Integrated Metabolism Flashcards
(39 cards)
Why do cell processes need to be controlled
Each cell has potential for carrying out many different chemical reactions/pathways
Many are conflicting in purpose
Co-ordinate metabolic activities within a cell
Cells do not work as individuals
Co-ordinate (integrate) metabolic activities of cells in different parts of the organism
Enable efficient utilisation of metabolites to meet current needs of the organism
What 4 ways are metabolic activities in cells controlled
Hormonal control
Substrate supply
Allosteric enzymes
Nervous control
What are the major carbohydrate metabolic processes in adipose tissue
Energy production (glycolysis, TCA)
NADPH production
Glycerol phosphate production
What are the major lipid metabolic processes in adipose tissue
Fatty acid synthesis (malonyl pathway)
Acylglycerol synthesis
Lipolysis
Energy production (b-oxidation, TCA)
What are the major carbohydrate metabolic processes in muscle tissue
Glycogen synthesis/degradation
Energy production (aerobically-glycolysis, TCA; anaerobically - glycolysis)
What are the major lipid metabolic processes in muscle tissue
Energy production (aerobically – b-oxidation, TCA)
What are the major protein metabolic processes in muscle tissue
Protein synthesis/degradation
Alanine (glutamine) production - transamination
What are the major carbohydrate metabolic processes in liver tissue
Interconversion of monosaccharides
Glycogen synthesis/degradation
Energy production (glycolysis, TCA)
Gluconeogenesis
Pentose metabolism
What are the major lipid metabolic processes in liver tissue
Fatty acid synthesis (malonyl pathway)
Acylglcerol and lipoprotein synthesis
Energy production (b-oxidation, TCA)
Ketone Body formation
What are the major protein metabolic processes in liver tissue
Transamination/deamination
Protein synthesis
Urea cycle
What happens overnight/ in the fasted post absorptive state in adipose
Pathways that prefer the breakdown/ lipolysis are more active (TAG breakdown under influence of glucagon to liberate FA to maintain energy status)
What happens in adipose tissue after a meal
Glucose is fed into adipose to supply acetyl CoA, new fatty acids are synthesised and stored as TAG, high concentration of insulins and breakdown and release of FA into the blood is suppressed
What happens in adipose under exercise conditions
FA are liberated from TAG to travel to other tissues e.g. muscle as a substrate for energy production
What happens overnight/ in the fasted post absorptive state in muscle
Energy demand of cell is stable, substrates provided from fats/lipids
Glucose is still used but predominantly lipids are used
Limited hormonal influence on energy metabolism as muscle does not have a receptor for glucagon and adrenaline is low
What happens in muscle tissue after a meal
Shift to preference for glucose as substrate, energy demand remains the same to fasted state
Not all glucose is stored as glycogen, some is oxidised immediately, some will be converted to lactate as some pyruvate is shunted away to lactate as there is an increased a,lung of pyruvate available (lactate travels to liver for gluconeogenesis)
What happens in muscle under exercise conditions
Increase in energy demand so both demand for lipid and glucose increase, lipids mainly received, from TAG breakdown in adipose, glucose influx is dicker from liver glycogen, or muscle breakdown, increased lactate production, adrenaline involvement
What happens overnight/ in the fasted post absorptive state in liver tissues
Glycogen is mainly broken down into glucose, gluconeogenesis is activated to maintain and supply glucose source, regulates blood glucose concentration, energy production main,y comes from Fa breakdown instead to maintain blood glucose concentration
What happens in liver tissue after a meal
Influx of amino acids, glucose and lipids which promote storage of glycogen, TAG (VLDL which are transported to other tissue), breakdown pathways are inhibited, increased urea production as not all amino acids necessarily used in protein synthesis
What happens in liver tissue under exercise conditions
During exercise there is an influx of lactate and glycerol into the liver which assist in regulating blood glucose concentration, majority of energy comes from utilising lipids, in duration exercise ketone bodies are produced, regulated by adrenaline and glucagon
What three major hormones are involved in energy metabolism in tissue
Insulin, glucagon and adrenaline
How do hormones control energy metabolism
act by changing activity of specific proteins via phosphorylation (kinase) and dephosphorylation (phosphorylase) (signalling cascades)
What is the role of insulin in energy metabolism
responsible for uptake and utilisation or storage of nutrients when concentrations in the blood rise. It reflects the fed state. Particularly involved in ensuring blood glucose concentrations are not too high
What is the role of glucagon in energy metabolism
responsible for raising blood glucose concentrations if they fall too low and protecting glucose by causing other nutrients (e.g. FA) to be used as a source of energy. Main target liver and adipose tissue (NOT muscle).
What is the overall effect of insulin
Glycogen synthesis is turned on because:
Glycogen synthase (GS) activated by dephosphorylation by phosphoprotein phosphatase-1 (PP1)
Glycogen degradation turned off because:
Glycogen phosphorylase (GP) is inactivated by dephosphorylation by PP1
Fatty acid synthesis is turned on because:
Acetyl-CoA carboxylase (ACC) activated by dephosphorylation by PP1
Lipolysis (breakdown of TAG) turned off because:
Hormone-sensitive lipase (HSL) activity reduced by (a) dephosphorylation by PP1 and (b) action of PDE
