Heart

The Heart by Bonnie and Obléo

The human heart is a hard working muscle and vital organ. Without a heart you would die immediately. The heart pumps blood through a complicated process. There are two upper chambers and they are called the left and atrea. The two lower chambers are called the left and right ventricle. The electric energy that stimulates the heart happens in the sinoatrial node. It produces a definite potential then discharges sending an impulse across the atria. inside the atria the electrical signal moves from cell to cell, while in the ventricles the signal is brought by specialized tissues called the Purkinje fibers. They then transmit the electric charge to the myocardium The human heart and its its disability's (cardiopathies) are studied primarily by cardiology. A human heart weighs about between 250 and 350 grams and is about as big as your fist. It is enclosed in a double walled protective sac its callled the pericardium the superficial part of the sac is called the fibrous pericardiu m. theis sac protects the heart anchors its surrounding structures and prevents blood overfill of the heart

the outer wall of the heart is compsed of three layers. the outer layeris named the epicardium or the visceral pericardium since it is also the inside wall of the pericardium. The middle layer is named the myocrdium its composed of muscle witch then contracts. The inside layer is call the heart pumps. it also,merges with the inside line (the endothelium)of blood vessels and covers the heart valve s.

The pathway of pumping blood through the human heart has a pulmonary circult and a systemetic circuit. Blood flows in to the circulatory system this is done by four valves they are the tricuspid valve, the mitral valve, the mitral valve, and the pulmonary valve.

Blood flows throughout the one direction it flows from the atria to the ventricles and out of the heart arterie

here are some cool vid's about the heart

media type="youtube" key="IR0nWe47eek" height="156" width="192"media type="youtube" key="dYgYcH7R29I" height="184" width="200" align="right" Here are links to sights about the heart. [|Wikipeadia the Heart] [|Heart Disease] [|Animal Hearts] here are some links to some cool youtubeyoutube vids http://www.youtube.com/watch?v=G5S0yQhK42s http://www.youtube.com/watch?v=3cW8__wFXDA