Essay on Human Heart: The human heart is pinkish about the size of a fist and weighs approx.
Essay on the structure and functions of Heart for students Ashiya Advertisements: The heart is a hollow muscular, cone-shaped organ, lying between the lungs in a block of tissue called the mediastinum. It tilts obliquely, Essay about the heart little more to the left than the right and presents a circular base above and an apex below.
It is usually located on the level of the fifth intercostals space about 9 cm from the midline. It weights about gm. The pericardium is the outer part that covers the heart and consists of two layers or sacs - the outer layer or fibrous pericardium is securely attached to the diaphragm, the outer coat of the great vessels and the posterior surface of the sternum and therefore maintains the heart in its position.
Its fibrous nature prevents over distension of the heart. The inner layer the serous pericardium consists of two layers the outer or parietal layer lines the outer fibrous sac and the inner or visceral layer covers the heart muscle.
The serous membrane secretes serous fluid into the space between the visceral and parietal layers that allows smooth movement between the layers, when the heart beats. The myocardium is the middle layer of the heart and is composed of specialised muscle tissue called as the cardiac muscle, on which the circulation of blood depends.
It varies in thickness, being thickest in the left ventricle, thinner in the right ventricle and thinnest in the artrium. The endocardium forms the inner linging of the heart is a thin, smooth, glistening membrane consisting of flattened epithelial cells which is continuous with the valves and with the lining of the blood vessels.
Interior of the Heart The heart is divided into a right and left side by a muscular partition called as the septum. The two sides of the heart have no communication with each other.
Each side is subdivided into an upper and lower chamber. The upper chamber on each side is called the auricle or atrium and is the receiving chamber into which blood flows through veins.
The lower chamber on each side is called the ventricle and is the discharging chamber from which the blood is driven into the arteries.
Each atrium communicates with the ventricles below it on the same side of the heart through an opening, guarded by a valve called as the artrio-ventricular valve. The valves ensure blood flow in one direction only- from the upper chamber or atrium to the lower chamber or ventricle.
The valve separating the right atrium from the right ventricle is known as the right artrio- ventricular valve tricuspid valve and is made up of three flaps or cusps. Similarly the valve separating the left atrium from the left ventricle is called as the left artrio-ventricular valve mitral valve and is composed of two flaps of cusps.
The valve between the artria and the ventricles open and close as a result of changes in the pressure of blood within the chambers. Also the valves are prevented from opening upwards by the Chordate tendineae tendinous cordswhich originate in the papillary muscles in the walls of the ventricle.
Flow of blood through the heart The heart acts as a pump which drives blood into and through the arteries, but the right and left side of the heart of function quiet separately from one another. Blood from all parts of the body is collected and gets poured into the right atrium through the two largest veins of the body, the superior and inferior venacavae.
When it gets filled, the right atrium contracts and drives the blood through the right artrio-ventricular valve into the right ventricle, which is turn contracts sending the blood through the pulmonary valve and into the pulmonary artery.
The pulmonary artery passes through the walls of the heart and divides into left and right pulmonary artery. These arteries carry the venous blood to the lungs where the inter change of gases takes place, carbon dioxide is excreted and oxygen is absorbed. The arterial or oxygenated blood is collected from each lung by four pulmonary veins, which empty their content into the left atrium of the heart.
This oxygenated blood passes through the left artrio ventricular valve into the left ventricle from where it is pumped into the aorta, the main artery of the body to all parts of the body.
Both the openings of the pulmonary artery and the aorta are also guarded by valves as pulmonary and aortic valves respectively. These valves are formed by three half-moon shaped semi lunar cusps. It should however be remembered that both the atrium contract at the same time followed by the simultaneous contraction of both ventricles.
The heart is supplied with arterial blood by the right and left coronary arteries. On the contrary, its deoxygenated blood or the venous return is by the coronary sinus which empties into the right atrium. The function of the heart is to maintain a constant circulation of blood throughout the body.
In human beings, when the heart is beating normally, the cardiac cycle occurs about 74 times per minute. Thus each cycle lasts about 0. The cardiac cycle consists of: Contraction of the artia - Artial Systole Contraction of the Ventricles - Ventricular Systole Relaxation or rest period of - Complete cardiac diastole The artria and ventricles.
Heart Sound One can hear two heart sounds for each heart beat or cardiac cycle. The Circulation of the blood The circulation of blood in the body is divided into three parts: The Pulmonary Circulation 3. The pulmonary circulation is concerned in carrying deoxygenated blood from the right side of the heart to the lungs and again bringing oxygenated blood from the lungs to the left part of the heart.
The pulmonary artery carrying deoxygenated or venous blood arises from the right ventricles.The Heart The heart is a group muscles that pumps blood throughout the blood vessels by repeated, rhythmic contractions. It is found in all animals with a circulatory system. It is found in all animals with a circulatory system.
Oct 14, · Words: Length: 2 Pages Document Type: Essay Paper #: Tell-Tale Heart Philosophy of Composition in the "Tell-Tale Heart" The central elements of this philosophy used by Edgar Allan Poe are length, method, and unity of effect (Xroads ).
The human heart is pinkish about the size of a fist and weighs approx. gms, the weight in females being about 25% lesser than the males. It is a hollow, highly muscular, cone-shaped structure located in the thoracic cavity above the diaphragm in between the two lungs.
Essay Thesis For Heart Of Darkness about thesis on friendship An articulation of school outcomes than stability. Scripts include key wishes or concerns, typical responses by governments to levy taxes and subsidies to promote the well being of society.
The heart is a muscle, which many people don't know. Your heart is about the size of your fist, and is not in the normal heart shape. The heart has four chambers filled with blood. The human heart is pinkish about the size of a fist and weighs approx.
gms, the weight in females being about 25% lesser than the males. It is a hollow, highly muscular, cone-shaped structure located in the thoracic cavity above the diaphragm in between the two lungs.