The heart is one component of the circulatory system, a network of elastic-like tubes that carries oxygen- and nutrient-rich blood throughout the body. Other parts of the circulatory system include the lungs, veins, arteries, arterioles (small arteries) and capillaries (very small blood vessels).

Blood circulating through this system brings oxygen and nutrients to all organs and tissues in the body while picking up waste products from the body's cells. The blood carries these waste products to the kidney, liver and lungs where they are filtered and removed.

An important part of the circulatory system, the heart comprises four chambers, two upper and two lower:

• Upper right atria
• Upper left atria
• Lower right ventricle
• Lower left ventricle

(Click here to view images of the heart chambers)

Blood flows in and out of these chambers via four valves. The valves open and close to let blood flow in only one direction when the heart beats. These valves are:

• Tricuspid valve (between the right atrium and right ventricle)
• Pulmonary or pulmonic valve (between the right ventricle and the pulmonary artery)
• Mitral valve (between the left atrium and left ventricle)
• Aortic valve (between the left ventricle and the aorta)

Click here to view images of the heart valves.

Each valve has a set of flaps which under normal conditions allows blood to flow in one direction. The mitral valve has two flaps, while the other flaps have three flaps each.

The four chambers of the heart beat uniformly due to an electrical impulse that starts in a bundle of highly specialized cells called the sinotrial node or sinus node. The signal from the sinus node moves across the chambers, causing them to beat.

Acting as a natural pacemaker, the sinus node generates electrical impulses at a given rate. However, emotional reactions and hormonal factors can affect how fast the impulses are produced, leading to an increased or decreased heart rate.

Information

For more information about Heart Care at Shands HealthCare or to make an appointment, call toll-free 1.866.931.1185.

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To make an appointment or find out more information about heart care services offered at Shands at the University of Florida, please call toll-free 1.866.931.1185.

You may also email our Consultation Center (consult@shands.ufl.edu) or use our secure online form.