QVprep Biology Lessons

Cardiovascular system, Heart, What are the major circulatory loops, Pulmonary circulation, Blood vessels



What is the cardiovascular system?: The cardiovascular system consists of the heart, veins, arteries and capillaries.

The primary function of the heart: The primary function of the heart is to circulate the blood and distribute oxygen and nutrients to all the tissues and organs that comprise the body. The left side of the heart, namely the left ventricle and left atrium are responsible for pumping blood to all parts of the body. The right side - right ventricle and right atrium pumps blood only to the lungs for re-oxygenation of the blood.

Heart: The heart is divided into three layers namely the endocardium, myocardium and epicardium.

What are the characteristic features of the heart?: The heart is a muscular pumping organ located medial to the lungs. The tip of the heart, known as its apex, is turned to the left, so that about 2/3 of the heart is located on the body’s left side. The top of the heart, known as the heart’s base, connects to the great blood vessels of the body: the aorta, vena cava, pulmonary trunk, and pulmonary veins.

What are the major circulatory loops?: There are 2 primary circulatory loops in the human body: the pulmonary circulation loop and the systemic circulation loop.

Pulmonary circulation: Pulmonary circulation transports deoxygenated blood from the right side of the heart to the lungs, where the blood receives oxygen and returns the oxygenated blood to the left side of the heart. The pumping chambers of the heart that support the pulmonary circulation loop are the right atrium and right ventricle.

Systemic circulation: Systemic circulation carries highly oxygenated blood from the left side of the heart to all of the tissues of the body except the heart and lungs. Systemic circulation removes wastes from body tissues and returns deoxygenated blood to the right side of the heart. The left atrium and left ventricle of the heart are the pumping chambers for the systemic circulation loop.

Blood vessels: Blood vessels allow the flow of blood from the heart to other parts of the body. All blood vessels contain a hollow region called the lumen through which blood flows. The wall of the blood vessel is thin in the case of capillaries or very thick in the case of arteries.