Why does the right side of the heart carry deoxygenated blood and left oxygenated?

The question is WHY? The actual scientific reason??

Im doing a level so yes a simple explanation but please also go into detail as I need to know it at an advanced level

Um, well I'm not sure if you are searching for the evolutionary basis or what, but the right side carries deoxygenated blood because that is what comes to it via the vena cavae. The vena cavae are two major veins that collect venous (deoxygenated blood) from the superior and inferior parts of the body and return it to the right side of the heart. This has its basis in evolution, but I'm not sure if you really need it, so I'll skip it.

The right side pumps the blood to the lungs via the pulmonary system of vessels. In the lungs, the blood gets oxygenated and then goes to the left side of the heart. This is why the left side carries oxygenated blood. This will be pumped in the aorta and then throughout the body.

Why does the pulmonary trunk originate in the right and the aorta from the left ventricle? The reason is based on development of the heart. It's complex, especially if you haven't studied anatomy, so I guess it will be best to skip it.

If you were asking for anything else, clarify it a bit

guessing you're doing a degree in biology then

Nah, I am doing MBBS.

Um, well I'm not sure if you are searching for the evolutionary basis or what, but the right side carries deoxygenated blood because that is what comes to it via the vena cavae. The vena cavae are two major veins that collect venous (deoxygenated blood) from the superior and inferior parts of the body and return it to the right side of the heart. This has its basis in evolution, but I'm not sure if you really need it, so I'll skip it.

The right side pumps the blood to the lungs via the pulmonary system of vessels. In the lungs, the blood gets oxygenated and then goes to the left side of the heart. This is why the left side carries oxygenated blood. This will be pumped in the aorta and then throughout the body.

Why does the pulmonary trunk originate in the right and the aorta from the left ventricle? The reason is based on development of the heart. It's complex, especially if you haven't studied anatomy, so I guess it will be best to skip it.

If you were asking for anything else, clarify it a bit

No im not really looking for the evolutionary reason (although if you can tell me id be really interested to know) tanx for the explanation, really appreciated!

Well, I'll try to keep it simple. Initially, we had a single heart which consisted of a single atrium and a single ventricle. There was one way circulation of blood through this heart. This is seen in fishes.
Then in frogs, we saw a fibrous septum separating the atrium into two parts. One held oxygenated and the other deoxygenated blood. These two opened in a single ventricle, so the blood eventually mixed up.
Gradually, we see a septum appearing in later species to divide the ventricle into two as well. First this division was incomplete, as in case of reptiles, but now, in case of mammals, it is complete, giving four chambers: two atria and two ventricles. This is helpful for us as warm blooded animals

Thats really interesting. I assume you're talking about single circulation in the first paragraph, so fish dont have a right and a left atrium and ventricle they just have one of each? Also clearly we survived once with just one singe ventricle and atrium why do we now require a double one? Is it because of our energy requirements
Tanx so so much!!

Yes, single circulation in fish is via a single atrium and ventricle.
The subsequent shift from the aquatic environment to terrestrial environment, which, as you already know, also led to the shift from cold-blooded animals to warm blooded animals. This also led to an increase in the metabolic requirements and the need of a continual supply of energy to maintain core body temperature. This meant that more oxygenated blood was required. As a result we see the development of a partition in the atria, and then in the ventricles, to prevent mixing of blood and to improve the oxygen supply to the tissues.

Tanx really appreciate it. What do you study?

No problemo
I am doing my MBBS now