The heart is a hardworking muscular organ that drives the circulation of blood enriched with oxygen and nutrients to the various tissues and organs of the body. This fist-sized organ is located in the left side of the chest cavity and is protected by the rib cage. The human body is dependent on the continuous beating of the heart, which works through the generation of electrical impulses in the cardiac muscle cells.
The heart is a dynamic machine that works as a pump in the center of the circulatory system. The heart consists of four chambers, made up of two upper atria and two lower ventricles. The heart is functionally divided into a left and a right side, with an atrium and a ventricle on each side separated by a valve. Blood that is collected from the body is low in oxygen and must return to the right side of the heart for oxygenation, while freshly-oxygenated blood from the lungs return to left side of the heart to be pumped out, back to the rest of the body.
The heart is a highly muscular organ which is covered by the epicardium and lined inside by an endocardium. The thick muscle in between these layers is called the myocardium, and is nourished by blood vessels known as the coronary arteries and veins. Electrical impulses that cause the heart to beat rhythmically are created in the sinoatrial node (in a healthy heart) and are passed down through the bundles of fiber traversing the cardiac muscles.
The function of the heart is governed by the cardiac cycle, which consists of two main phases. During the atrial diastolic phase or diastole, blood from the body and the lungs enter through valves into the atria, which in turn contract to push blood into the relaxed ventricles, after passing through the atrioventricular valves. These valves prevent the backflow of blood during contractions. This is followed shortly by the contraction of the ventricles, which pump the blood to the lungs and the rest of the body during the systolic phase, or systole. This may sound fairly simple, but the dynamic work of the heart is a complex process which may be affected by various factors, such as exercise, diet, stress, and various diseases or conditions. Any disorder or malfunction in any portion of the heart or the circulatory system may affect the efficiency of the pumping action of the heart.
A better understanding of the complex anatomy and function of the heart may help readers appreciate how this vital organ works. Here are some references that can guide you in learning more about cardiac anatomy and physiology:
Human Cardiac Anatomy Atlas. This interactive atlas of the human heart provides detailed descriptions of the parts of the heart. This website is sponsored by the University of Minnesota.
The Virtual Heart . This website offers information about the heart’s structure and function, as well as information about dysfunction in electrical conduction (arrhythmias), using several movies and other interactive java applets.
Simplified Anatomy of the Heart . WebMD presents a simple picture of the heart for beginners, including basic definitions of various heart conditions, tests and treatments.
National Geographic Heart Slideshow Presentation. This beautiful presentation shows an overview of a healthy heart and its function and what happens during a heart attack. It also features printable information with diagrams for further learning.
Heart Development. The Loyola University Medical Center provides basic information on how the heart develops during fetal life and information about congenital heart defects.
The Cardiovascular System. An overview of the anatomy and function of the heart and the circulatory (cardiovascular) system is provided by the Texas Heart Institute.
Blood, Heart and Circulation. Find many topics on the anatomy of the cardiovascular system, including various cardiovascular disorders, from the National Institutes of Health’s website.
Human Heart Facts (for kids). Kids can easily learn fun facts about the heart and other parts of the body on this website. Some diagrams can also be downloaded and printed for further learning.
The Human Heart – A Living Pump. This quick reference illustrates the pumping action of the heart.
Cardiac Cycle. Learn more about the different phases of the cardiac cycle, which are described in detail in this website. Other topics on cardiovascular disorders are also discussed.
Online Study Guide to the Anatomy and Physiology of the Heart. Enjoy learning about the circulatory system and discover how much you have learned by taking the quizzes provided.
Heart Anatomy and Physiology Review. A slideshow presentation that helps you review the basic concepts of heart structure and function.
Cardiology Teaching Package. The University of Nottingham offers a beginners’ guide to normal heart function, plus teachings on sinus rhythm and common cardiac arrhythmias. This is a very helpful resource, especially for nursing students.
YouTube Heart Anatomy. This is a 3 ½ minute video presentation on the heart as presented by a doctor.
Heart Anatomy & Function. A one-hour YouTube video presented by the Oregon Heart and Vascular Institute. It is like attending a class or a conference, but it’s online!
Heart Anatomy and Physiology Chapter Quiz. Find out if you need to learn more about the heart and its function by taking a quiz from this online learning center.
Heart anatomy and cardiac physiology. A rich resource offered by the Henry Ford College, which features various animations of heart function.
Heart Diagrams. This website offers diagrams of the heart as seen from different views.
Cardiac Anatomy Quiz Game. The Philips Learning Center offers an interactive word game to test one’s knowledge of cardiac anatomy. The website also provides new ways of maximizing online learning, including more than 100 free medical games.
Quizlet Heart Anatomy and Physiology. A fun way to test your knowledge of the structure and function of the heart – this website provides many tools and tests that will keep your heart beating fast!