Endocrine System - Pineal/Adrenal Flashcards
What is the primary function of the Pineal Gland?
Regulation of circadian rhythm (sleep-wake cycles); uses melatonin in order to do this.
What is the cytological makeup of the Pineal Gland?
Pinealocytes (95%) Glial Cells (5%)
What is a distinctive characteristic of Pinealocytes? Describe their function.
They have large nuclei with multiple nucleoli, meaning they are very active cells. They are secretory, producing and secreting melatonin (this activity increases during night time), and communicate with each other via gap junctions.
What are the dark areas in the Pineal Gland called? What are they composed of?
Brain sand (aka Corpus Arenacia)
Calcium Carbonate deposits
Aside from inducing sleep, what does Melatonin do? Why?
It reduces FSH and LH; during winter seasons it’s disadvantageous to have offspring, so FSH and LH are regulated to reduce that chance.
What are the primary functions of the Adrenal Glands?
Secretion of steroids (cortex) and catecholamines (medulla).
List the layers of organization of the Adrenal Glands, from outermost to innermost. Which is the largest?
Medullary Zones:
Zona Glomerulosa
Zona Fasciculata (Largest)
Zona Reticularis
Cortical Zones:
Chromaffin Cells
What factors act on which layers? What hormones are they regulating?
Angiotensin + Corticotropin (ACTH) -> Zona Glomerulosa -> Mineralocorticoids (aka Aldosterone)
ACTH -> Zona Fasciculata -> Glucocorticoids (and, to a much lesser extent, Androgens)
ACTH -> Zona Reticularis -> Androgens (and, to a much lesser extent, Glucocorticoids)
What is typically visible in the spongiocytes of the Zona Glomerulosa that helps identify it?
Lipid droplets; they are precursors to steroid hormones
What is the major artery of the Adrenal Glands and what are its 3 branches?
Capsular Artery
- Cortical Arteriole (gives rise to capillary plexus in ZG)
- Adrenocortical sinusoids (comes off first capillary plexus to give rise to another plexus in ZR)
- Medullary Arteriole (goes straight to medullary capillaries)
What is a noticeable feature of medullary cells like Chromaffin cells?
Sympathetic innervation (post-g, unmyelinated)
What are Chromaffin cells and what are their function?
They are neuroendocrine cells (modified neurons), and they are responsible for the secretion of catecholamines (epinephrine, norepinephrine).
What is Pheochromocytoma?
It is a rare tumor derived from Chromaffin Cells. It causes excessive production of catecholamines.
What can cause Cushing’s Syndrome?
A tumor in the pituitary gland that causes excessive release of ACTH, which stimulates overproduction of cortisol from the Adrenal Glands.
Symptoms: “Moon-face”, buffalo hump, abdominal striae, thinning of limbs, adrenal hyperplasia.
What is Addison’s Disease?
An autoimmune disorder that destroys the adrenal glands. Caused by an insufficiency of ACTH(?). By the time you see the signs of Addison’s, 90% of the adrenal glands will already be destroyed.
