EXAM #2: ENDOCRINE PANCREAS ANATOMY Flashcards
What are pancreatic islets embryologically derived from?
Endoderm
What hormone is secreted by Beta cells in the pancreas?
Insulin
What hormone is secreted by Alpha cells in the pancreas?
Glucagon
What hormone is secreted by Delta cells in the pancreas?
Somatostatin
What is contained in an immature secretory vesicle of the beta cells? What happens in this vesicle?
Proinsulin, which is cleaved into Insulin and Protein C
How does Clathrin differentiate between an immature vesicle and mature vesicle in the Beta cell?
Immature= clathrin coated Mature= no clathrin
Which has a longer half-life, insulin or protein c?
Protein C
Is GLUT-2 dependent or independent of insulin?
Independent
What is the mechanism of insulin release from the beta cells?
1) Glucose in via GLUT-2
2) Glycolysis increases ATP
3) ATP binds K+ sensitive channel, inactivating it and leading to membrane depolarized (Sulfonylurea Receptor)
3) Ca++ enters voltage gated channels
4) Insulin is released via exocytosis
What drugs target the K+ channel necessary for insulin release?
Sulfonylurea class drugs i.e.
- Gliclazide
- Glimepiride
What transporter is necessary for glucose entry in target cells?
GLUT-4
Is GLUT-4 dependent or independent of insulin?
Dependent
What does insulin do to target cells?
- Causes insertion of GLUT-4 transporters into membrane
- Glucose enters the cell
What is the embryologic origin of the adrenal cortex?
Mesoderm
What is the embryologic origin of the adrenal medulla?
Neural crest cells
What is required for the differentiation of neural crest cells to chromaffin cells in the adrenal medulla?
Cortisol
What is the mnemonic to remember the parents vessels of the suprarenal arteries?
IPAR
Inferior phrenic= superior suprarenal a.
Aorta= middle suprarenal a.
Renal= inferior suprarenal a.
What is the origin of the cortical and medullary arteries?
Supracapsular arterial plexus (plexus under the capsule from the suprarenal a)
What capillaries receives the hormones from the adrenal cortex?
Sinusoidal capillaries in the cortex
Where does the right suprarenal vein empty?
IVC
Where does the left suprarenal vein empty?
Left renal vein
What are the three zones of the adrenal cortex?
GFR:
Glomerulosa
Facsiculata
Reticularis
What is the mnemonic to remember the hormones released from the zones of the adrenal cortex?
Salt, sugar, sex
Aldosterone= G Cortisol= F Androgens= R
Histologically, what do you NOT see in the adrenal cortex would be expected b/c of the glands high output of secretory products?
Secretory vesicles; steroid hormones diffuse across membrane unlike peptide hormones
ACTH has a stimulatory effect on which two parts of the adrenal cortex?
Fasiculata and reticularis, NOT Glomerulosa
What is the expected gross finding in the setting of ACTH excess i.e. Cushing’s?
Cortical hypertrophy contributed by Fasiculata and Reticularis ONLY
What hormone has a major inhibitory effect on ACTH and cortisol secretion?
Glucocorticoids
What segmental levels of the SNS innervate the adrenal medulla?
T8-L1
Catecholamines are derived from what amino acid?
Tyrosine
List the steps in catecholamine synthesis?
1) Tyrosine
2) DOPA
3) Dopamine
4) NE
5) Epinephrine
What enzyme converts NE to Epi? What hormone activates this enzyme?
Phenylethanolamine-N-methyltransferase, which requires cortisol
In catecholamine synthesis, which is the only product that is NOT made in the cytoplasm?
NE
*Dopamine to NE enzymatic step occurs in the secretory vesicle
When catecholamine synthesis increases, what binding protein also increases?
Chromogranin
What is the Organ of Zuckerkandl?
Ectopic adrenal-medulla tissue in the region of the aortic bifurcation
A tumor of the Organ of Zuckerkandl i.e. a pheochromocytoma, is expected to increase the output of what?
Norepinehprine
*Without cortisol from the adrenal cortex, cannot convert NE to Epi
In Congenital Adrenal Hyperplasia, with the enzyme that produces cortisol deficient, describe the sequence of events that results in ambiguous genitalia in the female?
1) Decreased cortisol and shunting down the other pathways
2) Adrogens increased
3) Decreased cortisol leads to increased ACTH causing positive feedback and increased androgens
*Leads to ambiguious in the female patient
