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64 Cards in this Set

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What is secreted by the Delta cells of the Islets of Langerhans and what is it's function function?
Somatostatin, remember that it only has a local effect and it's function is to inhibit the alpha and beta cells of the islets of langerhauns.
What is special about somatostatin?
it always inhibits, it does not stimulate.
What is important about the alpha cells?
They secrete glucagon which is released into the general circulation
What is the local effect of glucagon?
Locally, it stimulates the Beta Cells to release insulin. You can remember this because glucagon is a gut hormone, and gut hormones in general stimulate the secretion of insulin by the Beta Cells.
Why are the Beta Cells important?
The Beta cells secrete insulin.
What is the inactive peptide assoc. with insulin (prohormone cleaved to create insulin and inactive peptide)?
What is one local effect of insulin?
it inhibits the secretion of glucagon from the Alpha Cella
what is insulin's secondary messenger.
The receptor that faces the cytosol has tyrosine kinase activity and it can phosphorylate itself and other proteins.
What are the tissues that require insulin for glucose uptake?
adipose tissue
resting skeletal muscle
In exercise: glucose can enter exercising muscle without the aid of insulin.
In what tissues is glucose uptake not affected by insulin?
-nervous tissue
-kidney tubules
-intestinal mucosa
-red blood cells and Beta cells of pancreas
-insulin accelerates but is not required for glucose uptake by the liver
In what tissues does insulin increase glycogen synthesis
liver and muscle
What are the effects of insulin on carbohydrate metabolism?
-Insulin increases the uptake of glucose and its metabolism in muscle and fat.
-Insulin increases glycogen synthesis in liver and muscle.
What are the effects of insulin on protein metabolism?
Insulin increases amino acid uptake by muscle cells.

Insulin increases protein synthesis, and decreases protein breakdown.
What are the effects of insulin on fat tissue?
1. Increase glucose uptake in adipose tissue by increasing by providing more transporters in the membrane
2. It will accellerate trigliceride uptake in the fat cells by activating an enzyme called LIPOPROTEIN LIPASE.
3. Insulin also accelerates the synthesis of triglyceride in adipose tissue.
Basically it converts carbohydrate to fat.
4. Important, INSULIN INHIBITS LIPOLYSIS by inhibiting an enzyme called HORMONE SYNSITIVE LIPASE.
What is lipoprotein lipase?
Lipoprotein lipase is an enzyme on the endothelium of capillaries and clears vldl and chylomicrons from the blood.
What are the names for lipoprotein lipase and how does it work?
The names are: lipoprotein lipase, extracellular lipase, and clearing factor lipase.
insulin activates lipoprotein lipase so that it can clear triglycerides from the blood stream.
What is hormone synsitive lipase?
it is the intracellular lipase that regulates lipolysis. This enzyme is INHIBITED BY INSULIN.
What hormones active hormone sensitive lipase?
all stress hormones
which of the stress hormones is not considered a major fat mobilizing hormone?
What are insulins effect on potassium?
-Insulin pumps K+ into cells.

