aorta, at the location of the aortic (semilunar) valve.

Coronary Circulation

• The coronary arteries encircle the heart within the atrioventricular sulcus, the depression between the atria and ventricles.

• Two branches arise from both the right and left coronary arteries to serve the atrial and ventricular walls.

Coronary Circulation

• The left coronary artery gives rise to the anterior interventricular artery, which courses within the anterior interventricular sulcus to serve both ventricles, and the circumflex artery, which supplies oxygenated blood to the walls of the left atrium and left ventricle.

Coronary Circulation • The right coronary artery gives rise to the

right marginal artery, which serves the walls of the right atrium and right ventricle; and the posterior interventricular artery, which courses through the posterior interventricular sulcus to serve the two ventricles.

• The main trunks of the right and left coronaries anastomose (join together) on the posterior surface of the heart.

Coronary Circulation

• From the capillaries in the myocardium, the blood enters the cardiac veins.

• The course of these vessels parallels that of the coronary arteries.

• The cardiac veins, however, have thinner walls and are more superficial than the arteries.

Coronary Circulation The two principal cardiac veins are• the anterior interventricular vein,

which returns blood from the anterior aspect of the heart, and

• the posterior cardiac vein, which drains the posterior aspect of the heart.

Coronary Circulation• These cardiac veins converge to

form the coronary sinus channel on the posterior surface of the heart .

• The coronary venous blood then enters the heart through an opening into the right atrium.

THE END