Heart Anatomy - Structure, Physiology, and Role

Introduction

The heart is a muscular organ positioned behind the sternum in the center of the chest. It has two upper chambers called atria and two lower chambers called ventricles. The right atrium and ventricle are referred to as the right heart, while the left atrium and ventricle are referred to as the left heart. The heart is around the size of the fist and weighs between 7 and 15 ounces. A person's heart may expand and contract more than 3.5 billion times at the conclusion of a lengthy life. The average heart beats 100,000 times every day, pumping around 2,000 gallons of blood.

What Are the Important Structures of the Heart?

Layers of the Heart - The heart wall is made up of three layers of tissue.

1. Epicardium - The exterior layer of the heart wall.

2. Myocardium - It is the middle layer of the heart wall.

3. Endocardium - It is the inner layer of the heart wall.

The Heart Chambers - The heart's interior cavity is split into four chambers:

1. The right atrium.

2. The right ventricle.

3. The left atrium.

4. The left ventricle.

The two atria are hollow chambers with narrow walls that accept blood from the veins. The ventricles are two thick-walled chambers that drive blood out of the heart. Differences in the thickness of the heart chamber walls are caused by changes in the quantity of myocardium present, which reflects the amount of force required by each chamber. The right atrium gets deoxygenated blood from systemic veins and oxygenated blood from pulmonary veins.

Heart Valve - The blood flow through the heart is regulated by four valves:

1. The Tricuspid Valve - It controls blood flow from the right atrium to the right ventricle.

2. The Pulmonary Valve - It controls blood flow from the right ventricle to the pulmonary arteries, which carry blood to the lungs for oxygenation.

3. The Mitral Valve - It allows oxygen-rich blood from the lungs to flow from the left atrium into the left ventricle.

4. The Aortic Valve - It allows oxygen-rich blood from the left ventricle to flow into the aorta of the heart.

Blood Supply -

1. Coronary Artery - Two coronary arteries supply the heart, and 80 percent of the supply to the heart muscle is carried by:

• Left Major Coronary Artery - It is a narrow artery that splits into two branches:

• The left anterior descending artery serves the interventricular septum.

• A portion of the left ventricular anterior wall.

The circumflex coronary artery provides blood to the left ventricle's lateral and posterior sections.

• Right Coronary Artery - Its branches serve the following:

1. Right ventricle.

2. Right atrium.

3. Inferior wall of the left ventricle.

Coronary arteries and veins run parallel to the surface of the heart. The majority of coronary veins join to form the coronary sinus, which opens into the right atrium. Other tiny veins, known as thebesian veins, enter all four chambers of the heart.

• Venous and Lymphatic Supply - Venous drainage is accomplished by the coronary veins and the coronary sinus.

• Lymphatic Drainage -

1. Brachiocephalic nodes are located in front of the brachiocephalic veins.

2. Tracheobronchial nodes are positioned near the tracheal distal end.

What Is the Physiology of the Heart?

• The Conduction System - The contraction of the heart is caused by electrical impulses from the heart muscle (the myocardium). The sinoatrial (SA) node, positioned near the top of the right atrium, initiates this electrical signal. The SA node is often known as the heart's "natural pacemaker." This natural pacemaker sends an electrical impulse to the muscle fibers of the atria and ventricles, causing them to contract. Despite the notion that the SA node delivers electrical impulses at a constant pace, the heart rate might fluctuate due to physical exertion, stress, or hormonal variables.

• The Cardiac Cycle - During one pulse, the conduction system coordinates contraction and relaxation alternately. The contraction part of the cardiac cycle is known as systole, while the relaxation phase is known as diastole. One cardiac cycle lasts 0.8 seconds at a normal heart rate.

• The Circulatory System - The cardiovascular system is made up of your heart and circulatory system. The heart functions as a pump, pushing blood to the organs, tissues, and cells. Blood transports oxygen to all cells while also removing carbon dioxide and waste materials produced by those cells. A complicated network of arteries, arterioles, and capillaries transports blood from the heart to the rest of the body. Venules and veins carry blood back to the heart. Two pumps deliver blood flow to the systemic and pulmonary circulations from the heart's four chambers. The superior and inferior vena cava carries deoxygenated blood from the entire body through the coronary sinus to the right atrium. As a result, the right atrium serves as a deoxygenated blood storage. The blood next passes through the tricuspid valve into the right ventricle, which is the major pumping chamber of the right heart.

The right ventricle sends blood to the pulmonary artery, which oxygenates the lungs. When blood flows through blood arteries, it oxygenates the lungs. This oxygenated blood is collected by the pulmonary veins and opens into the left atrium, which acts as a chamber for oxygenated blood collecting. Both the left and right atriums provide blood to the ventricle through passive flow and active pumping. As a result, after passing through the mitral valve, oxygenated blood fills the left ventricle.

What Is the Role and Function of the Heart?

The heart is a muscle pump that circulates blood to all of the body's tissues. Its operation is critical because the tissues require a constant supply of oxygen and the removal of metabolic waste products in order to survive. When cells are deprived of these needs, they quickly suffer irreversible alterations that lead to death. While blood is the transport medium, the organ that maintains the blood flowing through the veins is the heart. Throughout life, the average adult's heart pumps around 1.32086 gallons of blood each minute. The individual's life is jeopardized if it loses its pumping efficacy for even a few minutes.

Conclusion

The heart is an essential organ. If the heart stops, blood flow and oxygen delivery cease, resulting in permanent brain damage within four to five minutes. A shortage of blood supply to the cardiac muscle can cause coronary artery disease, valvular heart disease, intrinsic weakening of heart muscle (cardiomyopathy), or inadequate cardiac rhythms can all cause cessation or impairment of cardiac function.