Principles - Feedback control of glucose Flashcards
Why is feedback control of plasma glucose critical for the brain?
Brain is a glucose-obligate tissue
Which cells are found in the pancreatic Islets of Langerhans?
α cells - glucagon
β cells - insulin
δ cells - somatostatin
What happens to hormone levels in the post absorptive state?
glucose and insulin rise
glucagon falls
What are the functions of insulin?
glucose > glycogen
fatty acids > triglycerides
amino acids > protein
What are the functions of glucagon?
glycogen > glucose
triglycerides > fatty acids
How does insulin lower glucose?
Stimulates uptake of glucose from blood into muscle and fat cells
Activation enzymes in liver and muscle which convert glucose into glycogen
In addition to its effect on glucose, what other effects does insulin have?
Promotes incorporation of amino acids into protein in muscle
Promotes lipgenesis in adipose tissue
How does insulin promote glucose uptake into muscle and fat?
Causes GLUT4 glucose transporter proteins to be inserted into the plasma membrane of muscle and fat cells
What factors promote insulin secretion?
Increased glucose
Increase amino acids
Parasympathetic activity
Increased glucagon
Gastric Inhibitory Peptide
What factors inhibit the secretion of insulin?
Decreased glucose
Sympathetic activity
How is diabetes mellitus detected?
Oral glucose challenge test
What are the clinical effects of severe diabetes?
High [glucose]p after a meal
Glycosuria
Increased urinary volume
Dehydration
Thirst
What are the metabolic effects of severe diabetes?
Increase in lipolysis to generate fatty acids as an energy source
Metabolism of fatty acids > acetyl CoA > ketone bodies
Metabolic acidosis - acid drop breath
What is the difference in pathogenesis between Type I and Type II diabetes?
Type I - little/no insulin secretion, due to defect in β cells
Type II - defect in insulin sensitivity
How frequent is ketosis in untreated diabetes?
Frequest in Type I diabetes
Rare in Type II diabetes
