Endocrine System The endocrine system is a system of glands, each of which secretes a type of hormone to regulate the body. The endocrine system is an information signal system much like the nervous system. Hormones are like chemical messengers that “tell” certain organs to produce hormones. Hormones regulate many functions of an organism, including mood, growth and development, tissue function, and metabolism.
Hypothalamus- Helps body maintain homeostasis. Pituitary- helps regulate human growth and physical development or maturity; secretes hormones that control other glands. Often referred to as “the master gland.” Thyroid- regulates metabolism (the rate at which cells burn fuels from food to produce energy). This influences body temperature, weight, other factors. Pancreas- releases the hormones insulin and glucagon which regulate the amount of glucose in the blood. Adrenal- releases adrenalin.
The main function of the hypothalamus is homeostasis, or maintaining the body's status quo. Factors such as blood pressure, body temperature, fluid and electrolyte balance, and body weight are held to a precise value called the set-point. Although this set-point can change over time, from day to day it is remarkably fixed. To achieve this task, the hypothalamus must receive inputs about the state of the body, and must be able to make changes or adjustments if anything drifts out of whack. Extension information
The pituitary gland is sometimes called the "master" gland of the endocrine system, because it controls the functions of the other endocrine glands. The pituitary gland is no larger than a pea, and is located at the base of the brain. The pituitary gland secretes hormones that cause other glands in the body to start secreting their own hormones that affect such things as growth, adrenaline, milk production, puberty and sex hormones, skin pigmentation, and other things.
Negative Feedback and Homeostasis Negative feedback is the main mechanism for controlling blood levels of hormones and helping the body to maintain homeostasis. In a negative feedback system, levels of one type of hormone influence the level of other types of hormones. Negative feedback loops create "comfort zones". A common illustration of these loops is a thermostat. If you set a thermostat to 72 degrees and turn it on, the heating/air conditioning unit will take constant measurements of the temperature. If it gets too hot, it will turn on the AC. If it get too cold, it will turn on the heater. Thus, the room stays within a predetermined "comfort zone."
An example of a negative feedback in the body is demonstrated by the pancreas. When glucose levels in the blood get too high, the pancreas releases the hormone insulin. Insulin triggers the body to start converting the glucose to a form that can be stored for later use (glycogen, fat). When glucose levels in the blood get to low, the pancreas secretes the hormone glucagon which triggers the body to change the glycogen back into glucose while also causing the body to stop storing fat. Negative feedback loops exist for blood pressure, body temperature, and a whole host of other body functions.