Are all of your veins like little tiny loops where blood flows through, then back to the heart, or does blood sort of push and pull it’s way back and forth through your body? Basically, how the heck does the cardiovascular system work?
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The heart pushes blood out through arteries. The arteries divide and divide, eventually forming capillaries that are tiny blood vessels suffusing almost all your tissues, bringing oxygen to the cells. These combine again into larger and larger veins, bringing low oxygen blood back to the heart. The heart has two loops, pumping the blood from the veins to the lungs in order to get oxygenated (again dividing into capillaries and rejoining), then it returns to the heart and goes out the body anew.
Sorta, your cardiovascular system does work in a loop but veins are only the return path. The blood goes from the heart to the lungs where the red blood cells get oxygen, then back to get pumped throughout the body using arteries. From there, arteries connect to capillaries. Tiny vessels where the RBCs exchange oxygen for carbon dioxide and the cells take nutrients from the plasma and deposit their waste. The capillaries then connect to veins which bring the exhausted blood back to the heart.
The left side of the heart pumps oxygenated blood around the body.
Cells take out oxygen and put back waste CO2.
De-oxygenated blood returns to the right side of the heart, and is pumped into the lungs.
The lungs exchange CO2 for oxygen and the “good” blood goes back to the left side of the heart.
https://www.merckmanuals.com
Many veins, particularly those in the arms and legs, have one-way valves. Each valve consists of two flaps (cusps or leaflets) with edges that meet. Blood flowing toward the heart pushes the flaps open like a pair of one-way swinging doors. If gravity or muscle contractions try to pull the blood backward or if blood begins to back up in a vein, the flaps are pushed closed, so the blood does not flow backward. Thus, valves help the return of blood to the heart—by opening when the blood flows toward the heart and closing when blood might flow backward.
Basically the heart is a biological pump… Which pumps blood by contacting and expanding itself. Created pression/ depression and that makes the blood flow.
Lets start on the Left side of the heart in your left ventricle. This part of the heart pumps the blood to your entire body at high pressure via first the large arteries, which branch into smaller arteries, then into smaller arterioles, which then branch into capillaries which are so small they only allow blood cells to pass through single file.
Then your blood passes through these capillaries into the venules, which then converge into small veins, which converge into large veins, which then return to the right side of the heart via the right atrium, which goes into the right ventricle, which then pumps the blood at higher pressure again into the lungs. The lung vessels follow the same pattern but its all much shorter cause then it returns to to the left sife of the heart via the pulmonary veins to the left atrium, then into the left ventricle then is off back to the body.
The veins in the body have one way valves to prevent backwards flow since its a low.pressure system.
Thats the absolute basics.
Blood “circulates” for a reason. Blood makes a round-trip through the body, depositing nutrients as it goes, returns to the heart, picks up more nutrients, and makes the trip again.
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