Fed state, Postabsorptive, Fasting & Starvation states Flashcards
what is the major hormone controlling energy metabolism during the fed state?
INSULIN
what is the main energy source in the fed state?
glucose
How long does the Fed state last?
approximately 3 hours following a meal
How long does the Post absorptive or early fasting state last?
from 3 hour to 12-18 hours after a meal.
What is excess glucose used for? when does this occur?
used for fatty acid synthesis, occurs if energy intake» use of energy.
what tissues/ organs use glucose as energy during the fed state?
- brain & CNS
- Muscles
what is the effect of insulin on glucose uptake (muscle and liver)?
insulin increases glucose uptake (muscle) by targeting increased glucose transporter
and increases glucose uptake in the liver by targeting increased glucokinase
what is the effect of insulin on glycogen synthesis?
increased glycogen synthesis by increasing glycogen synthase and decreasing glycogen breakdown by inhibiting glycogen phosphorylase
during the fed state, glycolysis is ________ by activation of what?
increased by activation/ stimulation of pyruvate dehydrogenase
what is the effect of insulin in the fed state on fatty acid synthesis and Triacylglyceride synthesis ?
both are increased. fatty acid synthesis is increased by targeting acetyl CoA carboxylase and TAG synthesis is increased by targeting lipoprotein lipase (LPL)
where are branched amino acids metabolsed ?
the muscles
what is the major source of glucose in the EARLY fasting state?
Glycogenolysis , glycogen in liver + muscles are almost depleted during an overnight fasting
Do glycogenesis and lipogenesis occur in the early fasting state?
NO!
what process (Glycogenesis, glycogenolysis, glyconeogensis, glycolysis) is increased in the early fasting state?
Gluconeogensis and Glycogenolysis
what are the important sources for gluconeogenesis during early fasting?
- Lactate and alanine
- glycerol
What happens in the liver during the postabsorptive (early fasting state)?
- glycogenolysis= breakdown of glycogen to glucose
- gluconeogensis= Lactate, Alanine and glycerol to glucose
- Fatty acids undergo B-oxidation and metabolized to TG
what happens to glucose in the CNS + the brain during postabsorptive state?
Glucose is catabolized for energy with no return of gluconeogenic precursors
what happens to glucose in the RBCs during Postabsorptive state?
glucose is broken down to Lactate and ATP through the pentose phosphate pathway.
What hormones are involved in early fasting state regulation?
- glucagon
- epinephrine
- catecholamines
- glucocorticoids
what 2 hormones initiate hepatic (liver) glycogenolysis during the early fasting state?
Glucagon and epinephrine
what initiates glycogenolysis in muscles during early fasting?
catcholamines
what inhibits glucose uptake by muscles in the postabsorptive state?
Catecholamines
how long does it take for glycogen to be depleted following a meal?
18 hours
which hormones stimulate gluconeogensis in the early fasting state?
glucagon and epinephrine
what stimulates proteolysis (breakdown of amino acids for gluconeogensis?
Glucocorticoids
glucagon secretion is stimulated by_____?
Alanine
what do low levels of insulin affect?
causes decreased glucose utilization and increased lipolysis.
what occurs in the liver during the Fasting state (18-48 hour)?
gluconeogensis
glycogenolysis
ketogenic amino acids are broken down to ketones and used as what?
energy source for Brain + CNS
acetyl co A synthesizes what in the liver?
ketone bodies
when the body is in starvation state the levels of ketone bodies in the blood are _____ and glucose levels are _____
HIGH. LOW
when does the fasting state start and how long does it last?
from 18 hours up to 2 days following a meal
How long can starvation or long-term fasting last?
for a few weeks
What metabolic pathway is favored in the starvation state?
lipolysis (fat as energy source)
what is the last thing the body wants to break down for energy?
protein! we must spare it!
What is the energy source for most tissues (except the brain) during starvation?
Fatty acids
what is the main glucose precursor in starvation state?
glycerol
What happens to oxaloacetate and the TCA cycle during the fasting state?
oxaloacetate is not produced because TCA intermedates are used for gluconeogensis
what does acertyl Co A form during the starvation state?
Acetoacetyl CoA & ketone bodies
what is the main energy source for the brain during starvation?
ketone bodies
during starvation state, glucose use ______ and ketogenesis ________
decreases, increases
what do muscle use for energy in preference to glucose and amino acids during the starvation state?
fatty acids
what happens in the kidney during the starvation state?
gluconeogenesis from glutamine
