SC235: General Biology 1
Unit 4 Assignment
The heart is what some determine to be the most important organ in our bodies and one of the biggest contributors. It is one of the major organs that if we did not have, it would not be possible for us to live. The heart is about the size of a fist and is broken down into four chambers, the aorta, superior vena cava, pulmonary artery, and the coronary artery. The four chambers include the right and left atrium and the right and left ventricle. The heart is responsible for supplying oxygen and blood to the entire body. Blood passes through these four chambers and then exits and pumps into the rest of the body. The heart also has three layers of walls which are the epicardium, myocardium, and the endocardium. The epicardium is the outermost layer of the heart’s wall. The myocardium is the middle layer and finally the endocardium is the innermost. The heart is composed of different cell types which all contribute to structural, biochemical, mechanical, and electrical properties. Forming the walls of the heart are atrial and ventricular cardiomyocytes. Cells specialize in different roles. They determine the function of a tissue in the human body. Endothelial cells form the endocardium which is the interior lining of blood vessels and cardiac valves. Over 50 percent of the cells the heart contains are cardiac fibroblasts. There are also pacemaker cells and Purkinje fibers that are specialized cardiomyocytes that generate and conduct electrical impulses. The sinoatrial node is composed of some of these pacemaker cells and rests in the right atrium generating impulses to initiate contraction of the heart. Between the atria and ventricles is the antrioventricular node. It conducts electrical impulses from the atria to the ventricles. If organs were comprised of just one type of cell they would only be able to carry out one task rather than multiple...
References: About Education. Regina Bailey (2015) Retrieved from:
WebMD (2015) Retrieved from:
Nature Reviews. Mei Xin, Eric N. Olson, & Rhonda Bassel-Duby (2013) Retrieved from:
Please join StudyMode to read the full document