The Periodic Table of the Elements categorizes elements primarily by the number of protons in their nucleus (atomic number) and secondarily by the characteristics they exhibit.

Blood is created in bone marrow and is made up of cells suspended in liquid plasma. Red blood cells carry oxygen, white blood cells fight infection, and platelets are cell fragments that allow blood to clot.

The cerebrum is the major part of the brain and is responsible for the main senses (thinking, hearing, seeing).

The nucleus of a eukaryotic cell contains the genetic material of the cell and is surrounded by cytoplasm which contains many organelles. These include:

Chemical waste like excess water, minerals, and salt are filtered from the blood by the kidneys and secreted into the urine. Urine is transported from the kidneys to the bladder through ureters.