If Humans didn't have any blood in their body, then they wouldn't be able to survive. Blood is a resource used to regulate the vital organs keeping us alive. It's also used to help keep us defended against viruses and infections. This is the reason why doctors/nurses inject medicine/vaccines into our blood stream and not just in a random place.
blood carries oxygen all around the body
Yes. Blood volume is proportional to body size.
If there is no blood in our body we cant live, we need RBCs and WBCs in our blood.
it pumps blood around the body.
capillaries
every part in your body that is how you other than the hart
in a frog it lets them have blood the same with the humans they both give blood to the body
Humans have various types of cells in their body, including red blood cells, white blood cells, nerve cells, and muscle cells. Each type of cell serves a specific function in maintaining normal body functions.
Blood makes up 7% of the weight of the body in humans. See: http://en.wikipedia.org/wiki/Blood
It does the same thing it does for humans. Pumps blood through out the body.
Within humans, red blood cells and blood platelets do not have nuclei.
To "invent" something is to create it. No human created human blood - because what would humans have had before?