Heart System

HEART SYSTEM Heart System is a necessary system of the Human body. It is a pumping station of the Human body. As in a house, a pump makes the water flows throughout the body, similarly Heart system makes Oxygenated blood flows throughout the body. We can feel the efficiency and power of this system by a fact that Heart system works without rest throughout life

Parts of the Heart System      

Heart Organ Aorta Coronary Arteries Veins Heart Chambers Pulmonary Valve

Human Heart

Description of the Human Heart •

The human heart is a hollow, pear-shaped organ about the size of a fist. The heart is made of muscle that contracts and relax. These rhythms of contraction and relaxations are called Heart Beats,. Oxygen-poor blood from the body enters the heart. These contractions and relaxations pump blood throughout the body. Over a typical life span of 76 years, the heart will beat nearly 2.8 billion times and move 169 million liters of blood.

Human Heart is made up of special type of muscles called Cardiac Muscles which are flexible and strong as these muscles never rest because Rest means Death !

AORTA • Aorta, principal artery of the body that carries oxygenated blood to most other arteries in the body. The aorta gives rise to the coronary arteries, which supply the heart muscle with blood

CORONARY ARTERIES • The heart is nourished not by the blood passing through its chambers but by a specialized network of blood vessels. Known as the coronary arteries, these blood vessels encircle the heart like a crown. About 5 percent of the blood pumped to the body enters the coronary arteries, which branch from the aorta just above where it emerges from the left ventricle.

• Three main coronary arteries—the right, the left circumflex, and the left anterior descending—nourish different regions of the heart muscle. From these three arteries arise smaller branches that enter the muscular walls of the heart to provide a constant supply of oxygen and nutrients

VEINS • Veins are blood vessels that generally conducts the deoxygenated blood from the capillaries back to the heart. The pulmonary veins return blood from the lungs, where it has been oxygenated, to the heart; Veins enlarge as they proceed, gathering blood from their tributaries. They finally pour the blood through the superior and inferior veins cavae into the right atrium of the heart.

Heart Chambers • The human heart has four chambers. The upper two chambers, the right and left atria, are receiving chambers for blood. The atria are sometimes known as auricles. They collect blood that pours in from veins, blood vessels that return blood to the heart. The heart’s lower two chambers, the right and left ventricles, are the powerful pumping chambers. The ventricles propel blood into arteries, blood vessels that carry blood away from the heart.

Heart Valves • Four valves within the heart prevent blood from flowing backward in the heart. The valves open easily in the direction of blood flow, but when blood pushes against the valves in the opposite direction, the valves close.

Working of the Heart System • Oxygen-poor blood from the body enters the heart from two large blood vessels, the inferior vena cava and the superior vena cava, and collects in the right atrium. When the atrium fills, it contracts, and blood passes through the valve into the right ventricle. When the ventricle becomes full, it starts to contract, and the valve closes to prevent blood from moving back into the atrium. As the right ventricle contracts, it forces blood into the pulmonary artery, which carries blood to the lungs to pick up fresh oxygen.

• When blood exits the right ventricle, the ventricle relaxes and the pulmonary valve shuts, preventing blood from passing back into the ventricle. Blood returning from the lungs to the heart collects in the left atrium. When this chamber contracts, blood flows through the valve into the left ventricle. The left ventricle fills and begins to contract, and the valve between the two chambers closes.

• In the final phase of blood flow through the heart, the left ventricle contracts and forces blood into the aorta. After the blood in the left ventricle has been forced out, the ventricle begins to relax, and the valve at the opening of the aorta closes.

• In an adult, resting heart rate is normally about 70 beats per minute. However, the heart can beat up to three times faster—at more than 200 beats per minute—when a person is exercising vigorously. Younger people have faster resting heart rates than adults do. The normal heart rate is about 120 beats per minute in infants and about 100 beats per minute in young children. Many athletes, by contrast, often have relatively slow resting heart rates because physical training makes the heart stronger and enables it to pump the same amount of blood with fewer beats. An athlete’s resting heart rate may be only 40 to 60 beats per minute.

Diseases of the Heart System a) Coronary Heart Diseases b) Heart Valve Malfunctions c) Heart Failure

Coronary Heart Diseases • Coronary heart disease, the most common type of heart disease in most industrialized countries, It is caused by the buildup of fatty material called plaque on the inside of the coronary arteries Over the course of many years, this plaque narrows the arteries so that less blood can flow through them and less oxygen reaches the heart muscle

Heart Valve Malfunction • Malfunction of one of the four valves within the heart can cause problems that affect the entire circulatory system. A leaky valve does not close all the way, allowing some blood to flow backward as the heart contracts. This backward flow decreases the amount of oxygen the heart can deliver to the tissues with each beat. A valve, which is stiff and does not open fully, requires the heart to pump with increased force to propel blood through the narrowed opening. Over time, either of these problems can lead to damage of the overworked heart muscle

Heart Failure • The final stage in almost any type of heart disease is heart failure, in which the heart muscle weakens and is unable to pump enough blood to the body. In the early stages of heart failure, the muscle may enlarge in an attempt to contract more vigorously, but after a time this enlargement of the muscle simply makes the heart inefficient and unable to deliver enough blood to the tissues. Heart failure may develop when the death of heart muscle in a heart attack leaves the heart with less strength to pump blood, or simply as a result of long-term oxygen deprivation due to narrowed coronary arteries

Presented By Guidence & Material provided by Mr. Rajesh Kumar Science Master

Implementation on Computer by Rajesh Beri Computer Faculty

Govt. Sen. Sec. School, Town Hall, Amritsar This material is obtained from Subject book of Science and Encarta Encyclopedia