Endocrine pancreas Flashcards
What is the basic organization of the endocrine pancreas?
clusters of cells termed islets of langerhans
single islet consist of multiple cell types, each producing one type of hormone
insulin secreted by beta cells and lie in the center of islets
glucugon by alpha cells
what does insulin do
incr. glut4 receptors on skelectal muscles and adipose tissues. glucose enters tissues. serum conc. decr.
incr. glycogen syntehsis and lipogenesis and incr protein synthesis
What is type 1 DM?
insulin deficiency leading to a metabolic disorder charachterized by hyperglycemia
What is the pathophysiology of type 1 DM? genetic associations?
autoimmune destruction of beta cells by t lymphocytes (type IV). inflammation of islets. associated with HLA-DR3 and DR4.
autoantibodies against insulin= may be there yrs before clinical disease
manifestations of type I dm
childhood with insulin deficiency
high serum glucose
weight loss and low muscle mass and polyphagia (they are breaking down fat, proteins)
polyuria, polydipsia, glycosuria.sugar in urine draws water in
tx: insulin
complications of type I DM
excessive serum ketoacidosis
often arises with stress (infection)
epinephrine increases glucagon= exacerbating lipolysis
incr. lipolysis = incr. free fatty acids. liver converts free fatty acids to ketones
clinical features of DKA
hyperglycemia, anion gap metabolic acidosis, hyperkalemia (K outside of cells, and a buffer for acid). much of K is lost in urine you are depleting K stores even though there is high K in the blood Kussmaul respiration (rapid/deep breathing), dehydration, nausea, vomiting, mental status change, fruity smelling breath
tx of DKA
fluids, insulin, replacement of electrolytes, including K (which looks high in blood but is low in the body overall
type II DM: what is it, predisposition
end organ resistance to insulin leading to hyperglycemia
obesity: obesity leads to decr. number of insulin receptors.
very strong genetic predisposition
Insulin levels in type 2 DM
at first, insulin levels are increased- but later on, you see insulin deficiency d/t beta cell exhaustion
histo changes with type 2 DM
islets filled with amyloid
clinical features of DM type 2
polyuria, polydipsia, hyperglycemia. often clinically silent.
Dx of DM type 2
random glucose >200
fasting glucose >126
glucose tolerance test >200 mg/dL 2 hrs after glucose
(A1C>6.5)
tx of DM type 2
weight loss, drug therapy to counter insulin resistance, insulin
What is a main complications of type 2 DM
hyperosmolar non-ketotic coma
high glucose levels >500 mg/dL leads to life threatening diuresis.
hypotension and coma
ketones are abscent
What are the 2 major mechanisms for complications in type 2 DM?
non-enzymatic glycosylation of vascular basement membrane: stick sugar onto basement membrane (NEG) and osmotic damage
non-enzymatic complications
large and medium-sized vessels: leads to atherosclerosis, CV disease, amputations
NEG of small vessels leads to hyaline artherosclerosis, esp. in the kidney:
preferential involvement of efferent: hyperfiltration, then sclerosis of the mesangium, then kimmelstein-wilson syndrome, then nephrotic syndrome.
if you have afferent atherosclerosis- decr. blood supply,. and diffuse sclerosis of the glomerulus
NEG of hemoglobin leads to HbA1C.
MI is the most common cause of death.
What cells will take up sugar independent of insulin?
- schwann cells: converts glucose to sorbitol, leads to osmotic damage. this causes neuropathy
- pericytes of the the retinal blood cells. sugar in the pericytes goes to sorbitol, pericytes die, vessel wall is weakened and then you get aneurysms in the retina. if they rupture you can get blindness
- lens can take up glucose. it goes to sorbitol (aldose reductase) and can cause cataracts
pancreatic endocrine tumors
tumors of islet cells. oftent a component of MEN1 (along with parathyroid hyperplasia and pituitary adenoma)
insulinoma
episodic hypoglycemia with mental status changes that are relieved by glucose. glucose down, insulin and C-peptide up- you are making the insulin within the body if you see a high C-peptide.
what is a gastrinoma?
tumor that produces gastrin. gastrin goes to paietal cells and makes them produce acid. treatment resistant peptic ulcers- zollinger ellison syndrome
may be multiple ulcers and can extend to jejunum
what is a somatostatinoma
tumor that makes somatostatin
inhibits gastrin- low acid production (achlorhydria)
also inhibits CCK, which is important for gall bladder contraction. incr. risk of gall stones and steatorrhea
What is a VIPoma
tumor makes vasoactive intestinal pepitde
causes watery diarrhea, hypokalemia, and achlorhydria (low acid production)
