Adrenal Gland Greatest Hits

I think it’s safe to say that the average American knows way more about the dating habits of Snookie than the basic functions of their own adrenal glands. My fellow Americans let’s beat the statistics shall we.

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Jessica Biel – personal favorite tight leather sporting supporting actress

You know all this talk about adrenaline bores me to tears. Anytime anyone talks about the adrenal glands all you hear about is the “fight or flight” response. It’s like the preview to a summer blockbuster where all they show are the explosions and 15 seconds of car chases with tight leather wearing supporting actresses in the passenger seat (which I don’t mind so much). If anyone asked you what the movie is actually about, good luck. There is however, way more to this E-hollywood bad boy than running from a fight. He does the work. So right here and now we’re going to attempt to answer the question “Adrenal Cortex, what have you done for me lately?”

Anatomy 101

Your adrenal glands rest atop the kidneys like really ugly shoulder pads, secreting hormones into the bloodstream in response to stress. Anatomically speaking we’ve designated the adrenal gland into two distinct regions, the cortex and the medulla. The cortex (forming the exterior portion of the gland) is largely known for producing cortisol and aldosterone. The medulla (forming the center or guts of the gland) specializes in producing epinephrine and norepinephrine (one of the most notoriosly misleading names in physiology).

Fun fact – both epinephrine and norepinephrine contribute to the fight or flight response with a few subtle differences. So if you’ve been thinking this whole time that they were highschool rivals or that norepinephrine was Latin for “not friends with epinephrine” I promise that I won’t tell anyone…fingers crossed.

Also, why is it that the term cortex, which sounds a lot like “core” actually refers to the outside of the organ? Sorry, that just irritates me to no end.

Pop Culture

it happens all the time….one day a band makes it big, working their way to the top of the charts, but the next week it’s the lead guitarist who’s on the cover of Rolling Stone’s magazine. Whenever people talk about the human stress response to danger or exhiliration we tend to focus on the adrenal medulla, the site of epinephrine production A.K.A adrenaline. However, this is merely responsible for a short term response to stress…the increased heart rate, breathing rate, and rapid conversion of nutrients for the sudden burst of muscle action. We’ve forgotten all about the long term response to stress largely coordinated by the adrenal cortex, the electric bass player who never stopped setting the tempo.

Adrenal Cortex, boy you so crazy…

We like to talk about the big picture but the truth is that so many of our physiological responses begin with baby steps, minutia, small subtle changes that lead up to bigger, longer lasting events. If you want to affect an organ there is no secret doorbell with a note that says “push ringer to call the kidney.” Hormones like aldosterone act on the cellular level, and “talk” to the tiny functional units of the kidney.
One such hormone, aldosterone, produced by the zona glomerulosa of the adrenal cortex works on the distal convoluted tubule and collecting duct of the nephrons (tiny fuctional units of the kidneys) to increase the reabsorption of sodium from the plasma which in turn affects the water balance. Why do we care? This ultimately effects blood pressure. Your blood is more than 50% water (i.e. plasma) so since water makes up such a significant volume of the blood, influencing the salt/water concentration effects overall blood pressure. This again helps us to maintain metabolic balance.
Aldosterone production is triggered both by ACTH (adrenocorticortropic hormone) from our good friend the pituitary and angiotensin triggered by the juxtaglomerular cells (in the kidneys) when renal blood pressure drops (blood filtered through the kidneys).
Another fun trick the adrenal cortex has up its sleave is the production of cortisol. In response to prolonged stress. Cortisol is chiefly responsible for increasing blood glucose over time through glyconeogenesis, which is basically a means of utilizing non-carbohydrate sources such as lipids and amino acids to form glucose. This is just another way our bodies maintain homeostasis, that amazing zen-like balance of our metabolic needs. Cortisol also suppresses the immune system. This makes it quite useful in medicine as an effective anti-inflammatory agent.

It’s human nature…we like to compare things. That’s just how we roll and every now and then it helps us learn so….

Adrenal Medulla V.s. Adrenal Cortex

medulla – the production of epinephrine & norepinephrine – “Fight or flight” car chases, explosions, tight leather pants

cortex – the production of aldosterone & cortisol – homeostasis, zen-like balance, long term response to stress

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