The external structure of the heart
The heart is the most important part of the body. About the size of a fist, It is a muscular organ located behind and marginally left of the breastbone in the chest cavity. It is formed from the cardiac muscles that remain active throughout life. The heart works by pumping blood into the body. For the convenience of the study structure of the heart can be divide into these two major parts:
It is a contractive hollow structure of about 12-13 centimeters long and about 8 centimeters wide in the shape of a closed fist. It weighs about 310 grams in men and about 255 grams in women. It is situated in the thoracic cavity approximately on the left side between the lungs and is surrounded by double cardiovascular membranes on all sides. The heart cavity between these membranes is filled with transparent, sticky fluid that protects the heart from external trauma and keeps it moist is called pericardial fluid.
The internal structure of the heart
The human heart is a very complex structure of the body. For the convenience of the study, it can divide into these 8 parts:
1. Atrium and Ventricle
There are 4 chambers inside the heart, which are divided by the coronary sulcus into the atrium (two chambers above) and the ventricle (two chambers below). Both atrial chambers are separated by the inter-auricular sulcus and Both ventricles chambers are separated by the inter-ventricular sulcus. The left atrium is the largest chamber. The walls of the atrium are relatively thin.
This is a small oval-shaped pit on the posterior side of the inter-auricular sulcus. In the fetus, it is known as the Foramen Ovalis. The fossa ovalis is a depression in the right atrium of the heart, at the level of the interatrial septum, the wall between the right and left atrium.
3. Vena Cava
In the right atrium, two thick vena cava bring impure blood from different parts of the body, open from different holes. The vena cava, which brings blood from the anterior part of the body, is called the anterior vena cava and the vena cava which brings blood from the posterior part is called the posterior vena cava.
4. Coronary Sinus
The coronary sinus is a collection of veins joined together to form a large vessel that collects blood from the heart muscle (myocardium). The inter-auricular sulcus has a perforation of the coronary sinus with a coronary or Thebesian valve for blood coming from the heart walls.
5. Pacemaker or Sino-auricular Node
A pacemaker or sino-auricular node located near the pores of the vena cava in both atria. In short, is known as SA-Node. It is one of the major elements in the cardiac conduction system, the system that controls the heart rate.
6. Pulmonary arch
It passes from the right ventricle to impure blood to the lungs. Three crescent valves located at the base prevent blood from coming back into the heart.
7. Carotico-systemic arch
It works by transporting pure blood to the entire body by leaving the left ventricle to the heart. On the basis of this, three crescent valves are found to prevent the blood from coming back to the heart. The atrial cuspid opens into the ventricle by atrioventricular apertures containing the atrioventricular valve. These valves allow blood to enter the atrium from the atrium but do not allow the atrium from the atrium.
8. Tricuspid and Bicuspid Valve
The tricuspid valve located between the right atrium and the ventricle, the bicuspid valve between the left atrium and the ventricle allows blood to enter the ventricle from the atrium but does not allow the atrium from the ventricle.