The Ventricles of the Heart

The heart is a component of the cardiovascular system that helps circulate blood to the organstissues, and cells of the body. Blood travels through blood vessels and is circulated along pulmonary and systemic circuits. The heart is divided into four chambers that are connected by heart valves. These valves prevent the backward flow of blood and keep it moving in the right direction.

The lower two chambers of the heart are called heart ventricles. A ventricle is a cavity or chamber that can be filled with fluid, such as the cerebral ventricles. The heart ventricles are separated by a septum into the left ventricle and the right ventricle. The upper two heart chambers are called atria. Atria receive blood returning to the heart from the body and ventricles pump blood from the heart to the body.

The heart has a three-layered heart wall composed of connective tissueendothelium, and cardiac muscle. It is the muscular middle layer known as myocardium that enables the heart to contract. Due to the force needed to pump blood to the body, ventricles have thicker walls than do atria. The left ventricle wall is the thickest of the heart walls.

Function

Human Heart Cross Section
Human heart cross section showing blood circulation through the heart. jack0m/DigitalVision Vectors/Getty Images

The ventricles of the heart function to pump blood to the entire body. During the diastole phase of the cardiac cycle, the atria and ventricles are relaxed and the heart fills with blood. During the systole phase, the ventricles contract pumping blood to the major arteries (pulmonary and aorta). The heart valves open and close to direct the flow of blood between the heart chambers and between the ventricles and major arteries. Papillary muscles in the ventricle walls control the opening and closing of the tricuspid valve and mitral valve.

  • Right ventricle: Receives blood from the right atrium and pumps it to the main pulmonary artery. Blood passes from the right atrium through the tricuspid valve into the right ventricle. Blood is then forced into the main pulmonary artery as the ventricles contract and pulmonary valve opens. The pulmonary artery extends from the right ventricle and branches into left and right pulmonary arteries. These arteries extend to the lungs. Here, oxygen-poor blood picks up oxygen and is returned to the heart via the pulmonary veins.
  • Left ventricle: Receives blood from the left atrium and pumps it to the aorta. Blood returning to the heart from the lungs enters the left atrium and passes through the mitral valve to the left ventricle. Blood in the left ventricle is then pumped to the aorta as the ventricles contract and the aortic valve opens. The aorta carries and distributes oxygen-rich blood to the rest of the body.

Cardiac Conduction

Cardiac conduction is the rate at which the heart conducts the electrical impulses that drive the cardiac cycle. Heart nodes located in the right atrium contract sending nerve impulses down the septum and through out the heart wall. Branches of fibers known as Purkinje fibers relay these nerve signals to the ventricles causing them to contract. Blood is moved along through the cardiac cycle by the constant cycle of heart muscle contraction followed by relaxation.

Ventricular Problems

Heart in Congestive Heart Failure
This is a cutaway illustration of a human heart showing congestive ventricular heart failure. Blood vessels connecting the heart to the rest of the body are at top. The body's main vein the vena cava is blue and main artery, the aorta is red. The ventricle at right has an abnormally thick wall. This means that one side of the heart will fail to empty itself, and hence pump blood effectively at each contraction. This results in a black flow of pressure in the veins causing abnormal swellings (edemas) in the lungs or other organs. Other symptoms include shortness of breath and fatigue. Short-term treatment includes bed-rest and diuretic drugs. John Bavosi/Science Photo Library/Getty Images

Heart failure is a condition that is caused by the failure of heart ventricles to pump blood efficiently. Heart failure results from weakening or damaging of the heart muscle that causes ventricles to become stretched to the point that they cease to function properly. Heart failure may also occur when ventricles become stiff and unable to relax. This prevents them from filling properly with blood. Heart failure typically begins in the left ventricle and may progress to include the right ventricle. Ventricular heart failure can sometimes lead to congestive heart failure. In congestive heart failure, blood backs up or becomes congested in body tissues. This may result in swelling in the legs, feet, and abdomen. Fluid may also accumulate in the lungs making breathing difficult.

Ventricular tachycardia is another disorder of the heart ventricles. In ventricular tachycardia, the heartbeat is accelerated but the heartbeats are regular. Ventricular tachycardia may lead to ventricular fibrillation, a condition in which the heart beats both rapidly and irregularly. Ventricular fibrillation is the primary cause of sudden cardiac death as the heart beats so quickly and irregularly that it becomes unable to pump blood.

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Bailey, Regina. "The Ventricles of the Heart." ThoughtCo, Oct. 18, 2017, thoughtco.com/ventricles-of-the-heart-373254. Bailey, Regina. (2017, October 18). The Ventricles of the Heart. Retrieved from https://www.thoughtco.com/ventricles-of-the-heart-373254 Bailey, Regina. "The Ventricles of the Heart." ThoughtCo. https://www.thoughtco.com/ventricles-of-the-heart-373254 (accessed October 23, 2017).