Anatomy And Physiology

Anatomy Physiology



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The heart is a muscular pump in the body which pumps venous deoxygenated blood from the various organs of the body through the vena cava to the pulmonary circulation where it is processed by removing carbon dioxide  from the blood  into the lungs.  In exchange, the blood is oxygenated with oxygen and is pumped from the pulmonary circulation to the various body organs through the aortic artery which has branches for each and each organ.


In addition  to oxygen the heart pumps through the blood nutrients to the body tissues especially the sugar glucose.  Also toxins in the body are sent through the blood circulation to the liver sinuses where they are detoxified and neutralized using macrophages in the liver which are called kupfer cells.  After that the detoxified compounds are sent to the kidney, again with the blood stream where there it is filtered in the urine and is expelled from the body. 


for all these reasons the heart has a crucial role for sustaining life if not the most crucial organ in the body.  Therefore diseases of the heart especially heart failure ca have dramatic effects on the body due to the deficient supply of oxygen and nutrients to the body organs.  All body organs can be affected by a heart failure. 


A clinically important disease of the heart that can impair the pumping ability of the heart to pump blood to the circulation is stenosis of the coronary artery which supplies the heart muscle with oxygen and gluccose.  Therefore adequqate blood supply to the heart muscle with oxygen and glucose is of utmost importance for the proper supply of blood to the various organs in the body. 


The heart of humans is composed of a layer that lines its inner surface and which is called endocardium.  In addition, there is the muscular layer of the heart which is called the myocardium.  Its contraction and relaxation stimulates the process of pumping blood through the circulation.  Finally, there is an outer layer of the heart which is called the pericardium.  It is a sac that lines the outer side of the heart.  In addition, to these layers the heart has nerve fibers which coordinate the processes of contraction and relaxation of the heart muscle.


The heart from the inside is composed of four chambers.  these are: two upper chambers and which are called atria.  In addition, there are two lower chambers and which are called ventricles.  The two atria have low blood pressure inside them.  This is in contrast to the high blood pressure inside the ventricles.


The ventricles are considered the real pump of the hear because they pump blood to the pulmonary circulation through the right ventricle and they pump blood to the general circulation through the left ventricle.  The right ventricle usually pumps blood to a low pressure pulmonary circulation which is usually in the range between 15-30 mmHg. 


The right ventricle is thicker than the two atria and has a thickness of about 0.5 cm.  The left ventricle has a wall thickness of approximately 1.5 cm.  In the case of chronic hypertension an overload is made on the left ventricle due to the extra force it has to do in order to be able to pump the blood to the general circulation.


As a result left ventricular hypertrophy occurs with subsequent enlargement of the heart.  The same condition of left ventricular hypertrpohy can occur also in aortic valve stenosis in which case blood pumping from the left ventricle is impaired.  Thus causing its enlargement.


There are two types of valves that separate the ventricles from the atria and separate the ventricles from the major blood vessels, the aortic artery and the pulmonary vein which communicate blood between the heart and the lungs.  Between the atria and the ventricles there are atrioventricular valves which are called mitral valves.


There are two mitral valves between the left atrium and the left ventricle and between the right atrium and the right ventricle.  The other type of valve is the semilunar valve between the left ventricle and the aortic artery and between the right ventricle and the pulmonary vein.

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