Lecture13 - Endocrine System II

Lecture13 - Endocrine System II - – Some IRs also Glucose...

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Endocrine System II Pancreas : Attached to the digestive tract at the duodenum (junction between the stomach and small intestine) Endocrine Pancreas: specialized cells that secrete into nearby blood vessels, hormones that control the metabolism of glucose surrounded by exocrine pancreas Exocrine Pancreas: secretes digestive enzymes into intestinal tracts Releases Insulin, Glucagon and Somatostatin Insulin: increases protein synthesis, glucose utilization, fat storage Glucagon: Increases blood glucose from liver Somatostatin: Decreases glucose and amino acid uptake from intestine Mechanism of Insulin Secretion Blood Glucose > 100 mg/dl detected by glucose transporter GLUT2 Glucose Oxidation, generates ATP Closing of potassium channel, depolarization Opening of voltage dependent calcium channel, influx of calcium Movement of insulin vesicles to plasma membrane release into extracellular space Insulin Receptor (IR) has tyrosine kinase activity (transfers phosphate from ATP to proteins)
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Unformatted text preview: – Some IRs also Glucose transporters GLUT4 move to plasma membrane where they… – …increase glucose influx – IR substrates increase glycogen, lipid, and protein biosynthesis (energy storage) – Long term: transcription of genes, synthesis of proteins involved in amino acid influx Insulin inhibits Hormone-sensitive lipase, an enzyme which degrades lipids, resulting in net lipid storage Type 1 Diabetes: – Too little insulin due to damaged beta cells in pancreas, autoimmune – Increased glucagon – Increased glucose production by liver, decreased utilization – Hyperglycemia (excessive glucose in blood) – Increased production of ketoacids (protein degradation products) unchecked by insulin – Increased urine output – Glucose control assessed by glycated hemoglobin Type 2 Diabetes: – Insulin is relatively normal – Tissue response to insulin is impaired resulting in increased blood glucose – Associated with age and obesity...
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This note was uploaded on 04/06/2008 for the course BMVS 4064 taught by Professor Dr.lee during the Spring '08 term at Virginia Tech.

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Lecture13 - Endocrine System II - – Some IRs also Glucose...

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