Regulation of Carbohydrate and Lipid Metabolism Flashcards
What are the seven metabolic pathways?
Glycolysis, Gluconeogenesis, Glycogen metabolism, fatty acid metabolism, citric acid cycle, oxidative phosphorylation and amino acid metabolism
NADH carries e- from _____ is called _____.
Breakdown, catabolism
NADPH carries e- for ____ is called _____.
Biosynthesis, anabolism
What is the link between glucose pathways?
Glucose 6-phosphate
What are the three pathway products that become of glucose breakdown?
Glycogen, pyruvate, ribose 5-phosphate
What are the key links between all pathways?
Glucose-6-P, pyruvate, acetyl CoA
What step causes pyruvate to become acetyl CoA and why is it impossible to reverse the reaction?
Deccarboxylation
The reverse rxn is not energetically favorable
How are the major metabolic pathways regulated?
Compartmentalization in the cell
Reciprocal regulation of metabolic pathway enzyme
Organ specialization
Hormone regulation
What are the regulatory organs for metabolic pathways ?
Brain, muscle, cardiac muscle, adipose, kidney, liver
What is the primary fuel for the brain and what does it use in the absence of that fuel?
Glucose, ketone bodies
Why are fatty acids not generally used as brain fuel?
Take to long to break down, though they can cross the BBB
If the glucose level in the brain is less than 2.2 mM what could occur?
Coma and death
What fuels can muscles use?
Glucose, fatty acid, ketone bodies
Pyruvate is used to generate ____ which regenerates NAD+ for ____.
Lactate, glycolysis
What are the two factors that decrease the efficiency of muscles?
Lactic acid and dec of pH
Lactate is moved to the liver and what cycle does it enter to be made useful again?
Gluconeogenesis after being converted back to pyruvate
What substance in skeletal muscle has the ability to regenerate ATP from ADP?
Phosphocreatine
In the starvation state what substance does muscle break down?
Amino acids
Because muscles cannot breakdown ammonia, what happens to the amino group instead?
Alanine aminotransferase transfers the amino group to pyruvate to make alanine
Does the cardiac muscle store its glycogen reserves?
No where because it doesn’t have any
What are the primary fuel of cardiac muscle?
Fatty acids
Ketone bodies are second
Once converted to triaglycerols where are fatty acids shipped to and what takes them there?
Adipose, VLDL
What cuts up the free fatty acids?
Lipase
What must be generated to make TAG?
Glycerol-3-P
When blood glucose is low _____ activates lipase to hydrolze adipose ____ to release free fatty acids/glycerol.
Glucagon, TAG
What does glycerol stimulate in the liver?
Gluconeogenesis
What is the primary role of the kidney?
Excrete water soluble waste
What can the kidney do during prolonged starvation?
Produce up to 50% of blood glucose
What are the general functions of the liver in metabolic regulation?
Maintains blood glucose
Regulates all metabolites in the blood
Can store up to a day of energy as glycogen
Produced fatty acids for storage in the fed state
Produces ketone bodies in starvation
Why does the liver use glucokinase instead of hexokinase?
Glucokinase has a lower Km for glucose and the liver doesn’t want to use too much of the glucose it makes
What are the only organ which have glucose-6-P for maintain glucose levels?
Kidney and liver
Can the liver use ketone bodies? Why or why not?
No because the liver doesn’t have CoA transferase
Where is (nor)epinephrine released from?
Adrenal gland
What does epinephrine stimulate in the liver?
Gluconeogenesis and glycogen phosphorylase
What does epinephrine inactive in the liver?
Glycogen synthase (no glucose metabolism)
What does epinephrine promote in muscles?
Glycolysis (raises Fruc-2,6,BP to activate PFK)
What does epinephrine promote in adipose?
Mobilization of fatty acids`
What are the metabolic effects of epinephrine on physiological rate?
Inc heart rate
Inc blood pressure
In dilation of respiratory passage
Inc delivery of O2 to tissues
What are the metabolic effects of epinephrine on the actual metabolism?
Inc glycogen breakdown (muscle, liver) Dec glycogen synth (muscle liver) Inc Gluconeogenesis (liver) Inc glycolysis (muscle) Inc fatty acid mobilization (adipose) Inc glucagon secretion Dec insulin secretion
Low blood glucose causes release of _____ from ____ in pancrease islet cells.
Glucagon, a-cells
What does glucose stimulate in the liver?
Glycogenolysis and gluconeogenesis
What does glucose inhibit in the liver?
Glycogen synth and glycolysis
What does glucose activate in adipose?
Lipase to mobilize fatty acids and glycerol
High blood glucose causes release of ____ from ____ in pancreas is
Insulin, b-cells
What does insulin increase is tissues?
Rate of glucose uptake
What does insulin activate in the liver?
Glycogen synthase, stimulates FA biosynth
What does insulin inactivate in the liver?
Phosphorylase (storage)
What does insulin stimulate in adipose?
Uptake of FAs from VLDLs and TAG synth
What is cortisol?
Steroid hormone that indicates long-term stress
Where is cortisol produced from and how does it work?
Adrenal cortex, acts slowly by changing expression of metabolic enzyme genes
Passes thorugh plasma membrane and binds to nuclear receptors
What does cortisol stimulate in adipose?
Release of FAs
What does cortisol stimulate in muscle?
Breakdown of proteins, export of AA for gluconeogensis
What does cortisol increase in the liver?
Levels pf pyruvate carboxylase to stimulate gluconeogensis
