Heart - Keeping Body Alive, Muscle, Valves, Arteries, Aorta
Know your Body

Know Your Heart

Authored by DesiMD Doctor on 26 Sep 2013 - 02:30

Heart - Location in the body

The heart is a special type of muscle that pumps blood to other parts of body and brain. It is located on the left side, in your chest. The heart is enclosed in a sac called "pericardium". The heart has four different components that work together, so that it can beat and pump blood, so that all of us are alive.

The four components are:

  • Muscle of the heart ( squeezes blood out )
  • Valves of the heart (doors that allow blood to flow in one direction only)
  • Arteries of the heart called coronary arteries ( they are like the water pipes to our houses, they carry blood and nutrients to the muscle of the heart, to keep it alive
  • Electrical system of the heart (they are like electrical wires in our house; they carry electrical signals to the heart muscle. The signals allow the heart muscle to squeeze or relax).

So, let us learn how each system of the heart works with each other, so that the “lub, dub” (heart beats) happen.

Muscle of the heart

The heart has 4 chambers, 2 upper and 2 lower.  The upper chambers are smaller and called atrium. 

The four chambers and the valves
of the heart 
Heart - Chambers, Valves and main blood vessels
Modified from the drawing by Eric Pierce

They do not have much muscle in them. The lower chambers are called ventricles. They are bigger and thicker than the atrium. The left lower chamber is thickest and biggest of all the four chambers.

The right atrium receives blood from all parts of the body.  Then it empties into the right ventricle. The right ventricle empties blood into the lungs. The lungs fill the blood with oxygen and empty into the left atrium. The left atrium empties into the left ventricle. The left ventricle pumps blood to all parts of the body.

The blood carries oxygen to all parts of the body. Once the oxygen is removed it is called deoxygenated blood. This returns to the right atrium.

 Valves of the heart

There are valves in the heart that act like one way doors. The door between the right upper and lower chambers is called the tricuspid valve. The door between the left upper and lower chamber is called the Mitral valve. Both these valves allow blood to flow only in one direction that is from upper chambers (atrium) to lower chambers (ventricle).

The arrows indicate the direction of blood flow 
Heart - blood flow
 Modified fromthe  drawing by Eric Pierce

The door (valve) between the right lower chamber and the blood vessel (pulmonary artery) that carries blood to the lungs is called pulmonary valve. The door between the left lower chamber and the blood vessel (“aorta”) that carries blood to other parts of the body is called the aortic valve. Both these valves allow blood to flow only in one direction, that is from lower chambers (ventricles) to blood vessels that connect the lungs and rest of the body (pulmonary artery, aorta).
When these valves do not close properly we call them leaky valves (“regurgitation”). When they do not open properly we call them narrowing (“stenosis”).

Arteries of the heart

Veins and arteries are like pipe systems in our homes. The difference is that these pipes carry blood and other nutrients to and from different parts of the body to the heart.
The arteries carry blood from the heart to different parts of the body. The veins collect all the impure blood back to the heart to be purified in the lung. (Arteries in red, veins in blue)

Like the pipes in our home, the arteries can be clogged with debris. The difference is the debris is from cholesterol and inflammation.

The heart has its own pipe system, and it is called coronary arteries and veins. The coronary arteries come from the big blood vessel called aorta.


Aorta  recieves the first blood Supply
Modified fromthe  drawings by Patrick J.Lynch                                  

There are two main coronary arteries:

1) Left main coronary artery, that branches out to:

  • Left anterior descending artery: supplies blood to the front wall of the heart.
  • Left circumflex artery supplies to the left wall of the heart.

2) The right main coronary artery to the right side and bottom of the heart
The size of the artery is similar to a noodle.

Blockages in the coronary arteries cause lack of blood supply and nutrients to the heart. This leads the muscle to die and cause heart attack..
Once the muscle dies, the heart cannot pump blood as well as it did when it was healthy, this is called “cardiomyopathy” (weakness of the heart muscle). This leads to fluid buildup in the body and is called heart failure.

Electrical System of the Heart

The electrical system of the heart is made up of a main generator, fuse and wires.
The “main generator” called sinus node gives out a signal 60-100 times a minute; this goes down the

 Electrical system of the heart
Electrical conducting system of the Heart
Modified from drawing by Madhero88

wires, into the upper chamber and makes the upper chambers squeeze blood. Then the signal goes down the fuse, called AV node located between the upper and lower chambers.

From the AV node two wires come out, the wire that is going to the right heart muscle is called “right bundle” and the wire that goes to the left heart is called “left bundle”. The electrical signal goes down the wires and stimulates the lower chambers to pump blood to the lungs and other parts of the body.

When there is a problem with the generator, fuse, or the wire, there is decrease in signals to the heart, and the heart squeezes slowly causing slow heart rates called bradycardia. On the other hand if there are too many signals then the heart squeezes rapidly called tachycardia. These are called heart rhythm issues.

Interesting Facts about the Heart:

  • Human heart beats over 100,000 times per day; Around 70 Times per Minute
  • Your heart pumps nearly 1.5 million barrels of blood during your lifetime
  • Did you know your heart can beat even when separated from your body? This is because of its own electrical impulse.
  • Every day, your heart creates enough energy to drive a truck for 32 km
  • Your heart receives blood from 75 trillion cells.
  • The human heart is in the middle of the chest not on the left-hand side of the body
  • An orgasm 3 times or more a week, cuts the risk of coronary heart disease
  • In the case of a heart attack, women have nausea, indigestion, and shoulder aches instead of a chest pain.
  • Having a pet (cat) can reduce the risk of heart attacks and strokes by more than a third, say researchers.
  • Multivitamin supplements increase the risk of cancer and heart disease, according to recent studies.
  • Your heartbeat changes and mimics the music you listen to.
  • Your left lung is smaller than your right lung to make room for your heart.
  • Study finds that vegetarians are 19% less likely to die from heart disease.
  • Eating dark chocolate every day reduces the risk of heart disease by one-third.
  • One-third of first heart attacks are fatal, and another third result in permanent damage to the heart.
  • Smoking makes the risk of heart attack 200-400% greater than that of non-smokers
  • Working 11 hours or more a day, makes you 67% more likely to have a heart attack than those with an 8-hour work day - study.
  • The inventor of the heart stent approached numerous companies for funding and was rejected. The owner of Fuddrucker's restaurant, whom he on a golf course, helped with the funds
  • All of the arteries, veins, and capillaries in the body are long enough to go around the world more than twice.
  • The heart does not stop beating when you sneeze, though it’s thought that way. It only changes its rhythm briefly to catch up with the blood flow disturbed during the sneeze. 
*Disclaimer: This is not medical advice. The content is for educational purposes only. Please contact your doctor for any health care issues.