Posted by Racer on September 5, 2004, at 13:23:34
In reply to Re: To Scott (SLS) Cortisol question, posted by greenwillow on September 5, 2004, at 1:57:06
HPA axis: hypothalamic-pituitary-adrenal axis. If you really want to get pedantic, you can add the limbic system in, too.
This is the 'committee' responsible for getting you through stressful situations. Now, what you and I consider stressful isn't necessarily what your limbic system thinks of as stressful. Your HPA axis is responsible for things like getting you out of bed in the morning, which it considers stressful. It's also what leads to the release of cortisol, and eventually adrenaline. Simplistically: your limbic system tells your hypothalamus to look for something stressful. Your hypothalamus tells your pituitary to gear up for something stressful. Your pituitary then opens the channel to your adrenal glands, which turn on the cortisol pumps, until the pituitary recognizes enough of it that it checks with the hypothalamus to see if there's enough cortisol to turn the adrenal pumps off. Under normal circumstances, the hypothalamus would send the message to turn down production, but a number of things can cause this feedback system to lose its precision. Any member of this committee can cause it to break down, resulting in either under or over production of cortisol.
Addison's Disease leads to too little cortisol being produced, and Cushing's Disease leads to too much. Cushing's Syndrome is also related to too much cortisol cruising around, although it's not caused by the classic Cushing's Disease (benign pituitary tumor). Someone who takes steroids for an extended period will show signs of Cushing's Syndrome, for example.
(And, as an aside, mild Cushing's has some benefits: it's associated with an improvement in osteoarthritis, for example.)
Hope that helps, and it you have any other questions, ask away. With any luck, someone else will answer the next one ;-)
poster:Racer
thread:386371
URL: http://www.dr-bob.org/babble/20040904/msgs/386719.html