Seperately. NCGS 97-31 is the ratings guide and it sets a value for each body part. For example, 100% disability to the arm is worth 240 weeks of benefits at your weekly compensation rate. The leg is 200 weeks; the back is 300. In addition, there is a max payment of 20k for permanent damage to "other important organs". All that being said, your case may indeed go well beyond a ratings issue and you need to consult with an attorney.
I agree with Mr. Shapiro. I would only add that before you can be rated the injury has to be at maximum medical improvement (MMI). In other words everything has been done and despite the therapy, medications, and surgery, you still have suffered a permanent loss of a body part.
This response is meant to be information only and should not be considered to be legal advice. This information is not meant and should not be construed to be the formation of an attorney client relationship. I practice Virginia Workers compensation law and Social Security Disability law.
There is no "whole body" rating in NC. The ratings would be calculated separately. However, as others have indicated, you should speak with an attorney who can discuss what ratings mean in context of your claim.
Here in NC, you may have a more munificent way of finishing your case (instead of the ratings), depending on your work status. You really need to consult with a workers' comp certified specialist lawyer. If you are unable to work but you are concerned about ratings, then that tells me that you need to educate yourself before you make a very expensive mistake.
This answer is intended as general information and not as specific legal advice. If you want to have a free consultation with me, please contact me through AVVO.