The endocrine system consists of a complex collection of glands that produce chemical messengers called hormones. Its function is to regulate metabolism, homeostasis, growth, sexual development, and reproduction. Chemical Regulation

Glands - organs that manufacture and secrete hormones directly into the bloodstream How does the Endocrine System Regulate the Body? Hormone - “chemical messenger”that travel in the blood until it reaches the target cells. Each hormones fit into its target cells like a key fits a lock. The hormone causes a reaction in only the target cell or organ.

The endocrine system works with the nervous system to help regulate and control different bodily functions. The endocrine system acts more slowly than the nervous system because hormones are transported by blood while the nervous system sends electrical signals along nerves that travel much faster. The endocrine system is like snail mail… It works slowly but the effects last a long time… while the nervous system is like a text or …it travels quickly and is done! How is the endocrine system different from the nervous system?

Major Glands of the Endocrine System

In the brain : Hypothalamus - controls the release of pituitary hormones Pituitary - “Master Gland” that controls most other endocrine glands. Produces HGH (human growth hormone), TSH (thyroid stimulating hormone), FSH (follicle stimulating hormone) and several other hormones Pineal - releases hormones that control body cycles like melatonin that controls our sleep cycle (circadian rhythm)

Major Glands of the Endocrine System Thyroid - butterfly shaped gland located in the neck that produces thyroxin which controls the speed of metabolism Parathyroid - located behind the thyroid gland, controls levels of calcium and phosphorous in the body Thymus - found in the upper chest; controls the development of a healthy immune system

Major Glands of the Endocrine System Pancreas - located behind the stomach; controls the production of insulin and glucagon which control sugar levels in the blood Adrenal glands - located above the kidneys; produces epinephrine or adrenaline which increases blood pressure and heart rate in times of stress…FIGHT OR FLIGHT response.

Fight or Flight The adrenal glands secrete adrenaline and other hormones in response to stress. Fight or flight response is a protective measure. It provides a burst of energy through increased heart rate, blood pressure, and respiration. ­All of these physical responses are intended to help you survive a dangerous situation by preparing you to either run for your life or fight for your life (thus the term "fight or flight"). Fear -- and the fight-or-flight response in particular -- is an instinct that every animal possesses.

Major Glands of the Endocrine System Ovaries - located in the pelvis of females; produce estrogen and progesterone which control female sexual characteristics including menstruation Testes - located in the male scrotum; produce testosterone which controls male sexual characteristics including sperm production

A good example of a negative feedback mechanism is a home thermostat (heating system). The thermostat contains a thermometer that detects change in temperature. If the heating system is set at 67 degrees Fahrenheit and the temperature drops, the thermometer senses the drop and the heat is turned on. Once the temperature reaches 67 degrees again, the furnace is turned off which keeps the house at a stable temperature. Endocrine System: Negative Feedback Mechanism Negative feedback is a process that happens when your systems need to slow down or completely stop a process that is happening.

Endocrine System: Negative Feedback Mechanism Negative feedback is a process that happens when human systems need to slow down or completely stop a process that is happening to maintain homeostasis. The control of blood sugar (glucose) by insulin is an example of a negative feedback mechanism. When sugar levels rise, receptors in the body sense a change. In turn, the pancreas secretes insulin into the blood effectively lowering blood sugar levels. Once blood sugar levels reach homeostasis, the pancreas stops releasing insulin. If sugar levels get too low, glucagon is released to bring sugar out of storage and back into the blood. Insulin and glucagon constantly alternate to maintain homeostasis for blood sugar levels.