"The human body has eleven organ systems. The cardiovascular system includes the heart, blood and lymph vessels, blood, and lymph, and transports nutrients and waste products. The digestive system includes the mouth, esophagus, stomach, and intestines, and carries out digestion and absorption. The endocrine system includes all glands, such as the thyroid, ovaries, and pancreas, and produces and releases hormones. The immune system includes white blood cells, lymphatic tissue, and marrow, and defends against foreign invaders. The integumentary system includes the skin, nails, hair, and sweat glands, and provides protection and body temperature regulation. The muscular system includes skeletal, smooth, and cardiac muscle and produces body movement. The nervous system includes the brain, spinal cord, and nerves and interprets and responds to stimuli. The reproductive system includes the gonads and genitals and supports reproduction and sexual characteristics. The respiratory system includes the lungs, nose, mouth, throat, and trachea and carries out gas exchange. The skeletal system includes bones, tendons, ligaments, and joints and provides structure and support. The urinary system includes the kidneys, bladder, and ureters and carries out waste excretion and water balance."