Your Body. How It Works. The Endocrine System PDF Free Download
The human body has an amazingly complex array of systems, such as the circulatory, digestive, and muscular systems, and each has important functions. In order to operate properly, all of the systems in the body must work together. This means that the body can regulate itself and that the various organs involved can communicate with each other. The body has two systems for control and communication. One of these is the nervous system, which consists of the brain, spinal cord, and nerves. The nervous system receives and sends information through nerve cells (neurons) as electrical impulses. A nerve impulse can travel as fast as 100 meters/second (m/sec), and it targets a specific part of the body, such as a cell. The other control system is the endocrine system. It consists of a group of organs called endocrine glands, which are located in various parts of the body. (These glands will be discussed individually in later chapters.) Endocrine glands release chemical messengers called hormones that travel through the blood. Because hormones take time to travel through the circulatory system, a response by the endocrine system will take much longer than one by the nervous system. However, hormones can travel everywhere in the body. For this reason, hormones control responses that do not need to be immediate, but have to be generalized and longer lasting. These responses include growth, reproduction, metabolic rate, blood…
