Adrenal and Pancreas Histology Flashcards
What are the cells that the pancreatic islets are derived from?
Endoderm
Where in the pancreas are most of the pancreatic islet cells located?
Slightly more numerous in the tail of the pancreas
What forms the supporting framework for the pancreatic islet cells? What are the other two major components of the supportive framework?
Reticular fibers
ANS fibers
Capillary network
What percent of the pancreas is composed of beta cells? Alphas cells?
70% beta cells
20% alpha cells
Where are the beta cells of the pancreas located? What hormone do these secrete, and what is its function?
Scattered throughout
Secrete insulin to decrease BG levels
Where are the alpha cells of the pancreas located? What hormone do these secrete, and what is its function?
Peripherally
Secrete glucagon to decrease BG levels
Where are the delta cells of the pancreas located? What hormone do these secrete, and what is its function?
Scattered Somatostatin secretion to inhibit: -TSH -GH -Contraction of GI tract and gallbladder
Where are the G cells of the pancreas located? What hormone do these secrete, and what is its function?
Scattered throughout
Gastrin secretion–Stimulates HCl secretion by parietal cells
Where are the PP cells of the pancreas located? What hormone do these secrete, and what is its function?
Scattered
- Pancreatic polypeptide
- Inhibit pancreatic exocrine secretion
Where are the D1 cells of the pancreas located? What hormone do these secrete, and what is its function?
Scattered
VIP to increase motility and stimulates GI fluid secretion
Where are the EC cells of the pancreas located? What 3 hormones do these secrete?
Scattered
Secretes Motilin, substance P, and serotonin
What is the function of Motilin secreted by EC cells of the pancreas?
Promotes gastric and intestinal motility
What is the function of Secretin secreted by EC cells of the pancreas?
Stimulates secretion from the exocrine pancreas
What is the function of Substance P secreted by EC cells of the pancreas?
Neurotransmitter
What is the major neoplasm or symptoms that arises from Beta cells?
Insulinomas that cause hypoglycemia
What is the major neoplasm or symptoms that arises from Alpha cells?
Gluconoma
What is the major neoplasm or symptoms that arises from delta cells?
Somatostatinoma
What is the major neoplasm or symptoms that arises from G cells?
Gastrinoma
What is the major neoplasm or symptoms that arises from PP cells?
Asymptomatic
What is the major neoplasm or symptoms that arises from D1 cells?
Secretory diarrhea
What is the major neoplasm or symptoms that arises from EC cells?
Carcinoid syndrome
True or false: insulinomas are benign
True, but can cause BG to fall below 45 mg/dL
Pancreatic islet cells secrete a lot of proteins. What organelles, then, predominate throughout these cells?
rER
Golgi
What are the structures that hold pancreatic cells together?
Desmosomes
Which type of genetic material is available for transcription: euchromatic or heterochromatic DNA?
Euchromatic
What is the maturation process of insulin?
Proinsulin is secreted into clathrin coated vesicles, where an enzyme cleaves it into insulin and C-peptide
What happens to the vesicles that contain proinsulin as they mature?
Lose clathrin, and gain pumps to increase cell [H+]
What is the MOA of insulin release?
Beta cells take in glucose through GLUT-2, which inhibits K exporter, causing CA influx and release of insulin
What GLUT transporter is found on beta cells of the pancreas? Is this insulin dependent?
GLUT2
Non-insulin dependent
What are the drugs that Inhibit the sulfonylurea receptors to induce insulin secretion?
Gliclazide
Glimepiride
What is the MOA of gliclazide?
Inhibits the sulfonylurea receptor on beta cells, to induce Ca influx, and thus insulin release
What is the MOA of Glimepiride?
Inhibits the sulfonylurea receptor on beta cells, to induce Ca influx, and thus insulin release
What is the side of the Golgi that faces the rER? Cell membrane?
face rER = cis
cell membrane = trans
What happens to the beta cells in DM II?
There is a loss of GLUT-2 mRNA, leading to an impairment of glucose stimulated secretion of insulin
What is the MOA of insulin on target cells?
Induces the movement of GLUT4-containing endosomes to the cell membrane
What is Cushing’s disease? Syndrome?
Disease is a pituitary issue
Syndrome is primary
Where are the target cells for ACTH chiefly located in the adrenal gland, and what hormones are secreted by the target cells?
Zona fasciculata and reticularis
What cells give rise to pheochromocytomas?
Chromaffin cells
What are the two signalling molecules are essential in the differentiation of cells into chromaffin cells?
