*Overall information
-The heart is located in a region called the mediastinum, inside the thoracic cavity.
-It is shifted around ⅔ to the left of the midsternal line.
-The heart weighs around 250-400 grams (depending on your age) and has a cone-shaped structure. The broad base is at the top where large blood vessels enter and exit while the tip, known as the apex, points downward.
-A normal resting heart rate for adults is about between 60-100 beats per minute (bpm)
-The heart is responsible to:
+pump oxygenated blood, hormones and other essential substances from the heart to every other parts of the body
+receive deoxygenated blood and metabolic waste products from our body before pumping them to the lungs
*Layers of the heart:
-Endocardium: a thin layer of endothelium and a little bit of connective tissue layer underneath.
-Myocardium: made up of cardiac muscle tissue, which helps heart pumping action. The left myocardium layer is bigger than the right one because the left side of the heart has to pump blood to every part of your body while the right side just has to deliver blood to the lungs.
-Epicardium: transparent layer of connective tissue.
-Pericardium: consists of 2 layer:
+The inner layer is called visceral pericardium.
+The outer layer is called lateral pericardium which is composed of inelastic connective tissue, preventing excessive stretching of the heart when it contracts.
+The region between these two layers is filled with a special kind of fluid which serves as a lubricant, minimizing friction when the heart contracts to pump blood.
*Chambers of the heart:
-The heart consists of 4 chambers. The 2 upper chambers are called right and left atrium while the 2 lower ones are called right and left ventricles.
+Right atrium: receives deoxygenated blood from the super vena cava (SVC), inferior vena cava (IVC), and coronary sinus (a hole inside the right atrium).
+Right ventricle: there is a one-way flowing valve called tricuspid valve that empties deoxygenated blood from the right atrium to the right ventricle. This valve is anchored and kept tight to prevent blood black flowing up by chordae tendineae (collagen cords). These cords are also anchored by papillary muscles which originate from the myocardium layer. The right ventricle will pump deoxygenated blood through the pulmonary semilunar valve to the pulmonary trunk before splitting to left and right pulmonary arteries which eventually lead blood to your lungs.
+Left atrium: receives blood from 4 pulmonary veins which bring oxygenated blood from the left and right lung (2 from the right and 2 from the left).
+Left ventricle: oxygenated blood will be pumped from the left atrium to the left ventricle through the mitral valve. There will also be chordae tendineae and papillary muscle that serve the same function with those in the right ventricle. Blood inside the left ventricle will also be delivered through aortic semilunar valve to the aortic arch. There are three vessels originating from the aortic arch (brachiocephalic, left common carotid artery, left subclavian artery). Brachiocephalic will split into the right common carotid artery and right subclavian artery.
+Right ventricle and left ventricle are separated by an interventricular septum while interatrial septum separates the right and left atrium. These septums help prevent oxygenated and deoxygenated blood from being mixed.
Basic Human Anatomy and Physiology 