veins
the blood passes through your heart
All the blood flowing through the intestines passes through the liver on its way back to the heart.
Blood travelling 'from' any organ is in the venous system and will pass through the heart to be oxygenated, then into the arterial system on the way 'to' any organ.
The blood goes through the heart in the correct direction because there are a number of one-way valves in the heart chambers that blood can only pass through in the correct direction.
the heart
blood could not circulate through the body unless it passed through the heart.
The artery vessels provide blood to the heart.they purify the blood and pass it , while the veins take the bad blood and bring it back to the heart and purify it then the arterys pass it again to the other organs.
Low oxygen blood flows out of the heart through the pulmonary semilunar valve and into the pulmonary trunk. From there is goes through the left and right pulmonary arteries into each respective lung.
blood does not pass across the placenta
to pass blood on to your brain
The oxygen is passing from through the walls of the capillaries and the organs' walls. There are specially designed proteins which are allowed from the cell, to pass through the cell's wall (membrane).
The heart is a pump! So the heart itself is what brings in and shoots out blood. The heart is responsible for circulating the blood through your blood veins, arteries and capillaries. veins!