(When you learn these topics depends on what course you’re doing. Check your specification. Sorry, but there are too many GCSE specifications now to write separate articles for all of them!)
Blood vessels entering and leaving the heart
Here’s a table of the biggest blood vessels in your body. This is written in order as blood goes from the body to the heart and back out again: So four key blood vessels to learn: the vena cava, pulmonary artery, pulmonary vein, aorta. On many courses, you’re meant to know which atriums (atria) and ventricles they go to and from.
Other key blood vessels
On AQA AS-level and OCR A2 biology, you’re also meant to know about the coronary arteries. These loop round from the aorta to the heart muscle itself, giving it oxygen and food to beat with.
What’s the hepatic portal vein for? Simple. Blood coming from the small intestine is carrying a real mixture of stuff absorbed from food in the gut. Lots of useful chemicals, some not-so-useful ones, even some toxic ones. The liver takes them and reprocesses them into new, more useful chemicals before they’re allowed to go to the rest of the body.
But if the hepatic portal vein is taking blood into the liver, what’s the hepatic artery for? That’s simple too. The liver uses lots of energy to do its jobs, but the hepatic portal vein carries deoxygenated blood. That’s no good for aerobic respiration! To give the liver some energy, the hepatic artery carries oxygenated blood to it. So the liver gets everything it needs to do its job: food from the small intestine, oxygen from the heart.
This isn’t on the syllabus, but if you’re planning to do medicine you might want to know that there are actually two renal arteries and two renal veins (each kidney has its own renal artery and renal vein). There are also two venae cavae (Stupid Latin plurals! Why can’t it be vena cavas or venus cava or something?): one from the body above the heart and one from below the heart, and there are several separate hepatic veins from different parts of the liver.