It is a hollow, highly muscular, cone-shaped structure located in the thoracic cavity above the diaphragm in between the essay on the heart lungs. The human heart beats, at the rate of about 72 per minute at rest. Others Others. Veins collapse when empty. The cookie is used to store the user consent for the cookies in the category "Other.
The Cardiac Cycle
The human heart is pinkish about the size of a fist and weighs approx. It is a hollow, highly muscular, cone-shaped structure located in the thoracic cavity above the diaphragm in between the two lungs. It is protected by rib cage. The narrow end of the triangular heart is pointed to the left side, during working this end gives a feeling of the heart being on the left side. Heart is right in the centre between the two lungs and above the diaphragm in the ribcage. The narrow end of the roughly triangular heart is pointed to the left side and during working the contraction of the heart is most powerful at this end giving a feeling of the heart being on the left side.
The heart Fig. The space between the two layers is filled with fluid called pericardial fluid. This fluid protects the heart from external essay on the heart, push, shock and reduces friction during the heart beat and facilitates free heart contraction. The heart consists of four chambers. The two thin walled auricles which are upper chambers right and left. Right and left auricles are separated from each other by an inter-auricular septum. Right auricle receives deoxygenated blood from the body parts by anterior and posterior vena cava.
The two thick walled lower chamber right and left are called ventricles. Right and left ventricles are separated essay on the heart an inter-ventricular septum. The walls of left ventricle are much thicker as it supplies blood to large distance and up to the brain against gravity. The left ventricle has chordae tendinae and papillary muscles which prevent tricuspid and essay on the heart valves essay on the heart being pushed into auricles at the time of ventricular contraction. It brings deoxygenated blood from anterior body parts head, neck, chest and arms to the right auricle.
It brings deoxygenated blood from posterior or lower body parts i. abdomen and legs to the right auricle. lt is the largest vein. It arises from left ventricles and carries oxygenated blood to supply it to all body parts. Abdominal aorta is the largest artery. There are two coronary arteries right and left, arising from the base of aorta and supply blood to heart muscles, blockage at these arteries result a myocardial infraction or heart attack. Right atrio-ventricular valve Tricuspid valve -Located at the opening between right auricle and right ventricle. It is located at the junction of superior vena cava with right auricle it initiates and maintains the myocardial activity and its rhythmicity, called pace maker of heart.
Located posteriorly on right side of the interatrial septum near coronary sinus, in the destruction of S. The function of pace maker can be taken up by the A. Starts from A. Node along interventricular septum at the top. Impulses travel along bundle of HIS on to ventricles. Located at the terminal divisions of right and left branch of the bundle of HIS, essay on the heart. The South African Surgeon Dr. Christian N. Barnard born on November 8, in Beaufort West, South Africa. In he received an M. from University of Cape Town. The patient, 53 years old dentist Louis Washkansky, was given the heart of a 25 years old auto crash victim named Denise Darvall, essay on the heart.
The pumping action of heart Fig. The alternate contraction and relaxation dilation continues regularly. The waves of contraction is initiated by Sino-auricular node S. Node situated essay on the heart inner wall of right auricle. Right auricle is filled with deoxygenated blood, brought through the right and left superior vena cava from right and left side of the head, neck, chest and arm. Right and left posterior vena cava brings deoxygenated blood to right auricle from left and right lower body parts such as abdomen and legs. Simultaneously left auricle is filled with oxygenated blood when both auricles are filled with the blood, wave of contraction starts from S. Node and spreads over both the essay on the heart resulting the contraction of both auricles, simultaneously, and blood is pushed into ventricles of their sides through atrio-ventricular valves.
Atrio-ventricular valve tricuspid which is a three flap valve present between the right auricle and right ventricle, stops back flow of blood from ventricles to auricle. Atrio-ventricular valve which is a two flap bicuspid valve present between left auricle and left ventricle and stops back flow of blood from ventricle to auricle. Just after the filled of ventricles, relaxation starts in the walls of auricles due to this deoxygenated blood rushes from veins to right auricle and oxygenated blood through pulmonary vein in to left auricle Fig. Now atrio- ventricular node is excited, Present essay on the heart inter auricular septum on the wall of right auricle by the wave of contraction of auricles, wave of contraction spreads over to wall of ventricles through bundle of HIS and Purkinje Fibers.
Now both the ventricles contract simultaneously essay on the heart pressure of blood contained in them, blood of right ventricle is forced in pulmonary artery through semilunar valves, this valve prevent the backflow of the blood to the lungs for gaseous exchange, oxygenation and carbon dioxide removal and also provide nutrition to the lungs after this oxygenated blood comes to left auricle through pulmonary vein. From left auricle oxygenated blood passes into left ventricle through left auri-ventricular valve. Now from left ventricle oxygenated blood is pumped into aorta through aortic semilunar valve to supply it to all body parts.
