Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
54 Cards in this Set
- Front
- Back
|
What are the two main polypeptide hormones regulating/coordinating metabolism?
|
#1 Insulin
#2 Glucaon -can live without -Think "glucose gone" Fed vs. Fasting states |
|
|
What other signals in addition to Insulin and Glucagon levels help coordinate metabolism?
|
Epinephrine (bad times)
Thyroid hormone Growth hormone These also have metabolic effects |
|
|
Insulin and Glucagon as key regulators of metabolism affects which tissues most?
|
Adipose
Muscle Liver Brain (I want glucose!) |
|
|
Where is Insulin produced and what is its general effect?
|
Pancreatic Beta-cells in Islets of Langerhans
-Anabolic hormone promoting glycogen, TG, and protein synthesis. (Present in "FED" state) |
|
|
In what "state" do we see high insulin levels?
|
The "FED" state
|
|
|
What is important to know about the structure of Insulin?
|
It is synthesized as a single polypeptide, Proinsulin. Cleaved in 2 places and joined by two cystine bonds as Insulin + C-peptide
|
|
|
What is C peptide?
|
A marker for insulin production.
|
|
|
Where is insulin stored in the body?
|
In vesicles in inslets of langerhans of the pancreas.
|
|
|
What signal inhibits Insulin secretion by the pancreas?
|
Presence of Epinephrine, a sign that "Bad Time" are here. (Fight or Flight)
|
|
|
What is the effect of Insulin on the cells of the liver?
|
Decrease:
Gluconeogenesis Glycogenolysis [cAMP] Increase: Glycogen synthesis |
|
|
As far as carbohydrates are concerned, what is the action of Insulin in muscle tissue?
|
Increases glycogen synth and glucose uptake.
|
|
|
As far as carbohydrates are concerned, what is the action of Insulin on adipose tissue?
|
Increases glucose uptake, which can also be converted to Glycerol-3-P for FA synth in good times.
|
|
|
As far as Lipids are concerned, what is the effect of Insulin on adipose tissue?
|
Decreases TG catabolism
Inhibit "HSL" Increase TG synth Increase Glucose-------------------------->Glycerol 3-P |
|
|
As far as Lipids are concerned, what is the effect of Insulin on blood?
|
Increases Lipoprotein lipase activity
Increases FFA's in blood for TG synthesis in adipose tissue |
|
|
As far as Proteins are concerned, what is the effect of Insulin on all cells of the body?
|
Increases amino acid uptake
Increases protein synthesis |
|
|
How does insulin have such a varied effect on so many tissues?
|
Insulin binds specific insulin receptors. The receptors have tyrosine kinases which are effectors that phosphorylates tyrosine in target enzymes.
|
|
|
What is an Insulin receptor composed of?
|
(2) Alpha (the actual receptor), and (2) Beta subunits containing tyrosine kinase.
|
|
|
What is the second component of Insulin signaling?
|
Induced addition of additional glucose transporters to the cell membrane from intracellular stores.
|
|
|
When is the affect of low insulin levels regarding glucose membrane transporters?
|
Transporters are endocytosed.
|
|
|
What tissues have cells with Insulin-Independent glucose transporters?
|
Brain/Neurons
Hepatocytes Erythrocytes Intestinal mucosal cells Renal tubule cells Cornea *All these cells need glucose no matter good or bad times. |
|
|
Desribe insulin receptor down regulation.
|
When insulin is present, Insulin-Receptor complexes are Endocytosed, fuse with Lysosomes and are degraded, some are recycled.
If Insulin is present over long periods we see a decrease in membranous receptors and Type II diabetes. Insulin insensitivity. |
|
|
What are long-term effects of Insulin?
|
Synthesis of:
Glucokinase Phosphofructokinase Pyruvate kinase |
|
|
What is Glucagon?
|
A polypeptide produced and exocytosed by Alpha pancreatic cells in the Islets of Langerhans.
|
|
|
What is the effect of Glucagon?
|
Opposes the effects of Insulin, with the aid of epinephrine, cortisol, and GH. Glucagon=Bad Times.
|
|
|
What is the major effect of Glucagon?
|
Stimulate:
Glyogenolysis Gluconeogenesis -Both in liver |
|
|
Low blood sugar leads to what?
|
Hypoglycemia is the Primary stimulus for Glucagon secretion by the pancrease, the effects of glucagon increase blood glucose levels. This increase will inhibit Glucagon release.
|
|
|
High amino acid levels in the blood means what?
|
A meal containing protein was just eaten.
