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The Human Heart

William Einthoven

The Human Heart
Because the human body is incredibly complex, it is divided into different physiological systems. One of these important systems is the circulatory system. Some of the organs that comprise the system include the heart, blood, and blood vessels. To understand this system it is critical to understand the heart. The heart, by simplified dictionary definition, is described as a hollow muscular organ, with muscular contractions and expansions allowing the blood to circulate throughout the bodies of vertebrates (--216.188.210.39 17:15, 25 March 2006 (UTC) The heart wall is made up of three layers, and the chamber is divided into four parts. There are two lower chambers called the right and left ventricles and two upper chambers called the right and left atria (http://www.worldinvisible.com/apologet/humbody/heart.htm). These chambers are developed at different points in development.

In the embryonic stages of life, the human heart begins as a tubelike structure. As it grows, it requires more space. Therefore the heart begins to bend and twist forming the basic shape of the organ. During the next phase, the atria are separate, and there is a single dominant ventricle. The final step in the development of the heart is the complete separation of the atria and ventricles. Once the four chambers have separated the heart is completely developed. When the baby is born, the heart will continue to grow in size with the child. The healthy adult human heart is approximately the size of an average fist (The Heart: An Online Exploration).

The pumping of the heart is called the Cardiac cycle and occurs approximately 72 times per minute. Meaning that each cycle lasts for about eight-tenths of a second, with four-tenths of it spent by the heart resting (http://www.worldinvisible.com/apologet/humbody/heart.htm). During an average lifetime, the heart beats two and a half billion times. The pumping action of the heart is critical to the maintainance of life (The Heart: An Online Exploration). Therefore, the better the heart is understood the more medicine and science can do to help people live healthier lives.

William Einthoven and His Contributions
One of the key people who helped develop our understanding of the heart is the Dutch physiologist, Willem Einthoven. Born in 1860, Einthoven originally planned to follow his father’s footsteps to become a doctor. However, he ended up on a very different path which was heavily involved in physiology. Besides his important research vision, he found his place in heart history when he began research with a capillary electrometer to study heart sounds (“Willem Einthoven”). His work eventually lead to the discovery of Eithoven’s triangle (“Willem Einthoven”).

Einthoven’s triangle is the speculative triangle drawn around the heart. The points of the triangle show where the fluids surrounding the heart connect electrically with the limbs. Electrodes can be placed at the three points of the triangle to determine data from Leads I, II, and III. Einthoven’s law says if the values of two points are known the third can be found (Susan-needs rest of citation)



The right and left atria recieve blood from the body while the ventricles pump blood out of the heart and into the body (http://www.worldinvisible.com/apologet/humbody/heart.htm). The contracting of the left and right atrias before the ventricles is the most efficient for blood pumping. The central point of Einthoven's triangle is called the null point. The null point determines what angle hte heart rests on. Einthoven used the String Galvanometer to strengthen the ECG's ability to measure electrical waves (“ECG”). 18 April 2006 Ellen Rozek

This string galvanometer was precisioned and refined to make usable for physiologists. It's adaptabillity and speed of adjustment has helped lead investigators study the functions and diseases of the heart muscle. http://nobelprize.org/medicine/laureates/1924/einthoven-bio.html     17 April 2006      Kari Sloboth

Reference Section (--216.188.210.39 17:15, 25 March 2006 (UTC)jared butler) The Heart: An Online Exploration. The Franklin Institute Online 1996: http://fi.edu/biosci/develop/develop.html. 2 April 2006 Ankit Gandhi http://www.worldinvisible.com/apologet/humbody/heart.htm Lahn Nguyen http://www.obgyn.uic.edu/physio321/lecture3_04.pdf 10 April 2006 Susan Fry “Willem Einthoven”. Nobel Lectures, Physiology or Medicine 1922-1941, Elsevier Publishing Company, Amsterdam, 1965. http://nobelprize.org/medicine/laureates/1924/einthoven-bio.html, 2006. “ECG”. http://nobelprize.org/medicine/educational/ecg/ecg-readmore.html, 2006. http://www.mamc.amedd.army.mil/cardiology/EKG26.pdf 19 April Nick Netsch http://heart.healthcentersonline.com/ jared butler

Einthoven's triangle is an imaginary equilateral triangle with the heart at its center. Each of the sides represents one of the limb leads used for an electrocardiagram.http://www.whonamedit.com/synd.cfm/2561.html The sides of the triangle can be shifted so they are centered on the heart, the angle of the lead or trinagle side when shifted can help determine the sign (+/-) of the electrical signal in the heart at a specific time.http://www.cardioweb.co.uk/ecg/ecgpage34.asp      Lahn Nguyen April 25