Term
| 4 types of pacreatic cells and their function |
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Definition
| 1: alpha cells: glucagon (20-30%) 2: beta cells: insulin (70-80%) 3: delta cells: somatostatin (growth hormone inhibiting hormone 2-8% of cells) 4: F cells: pacraeatic peptide (1-2% of cells) |
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Term
| how does glucose enter the cells |
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Definition
| via glucose transporters (GLUT 1-4 mainly) on the plasma membrane. Translocation of GLUT 4 to the membrane occurs in response to an increase in insulin |
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Term
| what does glucagon stimulate |
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Definition
| glycogenolysis in the liver, gluconeogenesis in the liver, and lipolysis in adipose tissue |
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Term
| what does glucagon result in |
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Definition
| glycogen breakdown, lipid breakdown, increased blood glucose |
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Term
| what does insulin stimulate |
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Definition
| glycogen syntehsis (glycogenesis) in the liver and muscle, lipid synthesis (lipogenesis) in adipose tissue, and glucose uptake |
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Term
| what does increased insulin result in? |
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Definition
| increased import of glucose to fat and muscle cells, fat synthesis and storage, and decreased blood glucose |
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Term
| in regards to glycogenesis and glycogenolysis, what must happen to glucose-6-phosphate before it can leave hepatocytes? |
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Definition
| phosphate from G6P must be removed via glucose 6-phosphatase prior to exit via glucose transporter |
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Term
| insulin receptor family and details regarding insulin |
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Definition
| member of tyrosine kinase receptor (RTK) family. Insulin is the ligand soo...it binds the extracellular domain of an insulin receptor dimer. It then activates tyrosine kinase domain which causes receptors to autophosphorylate Tyr kinase domain which activates a signalling cascape which results in the phosphorylation of substrates and downstream effects |
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Term
| where is insulin receptor mRNA expressed in the body? |
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Definition
| in many tissues other than the beta cells of the pancreas...this receptor may be involed in many uncharacterized mechanisms |
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Term
| what does is the structure of the insulin receptor and what does the binding of insulin to an insulin receptor dimer do? |
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Definition
| insulin receptor is made up of 2 extracellular alpha chains and 2 beta transmembrane chains. insulin binds to the receptor and activates an intracellular tyrosine kinase domain which triggers its release or the insulin receptor complex is endocytosed and degraded. the internalized insulin protein is degraded by liver cells |
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Term
| what type of transporters are glucose transporters |
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Definition
| either secondary active transporters or facilitated diffusion type of transporter |
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Term
| what is a secondary active transporter |
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Definition
| a transporter that derives the energy used to transport a molecule from an electrochemical potential difference created by Na/K ATPase |
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Term
| what type of transporters are the GLUT family proteins? |
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Definition
| facilitated diffusion transporters |
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Term
| describe the sodium-glucose symporter |
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Definition
| an ion gradient is generated by the Na/K ATPase and is used to drive symport of glucose into the cell by the Na-glucose symporter. This is the mechanism used in intestinal glucose absorption |
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Term
| general information about GLUT family transporters |
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Definition
| at least 14 proteins in family. Uniporters. No energy required for facilitated diffusion. The rate of tranport is dependent on the Km of the glucose tranporter and blod glucose concentration. |
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Term
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Definition
| glut 1 has near maximal activity under all physioogical conditions. glut 2 regulates blood glucose mainly when levels are really high. |
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Term
| which GLUT tranporters mediate glucose uptake in an absence of insulin? |
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Definition
| GLUT1 and GLUT3...GLUT3 largely important in the brain |
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Term
| where is GLUT 4 primarily found |
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Definition
| in the muscle tissue. Km of 5mM so concentration. it mediates insulin-stimulated increase in glucose uptake |
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Term
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Definition
| for basial glucose uptake especially in erythrocytes |
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Term
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Definition
| liver and pancreas. in the liver, excess glucose from the blood is used in glycogenesis. in the pancrease, excess glucose is involved in insulin release. |
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Term
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Definition
| basal glucose uptake in neuronal tissues in the brain |
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Term
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Definition
| mediates insulin-stimulated glucose uptake in skeletal and cardiac muscle as well as fat cells |
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Term
| what signals for insulin to be released from pacreatic beta cells |
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Definition
| polarization of B cells keep insulin granules inside the cell. as glucose enters the cell via GLUT2 transporter, gated potassium channels keep K+ inside the cells which causes a depolarization of memebrane which leads to a voltage-diference to build up. The buildup triggers calcium channels to open which triggers the release of insulin granules |
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Term
| what is a common insulin degradation product |
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Definition
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Term
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Definition
| cystic fibrosis related diabetes...common as persons affected with CF live longer. distinct from types 1 and 2 DM |
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Term
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Definition
| insulin insufficiency, insulin resistance, higher rates of pulmonary infections. |
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Term
| types of treatments for CFRD |
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Definition
| insulin, diet/glycemic control, oral antidiabetic medications |
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Term
| what are the genetic influences on CFRD pathogenesis? |
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Definition
| CFTR mutations associated with exocrine pancreatic insufficiency and CFTR mutations with more severe phenotype |
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Term
| 3 key aspects of cellular stress in CFRD pathogenesis |
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Definition
| oxygen deficit (lack of oxygen to islents cause beta cell death), endocrine pancreas (ER stress causes misfolding of insulin moecules and therefore decreases production), lungs (dehydrated mucus causes bacterial infections, subsequent inflammation. also interrupts the insulin signaling pathway, cuasing insulin resistance.) |
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