Insulin, glucagone, DM Guyton Flashcards
What are 3 major hormones secreted by the pancreas
Insulin
Glucagon
Somatostatin
Which cells in the pancreas secrete glucagon?
Alpha
Which cells in the pancreas secrete insulin?
Beta
Which cells in the pancreas secrete somatostatin?
Delta
Excess carbohydrates are stored as ______ in the liver and muscles
Glycogen
If the liver and muscle is oversaturated with glycogen, carbohydrates are convert to ____ and stored in the _____ tissue.
Fatty acids
Adipose
In times of rest, what source of energy do muscles utilize most?
Fatty acids. The membranes are only slightly permeable to glucose without insulin
What are two periods when glucose is utilized over fatty acids in muscle energy
Strenuous exercise
After a meal
3 steps for glucose storage in the liver promoted by insulin (3)
Insulin inactivates liver phosphorylase (this is an enzyme that promotes breakdown of glycogen into glucose
Insulin enhances glucosekinase, leading to trapping of glucose into liver cell
Insulin promotes the glycogen synthase activity
What do neurons utilize as energy?
Glucose only! Cannot use carbs, protein, etc.
How does insulin effect fatty acid synthesis?
Increases
In insulin deficiency (i.e. DM), how does this effect the ability to store fat?
Decreases. The lack of insulin increases lipolysis, which increases plasma cholesterol and phospholipid plasma concentrations
How does insulin effect protein synthesis and storage?
Promotes it
How would insulin deficiency effect proteins?
Protein depletion and increased plasma amino acids
What hormone does insulin act synergistically with to promote growth?
Growth hormone
When discussing the mechanism of insulin secretion, the beta cells have a high number of _____ which allow glucose to come in and be phosphorylated by ______. This converts the glucose to _____.
GLUT-2
glucosekinase
Glucose-6-phosphate
Glucose-6-phophate is oxidized by ATP and activates _____ channels, which ______ (open/close) upon activation.
ATP-sensitive potassium
Close
Closure of the ____ channels on beta cells leads to opening of voltage gated ______ channels. This leads to ______ of pre-formed vesicles containing insulin.
potassium
calcium
exocytosis
How do sulfonylurea drugs stimulate insulin secretion?
By binding to the potassium channels, which closes them.
Which GI hormones increase insulin secretion? (4)
Gastrin
CCK
Secretin
GIP
Insulin presence promotes use of _____ over _____ for energy.
Carbohydrates
Fatty acids
Which hormone is secreted to increase plasma glucose?
Glucagon
What are 2 ways that glucagon increases blood glucose concentrations?
Increases glycogenolysis
Increases gluconeogensis
The conversion of _____ to _____ is the rate-limiting step in gluconeogenesis.
pyruvate
phosphenolpyruvate
