Like a hydraulic pump pushes the water in the water network of our cities, the heart - for all practical purposes a muscle pump - allows the blood to reach the entire human body, supplying the necessary nourishment, through a complicated system of pipes: the arteries.
It is located in the middle of the chest, inside the mediastinum, and it beats 100 thousand times a day on the average (around 70 times per minute). Enclosed in a membranous sac - called the pericardium - the heart of an adult has walls defined in three layers: the epicardium (the outermost layer), the endocardium (the inner layer) and the myocardium (the intermediate layer). It weighs around 300 grams - the size of a fist - and can be divided into two parts: right heart (atrium and ventricle), which moves venous blood (full of carbon dioxide) towards the lungs; left heart (atrium and ventricle) whose task is to send arterial blood coming from the lungs (rich in oxygen) to the entire body. To work properly the heart needs electrical pulses - the vital spark originates from the cells known as pacemaker cells - and mechanisms or cardiac valves that allow the blood (700 litres in 24 hours, 5 liters per minute) to flow in a single direction without ever “turning back”. There are 4 cardiac valves: tricuspid valve and pulmonary valve, both located in the right heart; mitral valve and aortic valve, located in the left heart. As it cannot capture oxygen from the blood that flows inside it, its supply is guaranteed by arterial branches - which recall the structure of a tree - called coronaries: both the right coronary and the left coronary originate from the aorta; after the first segment called common trunk, the left coronary is differentiated in anterior descending and circumflex. Other smaller blood vessels descend from the three main coronary branches; their purpose is to reach deep into the heart muscle in order to guarantee optimal blood supply to each individual point.