Pancreas Flashcards
(44 cards)
The insulin receptor shares a common enzyme with one seen in what type of cancer?
- Tyrosine Kinase!
- CML and occasionally ALL, a t(9;22) for the bcr-abl protein (Philly chromosome)
The 3 types of cells in the Islets of Langerhans are what/make what?
- alpha cells make glucagon
- beta cells make insulin
- delta cells make somatostatin
What are the physiologic functions of Somatostatin?
- he never met another hormone he liked
- decreases levels of GH+TSH+PRL; insulin+glucagon, gastric acid+CCK+secretin
What 2 drugs are somatostatin analogues?
- Octreotide
- Lanreotide
What are the most common uses for somatostatin analogs?
- Acromegaly/gigantism
- Neuroendocrine tumors (Carcinoid syndrome)
What stimulates release of Insulin?
- Blood Glucose is #1
- amino acids (Arg)
- Intestinal hormones (GLP, GIP)
What stimulates released of Glucagon?
- Hypoglycemia
- amino acids
Where are Insulin receptors found, and what type are they?
- cell surface
- intrinsic Tyrosine Kinase activity
Where are Glucagon receptors found, and what type are they?
- predominantly found on the LIVER
- G protein couple, G(as)
Describe the functions of Glucagon.
- it is a stress hormone, to INCREASE BLOOD GLUCOSE
- how? via stimulating liver (gluconeogenesis, glycogenolysis, lipolysis)
What metabolic products will increase as a result of Glucagon stimulation?
- Ketones (from hi lipolysis)
- Urea (from hi gluconeogenesis)
What effect does glucagon have on insulin?
-mild INCREASE in production (whaaaaat)
Describe the keys steps that occur inside a beta cell to release insulin.
- Glucose enters thru GLUT2
- cell makes lots of ATP
- hi ATP closes the K channel
- membrane depolarizes, opens the voltage gated Ca
- Ca influx, exocytosis of insulin granules
In general, contrast the types of enzymes stimulated by glucagon/insulin.
- Glucagon stimulates kinases (adds Pi)
- Insulin stimulates phosphatases (removes Pi)
What tissues in the body do NOT uptake glucose by facilitated diffusion?
- Skeletal muscle and Adipose tissue
- REQUIRE insulin to shove GLUT4 into their cell membrane
What is the relationship with Insulin and Potassium?
Insulin drives K into cells with Glucose (hence why it can treat hyperkalemia!)
Urea is to protein as Ketones are to _________
fatty acids (the metabolic byproducts)
Insulin increases the action of what hormone on the endothelial cell wall that empties VLDL and chylomicrons of TG?
- Lipoprotein Lipase
- cleaves TG, brings into cell as FFA
Insulin decreases the action of what lipolytic hormone inside adipose tissue?
-hormone sensitive lipase
Describe insulin’s effect on glycogen enzymes.
- promotes de-phosphorylation
- this activates Glycogen Synthase+Glucokinase (liver)
- this inactivates Glycogen Phosphorylase+Glucose-6-Phosphatase (liver)
What other substrates hit receptors that have tyrosine kinase activity?
- Insulin, IGF-1, any growth factor (VEGF, EGF, etc.)
- DON’T confuse with receptors ASSOCIATED with tyrosine kinase (PRL, GH, cytokines)
Glucagon, through pkA, does what to glycogen enzymes?
- promotes Phosphorylation!
- this INACTIVATES Glycogen Synthase+Glucokinase (liver)
- this ACTIVATES Glycogen Phosphorylase +Glucose-6-Phosphatase (liver)
Glucagon increases Gluconeogenesis by promoting what reactions?
Pyruvate–>PEP
F1,6BP–>F6P
Glucagon increases lipolysis through what enzyme?
- INHIBITS Acetyl CoA carboxylase
- this decreases formation of malonyl CoA