-This K+ lowering action of insulin is used to treat acute, life-threatening hyperkalemia.
What is the most potent and important stimulator of insulin
plasma glucose
What substances promote the secretion of insulin?
1. Glucose
2. Amino Acids (arginine)
3. Intestingal hormones which include GIP and Glucagon
What substances inhibit the secretion of insulin?
1. Somatostatin
2. Sympathetic innervation which releases norepinephrine which binds to alpha receptors.
In type 2 or NIDDM what is the body build, insulin level, mechanism of disease, treatment, and one last special feature regarding ketones?
-body build is usually obese
-insulin levels may be high, normal, or low
-resistance to insulin action in major target tissues do to downregulation of receptors
-with a controlled diet, the symptoms of type 2 diabetes often disappear.
-individuals tend to be detosis resistant (with some insulin activity there will be no ketoacidosis)
for type 1 diabetes or IDDM what is the body build and mechanism of the disease, and what are many of their symptoms attributed to?
-body build usually lean
-lack of insulin production but generally increased glucagon secretion.
-many of their symptoms are attributed to the increases in glucagon, not just the decreased insulin.
What are the metabolic effects on carbohydrates in insulin deficient individuals?
-increased blood glucose
-increased glycogen breakdown
-decreased peripheral glucose use
What are the metabolic effects on proteins in insulin deficient individuals?
-increased protein breakdown
-increased metabolism of amino acids
-increased gluconeogenesis
-increased ureagenesis
-decreased protein synthesis
When is urea produced in the liver?
When converting amino acids to glucose
What are the target tissures for glucagon?
What are the specific actions of glucagon on the liver
-increases liver glycogenolysis
-increases liver gluconeogenesis
-increases lypolysis in the liver
What is the main job of glucagon?
to maintain plasma glucose between meals.
What are the inhibitors of glucagon secretion from the alpha cells?
1. Hyperglycemia
2. Insulin
3. Somatostatin
What are the stimulators of glucagon?
1. Hypoglycemia
2. Amino Acids (arginine)
What is unique about growth hormone?
It is both an anabolic and growth hormone.
What type of hormone is insulin?
Insulin is a major anabolic hormone.
What are the acute actions of growth hormone?
The acute actions are the stress actions/direct catabolic effect.
What are the direct catabolic effects of growth hormone?
1. Decreases uptake of glucose in fat and muscle and therefore raises blood glucose
2. Mobilizes fats by increasing the activity of hormone sensitive lipase and thus raising free fatty acids.
What happens in growth hormone deficiency?
Body fat increases.
What are the long term effects/indirect anabolic effects of growth hormone?
The long term effects of growth hormone are carried out via growth factors.
what are the direct anabolic effects of growth hormone?
increased uptake of amino acids into cells.
what are the growth factors of growth hormone called?
somatomedins, or insulin-like growth factors (IGFs)
What is a major growth factor?
somatomedin C, aka IGF-1.
What is the sequence of the production and release of IGF-1?
GH will act on the liver and other tissues (eg muscle) to increase the production and release into the circulation of somatomedins, especially IGF-1
What is IGF-1?
It is a major anabolic growth factor.

-It is a circulating peptide growth factor similar in structure to proinsulin

-It circulates in the blood tightly bound to a large protein, thus giving it a long half life.
What is "non-suppressible insulin like activity" do to?
IGF-1, because of it's structure similarity to insulin.
What is the significance of IGF-1 concerning GH secretion?
plasma igf-1 serves as a reflection of 24-hour GH secretion.
What is the major anabolic effect of IGF-1?
it increases the synthesis of cartilage in long bones.
Why is IGF-1 a good index of overall GH secretion?
1. the release of IGF-1 into the circulation is dependent upon GH
2. IGF-1 has a very long half life
How are IGFs assoc. with body mass?
it is hypothesized that circulating IGFs increase LEAN BODY MASS
How would you describe the secretion of GH, like many of hormones from the hypothalamus-pituitary system
When is the secretion of GH pulsitile and when are they the most frequent.
Secretion is pulsatile mainly during the night.

Pulses are more frequent in pubertal adolescents.
what are the more frequent pulses during adolescence attributed to?
Facilitated by the pubertal increase in androgen secretion.
How is GH related to thryoid hormone?
Secretion of GH requires the presence of normal plasma levels of thyroid hormone.
When does secretion of growth hormone significantly diminish?
During the sixth decade secretion diminishes considerably in both men and women.
During what stages of sleep is GH mainly released?
stages 3 and 4
What hormone is the release and inhibition of GH similar to?
What are the main factors that inhibit GH secretion?
IGF-1 and Elevated Glucose
What are the main factors that promote GH secretion?
1. Deep sleep
amino acids (arginine, leucine)
What does a prepuberty growth hormone deficiency result in?
What does normal growth hormone but decreased IGF-1 during prepuberty result in?
Laron syndrome - a type of dwarfism
What happens to adults with a growth hormone deficiency?
Adults with a growth hormone deficiency is not a major problem and is very treatable.
what does a prepubertal hypersecretion of growth hormone result in?
What does a post pubertal hypersecretion of growth hormone result in?
What are the major characteristics of acromegally?
-Enlargement of the hands and feet
-protrucsion of the lower jaw (prognathism)
-body protein increased and fat reduced
-increase in the size of visceral organs and impaired cardiac function
-abnormal glucose tolerance curves