The superior vena cava is the large vein which returns blood to the heart from the head, neck and both upper limbs. The inferior vena cava returns blood to the heart from the lower part of the body. The return of blood via the vena cava can be compromised and cause disease. (Take that info and see if it helps)
I believe that a brain transplant is bad because you weren't born with that brain , you may have the other persons memories.
in your brain you have infinite nerves and each single nerve makes up who you are, if you have someone else's brain you may not be exactly the same any more.
i hope this helps
Weakness, Cowardice, Intimidation, or stupidity. Conflicts must be solved, you can't run from them.
You could take your heart rate.