ll.2 Actions of Insulin and Glucagon
How does insulin reduce blood glucose levels?
Allowing glucose to enter muscle and other target cells
What works to oppose the storage effects of insulin? Why?
Counter-regulatory hormones to regulate blood glucose levels during fasting, excercising, and stress
What factors decrease insulin secretion?
Decrease blood glucose levels (hypoglycemia) Somatostatin Sympathetic stimulation of alpha cells NorEpi Epi High levels of insulin (by negative feedback) Prostagladins
What factors increase glucagon secretion?
Decreased blood glucose (hypoglycemia) Increased amino acids (especially arginine) CCK (alerts alpha cells to a protien meal) Sympathetic stimulation of NorEpi and Epi
What are the Counter-regulatory hormones?
Glucagon, Catecholamines (Epi and NorEpi), Growth Hormone, and Glucocorsticiods (cortisol)
What factors decrease glucagon secretion?
Increased blood glucose (HYPERglycemia) Insulin Somastatin Fatty acids, ketoacids
What provides a sustained but regulated release of glucose during periods of fasting?
Insulin and the counter regulatory hormones
Two primart hormones produced in the pancreas that help regulate blood glucose levels
Insulin from the beta cells and glucagon from alpha celss
Plasma glucose control is via which 6 hormones
Insulin, Glucagon, Epinephrine, Norepinephrine, Growth hormone, and Cortisol
What stimulates insulin secretion
Parasympathetic stimulation of beta cells
What does insulin increase?
Protien sythesis
What does insulin do to blood glucose levels?
Reduces blood glucose levels
What tissues have specific receptors for insulin and are consiered insulin dependent cells?
Skeletal muscles and adipose tissues
The action of insulin facilitates a stable, normal glucose range of
about 20-120 mg/dl
What does glucagon stimulate?
amino acid conversion into glucose (gluconeogenesis)
Insulin is
an anabolic hormone produced by the beta cells in the islets of Langerhans in the pancreas
What does glucoagon produce?
an increase in blood glucose
How does insulin initate its effects?
binding to and activating a membrane receptor
What does glucagon maintain?
blood glucose in between meals and during fastin
What does insulin reduce? How?
blood glucose level by stimulating the conversion of glucose to glycogen (glycogneogenesis) as a carb source
Insulin and the counter regulatory hormones usually maintain
blood glucose levels within range of 70-120 mg/dl
What tissues do not directly depend on insulin for glucose transport, but require an adequate supply of glucose for normal function
brain, liver, blood cells
Insulin is essential to process
carbs, fats, and protiens
Normally, endogeneous insulin is
continuously released into the bloodstream in small pulsatile increments (a basal rate) with increased released (bolus) when food is ingested
What does insulin simulate?
fat storage by increasing transport of glucose into fat cells
After a protien meal, what does high concentrations of amino acids stimulate?
glucagon secretion to convert amino acid into glucose
What does glucagon initiate
glycogenolysis or breakdown of liver glycogen to raise blood glucose (gluconeogenesis)
What is insulin necessary for in children and adolscents?
growth and development
What factors increase insulin secretion?
increased blood glucose levels (HYPERglycemia) increased amino acids (arginine, lysine, leucine) increased fatty acids increased gastroinstetional hormones glucagon CCK Secretin Parasympathetic stimulation of beta cells ACH Growth hormone cortisol
Although _____ cells are not consider insulin __________, _________ recepters sites on the ______ facilitate hepatic uptake of glucose and its conversion to glycogen.
liver, dependent, insulin, liver
Counter-regulatory hormones work to increase blood glucose levels by:
stimulating glucose production and output by the liver, and decreasing the movement of glucose into the cells
What inhibits insulin secretion
sympathetic stimulation of alpha cells
What does insulin slow?
the breakdown of fat to TG, FFA, and ketones
What does insulin inhibit?
the release of stored glucose from the liver glycogen (glycogenesis), and the breakdown of protien and fat for glucose production (gluconeogenesis) in the liver and kidneys
What does glucagon increase?
transport of amino acids into the liver
