What Is The Heart?
The heart is a hollow, muscular organ that pumps blood through the body. An adult's heart is about the size of a man's clenched fist and is shaped like an egg. It lies in the center of the chest, protected by the breastbone and the rib cage.
What Is The Heart Made Of?
It is mostly strong muscle tissue called the myocardium. A paper-thin layer of tissue, called the pericardium, covers the outside of the myocardium.
What Does The Inside Of The Heart Look Like?
The heart is divided into four chambers, two upper and two lower ones. A thin, solid wall of tissue separates the right side of the heart from the left side. Each top chamber is called an atrium. Each lower chamber is called a ventricle. Valves connect the upper and lower chambers. A valve is like a one-way door that allows blood to flow through it in only one direction. In both sides of the heart, the blood is pumped from the atrium down to the ventricle.
How Fast Does The Heart Beat?
For an adult, the normal rate is 60 to 100 beats a minute. Your heart will beat faster when you get very excited, are frightened,when exercising strenuously or when your heart is not working properly due to disease.