"Harry, you have to learn the fundamentals of how a heart works, because when you have a hands-on approach in Potions, I expect no less of you to know all about it and how to dissect it, since you are my son," a very frustrated Severus Snape ground out.
Not wanting to antagonize his father any longer, he nodded his head tiredly and braced himself for the lengthy lecture his father was going to execute.
"Good. Now let me start by telling you about the systems that your body has quite a few different systems, namely the nervous system, the respiratory system, the skeletal system (remind me to tell you about that later, it will prove useful when deboning Serpentine Fish), the digestive system, the reproductive system and finally the circulatory system. The heart is in the circulatory system, which is responsible for transporting blood around the body. There are many organs in the system which does its own work for efficiency. For your information, the reason why wizards have a much longer life expectancy than muggles is due to the fact that their magical core is fused with their life core, thus always sustaining your soul."
The Potions Master paused to let the information sink into Harry, amused at the sight of eyes widening and jaw dropping spectacle of his son. He went into the kitchen to fetch a glass of water, before returning and drinking a hearty gulp from it.
"The heart plays an important part in the circulatory system as it is the muscular organ which is responsible for pumping blood to the different parts of the body. It is fist sized and has four chambers, namely the left and right atriums, which are the upper chambers and the left and right ventricles, which are the lower chambers. A septum is a wall like muscle, in the middle of the left and right chambers. So why must our blood be pumped? First of all, our body needs oxygen to do its work, which calls for oxygenated blood. When oxygenated blood enters the left atrium through the pulmonary vein, it flows to the left ventricle which pumps the blood out of the heart through the aorta. After the oxygenated blood travels through the body, the body absorbs the oxygen and dispels carbon dioxide into it, making it deoxygenated blood. The blood now enters the right atrium of the heart through the Vena Cava and enters the right ventricle which pumps the blood to the lungs through the pulmonary artery. Once at the lungs, carbon dioxide is expelled by breathing out and taking in fresh air automatically allows oxygen to be taken and absorbed by the bloodstream which enters the left atrium again, thus repeating the cycle again as long as the heart is alive. The magic in the blood of any magical species, including us wizards, helps to cleanse out any germs in the heart, making it the cleanest organ in the body, which is why it is so highly sought after. So I will not have you fooling around and wasting a perfectly good heart. Do you understand?"
Harry could only nod and stare at his dad as he tried to process the information into his ten-year-old brain. Severus saw this and chuckled at the sight, thinking that he would surprise him son further by starting another lecture.
"Now son, did I mention about the valves that close when the blood is pumped to certain chambers and open when the blood is coming into the heart? No? Well, this is what happens…"
From then on, Harry Snape knew never to work sloppily in Potion making ever again.
A/N: So, what do you guys think? Since I had my science exams coming up round the corner, I thought of revising by writing a fic about some subjects, and since this one is done, I uploaded it for you guys to read! Feel free to comment and hope you will learn about the heart like I did! Writing fics for subjects does help in revising, I just tried it. :)