The Endocrine System
The endocrine system is a collection of specialized cells that are built to produce and release hormones - chemical messengers who travel around the body through blood and other fluids. Hormones cooperate and interact with the nervous system to control many of the body's functions.
Some of the body functions regulated by the endocrine system include:
controlled by the hypothalamus and pituitary:
the menstrual cycle and sperm and testosterone production
the renin-angiotensin-aldosterone system and blood pressure
parathyroid glands and calcium
anti-diuretic hormone and fluid balance
pancreas, - regulator of blood sugar as well as cellular metabolism and digestion and absorption
liver - processor, storager, and isposer of nutrients and wastes
fat and adipokines - bad things
Some hormones are a part of feedback loops regulating homeostasis. Other hormones are active only at certain times, as occurs during human development, puberty, or the menstrual cycle.
Certain things make the endocrine system special:
- Its hormones can reach almost every cell in the body, except, for the most part, the central nervous system, protected by the blood-brain barrier.
- specific hormones affect specific groups of target cells, working through specific receptors
- endocrine control tends to be slower than the nervous system, depending on the cardiovascular system to get things around. At the very fastest, a hormone is secreted and works on its target in 20 seconds or so.
- enocrine communication is highly effective for longer term control
- immunology?