Physio: Pancreatic Hormone Flashcards
(38 cards)
According to the source, which hormone secreted by the pancreatic islets acts as a paracrine regulator that inhibits both insulin and glucagon release from neighboring endocrine cells?
a) Insulin
b) Glucagon
c) Pancreatic polypeptide
d) Somatostatin
d) Somatostatin
The source states that insulin is initially synthesized as a larger peptide precursor. What is the name of this precursor before it is converted to proinsulin?
a) Preproinsulin
b) Proinsulin
c) C peptide
d) Alpha chain
a) Preproinsulin
Insulin consists of two peptide chains connected by disulfide bridges. What are these two chains called, according to the source?
a) A chain and C chain
b) Alpha chain and beta chain
c) Pro chain and Insulin chain
d) Disulfide chain and Peptide chain
b) Alpha chain and beta chain
The source describes insulin as having diverse metabolic effects. Which term is used to characterize the overall nature of most of these effects?
a) Catabolic
b) Inhibitory
c) Anabolic
d) Degenerative
c) Anabolic
Which of the following is explicitly listed as a primary target organ for insulin action in the source?
a) Kidney
b) Brain
c) Skeletal muscles
d) Pancreas
c) Skeletal muscles
Liver and adipose tissues as well.
According to the source, insulin is the only hormone in the body that performs which primary function regarding blood glucose?
a) Increases blood glucose levels
b) Stimulates gluconeogenesis
c) Inhibits glucose uptake by muscle
d) Lowers blood glucose levels
d) Lowers blood glucose levels
In skeletal muscle and adipose tissue, insulin stimulates glucose uptake. According to the source, this is primarily achieved by stimulating the translocation of which specific glucose transporter isoform to the cell membrane?
a) GLUT1
b) GLUT2
c) GLUT3
d) GLUT4
d) GLUT4
According to the source, how does the phosphorylation of glucose to glucose-6-phosphate inside the cell contribute to further glucose uptake?
a) It facilitates the transport of glucose-6-phosphate across the membrane
b) It activates the GLUT transporters to move more quickly
c) It keeps the concentration of free intracellular glucose low, favoring continued diffusion
d) It directly inhibits the action of glucagon
c) It keeps the concentration of free intracellular glucose low, favoring continued diffusion
Unlike skeletal muscle and adipose tissue, the source indicates that glucose uptake in the liver utilizes which glucose transporter isoform?
a) GLUT1
b) GLUT2
c) GLUT3
d) GLUT4
b) GLUT2
According to the source, is the GLUT2 transporter in the liver insulin-dependent?
a) Yes, its presence in the membrane requires insulin
b) Yes, its activity is directly regulated by insulin signaling
c) No, it is always present in the cell membrane regardless of insulin
d) Only its conversion of glucose is insulin-dependent
c) No, it is always present in the cell membrane regardless of insulin
Which of the following liver enzymes involved in glycogen metabolism is activated by insulin, according to the source?
a) Glycogen phosphorylase
b) Glucose-6-phosphatase
c) Glycogen synthase
d) Both glycogen phosphorylase and glucose-6-phosphatase
c) Glycogen synthase
Which liver enzyme, responsible for converting glucose to glucose-6-phosphate, is stimulated by insulin, indirectly contributing to increased glucose uptake in the liver?
a) Hexokinase
b) Fructokinase
c) Glucokinase
d) Glucose-6-phosphatase
c) Glucokinase
According to the source, insulin inhibits the synthesis of glucose from non-carbohydrate precursors such as amino acids, lactic acid, and glycerol. What is this metabolic process called?
a) Glycogenesis
b) Glycolysis
c) Glycogenolysis
d) Gluconeogenesis
d) Gluconeogenesis
In adipose tissue, insulin stimulates lipogenesis (synthesis of triglycerides). According to the source, which enzyme in the blood does insulin stimulate to supply free fatty acids to adipocytes for triglyceride synthesis?
a) Hormone-sensitive lipase
b) Adipocyte triglyceride lipase
c) Lipoprotein lipase
d) Glycerol phosphate acyltransferase
d) Glycerol phosphate acyltransferase
Also,
Pyruvate dehydrogenase
Actetyl coa carboxylase
According to the source, how does insulin influence hormone-sensitive lipase activity within adipocytes?
a) It activates hormone-sensitive lipase
b) It inhibits hormone-sensitive lipase
c) It has no effect on hormone-sensitive lipase
d) It increases the synthesis of hormone-sensitive lipase
b) It inhibits hormone-sensitive lipase
Insulin stimulates lipoprotein lipase.
According to the source, insulin stimulates protein synthesis in skeletal muscle primarily by increasing the uptake of what substances by muscle cells?
a) Glucose
b) Free fatty acids
c) Triglycerides
d) Amino acids
d) Amino acids
Insulin inhibits protein catabolism by suppressing the activity of which type of cellular enzymes that degrade proteins, according to the source?
a) Proteasomal enzymes
b) Cytosolic enzymes
c) Lysosomal enzymes
d) Mitochondrial enzymes
c) Lysosomal enzymes
According to the source, what type of receptor is the insulin receptor on the cell surface?
a) G protein-coupled receptor
b) Ligand-gated ion channel
c) Nuclear receptor
d) Enzyme-linked receptor
d) Enzyme-linked receptor
Name the enzyme.
Upon insulin binding, the two monomers of the insulin receptor are brought together and undergo cross-phosphorylation. This phosphorylation occurs on which part of the receptor’s beta-subunit?
a) Extracellular insulin recognition site
b) Transmembrane domain
c) Cytosolic tyrosine kinase domain
d) Disulfide bridges
c) Cytosolic tyrosine kinase domain
Activated, phosphorylated insulin receptor substrates (IRS proteins) then trigger intracellular cascade pathways. According to the source, what is a key downstream effect of these pathways related to glucose uptake?
a) Activation of gluconeogenesis enzymes
b) Translocation of glucose transporters from vesicles to the cell membrane
c) Inhibition of glycogen synthesis
d) Increased protein catabolism
b) Translocation of glucose transporters from vesicles to the cell membrane
The source states that insulin secretion from pancreatic beta-cells is controlled by a negative feedback mechanism related to blood glucose levels. What happens to insulin secretion when blood glucose concentration increases?
Insulin secretion stimulates glucose uptake
Insulin secretion inhibits gluconeogenesis
Insulin secretion increases
At the cellular level, insulin secretion from beta-cells is accomplished via exocytosis, which is stimulated by the entry of which ion?
a) Na+
b) K+
c) Ca2+
d) Cl-
c) Ca2+
In the resting state, outward flux of which ion contributes to maintaining the negative resting membrane potential in pancreatic beta-cells, keeping the voltage-dependent Ca2+ channel closed?
a) Na+
b) K+
c) Ca2+
d) Cl-
b) K+
