The Heart Essay

The heart is a very important organ in the body. It’s around the size of someone’s hand closed up together in a fist and is located in the chest between the lungs. The main purpose of the heart is to pump blood around the body ( The Structure of the Heart). The heart consists of epicardium, myocardium, and endocardium layers that protect its walls. The epicardium is the membrane of the external heart surface. The endocardium lines the interior portion of the chambers in the heart. Lastly, between these two layers and the thickest, the myocardium is made of cardiac muscles and performs the work of the heart. Collagenous and elastic fibers between the hearts walls and chambers are called fibrous skeleton (Anatomy and Physiology pg.717- 718). It functions as a structural supporter and provides electrical insulation between the atria and ventricles. This is important for timing and coordination of electrical and contractile activity.

There are four important chambers that are inside of the heart and play important roles in the circulation of blood: Right/ Left Atrium and Right/ Left Ventricles. The superior half of the heart, both atriums, are thin walled receiving chambers for blood returning to the heart. Both ventricles, inferior half, eject blood into the arteries and keep it flowing throughout the body. It is essential that blood flows in the correct direction through the heart so there are a number of valves needed. The tricuspid valve separates the right atrium from the right ventricle and the pulmonary valve divides the right ventricle from the pulmonary artery. The bicuspid valve separates the left atrium from the left ventricle, and the aortia valve separates distinguishes the left ventricle from the ascending aorta (The S...

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... begins with the atria depolarizing, which is being represented in the EKG by the P wave. After the P wave, the QRS complex wave represents ventricular depolarization. It also showcases the repolarization the atria but cannot be seen because of how strong the ventricular depolarization wave is. At the end of the QRS wave, the T wave represents ventricular repolarization. Adding to the waves of the EKG, there are also intervals and segments that play a role as well. An interval is part of the EKG that has at least one wave and a straight line. The PR interval is the time taken by the impulse sent from the SA node to travel to the ventricles. Segments refer to a period of time from the end of one wave to the beginning of the next wave . The PR segment deals with the time of the AV node to delay and send signals to the ventricles (Lesson #5: Physiology of the Heart).