This is the day in a life of a blood cell written from the blood cells perspective, it shows what happens in the cardiovascular system:
Hi, my name is Raya the red blood cell. I am in the lungs right now just about to pick up some oxygen, would you like to come with me on my journey through the pulmonary and systemic circuit?
Ok, so I am in the lungs picking up some oxygen to transport and lucky for me all I have to do is float near the edge of the tunnels, and the oxygen floating around gets attached to my body. After I have picked up enough oxygen, I travel to the pulmonary vein which is the road into the heart.
The pulmonary vein is the one that feeds oxygenated blood (me at the moment) into the left atrium. From there I wait for the bicuspid valve to open before I push through to the left ventricle, now this part of the heart has really thick muscular walls, something called the septum separates the oxygenated and deoxygenated blood. Then I go through the semi-lunar valve into the aorta (which is an artery).
Now I find myself in an artery going away from the heart. Arteries work under very high pressure as they need to get to the working muscles quickly therefore the diameter of the lumen is narrow causing increased pressure. As a result, of working under increased pressure there are thick muscular walls in arteries. If they didn’t, they would rupture, and you would bleed to death!
Arteries break down into arterioles which feed into the capillaries of your body. Now, these are the smallest blood vessels in your body, and guess how thick they are? Only one cell thick!
I have now just arrived at the destination of oxygen demand, the foot.
This is an hour gaseous exchange occurs. Oxygen and nutrients (that were picked on the way) jump of me and squeeze out of the capillary.
While I am there I make another pick up of carbon dioxide and waste products that into the bloodstream from the capillaries I enter the venules which feed into veins.
Veins don’t work as high of a pressure as arteries, therefore they need valves to prevent backflow of the blood. The diameter of the lumen here is larger and the walls are thin, not very elastic either. Veins carry deoxygenated blood into the heart.
A quick fact: did you know that our heart is a muscle meaning if you train it your heart increases in size and mass. This is called cardiac hypotrophy. The increase of size in your heart allows the heart to pump more blood at once, this helps the working muscles to meet the demands of oxygen needs at a quicker rate.
Now back to me, I have just traveled up into the vena cava. The vena cava flows into the right atrium, from that the tricuspid valve opens to the right ventricle which pushes up to the semi-lunar valve and into the pulmonary artery. Finally, back to where we started.
I do this continuously for the rest of my life, and no, it isn’t boring, I get to travel everywhere in the body.
I just have time for a quick Q and A before I go round again.
Why does the heart pump blood?
The heart pumps blood to get the needed oxygen and nutrients around the body and get rid of CO2 and waste products.
When does your heart rate increase?
Mostly when you are active like exercising and playing sports, your heart rate also increases when you’re nervous or have a surge of adrenaline.
Oh, that’s all I have time but have a great day and make sure to exercise so more Raya’s can get pumped around your body.
