une ch 28
formation and degradation of glycogen
|glycogen synthesis f/s/p ||Fx: maintain blood glucose later(liver). glucose so you can use it for energy for contractions at a later time (muscle).
Substrates: ATP, glucose, UTP
Products: ADP, (glucose-6-phosphate is an intermediate), glycogen, pyrophosphate (PPi --> 2Pi), and U|
|glycogen synthesis c/r/c/t ||Control Enzyme: glycogen synthase
Regulation: Insulin/Glucagon ratio and amount of glucose present (liver), epinephrine can also inhibit. Muscle insulin level (muscle).
tissues: liver and muscles|
|glycogenolysis (glycogen degradation)f/s/p ||Function: Provide blood glucose (liver). Provide glucose to produce energy for muscle contractions (muscle).
Substrates: Glycogen, Free phosphates
Products: free glucose and g-1-p or g-6-p|
|glycogenolysis (glycogen degradation)c/r/c/t ||Control: debrancher enzyme, glycogen phosphorylase
Reg: G phosphorylase, also epi has an effect. (Phosphorylation activates control enzyme.) In muscle, GNL is regulated via activation of glycogen phosphorylase by [AMP], [Ca2+],presence of epi
|What is the effect of a high carbohydrate meal, fasting, or stress upon the blood concentrations of insulin, glucagon, and epinephrine? ||High Carb Meal: increased insulin, decreased cortisol, glucagon, and epinephrine.
Fasting: decreased insulin, increased glucagon, epinephrine and cortisol rise slowly.
Stress: insulin decreases and stress hormones go up.|
|What is the effect of a high carbohydrate meal upon blood glucose and the glucose in liver cells? ||Blood glucose levels will immediately increase.
Insulin will rise and promote the uptake of glucose into the tissues.
Glycogen synthesis will be activated and glycogen degradation will be inhibited.|
|What is the effect of changes in the insulin, blood glucose or epinephrine upon glycogen (GG) synthesis and glycogen degradation in muscle? ||GG Synth inc when insln inc and dec when insln dec. It inc when bglu up and dec when bglu down.
Muscle GG stores stable at rest,during stress/exercise epi released into the blood which stimulates GNL to meet energy needs.
glucagon=NO effect on muscles.|
|In order of their activation, be able to name and give the reason for the activation of all the intermediates in the cAMP cascade in liver. ||Glucagon ----> G-Proteins ----> Adenylate Cyclase --> cAMP --> (PKA)--> Phosphorylase Kinase --> Phosphorylase B --> Phosphorylase A -> G-1-P-> G-6-P-> Glucose
At same time, active PKA phosphorylates gg synthase to its inactive form, thereby dec gg synth|