Question

Briefly discuss the layers, chambers, valves, vasculature, and the conduction system of the heart

Answer 1

The wall of the heart is composed of three layers

1. The pericardium, also called pericardial sac, is a double-walled sac containing the heart and the roots of the great vessels. The pericardial sac has two layers, a serous layer and a fibrous layer. It encloses the pericardial cavity which contains pericardial fluid.

2. The middle and thickest layer is the myocardium, made largely of cardiac muscle cells. It is the contraction of the myocardium that pumps blood through the heart and into the major arteries.

3. Endocardium lines the chambers where the blood circulates and covers the heart valves. It is made of simple squamous epithelium called endothelium,

Chambers of heart

The human heart consists of four chambers: The left side and the right side each have one atrium and one ventricle.

Each of the upper chambers, the right atrium and the left atrium, acts as a receiving chamber and contracts to push blood into the lower chambers, the right ventricle and the left ventricle.

ventricles serve as the primary pumping chambers of the heart, propelling blood to the lungs or to the rest of the body.

valves of heart -

The septum between the atria and ventricles is known as the atrioventricular septum.

The valves between the atria and ventricles are known generically as atrioventricular valves. Valve between left atrium and left ventricle is the mitral valve and valve between right atrium and right ventricle is known as tricuspid valve

The valves at the openings that lead to the pulmonary trunk and aorta are known generically as semilunar valves.

Valves between left ventricle and aortic opening is called as Aortic valve and valve between right ventricle and pulmonary artery is known as pulmonary valve.

Vasculature of heart -

There are three dilations in the wall of the aorta just superior to the aortic semilunar valve. Two of these, the left posterior aortic sinus and anterior aortic sinus, give rise to the left and right coronary arteries, respectively

The left coronary artery distributes blood to the left side of the heart, the left atrium and ventricle, and the interventricular septum. The circumflex artery ad left anterior descending artery (LAD) are the major branches.

The right coronary artery proceeds along the coronary sulcus and distributes blood to the right atrium, portions of both ventricles, and the heart conduction system.The marginal arteries and posterior interventricular artery are the major branches.

Coronary veins drain the heart and generally parallel the large surface arteries

The great cardiac vein -- It receives blood from posterior cardiac vein, the middle cardiac vein, and the small cardiac vein. The coronary sinus is a large, thin-walled vein on the posterior surface of the heart lying within the atrioventricular sulcus and emptying directly into the right atrium. The anterior cardiac veins drains directly in right atrium.

Conduction system of heart --

The cardiac conduction system is a group of specialized cardiac muscle cells in the walls of the heart that send signals to the heart muscle causing it to contract.

The main components of the cardiac conduction system are the SA node, AV node, bundle of His, bundle branches, and Purkinje fibers.

The SA node (anatomical pacemaker) starts the sequence by causing the atrial muscles to contract. From there, the signal travels to the AV node, through the bundle of His, down the bundle branches, and through the Purkinje fibers, causing the ventricles to contract. This signal creates an electrical current that can be seen on a graph called an Electrocardiogram ECG.