HEART
The study of heart and its disease is known as Cardiology. Heart is the busiest organ of the body. Human heart is about the size of first. It is located slightly left of middle in the chest. The main function of the heart is it pumps oxygenated blood to the body and deoxygenated blood to the lungs.
• Normal heart beat rate in human -
70 to 72 times per minute (male).
• In many required for a single cardiac cycle - 0.8 seconds.
Circulation of blood in the body is regulated by the Heart. The human heart has four distinct chambers - 2 Auricles and 2 Ventricles. 2 upper chambers are called Auricles. 2 lower chambers are called Ventricles. Double membrane that covers herat is Pericardium. Fluid filled in pericardium - Pericardial fluid. Blood enriched with oxygen is called Pure blood. Blood abundant in CO2 and poor in oxygen is called impure blood. Left chambers of the heart are filled with pure blood. Right chambers of the heart are filled with impure blood. Direction of blood flowing through the heart is from atria to ventricle. The chambers that receives pure blood - Left atrium (auricle). The chamber that receives impure blood - Right atrium ( auricle). Interatrial septum is the thin muscular wall that separates that right and left atria. Interventricular septum is the thick muscular wall that separates left and right ventricle. Hormone secreted by the atrial wall of heart is ANP ( Atrial Natriuretic Peptide ). Thick fibrous tissue that separates atrium and ventricle is called Atrioventricular septum. Left chamber with thick wall is called Left Ventricle. The valve between left Auricle and Ventricle is called Bicuspid Valve ( Mitral valve ). The valve between right auricle and ventricle is called Tricuspid valve. The blood vessels that carries pure blood is Artery and the impure blood is Vein. Pulmonary artery is the only artery that carries impure blood. Pulmonary vein is the only vein that carries pure blood. The blood vessels that connect arteries and veins are called Capillaries. The wall of blood capillary is formed of Endothelial cells. When blood passes through lungs, gases are exchanged through capillaries or alveoli.
• Largest blood vessels in the human body - Aorta
• The largest artery in the human body - Aorta
• The largest vein in the human body - Inferior Vena cava
Avarage length of blood vessels in human is around 1 lakh km. Heart is only organ in the human body which is not effected by cancer. The heart beat of the human being starts when the growth of embryo is 4 weeks. Restless muscle of the human body is Cardiac muscle. Myocardial muscles that help heart to beat in same rhythm. Tachycardia is the condition of more than 100 heart beats per minute. Bradycardia is the condition of less than 60 heart beats per minute. Chest pain caused by reduced blood flow to heart muscle is Angina pectoris. Acetyledine is the chemical substance which decreases the heart beat. The hormone which stimulates the heart beat is Adrenaline.
Heart Chambers
• Human - 4
• Mammals - 4
• Birds - 4
• Crocodile - 4
• Amphibians - 3
• Reptiles - 3
• Fish - 2
Pacemaker is known as ' heart of the heart '. SA node ( SinoAtrial node ) is known as the pacemaker of the heart. It is used to stimulate the heart which works as an artificial heart. The contraction and relaxation of the heart is together called Heartbeat or cardiac cycle. Ventricular filling period is the first phase of cardiac cycle.
Rheumatic fever is the disease which damages the heart valve. ECG ( Electrocardiograph ) is the instrument used for checking heart ailments. ECH was invented by William Einthoven. In ECG the depolarisation of atria is represented by - p - wave. First successful heart - lung machine was developed by - John H. Gibbon (USA). Heart and lung transplant surgery ( together in the same patient ) was done by - Dr. Bruce Reitz (March 9,1981).
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