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Ventricles of the Heart

Contents

The cardiac ventricles are the two lower chambers of the heart quadrants. They are larger and more apically narrowed than the atria. They function by collecting the blood that flows into them from the atria and then contract in order to expel the accumulated blood volume into the peripheral tissues, using the major vessels to carry it to the extremities.

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Anatomy

The right ventricle collects deoxygenated blood from the right atrium as the tricuspid valve relaxes and pumps it via rhythmic contractions through the pulmonary valve in its roof and into the pulmonary trunk which passes the blood onto the pulmonary artery and into the lungs. It is bordered anterosuperiorly by the sternum and this circular convex area majorly contributes to the sternocostal surface of the heart. The inferior surface is situated upon the diaphragm and this small flat area makes up part of the diaphragmatic portion of the heart. The ventricular septum borders the right ventricle posteriorly and bulges somewhat into it, creating a transverse semilunar cross section. The conus arteriosus, conical arterial pouch or infundibulum can be found in the upper left corner of the ventricle and gives rise to the pulmonary artery. The tendon of the conus arteriosus is a fibrous band that extends superiorly from the right atrioventricular fibrous ring and stretches between the posterior surface of the conus arteriosus and the aorta. The right ventricular wall is three to six times thinner than the left because it starts off thicker and reduces in mass towards the apex. Despite this difference in muscle mass, the inner chambers of the ventricles are the same size and can accumulate approximately 85 millilitres in the adult.

The left ventricle receives blood from the left atrium of the heart via the relaxation of the mitral valve. When it contracts, it pushes the blood volume through the aortic valve and into the aorta. In comparison with the right ventricle, the left is both shorter in length and is transversely circular in a concave manner. It forms the lesser part of the sternocostal surface of the heart anterosuperiorly, the larger part of the diaphragmatic surface inferiorly as well as the apex of the heart. The reason for the increased thickness of the left ventricular wall is that is has to be able to withstand the five times stronger contraction forces and blood pressure needed to propel the blood around the entire body without having it stall or collect anywhere. It collects oxygenated blood returning from the lungs at approximately 80 mmHg and expels it into the aorta at around 120 mmHg during every heartbeat. The typical blood volume that can be pumped out of the heart per minute at rest, which is also known as the cardiac output, is about 5 liters/min and this numerical evaluation can increase to between 25 and even 45 liters/min in athletes during exercise.

Pathology

The ventricles can be deficient in several ways. Single ventricle defects fall into the category known as congenital heart defects, which are present at the time of birth. They are rare and affect only one side of the heart, either the left or the right ventricle at a time. The chamber may be smaller in comparison to its opposite cardiac quarter, underdeveloped or in some cases, the cardiac valve separating the ventricle from its atrium may be missing. Several examples of well known ventricular defects have been mentioned below: Hypoplastic left heart syndrome occurs when one side of the heart is underdeveloped. In this case the left ventricle and the left atrium are too small a patent ductus arteriosus is present postpartum. Pulmonary atresia with an intact ventricular septum ensues when the pulmonary valve is completely aplastic. This means that the only blood that is being oxygenated by the lungs is that which shunts through the embryonic openings which remain patent. Finally, tricuspid atresia involves the aplasia of the tricuspid valve which sits between the right atrium and ventricle. blood cannot properly flow from the heart to the body and isn’t being oxygenated to an optimum level.

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Show references

References:

  • Ventricle. http://www.britannica.com/EBchecked/topic/625559/ventricle.
  • Single Ventricle Defects. American Heart Association, Inc. 

Author:

  • Dr. Alexandra Sieroslawska

Illustrators:         

  • Right Ventricle (green) - Yousun Koh 
© Unless stated otherwise, all content, including illustrations are exclusive property of Kenhub GmbH, and are protected by German and international copyright laws. All rights reserved.

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