10 Endocrine Pancreas
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more in the tail than head of pancreas
made of amino acids..
Islets are richly innervated by both adrenergic and cholinergic nerves.
In general, any condition that activates the sympathetic branch of the autonomic nervous system (such as hypoxia, hypoglycemia, exercise, hypothermia, surgery, or severe burns) suppresses the secretion of insulin by stimulation of α2 (Gi) adrenergic receptors.
a2 adrenergic receptor antagonists increase basal concentrations of insulin in plasma
However, liver gluconeogenesis is also increased and is the dominant effect. The end result is hyperglycemia.
β2 adrenergic receptor antagonists decrease insulin in plasma. However, there is an overall decreased glucose level in plasma, as b2 receptors on hepatocytes are also blocked from gluconeogenesis.
Glycogenolysis and gluconeogenesis in hepatocytes is stimulated by beta-2 agonism via activation of glycogen phosphorylase kinase by epinephrine and glucagon (Gs).
Lipolysis is stimulated by activation of hormone-sensitive lipase (HSL) in adipocyte cytoplasm by epinephrine via the beta-3 agonism (Gs) and glucagon (Gs).
PIP2 phosphorylated to make PIP3..
also tells bones and keratinocytes to grow (tall children)
Muscle triggers by Ca and exercise, not glucagon
Gluconeogenesis mostly in liver
Insulin: aa uptake in muscle
Hypoglycemia..
IV dextrose is best. If not, then IM
Beta blocker overdose
Activates glucagon receptor not beta receptor. Same downstream effect
high protein: insulin high to make protein in muscle. Glucagon high to make glucose from aa and prevent lipid synthesis
result: less fat after protein meal..
Whipple's triad: fasting hypoglycemia, neuroglycopenic problem, problem relieved by glucose
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elevated c-peptide/pro-insulin: prove from pancreas
exogenous insulin: people may use for gains
Looks like diabetes
Glucagonomas are glucagon-secreting neuroendocrine tumors of alpha cells in the pancreas.
Other symptoms:
Deep vein thrombosis
Depression
Diarrhea
Anemia of chronic Disease (normocytic, normochromic anemia)
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Pancreatic neuroendocrine (islet cell) tumors that secrete vasoactive intestinal polypeptide (VIP). The increased pancreatic secretions and increased GI relaxation result in severe diarrhea, which can in turn cause hypokalemia and achlorhydria.
VIPoma is also termed “WDHA syndrome” for
Watery
Diarrhea
Hypokalemia
Achlorhydria..
Enzyme stimulated by insulin. Insulin promotes transcription.,
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amino acids, glucose, GLP-1, Ach stimulate release..
E, NE, somatostatin, Growth hormone, glucocorticoids..
Autonomic control plays a minor role in insulin control, except during sympathetic activation..
Stimulation of α2 adrenergic receptors (Gi) inhibits insulin secretion..
B2(Gs) adrenergic receptor agonists increase insulin release..
β2 (Gs) adrenergic receptor agonists and vagal nerve stimulation enhance release..
The effects on blood glucose levels are also determined by glycogenolysis in hepatocytes and gluconeogenesis in hepatocytes assisted by lipolysis in adipocytes..
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Glucagon increases urea production because amino acids are used for gluconeogenesis (stimulated by glucagon), and the resulting amino groups are incorporated into urea..
Uses:
Are of neuroendocrine origin..
Histology shows rosettes:..
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Aka zollinger ellison syndrome.,
Excess production of HCl will cause recalcitrant gastric ulcers, duodenal ulcers, and chronic watery diarrhea., Other symptoms of ZES include epigastric pain, steatorrhea, and vomiting. Gastrin activates stomach parietal cells (which secrete HCl) and enterochromaffin-like cells (which secrete histamine).
Used to diagnosis gastrinoma. Indicates that gastrin levels remain elevated after the administration of secretin (normally inhibits gastrin release).,
