The document summarizes the major veins, arteries, and structures involved in the cardiac cycle. It describes: 1) The superior vena cava, which returns deoxygenated blood from the head and arms to the right atrium. 2) The pulmonary artery, which carries deoxygenated blood from the right ventricle to the lungs. The blood then becomes oxygenated through capillaries and pulmonary veins return it to the left atrium. 3) The aorta, which is the largest artery and carries oxygenated blood from the left ventricle throughout the body. 4) The atria and ventricles contract (systole) and relax (diastole

1. IN A SHORT VIEW

3.  It has large diameter 24 mm short vein that
returns deoxygenated blood to the heart from
the head and arms into the right atrium .
 It is a valveless vein that conveys blood from
the upper half of the body and return to the
right atrium.
 And as it carries blood from head, neck, upper
chest , and arms to heart . So cancer is usually
the main cause due to blockage in vena cava .

4.  Pulmonary artery carries deoxygenated blood
from the right ventricle to the lungs.
 The blood here passes through capillaries
adjacent to alveloi and becomes oxygenated as
the part of the process of respiration .
 And there are two pulmonary arteries present
in heart which act to deliver deoxygenated
blood to its respective lungs.

5.  Pulmonary veins are the veins that transfer
oxygenated blood from the lungs to the heart.
 The largest pulmonary vein are the four main
pulmonary veins two from each lungs that
drains into the left atrium of the heart.
 It’s function its just opposite to the pulmonary
artery.

6.  Aorta carries blood to the body which means it
helps in supplying oxygenated blood to the
body.
 Aorta is the largest artery in the body . the
aorta starts at the heart’s left ventricle, arches
upward towards the neck, then curves back
downward, extending into the abdomen.

7.  Atrium is divided into two parts :
 Right Atrium & Left Atrium
 Both the atrium are present on the upward side
of heart and the blood firstly enters into the
atrium then goes towards ventricles .
 When the atrium systole [contract] the blood is
pressurised to go into the ventricles below the
atrium .
 And the condition where atrium diastole , it
means they are getting relaxed .

8.  Ventricles are also divided into two parts :
 Right & Left ventricles
 Same condition apply on ventricles as in the
case of atrium [systole & diastole ]
 And the systole and diastolic condition of both
ventricles and atrium is just for 1 sec or less.

9.  Well , there are some valves are present in
heart that prevent the backflow of blood these
are :
 Tricupid valve
 Semi-kunat valve
 Bicurpid valve
 These valves are present inside atrium and
ventricles

11.  So cardiac cycle complete in three stages :
 STAGE 1: Ventricular diastole , Atrial systole
 Ventricles are relaxed and pressure is low in
ventricles compared to atrium .
 AV valve open partially followed by atrial
contraction which forces the blood through AV
node .
 It closes the valves in the vena cava and
pulmonary vein which prevent the flow of blood .

12.  Now both atrium will relax , and both ventricles
will relax simultaneously .
 Which result higher pressure in ventricles
compared to atria above .
 Difference in pressure closes each AV valve .
 Higher pressure in ventricles compared aorta &
pulmonary artery opens the semi-lunar valve .
 Blood is ejected into these arteries so, blood flows
through the systemic circulatory system via aorta
and vena cava and through the lungs via
pulmonary vessels .

13.  Both ventricles and atria becomes relax for the
short period of time .
 Higher pressure in the aorta & pulmonary
artery than in the ventricles closes semi- lunar
valve.
 Higher pressure in vena cava & pulmonary
vein than in the atria results in the refilling of
the atria.
 In this way the cycle is complete .
 This whole process takes less than 1 SEC .