The Adrenal Glands
- The adrenal glands are triangular shaped organs that sit on top of the kidneys.
- Each adrenal gland is composed of an outer portion called the cortex, and an inner portion called the medulla.
- The adrenal cortex secretes mineralocorticoids, glucocorticoids, and androgens.
- The cortex is further divided into three layers, or zones: glomerulosa (outer layer), fasciculata (middle layer), and reticularis (inner layer).
- The innermost portion of the adrenal gland, the adrenal medulla, secretes catecholamines and is under the direct influence of the sympathetic nervous system.
- Catecholamines: epinephrine and norepinephrine
The Adrenal Cortex (G-F-R)
|Zona||Position||Hormone Class||Hormones||Deeper = Sweeter|
|Reticularis||Inner layer||Androgen||DHEA, DHEA-S, androstenedione||Sex|
- The hypothalamic-pituitary-adrenal (HPA) axis is a major neuroendocrine system that involves the hypothalamus, pituitary gland, and the adrenal glands.
- Corticotropin-releasing hormone (CRH)
- Stress response
- Released from hypothalamus
- Stimulates the release of adrenocorticotropic hormone (ACTH)
- Released from anterior pituitary
- Stimulates the release of cortisol
- Released from adrenal gland (zona fasciculata of adrenal cortex)
- Provides negative feedback, acting on the hypothalamus and pituitary to suppress CRH and ACTH production