Insulin is released. Glucagon will prevent Post-Prandial hypoglycemia, which would occur if there were no carbohydrates in the meal to send through glycolysis. |
|
|
What does ephinephrine in the blood mean?
|
Fight or Flight status, need ATP immediately, glucagon secreted to release glucose from glycogen.
|
|
|
What is the effect of Glucagon on the liver?
|
Increases:
Glycogenolysis Gluconeogenesis FA Beta-Oxidation Ketone Synthesis Amino Acid Uptake (for gluconeogenesis) |
|
|
What are the effects of Glucagon on Adipocytes & Myocytes?
|
Very little to none.
|
|
|
What is the mechanism of action of glucagon on Hepatocytes?
|
High affinity receptors in Hepatocytes bind Glucagon and activate Adenylate Cyclase, the increase in cAMP activates cAMP dependent protein kinase and glycogen metabolism.
|
|
|
For how long after a meal do we absorb nutrients? Also, what is this period of time termed?
|
2-4 hours, Known as post-prandial, this is the FED state.
|
|
|
Why does the liver get first dibs on nutrients from absorption?
|
Its the first organ the portal system delivers blood to. Its also very metabolically active and needs nutrients.
|
|
|
What percentage of glucose from portal circulation is taken by the liver?
|
Approx. 60%, this is then phosphorylated to G-6-P by GK. 5-10% sent to pentose-po4 shunt. The rest goes to glycolysis, glycogen, and AcCoA from glycolysis for FA synth.
|
|
|
What are the relative levels of Insulin:Glulcagon in the FED state?
|
Insulin>>>Glucagon
|
|
|
What are the relative levels of Insulin and glucagon in the Fasting State?
|
Glucagon>>>>Insulin
OR: Absence of Insulin. |
|
|
What are the approx. levels of energy reserves that can be mobilized during a Fasting state?
|
~0.2 Kg Glycogen
~15 Kg Fat ~6 Kg Protein There are more Fat and protein but using more than this amount is before fatally compromising function. |
|
|
What happens to Insulin-dependent transporters during the fasting state?
|
They remain functional. They are needed to transport any glucose that they encounter for the tissues they support. These tissues absolutely need glucose.
|
|
|
How lond does it take for the body to adjust to start using Ketone bodies for energy production?
|
Approximately 10 days to 2 weeks of the "Fasting" state.
*Cells begin to express enzymes that convert Ketones to Glucose |
|
|
What does Diabetes Mellitus mean?
|
Sweet Urine
|
|
|
What are the two types of diabetes mellitus?
|
Insulin dependent (TypeI)
Insulin independent (Type II) |
|
|
Which type of diabetes was once known as Juvenile diabetes?
|
Type 1 diabetes mellitus
|
|
|
Which type of diabetes was formerly known as"Adult Onset Diabetes"?
|
Type II diabetes mellitus
|
|
|
What percentage of adults in the USA have one of the forms of diabetes mellitus?
|
2-3% (6 million diabetics, good for podiatry)
|
|
|
Diabetes mellitus is the leading cause of which morbidities?
|
Adult blindness
Amputation Renal failure Heart attack Stroke |
|
|
What percentage of diabetics have Type I?
|
20%.
|
|
|
What is the cause of Type 1 diabetes?
|
Autoimmune destruction of pancreatic Beta-cells leading to absolute insulin deficiency. This autoimmune response can be either viral infection or a genetic factor.
|
|
|
What happens to the blood of Type 1 diabetics if they do not get their insulin injection?
|
Potentially fatal ketoacidosis.
|
|
|
Symptoms of Type 1 diabetes (untreated type 2 as well) are?
|
Polyuria (Lots of pee)
Polydipsia (Thirst) Polyphagia (Hunger) Fatigue, weight loss, weakness. Clincally FBG>7.8mM |
|
|
Why in both types of diabetes mellitus is the urine sweet?
|
Blood glucose levels exceeds transport capacity for reabsorption in the proximal kidney tubules and is excreted. Glucose is hydrophilic and pulls water with it as well hence thirst.
|
|
|
What does an insulin injection do?
|
Prevents excessive hyperglycemia and other metabolic problems, but blood levels of metabolites are never normal even in the treated state. They jump up and down abruptly unless using an infusion pump.
|
|
|
What causes Premature atherosclerosis, retinopathy, and neuropathy in diabetic patients of both types?
|
Elevated blood glucose levels.
|
|
|
What causes Type II diabetes?
|
Genetic predisposition tied to prolonged "Good" times (meaning high caloric/sugar diet)
Linked to obesity and alcoholism. |
|
|
Do Beta-cells function normally or abnormally in a Type II diabetic?
|
Normally, Insulin is present in the blood. The problem is Insulin-receptor down-regulation.
|
