The heart is a muscular organ that is around the size of a closed fist that pumps blood throughout the body, functioning as the circulatory pump. It takes the deoxygenated blood through the veins and sends it to the lungs for oxygenation before injecting it into the different arteries, which drove oxygen and nutrients to the body tissues transporting the blood through the body. The heart is positioned in the thoracic cavity medial to the lungs and posterior to the sternum.
On its superior end, the foundation of the heart is attached to the aorta pulmonary arteries and vena cava and veins. The interior of the heart is called the apex, sets superior to the diaphragm. The base of the heart is positioned along the body’s midline and the apex pointing toward the left side. Due to the heart points to the left, about 2/3 of the hearts mass is located on the left side of the body, and the other 1/3 is on the right side.
Anatomy of the heart
The heart sits within a fluid-filled cavity described as the pericardial cavity. The walls and insulation of the pericardial cavity are a unique membrane known as the pericardium. The pericardium is a serous membrane that creates serous fluid to lubricate the heart and prevent friction between the heart and surrounding organs. Notwithstanding lubrication, the pericardium acts to hold the heart in position and maintains a hollow space for the heart to develop into when it becomes full. The pericardium has two layers – the visceral layer that shields the outside of the heart and the parietal layer that create a sac around the outside of the pericardial cavity.
Structure of the Heart Wall
The heart wall consists of 3 layers: myocardium, epicardium, and endocardium.
The epicardium is the outermost layer of the heart wall and is another name for the visceral layer fo the pericardium. Therefore, the epicardium is the third layer of serous membrane that aids to lubricate and shield the outside of the art. Underneath the epicardium is the second, thicker layer of the heart surface, the myocardium.
Myocardium: The myocardium is the central muscular layer of the heart wall that includes the cardiac muscle tissue. Myocardium makes up the majority of the density and mass of the heart wall, and the is part of the heart responsible for pumping blood Below the myocardium is the thin endocardium layer.
Endocardium: The endocardium is the simple squamous endothelium layer that lines the inside of the heart. The myocardium is very smooth and is responsible for keeping blood from sticking to the inside of the heart and forming potentially leaky blood clots.
The heart all varies in thickness in different areas. The atria of the heart have a substantially thinner myocardium due to the need to the need not to pump blood very very, going only to nearby ventricles. The ventricles, however, have very thick myocardium to pump blood throughout the body to areas such as the lungs. The right side of the heart has less myocardium in the walls than the left side since the left side has to pump blood into the entire body while the right side only has to pump to the lungs.
Chamber of the heart
The heart comprises of four chambers, the right atrium, left atrium, right ventricle and left ventricle. The area is smaller than the ventricles and has thinner, fewer muscular walls than the ventricles. The area serves as receiving chambers for blood, in-turn they are not connected to the veins that send blood to the heart. The ventricles are the bigger, stronger pumping chambers that carry blood out of the heart. The ventricles are connected to the arteries that carry blood away from the heart.
The heart chambers on the right side of the heart are thinner and have less myocardium in their walls when compared to the left side of the heart. This variance in size between the two sides is based on their functions and the size of the two circulatory loops. The right side of the heart controls pulmonary circulation that is carried to the nearby lungs while the legal side of the heart pumps blood all the way to the extremities of the body like the hands and foot, in the systemic circulatory loop.
The heart functions by pumping blood to the lungs and other systems in the body. To prevent blood from flowing backward or to regurgitate back into the heart, a network of one-way valves exist in the heart. The heart valves can be segmented into two types: atrioventricular and semilunar valves.
Atrioventricular valves. The atrioventricular (AV) valves are positioned in the center of the heart between the atria and ventricles and only enable blood to flow from the atria into the ventricles. The AV valve on the right side of the art is referred to as the tricuspid valve due to it consisting of three cusps or flaps that separate in order to allow blood to pass through and connect to block the blood from regurgitating. The Av valve on the left side of the heart is referred as the mitral valve or the bicuspid valve due to it having two cusps. Th AV valves are attached on the ventricular side to fibrous strings named chordae tendineae. The chordae tendineae draw on the AV valves to prevent them from folding backward and permitting blood to regurgitate past them During the withdrawal of the ventricles; the AV valves look like domed parachutes with chordae tendineae function as the ropes holding the parachutes taut.
Semilunar valves – are named for the crescent moon shape of their cusps. These are positioned between the arteries and ventricles that carry blood ways from the heart. The semilunar valve on the right side of the heart is the pulmonary valve; which is named because it prevents the backflow of the blood forms the pulmonary truck into the right ventricle. The semilunar valve on the left section of the heart is the aortic valve; which is defined for the function of preventing the aorta from regurgitating blood back into the left ventricle. The semilunar valves are smaller than AV valves and do not have chordae tendineae to hold them in place. Rather the cusps of the semilunar valves are cup shaped to catch regurgitating blood and uses the blood’s pressure to snap shut.
The heart si able to set its rhythm as well as conduct necessary signals to control and coordinate this rhythm throughout its structures. About 1% of the cardiac muscles class in the heart are responsible for forming the conduction system that set the pace or thy rest of the cardiac muscle cells.
The condition system starts with the placemark of the heart- a small bundle of cells called the sinoatrial SA node. The SA node is positioned in the wall of the right atrium inferior to the superior vena cava. The SA node is responsible for establishing the pace of the heart as a whole and directly signal the atria to contract. The signal from the SA node is selected from another mass of conductive tissue called the atrioventricular (AV) node
The AV node is positioned in the right atrium in the inferior portion of the interatrial septum. The AV node pulls up the signal transmitted by the SA node and carries it through the atrioventricular (AV) bundle. The AV bundle is a strand of the conductive membrane that runs via the interatrial septum and into the interventricular septum. The AV bundle divides into left and right branches in the interventricular septum and resumes extending through the septum until they touch the apex of the heart. Many Purkinje fibers, branching off from the left and right bundle carries the signal to the walls of the ventricles, exciting the cardiac muscle cells to contract in coordination to efficiently pump blood out of the heart.