Glucagon Flashcards
Glucagon is secreted from what type of cells
alpha cells of pancreas
glucagon is secreted in response to ? Primary function?
- glucose deficiency; amino acids in blood
- acts to increase circulating glucose levels
primary target of glucagon is
the liver
glucagon stimulates conversion of amino acids to
- glucose
glucagon stimulats the release of what three things
- glucose
- free fatty acids
- ketoacids
- **these in turn suppress glucagon release
what function does glucagon have on liver in terms of glucose
- promotes gluconeogenesis
- promotes glycogen breakdown and inhibits glycogen synthesis
what function does glucagon have on liver in terms of keytone bodies
- glucagon promotes fatty acid oxidation
- excessive oxidation leads to formation of keyton bodies
- can be used by the brain as fuel in fasting state
glucagon has what effect on adipose tissue and skeletal muscle
increases release of fatty acids (only at high concentration of glucagon)
Proglucagon is converted to what in the intestinal tract
Glucagon-like peptide-1
function of Glucagon-like peptide-1
increases insulin secretion in response to a carbohydrate or protein meal : the incretin effect
islet alpha cells of pancreas are inhibited by
- parasympathetic activity
- insulin
summary of glucagon effects
- glycogenolysis (hepatic glucose production)
- gluconeogenesis
- ketogeneisis
- lipolysis (adipose tissue)
- **increase in plasma glucose, FFA, ketoacids, and decrease in plasma amino acids
List sites where Somatostatin is produced
- pancreatic delta cells
- hypothalamus
- GI tract
list actions of Somatostatin
- may inhibit or modulate response of insulin and glucagon secretion
- inhibits GH secretion
function of cortisol on glucose
increased cortisol = increased blood glucose by gluconeogenesis
Effect of growth hormone on carbohydrate metabolism
- decreases glucose uptake and use by muscle, liver, and adipocyte
- increases liver glucose output by gluconeogenesis
- NET EFFECT -> increase in glucose
Function of epinephrine on carb metabolism
-
mobilizes fuel in times of STRESS
- increased glycogenolysus
- inhibition of glycogen synthesis
- increased gluconeogenesis
Which condition is associated with increased plasma growth hormone levels: abundance of food or scarcity of food?
both conditions are associated with increased plasma GH levels
- ex: overnight fast: low blood glucose
- GH stimulates liver glucose production to compensate
fasting state causes release of what hormones
- glucagon
- cortisol
- epinephrine
- growth hormone
stimulates liver glucose production to compensate
fasting state causes inhibition of release of what hormones
- insulin-like growth factor
- insulin
- thyroid hormones
why does the body not go into hypoglycemia after a protein meal
- insulin secretion is increased which could inhibit liver glucose production -> hypoglycemia
- BUT glucagon secreted in response to amino acids in protein balances the action of insulin
what hormones are secreted after high protein intake
- glucagon
- insulin
- growth hormone
- insulin-like growth factor
- **get protein synthesis and growth and no change in caloric storage
what hormones are secreted with ingestion of large carbohydrate meal
- insulin secretion increased to store glucose load
- increase in incretin: to augment insulin response
- glucagon and IGF-1 secretion suppressed due to lack of amino acids
- **increase in caloric storage; no change in protein synthesis or growth
brain utilizes what percentage of glucose during exercise
20%
can skeletal muscle secrete glucose?
no
during exercise, a balance must be made between glucose uptake by and release by
- skeletal muscle
- liver
elevation of what hormones during exercise promotes the use of as fuel
- hormones
- GH
- epi
- NE
- FFA
within the first 6 minutes of exercise, most energy is derived from
glycogen and glucose
after 10 minutes of exercise, most energy is derived from
FFA
The myokine IL-6 increases during exercise. what is its function
- increases glucose uptake and fat oxidation in skeletal muscle
- may also increase hepatic glucose production and lipolysis of adipose tissue
what happens to insulin secretion during exercise?
insulin secretion is suppressed during exercise by catecholamines
since insulin secretion is inhibited in exercise, how does glucose get into skeletal muscle
glucose uptake into skeletal muscle is facilitated by contraction medatiated mechanisms using GLUT-4
why does plasma glucose spike in response to an intense acute exercise
- increased release of catecholamines stimulates liver release of glucose
- working muscles utilizes stored glucose first during intense exercise
training has what effect on plasma glucose throughout exercise
plasma glucose remains higher and more stable than untrained individual
training has what effect on plasma glucagon throughout exercise
trained individual has a lower plasma glucagon throughout exercise
training has what effect on plasma insulin throughout exercise
plasma insulin remains lower in trained individual
