The heart represents the engine of our body and is indispensable for the circulation of the blood . Organ necessary to convey the oxygen taken from the lungs to the cells, organs and tissues of the human body to feed them, it deals with the exchange of carbon dioxide , which represents the waste of the metabolic cycle.
What is the heart?
It is a muscular organ divided into two cavities, right and left , both having an atrium and a ventricle ; these are arranged vertically and are isolated from each other by walls called septa . In an adult man the weight of the heart reaches 250-300 g, while in infants it weighs approximately 20-21 g.
How is the heart composed?
It is located in the center of the chest slightly moved to the left ; protected by the sternum , it rests on the diaphragm . It resembles a conical shape and is the whole from the superposition of fabrics such as:
- the sac of the pericardium , in which it is wrapped;
- the epicardium ;
- the heart muscle, or the myocardium ;
- the endocardium , which represents the inner lining of the heart.
Its muscle tissue made up of voluntary muscles – unlike the other muscles of the human body – autonomously generates the nervous stimulus that guarantees its beat .
More specifically, the myocardium is made up of heart cells and muscle fibers called myocardiocytes . They ensure that the nerve impulse, indispensable for the heartbeat, arrives, thus allowing circulation to bleed .
The impulse that generates the contraction movement of the heart, by means of the muscle fibers, starts from the sinoatrial node , which is placed between the superior vena cava and the right atrium . The vagus nerve together with the sympathetic fibers ensure the coordinated functioning of the heart with the brain stimuli , connecting the organ with the sensory, sympathetic and parasympathetic system ; other autonomous fibers make up the cardiac plexus .
The heart is made up of four valves : the tricuspid and mitral valves make up the atrioventricular valve , which is needed to control and regulate blood flow between the atria and ventricles. Two other valves – the pulmonary and the aortic (called semilunar valves together) – connect the heart and blood vessels.
The heart is in direct communication with the blood vessels in order to obtain – from the tissues and organs – oxygen and return carbon dioxide . The conductors of blood laden with carbon dioxide are two veins : the lower hollow and the upper hollow , which connect the tissues to the heart. The blood necessary for the flow between the heart and lungs is managed by the pulmonary artery and the pulmonary vein . To distribute oxygen-laden blood throughout the body is the aorta , which is the main artery of our body.
Heart composition:
- Right atrium
- Left atrium
- Right ventricle
- Left ventricle
- Aortic valve
- Mitral valve
- Pulmonary valve
- Tricuspid valve
What does the heart guarantee?
The primary function of the heart is to circulate blood throughout our body ; from organs to cells and tissues, meeting their demand for oxygen. At the same time it has the task of taking and returning the carbon dioxide to be expelled to the lungs .
Through the aorta , blood travels throughout the body together with oxygen; this is called arterial blood . It nourishes the body, arriving in each tissue and dividing into smaller and smaller capillaries . The blood rich in carbon dioxide – the result of cellular work – makes its return to the heart through the hollow veins . In the daily course of ordinary life, the heart supplies the body with 5 liters of blood per minute ; in full physical activity, there is also talk of 20 or 30 liters of blood loaded with oxygen per minute. The correct pressure ratio on which to settle is between 130 systolic (high) and 80 diastolic (low) mmHg.
The cardiac cycle is the work that the heart does: it is the succession of two repeated movements, systole and diastole , which are repeated – at rest – for about 70/80 times per minute. Systole is the contraction phase, while diastole is the relaxation phase. Their continuous work allows to maintain the blood pressure in the cardiac areas, providing for their closure in order to avoid retrograde flow.
In the diastole phase the valves open , the musculature relaxes so that the blood flows into the chambers between the atria and ventricles . At the same time the semilunar valves remain closed, so that blood cannot circulate in the vascular beds.
In the systole phase , the opposite occurs: in a coordinated movement, the atria and ventricles contract. The pressure that is created pushes the blood towards the atrio-ventricular valves making them close. At this point the blood , unable to return to the atria, is pushed into the veins and therefore enters the circulation .
The coronary arteries have the task of keeping the heart active by pushing oxygen-laden blood into the heart muscle. If the myocardium does not receive enough blood for certain factors (for example due to the narrowing of the coronary arteries or other roughness), the heart and all its apparatus would be affected by lack of oxygenation.
When we talk about ischemic heart disease or myocardial ischemia , we refer to acute coronary syndrome or simply myocardial infarction . Pathologies and other problems related to the heart muscle can also be: valve injury, inflammation or problems related to nerve conduction leading to arrhythmia .
