biochem - feast/starve cycle Flashcards
brain derives energy from…
glucose and ketone bodies only
cannot use FA
glucose levels for
- normal
- renal threshold
- diabetic coma
- overnight fast
- hypoglycemia
-normal 8 mM
-renal threshold at 10mM –> glucosuria, excess urination
-diabetic coma 60 mM
-overnight = 5 mM
-
after a meal glucose from where 0-4 hrs up to 24 hrs starting at 8 hrs
gut
liver glycogen
gluconeogenesis - dominant process at 16 hrs
insulin
polypeptide secreted by beta cells in pancreas in response to elevated blood glucose
SIGNALS well fed state and promotes increased transport of glucose into adipose and muscle, glycogen synthesis, de novo TG synthesis, deposition of fat, and protein synthesis
-inhibits breakdown of fat, protein, and glycogen
glucagon
made from alpha cells in pancreas in response to low blood glucose, low insulin
signals fasting state and promotes glycogenolysis, lipolysis, and gluconeogenesis
where is there no glucagon receptor (so no effect on)?
muscle
in pancreas glucose binds and causes
glucagon to go down, and insulin to go up
liver fat production
in liver glucose can be converted to triacylglycerols and packged into VLDLs and released into blood –> FAs of VLDLs are stored in adipose tissue
intestinal triacylglycerol absorption
packaged into chylomicrons and secreted into lymph into blood
insulin activates which transporter?
GLUT4 on muscle and fat tissue
RBCs require
glucose
oxidize it to pyruvate and lactate
no mitochondria
what vessel transports aa and glucose to liver
hepatic portal vein
in liver, what activates... 1- glucose transport 2-glycogen storage 3-glycogen breakdown 4-FA synthesis 5- FA oxidation 6-glycolysis 7 - gluconeogenesis
1 - insulin and glucagon both have no effect on transport
2 - insulin activates glycogen storage
3 - glucagon activates glycogen breakdown
4 - insulin activates FA synthesis
5 - glucagon activates FA oxidation
6 - insulin activates glycolysis
7 - glucagon acivates gluconeogenesis
in adipose, what inhibits
1- glucose transport
2 - TG deposition
3- TG mobilization
1 - glucagon inhibits glucose transport in fat
2 - glucagon inhibits TG deposition in fat
3 - insulin inhibits TG mobilization; glucagon ACTIVATES TG mobilization
in muscle, what enzyme works? what is its effect on... glucose transport glycogen synthesis glycogen breakdown protein synthesis protein breakdown
insulin only
activates - glucose transport, glycogen synthesis, protein synthesis
inhibits - glycogen breakdown and protein breakdown
TGs of chylomicrons and VLDL
where are each produced? and where are they digested/by what?
chylomicrons are made from dietary fat and VLDL is made from glucose in liver
digested in capillaries by lipoprotein lipase to form FAs and glycerol –> stored by adipose as TGs
as blood glucose decreases…insulin? and glucagon?
insulin decreases and glucagon increases –> stimulating release of stored fuels into blood
when in fasting state, the liver…
supplies glucose and KB to the blood
it maintains blood glucose via glycogenolysis and gluconeogenesis and makes ketone bodies from FAs of adipose
2 ketone bodies?
B-hydroxybutyrate
acetoacetate
ketone bodies have a _____ ______ effect
protein sparing
what happens 2-3 hrs after a meal to release glucose into blood
glycogenolysis - glycogen is broken down;
glycogen stores deplete within 30 hrs
what happens 4-6 hrs after a meal?
gluconeogenesis
gluconeogenesis carbon sources
lactate from RBCs or exercising muscle
glycerol from TGs of adipose breakdown
AAs (alanine) from muscle protein
propionate from oxidation of odd chain FAs
ketone body formation
adipose tissue breaks down TGs in response to rising glucagon
FAs and glycerol are released
B oxidation converts the FAs to acetyl coA which is used in liver to make KBs
