The heart is a wonderful organ because it can pump oxygen and nutrient-rich blood throughout the body to sustain life. It works up to 100,000 times a day, each pumping 5 to 6 gallons of blood (or 2,000 gallons per day).
How the heart works
1. How does the heart pump blood?
2. Location and structure of the heart
3. The cycle of pumping blood through the heart
4. The movement of blood through the lungs
5. Coronary artery of the heart
6. Heart activity
1. How does the heart pump blood?
When the heart beats, it pumps blood through a system of blood vessels called the circulatory system. These vessels are elastic, and muscle tubes carry blood to all parts of the body.
Blood is an essential component of living organisms. In addition to carrying fresh oxygen from the lungs and nutrients to the tissues of the body, the blood also carries bodily wastes, including carbon dioxide, away from the tissues of the body. This process is necessary for sustaining life and promoting the health of all parts of the body.
There are three main types of blood vessels:
Artery. They start with the aorta, the large artery leaving the heart. Arteries carry oxygen-rich blood from the heart to all tissues in the body. They then branch out into numerous, smaller and smaller numbers as they carry blood to and from the body’s organs.
The capillaries. These are small, thin blood vessels that are connected to arteries and veins. The thin walls of its vessels allow oxygen, nutrients, carbon dioxide, and other wastes to escape from the body’s cells.
Vein. These are the blood vessels that return blood to the heart. This blood has a lower oxygen content and is rich in wastes which will be eliminated or eliminated from the body.
The veins will get larger as they get closer to the heart. The superior vena cava is the large vein that carries blood from the head and arms to the heart. The inferior vena cava carries blood from the abdomen and legs to the heart.
It is a large system of blood vessels which are arteries, veins and capillaries. They are over 60,000 miles long. With this length can be enough to go around the world more than twice.
2. Location and structure of the heart
The heart is located around the rib cage to the left of the breastbone and between the lungs. Looking from the outside of the heart, we can see that the fruit is made of muscle. Strong muscles cause the heart to contract, pumping blood to the rest of the body.
On the surface of the heart there are coronary arteries, which supply oxygen-rich blood to the heart muscle itself. The main blood vessels that enter the heart are the superior vena cava, inferior vena cava, and pulmonary vein. The pulmonary artery leaves the heart and carries oxygen-poor blood to the lungs. The aorta comes out and carries oxygen-rich blood to the rest of the body.
Inside, the heart is a hollow organ with four chambers. It is divided into left and right sides by a muscular septum. The right and left sides of the heart are divided into two upper chambers called the atria. This is where the blood comes from a vein. The other two lower chambers, called the ventricles, are where blood is pumped through the arteries.
The atria and ventricles work together, contracting and relaxing to pump blood out of the heart. When blood leaves each chamber of the heart, it passes through a valve. There are four valves in the heart: the mitral valve, the tricuspid valve, the aortic valve, and the pulmonary valve. The tricuspid and mitral valves are located between the atria and the ventricles. The aortic and pulmonary valves are located between the ventricles and the major blood vessels leaving the heart.
These valves work similarly to check valves in a water system. They prevent the blood from flowing the wrong way. Each valve has a set of caps (buttons). Mitral valves have two flaps, while others have three flaps. These flaps are attached and supported by a ring of fibrous tissue called the annulus. These date rings help maintain the correct shape of the valve.
The mitral and tricuspid valve flaps are also supported by rigid fibrous cords called cordae tendineae. This cover is similar to a parachute. They extend from the leaflets to the small muscles (papillary muscles) that are part of the inner wall of the ventricles.
3. The cycle of pumping blood through the heart
The right and left sides of the heart work together. This process repeats over and over again, causing blood to flow continuously to the heart, lungs and body.
3.1 Right side of the heart
Blood enters the heart through two large veins, the lower and upper vena cava, and drains oxygen-poor blood from the body to the right atrium of the heart. When the atria contract, blood flows from the right atrium into the right ventricle through the tricuspid valve.
When the ventricles are full, the tricuspid valve closes. This will prevent blood from flowing back to the atria while the ventricles are contracting. When the ventricles contract, blood leaves the heart through the pulmonary valve, then into the pulmonary artery and into the lungs. There, it is oxidized and then returned to the left atrium via the pulmonary veins.
3.2. On the side of the heart
Pulmonary veins drain oxygen-rich blood from the lungs to the left atrium of the heart. When the atria contract, blood flows from the left atrium into the left ventricle through the mitral valve.
When the ventricles are full, the mitral valve closes. This will help prevent blood from flowing back to the atria while the ventricles are contracting.
When the ventricles contract, blood leaves the heart through the aortic valve and enters the body.
4. The movement of blood through the lungs
When blood passes through the valve, it enters the lungs. This is called pulmonary circulation. From the pulmonary valve, blood goes to the pulmonary artery and then to the small capillaries in the lungs.
Here, oxygen from the tiny air sacs in the lungs passes through the walls of capillaries into the bloodstream. At the same time, carbon dioxide – a waste of metabolism, passes from the blood into the air sacs. Carbon dioxide leaves the body through respiration. Once the blood is purified and oxygenated, it returns to the left atrium through the pulmonary vein.
5. Coronary artery of the heart
Like all organs, the heart is made up of tissues that require oxygen and nutrients. Although the chambers of the heart are filled with blood, the heart does not receive any nourishment from the blood. The heart receives its own blood supply from a network of arteries called the coronary arteries.
Two large coronary arteries start from the aorta near where the aorta and the left ventricle meet: The right coronary artery supplies blood to the right atrium and the right ventricle. It quickly divides into the posterior descending artery and supplies blood to the lower left ventricle as well as the posterior part of the septum.
The main branches of the left coronary artery are the coronary artery and the left anterior descending artery. The coronary artery supplies blood to the left atrium, and the left posterior ventricle and left anterior descending artery supply blood to the front and bottom of the left ventricle as well as the anterior part of the septum. These arteries and their branches supply all parts of the heart muscle.
Coronary artery disease usually occurs when plaque builds up in the arteries and prevents the heart from receiving the blood it needs. When this happens, a network of small blood vessels in the heart is not opened.
6. Heart activity
The atria and ventricles work together, alternately, and relax to pump blood through the heart. The heart’s electrical system is the source of energy that helps carry out this process.
The heartbeat is triggered by electrical impulses traveling down a special pathway through the heart. This electrical impulse begins in a small bundle of specialized cells called the central node located in the right atrium. This node is called a natural pacemaker. Electrical activity travels through the septum of the atria and causes them to contract.
A group of cells in the center of the heart between the atria and the ventricles is the atrioventricular node – it’s like a gate that slows down an electrical signal before it reaches the ventricles. This delay gives the atria time to contract before the ventricles fire.
The His-Purkinje network is a fiber pathway that sends electrical impulses to the muscle walls of the ventricles and causes them to contract.
At rest, the normal heart will beat about 50 to 99 times per minute. And when exercising, emotions change, fever and the use of certain medications
