The Heart

Every second of every day something incredible happens inside your body. One of your body's organs, the HEART, works day and night to constantly pump blood into your lungs where it loads up on oxygen and then pumps blood out to the rest of your body where it delivers nutrients and oxygen and removes waste products. If this finely tuned engine stopped you'd be dead in minutes!

Let's investigate the heart's valves, chambers, and vessels and uncover what it does and how it works! 
 

 
Where is your heart?
     Your heart is in the center of your chest. Your heart is not right under your skin but lies behind your breastbone, inside your ribcage, and between your lungs. Look here

How big is your heart?
     The heart is about the size of your fist. (When you were a baby it was the size of your baby fist).

What does the heart look like?
The heart is a muscle, just like the other muscles in your body!! It weighs about a pound, or less than half a kilogram.

     The heart has 4 chambers, which you can think of as "rooms" of the heart. There are 2 atria ("A" in the picture) and 2 ventricles ("V" in the picture). Read more about Heart Chambers  then try to Label the Heart Parts.

What does the heart do?
     This muscle, which beats at about 70 times a minute, pumps blood in a one-way path around your body through blood vessels. The heart and the vessels are called the Circulatory System. The heart valves stop blood from flowing the wrong way.
Watch your blood flow through the heart.

     The heart pumps thousands of liters of blood through your body every day. Blood is pumped out of the heart in two directions. First it sends blood without any oxygen to the lungs to get oxygen. It then pumps the blood containing oxygen around all the other parts of the body. After delivering its oxygen, the blood returns to the heart to start the process of getting oxygen all over again.
Map of the Human Heart.
 

 
What do the valves do?
     Between the chambers there are valves which stop blood from flowing the wrong way. The valves open and close and help to move blood through the heart to the right place at the right time.

     When the valves open, blood surges into the chambers. The valves close, the heart contracts, and the blood flows out. Follow the arrows of blood as it flows through the heart. watch this demonstration .

 
The human heart beats over two and a half billion times in a lifetime.


About your Heart Beat

     The heart's rate when you are a baby is about 120 beats per minute. As you grow, your heart rate slows. A seven year old child's heart beats about 90 times per minute. By the age of 18, the heart rate is about 70 beats per minute" Listen to a Heart Beat

     During exercise, more oxygen and nutrients are needed by the muscles so blood must be delivered faster than when the body is resting. To meet these demands, the heartbeat increases.

Finding Your HeartBeat
You can easily find places on your body where you can feel your pulse, the beat of blood as it rushes through your veins and arteries. Your wrist is a good place to try.

 
Are all hearts the same?      
      Did you know that all vertebrate hearts are not the same? A mammal heart is different from a fish heart, for example, even though both mammals and fish are vertebrates. Birds and mammals (humans are mammals) have a 4-chambered heart that separates oxygen-rich and oxygen-depleted blood. Fish have a 2-chambered heart. Amphibians have a 3-chambered heart with two atria and one ventricle. Some reptiles have a partial separation of the ventricle but others have a 4-chambered heart.

Don't miss this Picture of a
Mammalian Heart

 
Who knows about the heart?
     A Cardiologist is the special doctor who knows about the heart, its functions and its diseases, and the circulatory system. Read about the Milestones in Cardiology.

   While there have been many medical breakthroughs in heart surgery, transplants and treatments a large number of people still die from heart-related illnesses each year. Watch an Open Heart Surgery Movie

Over 60 million North-Americans die from heart disease each year.
The average age for heart attack victims is 65.
Over 700,000 North-Americans die from cardiac arrest (myocardial infarction) each year.      What is a heart attack?