Sometimes the pacemaker becomes faulty slow heart beat causing heart essay on the heart. Einthovan is the father of ECG. An instrument called electrocardiograph can record the electrical changes during the heart beats. The electrodes attached to the skin of the chest, near the heart, pick up electrical signals from the heart. The graph of electrical voltage produced by heart with time recorded by an electrocardiograph is called electrocardiogram or ECG. Node has a unique property of self excitation, thus it is called pace-maker. Paul M. Zoll an American developed a technique for pacing the heart through the pace-maker, essay on the heart, intact into the chest.
Rhythmic contractions and relaxations of auricles and ventricles is known as heart beat Fig. The contraction phase is systole, essay on the heart, followed by relaxation phase known as the diastole. A full heart beat in human beings lasts for about 0. When ventricle contract and A. The human heart beats, at the rate of about 72 per minute at rest. Every time the heart pumps blood into arteries, they distend rhythmically. This rhythm or wave can be felt and counted in the superficial and radial arteries near the wrist Fig. This count represent the count of the heart beat. Blood vessels:. Blood vessels form a network of tubes which carry blood away from the heart and towards the heart and perform the function of transport to the tissues Fig.
An artery is a vessel which carries oxygenated blood to various body tissues except pulmonary artery which carries deoxygenated blood. Artery has thick, muscular and elastic walls. The outer layer of walls is called tunica externa middle one is called tunica media and inner is called tunica interna. Tunica externa is made up of connective tissue, tunica media is made up of collagen fibers and un-striped muscles. Tunica interna is made up of endothelium and connective tissue, essay on the heart. Lumen of arteries is small and valves are absent in arteries. Arteries do not collapse when empty. Blood flows with jerks and under great pressure in arteries. Smallest artery breaks into arterioles.
Veins carry deoxygenated blood to heart except pulmonary vein which carry oxygenated blood. Veins are also composed of outer tunica externa, middle tunica media and inner tunica interna. The walls of veins are thin, less muscular and non- elastic. Veins have valves in their inner lining. Blood flows under little pressure in veins. Small veins are called venules. Veins collapse when empty. Capillaries are microscopic vessels, their walls are made up of squamous epithelial cells. Capillaries have power of vasodilation dilating and vasoconstriction decrease blood supply.
Top Menu BiologyDiscussion. com Follow Us On: Facebook Twitter Google Plus Publish Now. Navigation Home Static Main Menu Home Questions and Answers Forum Share Your Knowledge Content Quality Guidelines Disclaimer Privacy Policy Contact Us. Related Articles: Structure of Heart With Diagram Circulatory System Human Physiology Difference between Arteries and Veins Human Heart. Circulatory System: Types and Importance of the Circulatory System. Nervous System: Need, Structure Types and Other Details with diagram. This is a question and answer forum for students, essay on the heart, teachers and general visitors for exchanging articles, answers and notes.
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An instrument called electrocardiograph can record the electrical changes during the heart beats. The electrodes attached to the skin of the chest, near the heart, pick up electrical signals from the heart. The graph of electrical voltage produced by heart with time recorded by an electrocardiograph is called electrocardiogram or ECG. Node has a unique property of self excitation, thus it is called pace-maker. Paul M. Zoll an American developed a technique for pacing the heart through the pace-maker, intact into the chest. Rhythmic contractions and relaxations of auricles and ventricles is known as heart beat Fig. The contraction phase is systole, followed by relaxation phase known as the diastole. A full heart beat in human beings lasts for about 0.
When ventricle contract and A. The human heart beats, at the rate of about 72 per minute at rest. Every time the heart pumps blood into arteries, they distend rhythmically. This rhythm or wave can be felt and counted in the superficial and radial arteries near the wrist Fig. This count represent the count of the heart beat. Blood vessels:. Blood vessels form a network of tubes which carry blood away from the heart and towards the heart and perform the function of transport to the tissues Fig. An artery is a vessel which carries oxygenated blood to various body tissues except pulmonary artery which carries deoxygenated blood. Artery has thick, muscular and elastic walls. The outer layer of walls is called tunica externa middle one is called tunica media and inner is called tunica interna.
Tunica externa is made up of connective tissue, tunica media is made up of collagen fibers and un-striped muscles. Tunica interna is made up of endothelium and connective tissue. Lumen of arteries is small and valves are absent in arteries. Arteries do not collapse when empty. Blood flows with jerks and under great pressure in arteries. Smallest artery breaks into arterioles. Veins carry deoxygenated blood to heart except pulmonary vein which carry oxygenated blood. Veins are also composed of outer tunica externa, middle tunica media and inner tunica interna. The walls of veins are thin, less muscular and non- elastic. Veins have valves in their inner lining. Blood flows under little pressure in veins. Small veins are called venules. Veins collapse when empty. Capillaries are microscopic vessels, their walls are made up of squamous epithelial cells.
