Hypothalamic-Adenohypophyseal-Adrenocortical Axis I: CRH & ACTH
About this set
Created by:
Evie35 on April 17, 2010
Subjects:
physiology, hypothalamus, Adrenal Gland, Pituitary Gland, cortisol, acth, crh
Description:
Relevant to veterinary medicine
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28 terms
Terms | Definitions |
|---|---|
 hormones of the Hypothalamic-Adenohypophyseal-Adrenocortical Axis | CRH (corticotropin releasing hormone), ACTH (adrenocorticotropic hormone), steroid hormones (corticosteroids) |
| CRH is secreted by this part of the brain | hypothalamus |
| ACTH is secreted by this part of the brain | adenohypophysis/anterior pituitary |
| ACTH secretion is stimulated by this | CRH |
| CRH secretion is stimulated by this | stressful physical, chemical, and emotional stimuli such as trauma, exercise, hemorrhage, pain, hypoglycemia, LPS, overcrowding, extreme temps. |
| ACTH secretion is inhibited by this | cortisol |
| steroid hormones are secreted by this part of the brain | adrenal cortex |
| the steroid hormones produced in the brain | aldosterone, cortisol, estradiol |
| aldosterone is produced in this part of the adrenal cortex | zona glomerulosa |
| cortisol is produced in this part of the adrenal cortex | zona fasiculata |
| estradiol (sex steroids) is produced in this part of the adrenal cortex | zona reticularis |
| cortisol inhibits the production of these hormones by negative feedback inhibition | CRH & ACTH |
| this causes too little production of ACTH | diminished blood flow to adenohypophysis |
| this causes too much production of ACTH | destruction of adrenal cortex (less cortisol to perform negative feedback inhibition) |
| ACTH promotes the uptake of this substance in all three zonae of the adrenal cortex so they can enzymatically convert it into aldosterone, cortisol, and estradiol | cholesterol |
| ACTH promotes mitosis/growth, overall health and integrity, but does not directly stimulate the pathway to make this | aldosterone |
| these substances do not influence the production of CRH or ACTH, only cortisol does | aldosterone & estradiol |
| Cushing's disease is an adenoma in the pituitary of these cells | corticotrophs |
| in Cushing's, the adenohyphysis is not listening to cortisol negative inhibition feedback, so it keeps making this | ACTH |
| in Cushing's, overproduction of ACTH causes this to happen | adrenal cortex overproduces cortisol which exerts excessive negative feedback inhibition on the hypothalamus to reduce production of CRH |
| in Cushing's, even though the hypothalamus's production of CRH is inhibited, ACTH is still being made because of this | only a small amount of CRH is needed to stimulate the adenohypophysis to make ACTH |
| in Addison's disease, an animal can't make adequate amounts of this | cortisol |
| ACTH is not bound by these | plasma proteins |
| ACTH causes increased glucose entry, glycogenolysis, and glycolysis at these zonae | fasciculata and reticularis |
| ACTH turns on enzymes but needs these 2nd messengers because it's stuck at the membrane | cAMP and PKA |
| ACTH is not actually needed at this zona because increased K+ and angiotensin II stimulate its pathway | glomerulosa |
| essential enzyme in glucocorticoid pathway to produce cortisol | 17-OH (17-hydroxylase) |
| ACTH is degraded by these | cytoplasmic enzymes |
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