<P> The reproductive system consists of the gonads and the internal and external sex organs . The reproductive system produces gametes in each sex, a mechanism for their combination, and in the female a nurturing environment for the first 9 months of development of the infant . </P> <P> The respiratory system consists of the nose, nasopharynx, trachea, and lungs . It brings oxygen from the air and excretes carbon dioxide and water back into the air . </P> <P> The urinary system consists of the kidneys, ureters, bladder, and urethra . It removes toxic materials from the blood to produce urine, which carries a variety of waste molecules and excess ions and water out of the body . </P> <P> Human anatomy is the study of the shape and form of the human body . The human body has four limbs (two arms and two legs), a head and a neck which connect to the torso . The body's shape is determined by a strong skeleton made of bone and cartilage, surrounded by fat, muscle, connective tissue, organs, and other structures . The spine at the back of the skeleton contains the flexible vertebral column which surrounds the spinal cord, which is a collection of nerve fibres connecting the brain to the rest of the body . Nerves connect the spinal cord and brain to the rest of the body . All major bones, muscles, and nerves in the body are named, with the exception of anatomical variations such as sesamoid bones and accessory muscles . </P>

What is the 4 major parts of the body