Cortisol
Nerve growth factor (NGF)
In chromaffin cells, why is cortisol required for the synthesis of epinephrine?
Activates Phenylethanolamine N-methyltransferase
What is the role of plasma chromogranin A? Why is it elevated in a pt with a pheochromocytoma?
Binds to excess catecholamines, so an aberrant increase in catecholamines will cause an increase in this binding protein
Where in chromaffin cells are the enzymes located for the conversion of tyrosine to dopamine? Dopamine to norepi? Norepi to epi?
From Y to dopamine, all the enzymes are in the cytoplasm
Dopamine to NE is found in secretory vesicles
NE to epi is in the cytosol, so NE must be transported out of the vesicle to the cytosol
Sympathetic outflow to the adrenal medulla arises from which spinal cord segments?
Preganglionic sympathetic neurons of T8-L1
What germ layer is the outer cortex of the adrenal glands derived from?
Mesoderm
What germ layer is the inner medulla of the adrenal glands derived from?
Neural crest cells of the neuroectoderm
What are the three major arteries that supply the adrenal gland, and what is the parent artery of each?
- Superior suprarenal artery (inferior phrenic)
- Middle suprarenal artery (aorta)
- Inferior suprarenal artery (renal)
What are the components of the mnemonic to recall the arterial supply to the suprarenal arteries?
IPAR
Inferior phrenic
Aorta
Renal
What is the plexus that is formed from the suprarenal arteries when they penetrate the capsule? What are the two sets of arteries that issue from this plexus?
Subcapsular plexus
- Cortical arteries form a network of sinusoidal capillaries in the cortical parenchyma
- Medullary arteries penetrate the cortex and enter the medulla where they form a capillary network
What do the cortical arteries that issue from the subcapsular plexus go?
Form a network of sinusoidal capillaries in the cortical parenchyma
What do the medullary arteries that issue from the subcapsular plexus go?
Penetrate the cortex and enter the medulla where they form a capillary network
What is the order of veins that drain the confluence of the capillaries formed by the renal arteries?
Medullary venules are the confluence of the capillaries»_space; medullary veins»_space; suprarenal vein»_space; IVC (right side) or left renal vein (left side)
What forms the capsule of the suprarenal gland?
Dense irregular collagenous tissue
What is the major difference between the right and left suprarenal veins? What is the clinical significance of this?
Right is much shorter, meaning that this vein may be avulsed during surgery or high-energy deceleration injuries
What is the largest layer of the adrenal cortex?
Zona fasciculata (78% of total volume)
Explain how it gets sweeter as you get deeper?
mineralcorticois synthesized at glomerulosa, then glucocorticoids, then sexy
What are the general histological characteristics of the adrenal areas?
Large amount of sER to synthesize steroids, and lipid droplets
No secretory vesicles, since lipid soluble
Why don’t the adrenal cells have vesicles for secretion?
Only produce lipid soluble hormones
What are the two tropic chemicals that influence the zona glomerulosa?
Angiotensin
Potassium
What is the major hormone that influences the zona fasciculata?
ACTH
What are the major hormones that influence the zona reticularis?
ACTH
What happens to the zones to the adrenal cortex with Cushing’s disease?
hypertrophy of the Zona fasciculata and reticularis
What are the steps of epi synthesis? (5)
- Tyrosine
- DOPA
- Dopamine
- NE
- Epi
What is the enzyme that converts Y into dopa?
Tyrosine hydroxylase
What is the enzyme that converts DOPA to dopamine?
DOPA decarboxylase
What is the enzyme that converts dopamine to NE?
Dopamine beta-hydroxylase
What is the enzyme that converts NE to epi? What is the stimulus that is necessary for this enzyme?
Phenylethanloamine N-methyltransferase
Cortisol
What is the organ of Zuckerkandl?
medullary tissue located around the abdominal aorta between its bifurcation and the IMA. Chromaffin cells primarily produce norepinephrine with small amounts of epinephrine.
What is the tubercle of Zuckerkandl?
Extension of thyroid tissue
What hormone does the organ of Zuckerkandl primarily produce? Why?
NE, since there is a lack of cortical tissue here
What hormones are produced by the adrenal medulla?
NE /epi
What is the radiological finding of blood supply to the adrenal gland look like?
Mercedes benz
What is congenital adrenal hyperplasia?
Enzyme to produce cortisol is defective, driving precursor steroids to be driven toward androgen production. The pituitary reacts by increasing ACTH, making matters worse
What is the enzyme that is defective in congenital adrenal hyperplasia?
21-hydroxylase