Structure of human heart and blood circulation

Structure of heart and blood circulation

Human circulatory system, also called the blood vascular system consists of a muscular chambered heart, a network of closed branching blood vessels and blood.



External structure: the human heart is four chambered structure with two auricle and two ventricle.the two upper chamber are auricle and lower are ventricle.heart is externally covered by tough thin,membranous double layered sac like structure called pericardium.pericardial fluid is present in between two layers. pericardium and pericardial fluid prevent the heart from injury,mechanical shock and keep it lubricated to beat smoothly.heart is conical and lie between two lungs in the thoracic cavity.heart is made up of non fatigue cardiac muscle.


Internal structure : internal structure of heart is studied by the vertical section of heart.it consist of two auricle and two ventricle.auricle are thin walled chamber separaed by inter auricular septum.they collect the blood entering the heart.right auricle is greater than left.right auricle receive deoxygenated blood while left receive oxygenated blood.A thin, muscular wall called the interatrial septum separates the right and the left auricle.
The ventricles are thick walled and large. left ventricle is larger than right and possess thicker wall. A thick-walled, the inter-ventricular septum, separates the left and the right ventricles The atrium and the ventricle of the same side are also separated by a thick fibrous tissue called the atrio-ventricular septum. However, each of these septa are provided with an opening through which the two chambers of the same side are connected.
The opening between the right auricle and the right ventricle is guarded by a valve formed of three muscular flaps or flaps, tricuspid valve, whereas a bicuspid or mitral valve guards the opening between the left atrium and the left ventricle. The openings of the right and the left ventricles into the pulmonary artery and the aorta respectively are provided with the semi lunar valves. The valves in the heart allows the flow of blood only in one direction, i.e., from the auricle to the ventricle and from the ventricles to the pulmonary artery or aorta. the valves prevent the backflow of blood .






Blood circulation





During blood circulation heart acts as pumping machine.it is made up of cardiac muscles which never fatigue and beats constantly for lifetime.human have double circulation.









pulmonary circulation :

the circulation of blood between heart and lungs is called pulmonary circulation.the right auricle receives deoxygenated blood from superior and inferior venacava.right auricle when is full,contracts and pass blood into right ventricle through tricuspid valve.when right ventricle contracts,blood flows into pulmonary artery through semilunar valve.pulmonary artery goes to lungs and exchange of cases takes place there.the capillaries reunite to form venules and then pulmonary vein.then finally pulmonary vein pour blood into left auricle.

systemic circulation :The circulation of blood between heart and body parts except lungs is called systemic circulation.the oxygenated blood from left auricle is transferred to letf ventricle through bicuspid valve. the blood from left ventricle is transferred to aorta when ventricle contracts through aortic valve.aorta divides into artery,arterioles,capillaries and supply oxygen to different body part and reunite to form venules,veins and venacava and finally pour deoxygenated blood into right auricle.

Hepatic Portal Circulation: A vascular connection exists between the digestive tract and liver called the hepatic portal system. The hepatic portal vein carries blood from intestine to the liver before it is delivered to the systemic circulation. A special coronary system of blood vessels is present in our body exclusively for the circulation of blood to and from the cardiac musculature.there is no pumping action in hepatic portal system.



Heart gets blood supply from coronary artery

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