Human Blood Circulatory System

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Human circulatory system, also known as the blood vascular system contain a muscular chambered HEART, a network of closed branching blood vessels and blood, the fluid which is circulated.

  HUMAN BLOOD CIRCULATORY SYSTEM

Heart:-

1.    Origin-mesodermal 

2.    Four chambered –

                                  I.          Two upper artia

                                II.          Two lower ventricles

3.    Size-clenched fist

4.    Position-in between two lungs, slightly tilted to the left

5.    Heart muscles nature-(cardiac muscles):

    i) involuntary   ii) striated   iii) branched 

6.    Neural centre-medulla oblangata 

A thin, muscular wall called the inter-atrial septum separates the right and left atria, whereas a tick-walled, the inter-ventricular septum, separates the left and the right atrium. The atria and the ventricles 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 atrium and the right ventricle is guarded by a valve formed of three fibers flaps or cusps, the tricuspid valve, whereas a bicuspid or mitral valve guards the opening between the left atrium and the right ventricle . The opening of the right and the left ventricle into the pulmonary artery and the aorta respectively are provided with the semilunar valves. The valves in the heart allows the flow of blood only in one direction, i.e., from the atria to the ventricles and from the ventricles to the pulmonary artery or aorta. These valves prevent any backward flow.

  •   Heart beats 72 times per minute.
  •   Duration of cardiac cycle is 0.8 seconds.             
  •   Volume of blood pumped out by each ventricle per minute and averages 5000 ml or 5 liter in a healthy individual.  
  •   First heart sound-Lub    
  •   Second heart sound-Dub

        Pathway of blood circulation in heart:-

        Deoxygenated blood comes from superior vena cava and inferior vena cava in the right atrium=>from right atria to right ventricle=>from right ventricle to pulmonary artery=>AT LUNGS LEVEL=>deoxygenated blood convert into oxygenated blood=>this oxygenated blood come towards the heart with the help of pulmonary vein=>pulmonary vein to left atrium=>left atrium to left ventricle=>left ventricle to aorta =>from aorta to whole body organs 

        Electrocardiograph (ECG) :-

         Graphical representation of the electrical activity of the heart during a cardiac cycle. 


                                                                              

        P-wave: represent the electrical excitation (or depolarization) of the atria.

        QRS-Complex: represent the depolarization of ventricles.

        T-wave: represents the return of the ventricles for the excited to normal state (Repolarization)




        Disorders of Circulatory System:-

        1)High Blood Pressure(HBP): 

                  (Hypertension) Blood pressure higher than normal (120/80). If repeated check of blood pressure of an individual is 140/90 or higher, shows hypertension. HBP leads to heart diseases and also affects vital organs like brain and kidney

        2)Coronary Artery Disease(CAD): 

        Affect the vessels. Caused by deposits of calcium, fat, cholesterol & fibrose tissue ,which makes the lumen of arteries narrower.

        3)Angina: 

        Ak angina pectoris. Symptom of acute chest pain appears when no enough oxygen is reaching to the heart muscle. affect the blood flow.

        4)Heart Failure: 

        (Ak congestive heart failure) the state of heart when it is not pumping blood effectively  enough to meet the needs of the body.

        5)Cardiac Arrest/Heart attack: 

        when heart stop beating or when the heart muscle is suddenly damaged by an inadequate blood supply.

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