HEART
The organ in your body that stores extra sugar is the Liver.
The spongy part of your bones (the bottom and top tips) create red blood cells. We do not "store" extra blood. Often our blood pressure would drop, (low blood volume) and to compensate your blood vessels will constrict (become smaller) so that it will seem like there is more blood in your system. Think of a four lane road compared to a one lane road(constricted)
veins
Blood is made in bone marrow. So the marrow makes blood, and sends it to the necessary part of the body, or stores it.
which part of the body doesn't enter the blood
When you are sick, extra white blood cells are created by the immune system to help fight off the infection or illness. White blood cells are an important part of the body's defense against pathogens and foreign invaders.
every body part you have sends blood to your heart
Blood vessels carry the blood to every part of the body.
The veins function as a blood reservoir and contain over 60 percent of the body's blood. This allows them to store extra blood that can be quickly mobilized when needed, such as during physical activity or in response to stress.
Blood vessels are not woven into the body, they are part of it.
Another name for extra body parts is supernumerary. They occur when there is a mutation within the human body's creation process. This causes an extra body part to happen.
The part of the blood cell that carries water around the body are the plasma cells