The heart is a muscle found in any animal that has a circulatory system. The heart is paramount to keeping the animal or person alive. Its job is to push blood around the body and throughout the blood vessels. The heart acts like a pump pushing the blood in a repeated, rhythmical fashion.
The heart consists of 4 individual chambers. The two on topare known as the ‘Left and Right Atria’ and two on the bottom are referred to as the ‘Right and Left Ventricles’. The two atria are where the blood enters the heart. The right atrium receives the deoxygenated blood from the body via the superior vena cava, inferior vena cava and coronary sinus. The left atrium received oxygenated blood from the lungs via the left and right pulmonary veins. There are no valves present in the atria and this in turn causes the ‘Jugular venous pressure’ which is the pulsation that one can feel from the jugular vein found in the neck. This process is usually used when checking if a person is dead or alive after a traumatic event or life threatening incident.
The workings of the heart are quite simple on the surface; The right atrium receives deoxygenated blood which pumps it to the right ventricle and then to the lungs to be oxygenated. Once it comes back from the lungs it goes to the left atrium then to the left ventricle where it is sent through the aorta to the rest of the body. However, break open the surface and it becomes a whole different story.
The heart pumps due to an electrical impulse which works as a ‘pacemaker’. The electrical pulse begins at the SA node, Sinoatrial Node. The SA node is located in the right atrium of the heart very close to the entrance of the superior vena cava. It is known as the generator of the sinus rhythm of the heart and consists of a collection of cells in the wall of the right atrium. These cells are known as modified cardiac myocytes. A majority of heart cells have the ability to create an electrical impulse and the SA node is the group of cells which initiates the electrical impulse. These cells inform the heart when it needs to pump.
From the SA node the electrical impulse passes through both the Atria and forward into the Artioventricular node. The AV node is based between the atrium and the ventricle in a specialised area of the heart near the opening of the coronary sinus. The electrical impulse then passes from the AV node through the Purkinje fibres which are located in the inner ventricular walls of the heart, just under the endocardium. Finally, both the SA node and AV node stimulate the myocardium.
The heart is full of intricate little tiny systems which make it function correctly. Without these little processes the heart would not function correctly and therefore would cause issues for the human body.