Lec 27 Sugar and Fat Flashcards
What is hyperphagia
excessive consumption food
can reflect increased motivation of consume palatable food or deficits in brain circuitiires that regulate satiety
Which two parts of brain encode info related to reward value of food?
orbitofrontal cortex and amygdala
What is the most significant counter-balance to insulin?
glucagon
What are the 5 cells types and hormones of the endocrine pancreas?
alpha: glucagon
beta: insulin
d cells: somatostatin
PP: pancreatic peptide
e cells: ghrelin
Where is ghrelin secreted from? function?
- mainly stomach, also pancreas
- increases hunger
What 4 things stimulate beta cells release of insulin from pancreas?
- glucose
- amino acids
- fats
- GLP-1
What is function of GLP-1 on pancreatic islet? where is it released from?
- increase insulin secretion
- inhibit glucagon secretion
released from L cells of ileum
If you shoot sugar into vein what is action of GLP-1?
no action – only acts if glucose in GI not in serum
What is c peptide? why is it important?
- C peptide = connecting peptide, part of pro-insulin that gets cleaved during insulin secretion thus equal molar amount C peptide and insulin secreted
- C peptide circulates around for a while before getting excreted from kidney vs insulin binds and taken up by cells quickly
- C peptide is a good marker of how much insulin the pancreas is actually putting out
What is mech/pathway of glucose acting on pancreatic beta cell to secrete insulin?
- glucose enters via GLUT2 channel
- glucokinase breaks down glucose in mitochondria
- ATP from breakdown closes K channel and keeps K inside cell –> depolarization
- voltage dependent Ca channel opens
- Ca comes in and stimulates movement of vesicles with insulin out of cell
Does insulin receptor require JAK? Is TK activity part of insulin receptor or separate?
- does not require JAK
- TK activity is part of receptor
What are 3 paths of insulin action via P1-3K signaling pathway?
Normal: via P1-3K signalling pathway
- synthesis of lipids, proteins, glycogen
- cell survival and proliferation
- GLUT4 release from vesicle to membrane
What action of insulin via MAP kinase pathway?
- cell growth, proliferation, gene expression
- not really the normal way, in normal circumstances we don’t grow in response to insulin
What is GLUT4? Where is it located? Insulin dependent or independent?
- major insulin responsive glucose transporter
- primarily in peripheral tissues [muscle/fat] and some in brain
- very much insulin dependent
What type of glucose transporter in muscle and fat?
glut4
What types of glucose transporters in brain?
mainly GLUT3
also glut1 and glut4
What is GLUT3? Where is it located? Insulin dependent or independent?
- Glut3 is insulin independent
- located in brain
What is GLUT1? Where is it located? Insulin dependent or independent?
Glut1 is partially dependent
located in brain
What is glut2? where is it located?
- low affinity, glucose concentration dependent transporter
- in pancreas and liver
- also does reverse action in liver when senses high glucose in liver compared to serum it transports glucose back out
What are the 4 major counter-regulators to insulin action? Which are fast/short term?
short term: glucagon and epinephrine
substrate mobilization: cortisol and growth hormone
What two insulin counter-regulators do substrate mobilization? what is “substrate mobilization?”
- cortisol and growth hormone
- cortisol breaks down fat/muscle
- deliver substrate to liver to make more glucose
What is normal blood glucose level?
72-90 mg/100 mL
Where does GLP-1 get released from? what causes its secretion? what is main action?
- from throughout intestine but mainly ileum
- secreted after eating
- goes to pancreas –> increases insulin secretion, decreases glucagon secretion
- indirect effect is that helps sensitize body to insulin
- decreases appetite
