Pancreatic Endocrinology & States Flashcards
What are the 2 most important hormones in respect to absorptive and post-absorptive states?
Insulin, Glucagon
Insulin is released by:
Beta cells of pancreas
Glucagon is released by:
Alpha cells of pancreas
Glucose in blood stimulates which hormone?
Insulin, a spike is insulin follows a peak in glucose, and a decrease in glucagon
Secretion of Insulin (increases or decreases) during the absorptive state.
INCREASES
What 2 main effects does insulin have?
Metabolic (CHO, lipid and protein synthesis)
Growth-promoting (DNA synthesis, cell division)
What do the tissues do in order to keep the uptake of glucose coming in?
By changing it into storage forms. Glycogen in muscle and liver
Besides glycogen formation, what other forms can glucose be stored in?
In triglycerides, done in liver and adipocytes
What’s the only tissue type to uptake AA in Addition to glucose?
MUSCLE
The liver can form TG but doesn’t want to store it, where’s the only place that TG are stored?
Adipocytes
In a fasted state with LOW INSULIN and HIGH GLUCAGON what happens in MUSCLE tissue?
DECREASE glucose uptake, BREAKDOWN of glycogen + Proteins, RELEASE AA, UPTAKE FA and utilization
In a FASTED state with LOW INSULIN and HIGH GLUCAGON what happens in ADIPOCYTES?
DECREASE glucose uptake, BREAKDOWN of TG -> FA and glycerol
In a FASTED state with LOW INSULIN and HIGH GLUCAGON what happens in LIVER?
RELEASE glucose, SYNTHESIS of ketones
In a fasted state, why is it essential to MAINTAIN GLUCOSE levels?
the brain, if don’t then COMA
What effect does insulin have on Glucose transporters?
Bind of insulin triggers second messenger system to cause VESICLES that contain GLUT4 to fuse with PM and increase glucose uptake
What happens to GLUT4 transporters when insulin decrease?
Then endocytose back into vesicle form
Beside just increasing glucose in the cell, Insulin also increases GLYCOGEN FORMATION in the muscle cells how?
by stimulating the key enzyme, GLYCOGEN SYNTHASE.
and inhibiting the enzyme that breaks glycogen down, GLYCOGEN PHOSPHORYLASE
How does insulin increase PROTEIN SYNTHESIS in the muscle?
AA transport into cell, stimulating ribosomal enzymes, inhibit enzymes that break proteins down
In order for glucose to be stored in adipocytes, what has to happen to it?
Needs to go through partial glycolysis and then join with a FA to make a TG
Since the Liver does not store TG, how does it send it to the adipocytes for storage?
With VLDL
How are TG exited from the GI tract?
Endocytosis in a CHYLOMICRON
When the chylomicron arrives at the APIDOCYTES, what has to happen to it for it to be absorbed?
LIPOPROTEIN LIPASE must break it down in to FA to diffuse across membrane
What are the potential fates of AA in the liver?
Excreted as urea in urine, Form FA, metabolized to water and CO2
Beside plasma concentrations of glucose, what else causes the release of insulin?
PARASYMPATHETIC ANS on muscarinic receptors on beta cells
How do the beta cells respond to high levels of glucose to release insulin INSIDE the cell?
More glucose inside –> More ATP via Krebs–> closes K channels –> Ca open and influx Ca –> work as second messenger to dock Insulin vesicles –> exocytose and RELEASE
How does sympathetic ANS effect insulin levels?
Releases Epinephrine which INHIBITS insulin release
How does Gluose-dependednt insulin peptide (GIP) effect insulin levels?
STIMULATES secretion
Where does Amylin come from and what does it do?
Released WITH insulin by BETA cells but goes to BRAIN to tell it it’s in a fed state
What else increased intracellular Ca and thus second messages to increase insulin secretion?
CCK and ACh
What decreases intracellular cAMP to DECREASE secretion?
Epi, Somatostatin, glucagon
During moderate exercise, what do we expect to see in in plasma glucose, glucagon and insulin levels?
glucagon INCREASE (moving into a fasting state), Glucose + Insulin DECREASE
If brain can’t have glucose what’s a substitute fuel?Who makes it?
Ketones synthesized in the liver as response to high glucagon levels
Glycogen in the muscle can be broken down into 2 fates depending on if Oxygen is present or not.
with O2 –> Pyruvate, w/o O2 –> Lactate
Gluconeogenesis is performed where?
Liver & Kidneys
Who sends things to the liver for gluconeogenesis and what do they send?
Muscle –> lactate/pyruvate + AA, Adipose –> glycerol
FA from the adipose goes into circulation to be burned by other tissues or it can go back to the liver for formation of what?
KETONES
The overall effect of GLUCAGON is to INCREASE plasma concentration of ______ and __________.
glucose, ketones
Which is a stronger signal - the ABSENCE of INSULIN or the PRESENCE of GLUCAGON?
Insulin is always the stronger signal, whether it’s present or not
T/F. sympathetic NS increase EPINEPHRINE secretion?
FALSE. EPI comes from Adrenal medulla
In addition to alpha cells, EPINEPHRINE also STIMULATES:
Glycogenolysis in liver and muscle, and Gluconeogenesis in liver and kidney, and lipolysis in adipocytes.
How does EPI have all these effects?
By turning UP and DOWN enzyme systems
What effect does EPINEPHRINE have on SYNTHETASE?
Inhibition!
What effect does EPINEPHRINE Have on Phosphatase?
STIMULATE! (adrenergic input INCREASES CATABOLISM INSIDE)
T/F. Cortisol secretion fluctuates depending on his in fed or non-fed state.
FALSE
What happens in a fasting state if cortisol deficient?
Hypoglycemia, serious enough to interfere with brain function
Cortisol has similar effects as:
Epinephrine & Growth Hormone
How do cortisol and GH effect glucose transporters?
Inhibit the second messenger system so fewer GLUT4 are inserted in the membrane and glucose stays HIGH OUTSIDE
What 4 hormones all work in synergy to OPPOSE INSULIN?
- Glucagon
- Epinephrine
- Cortisol
- Growth Hormone
how do the 2 types of DIABETES differ?
Type 1 –> NO RELEASE of INSULIN, Type 2 –> Problem in RECEPTOR BINDING
what’s the result of no release of insulin?
No Glut4 –> HIGH levels of glucose in blood –> high glucose in urine and formation of KETONES –> impaired brain function, coma, death
What’s an effective treatment of Diabetes?
Type 1 –> Insulin, Type 2 –> Metformin
Which of the following hormones are associated with appetite? A. leptin B. Ghrelin C. Insulin D. Neuropeptide Y (NPY) E. All of the above
E
Wheres does leptin come from?
Adipose tissue, released in proportion of how much fat is in storage
So, if you have lots of TG stored in adipose tissue, what is your leptin release like?
Increased to DECREASE appetite
How does leptin reduce food intake?
Acts on hypothalamus by inhibiting release of NPY
What effect does leptin have on metabolic rate?
INCREASES it
T/F. Both leptin and insulin are transported across the brain-barrier.
TRUE - as well as amylin and glucagon
