The Human heartis a hollow, muscular organ that pumps blood through the blood vessels by repeated, rhythmic contractions.
The human heart is not just the physical organ, according to the human understanding. It also holds a special place in our collective psyche as it is equated with love. It has many other associations, but here we shall just outline a few examples:
- · have a heart – be merciful
- · change of heart – change your mind
- · to know something by heart – memorise something
- · broken heart – to lose love
- · heartfelt – deeply felt
- · have your heart in the right place – to be kind
- · cry your heart out – to grieve
- · heavy heart – sadness
- · have your heart set on – to want something badly.
Heart structure
A heart is the main organ of our body’s circulatory system, pumping blood throughout the body. it is a muscular pump which contracts at regular intervals in order to squeeze the blood through it into the blood vessels.
The human heart has got four chambers; two upper chambers (the atria) and two lower ones (the ventricles), which work in coordination for the successful execution of different heart functions. The right atrium and right ventricle together make up the “right heart,” and the left atrium and left ventricle make up the“left heart.” A wall of muscle calledthe septumseparates the two sides of the heart. The right chambers contain unclean or the deoxygenated blood. On the other hand, the left chambers contain clean or the oxygenated blood. Talking of the heart structure, it is made up of connective tissue and cardiac muscles. The latter is a type of involuntary muscle, that is, it contracts and relaxes on its own without requiring you to deliberately apply force. The heart is a delicate organ. Any damage to it will cause disturbance in the heart functions. So, it gets protection from the rib cage.
A double-walled sac called thepericardiumencases the heart, which serves to protect the heart and anchor it inside the chest. Between the outer layer, the parietal pericardium, and the inner layer, the serous pericardium, runs pericardial fluid, which lubricates the heart during contractions and movements of thelungsand diaphragm.
The human heart’s outer wall consists of three layers. The outermost wall layer, or epicardium, is the inner wall of thepericardium. The middle layer, ormyocardium, contains the muscle that contracts. The inner layer, orendocardium, is the lining that contacts the blood.
The tricuspid valve and the mitral valve make up the atrioventricular (AV) valves, which connect the atria and the ventricles. The pulmonary semi-lunar valve separates the right ventricle from thepulmonary artery, and the aortic valve separates the left ventricle from the aorta. The heartstrings, or chordae tendinae, anchor the valves to heart muscles. The sinoatrial node produces the electrical pulses that drive heart contractions.
Concerning shape, it looks like a cone. The base of this cone is positioned upward which gradually tapers down to the apex. The pumping organ is roughly the size of a wrist, while measuring 12 cm, 8 cm and 6 cm along length, width and thickness, respectively.
The effect of exercise on the muscles of the heart organ is the same as shown by the skeletal muscles. That is, as an outcome of exercise, they grow both in size and strength. That is why, the well-trained athletes usually have much larger hearts. Such a thing also makes the heart functions better.
The Functions of the Human Heart
The heart circulates blood through two pathways: the pulmonary circuit and the systemic circuit. The heart functions involve the supply of oxygenated blood to all parts of the body. The circulatory system consists of three main types of blood vessels: arteries, veins and capillaries.
Arteries carry oxygenated blood and distribute it to different parts of the body. On the other hand, the veins receive unclean blood, containing carbon dioxide and waste products, from the body parts and take it back to the heart.
The human heart contains both the oxygenated and deoxygenated blood. It is its job to keep both of them separate in order to avoid contamination of the pure blood. The right chambers of the heart receive blood, devoid of oxygen, from the veins. This blood then goes to thelungsto receive oxygen and get rid ofcarbon dioxide.
Afterwards, this oxygen-rich blood goes back to the heart from where it reaches all the body parts through the arteries. In this way, every individual cell is able to get oxygen. This oxygen will assist in the process of extracting energy from food.
A healthy human heart contraction happens in five stages.
- In the first stage (early diastole), the heart is relaxed.
- Then the atrium contracts (atrial systole) to push blood into the ventricle.
- Next, the ventricles start contracting without changing volume.
- Then the ventricles continue contracting while empty.
- Finally, the ventricles stop contracting and relax. Then the cycle repeats.
Valves prevent backflow, keeping the blood flowing in one direction through the heart.
Function of the Blood and Blood Vessels:
The function of the blood is to serve as a circulatory fluid. The blood carries the respiratory gases and nutrients to every individual cell in the body. On its return, it brings carbon dioxide, a waste respiratory gas, for its discharge out of the body.
Diseases of the human heart
Coronary Artery Disease:The blood vessels which transport blood to the heart become narrow due to a deposition of plaque, forcing the heart to work harder. As a result, the heart muscles gradually become weak. This is a fatal disease which is the result of a high blood cholesterol level.
Myocardial Infarction:It is one of most dangerous heart diseases. More commonly known as heart attack,myocardial infarctionmay lead to death on the spot if the individual is unable to get prompt medical help. A heart attack more commonly occurs in patients who are already suffering from coronary artery disease.
The flow of blood to the heart is either reduced or there is complete blockage, depriving the heart cells of oxygen. As a result, all the heart functions come to an end.
Congestive Heart Failure:It is a common disease affecting human heart, which develops as a result of coronary artery disease or a heart attack. The heart of the patient suffers from damage and is unable to perform the heart functions up to its full capacity. As a result, insufficient blood is pumped and the body’s oxygen requirements are not fulfilled. The patients experience fatigue and shortness of breath.
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