Hormone

TWO SYSTEMS help the body's parts and organs work together. One is the nervous system (see page 221). The other is the hormonal or endocrine system, based on body chemicals called hormones. There are more than 50 different hormones. Each is made in a gland. Hormones flow around. the bloodstream and affect certain cells, tissues and organs. They may cause them to work faster or slower, or release their products. For example, adrenaline from the adrenal gland makes the heart beat faster. and more blood flow to the muscles, so the body is ready for action. The pituitary gland near the brain makes hormones that control other hormonal glands