Capillaries have power of vasodilation dilating and vasoconstriction decrease blood supply. Top Menu BiologyDiscussion. com Follow Us On: Facebook Twitter Google Plus Publish Now. Navigation Home Static Main Menu Home Questions and Answers Forum Share Your Knowledge Content Quality Guidelines Disclaimer Privacy Policy Contact Us. Related Articles: Structure of Heart With Diagram Circulatory System Human Physiology Difference between Arteries and Veins Human Heart. Circulatory System: Types and Importance of the Circulatory System. Nervous System: Need, Structure Types and Other Details with diagram. This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes.
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It does not store any personal data. Functional Functional. The tricuspid valve prevents the blood from flowing back into the right atrium. During the systole phase the right ventricle receives impulses from the Purkinje fibers and contracts. The atrioventricular valves close and the semilunar valves open. The de-oxygenated blood is pumped into the pulmonary artery. The pulmonary valve prevents the blood from flowing back into the right ventricle. The P cells and the T cells. This results in simultaneous systole of the two atria, squeezing the blood into the ventricles.
Sinoatrial exit block is a result of failure of the T cells to transmit the electrical signal to the right atrium. Depolarisation and contraction of the atria is represented by the P wave on the ECG. Heart wall thickness varies from part to the part and from person to person. For example the atria part of the heart has thinner layer of myocardium than ventricular because atria does not pump blood far. In ontrast, ventricles owns a very thick layer of myocardial in order t middle of paper valves to open and the AV valves to close by pressure of the ventricles.
By this way valves allows for blood flow from the ventricles into the arteries. This phase is called Repolarization then is prepare to the state of diastolic during this phase. It is the set up, rhythmic stimulation of the myocardium during the cardiac cycle that allows efficient contraction of the pump, thereby permitting blood to be pumped throughout the torso. State three reasons why patients may need an electrocardiogram ECG. To look for the cause of chest pain To evaluate problems which may be heart-related, such as severe tiredness, shortness of breath, lightheadedness, or passing out To identify irregular beats. In the capillaries, the blood performs three functions then it releases its oxygen to the tissues, it furnishes to the body cells the nutrients and other essential substances that itiating the heartbeat.
The contraction then spreads over the auricles in the septum between the auricles, it excites another node called the auriculoventricular node. The auriculoventricular bundle conducts the impulse from this node to the muscles of the ventricles, and in this way contraction and relaxation of the heart are coordinated. Each phase of the cardiac cycle is associated with the production of an electrical potential that can be recorded by electrical instruments to produce a reading known as an electrocardiogram. Circulation of the blood in superficial capillaries can be observed under the microscope. Heart is made up of muscle and it has walls. It contacts to pump blood into the blood vessels and all over your body.
The heart beats to maintain the blood circulating. The heart beating leads the cardiac cycle and which pumps blood to the cells and tissues of the body. The veins supply the deoxygenated blood from the body to the right side of heart. The pericardium protects and anchors the heart; prevents overfilling of blood; and helps to work in a friction-free environment. The wall of cardiac muscle is composed of myocardium which is the fibrous skeleton of the heart. This muscle is more elaborate and thicker in areas like around the valves and at the base of the great vessels that leaves the heart. Endocardium thin serous endothelial layer of inner myocardium lines each of the chambers.
These sounds are results of vibration caused by closure of these valves. Other sounds known as "heart murmurs" are sometimes a sign of heart disease. The glass probe poked into the pulmonary trunk will follow the cycle of blood from the pulmonary artery to the lungs and then through pulmonary veins will enter the left atrium. The Heart and Circulatory System The regular heart beat and pulse is produced by contractions of the heart muscle during the cardiac cycle. These contractions are caused by an electrical stimulus called the cardiac impulse. This natural pacemaker of the heart, called the Sinoatrial node, is located in the Right Atrium. The electrical impulse leaves the Sinoatrial node and travels to the right and left Atria, causing them to contract together.
After contraction, there is a period of insensitivity to stimulation which allows the Ventricles to fill with blood. It is then oxygenated and returns to the left atrium in the pulmonary veins it travels through the mitral atrioventricular valve into the left ventricle and is then pumped out of the heart to the systematic circulatory system passing through the aortic semilunar valve into the aorta. Widamaier, et al The heart is situated in the thoracic cavity protected by a sac called the pericardium. The inner heart wall is made up of three layers the outside of the heart wall is called the epicardium this lubricates the heart and prevents friction.
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