APPP Quiz – Kidney and Pancreas Flashcards
What is insulin produced by?
beta cells in the islets of Langerhans of the pancreas
Glucose is by far the most important controller of insulin secretion. How does it trigger insulin secretion?
- increases ATP/ADP ratio
- closes K+ channel
- elicits depolarization of membrane
- facilitates Ca2+ entry
- causes exocytosis of secretory granules containing insulin
(can increase insulin secretion in absence of any other stimulatory agent)
What can trigger insulin secretion?
- glucose
- amino acids
- fatty acids
- sulfonylurea drugs
How do sulfonylureas increase insulin secretion?
block K+ channels by direct action on site located at or near the channel (sulfonylurea urea receptor)
What can inhibit insulin secretion?
catecholamines
What can enhance insulin secretion?
GLP-1
What happens when insulin binds to its receptor? (4)
- glucose uptake
- glycogen synthesis (in liver)
- protein synthesis (after amino acid uptake)
- lipid storage (formation in adipocytes)
How does insulin regulate glucose?
- insulin lowers plasma glucose levels by stimulating glucose uptake (with GLUT4 in muscle and adipose tissue)
- suppresses hepatic production of glucose
How does insulin regulate lipids? (2)
insulin can lower plasma triglyceride and fatty acid levels by multiple mechanisms
- increase glucose transport (which is then esterified to triglyceride)
- inhibit lipolysis
How does insulin regulate protein?
insulin increases uptake of amino acids into many tissues (muscle, liver, adipose), and stimulates protein synthesis and inhibits protein degradation
What are the net effects of insulin? (4)
- decrease blood glucose
- decrease blood triglycerides and cholesterol
- decrease blood free fatty acids
- decrease blood amino acids
What are the 3 key functions of insulin?
- help blood sugar enter body cells
- moderate breakdown of body’s reserves of carbohydrates, proteins, and fats
- inhibit glucose production in liver
What does T2D usually result in?
loss of first-phase insulin released and beta cell loss related to prolonged exposure to beta cells at high glucose, fatty acids, pro-inflammatory cytokines (TNF-a), and islet amyloid deposits
What happens to beta cells as insulin resistance develops?
- beta cells attempt to compensate by producing more insulin
- after onset of beta cell dysfunction, pancreas is no longer able to compensate via hypersecretion
- control of blood glucose gets worse, leading to impaired glucose tolerance, and increasing fasting and post-prandial glucose levels, and eventually T2D
What is glucose toxicity?
hyperglycemia itself will worse insulin resistance and beta cell function
What are the 4 laboratory tests for diabetes?
- post-prandial (casual) blood glucose
- fasting plasma glucose
- OGTT
- glycosylated hemoglobin (HbA1c)
Fasting Plasma Glucose (FPG)
mainly reflects hepatic gluconeogenesis and basal metabolic needs
- impaired fasting glucose: 6.1-6.9 mmol/L
- diabetes: ≥ 7.0 mmol/L
Postprandial (Casual) Blood Glucose
reflects dietary intake and should be monitored as it significantly contributes to overall daily glycemic profile