Metabolic homeostasis: anabolic/catabolic state Flashcards
(23 cards)
What are the 4 basic metabolic pathways?
Fuel oxidative pathways
Fuel storage and mobilisation
Biosynthetic pathways
Detoxification/waste disposal pathways
What is the anabolic pathway?
What is the catabolic pathway?
Synthesise large molecules (biosynthetic and fuel storage)
Breakdown large molecules (fuel oxidation)
What balance must be met and what is it called?
Fuel availability vs Tissue needs
Metabolic homeostasis
What are the effects if metabolic homeostasis isn’t met? (2)
Significant decreases: hypoglycaemia, limited brain metabolism
Too much: Hyperosmolar effects, coma, neurological effects
How is the balance between use, release and storage maintained? (3)
Blood
Hormones
Central Nervous sytem
When hormones are released, what are the 3 main parts they effect?
Muscle
Liver
Adipose (fat) tissue
What is insulin and where is it produced?
Insulin is an anabolic hormone
Released from Beta cells of islets of langerhans
How is insulin stimulated and what is its action? (3)
Stimulated by glucose entering cells
Insulin promotes: Glucose -> fuel, storage as glycogen, inhibited fuel metabolism
What is glucagon and where is it produced?
Contra-insular hormone
Released from alpha cells of pancreas
How is glucagon stimulated and what does it promote?
Stimulated by insulin and glucose levels falling
Promotes: Glucose production (gluconeogenesis, glycogenolysis)
What is the absorptive state and what are the effects of it (3)?
Well-fed state: 2- 4 hrs after eating a meal
- Elevated insulin:glucagon ratio
- Readily available substrates
- Anabolic state
What happens to the liver after a meal?
Liver is bathed in blood containing nutrients
-Takes up carbs, lipids and A.A.
What happens when carbohydrates are metabolised? (5)
Increased glucose uptake Increased phosphorylation of glucose Increased gluconeogenesis Increased glycolysis Increased insulin to glucagon, increase in glycolytic enzymes
Where is fat metabolised and what is the effect?
Liver
Increased triacylglycerol synthesis
How are amino acids metabolised? (2)
Protein synthesis in the liver
Exported to other tissues to be used or degraded
What is the fasting state and what are the effects (3)?
If no food is taken in after the end of the absorptive state
- Glucose levels, A.A acids fall
- Insulin decrease, glucagon and epinephrine increase
- Catabolic state
What are the 4 things that control flow of intermediates through the metabolic pathway?
Substrate availability
Allosteric regulation of enzymes
Covalent modification of enzymes
Induction-repression of enzyme synthesis
What are the 3 enzymes that are active in there absorptive AND fasting state?
Glycogen phosphorylase
Glycogen phosphorylase kinase
Hormone sensitive lipase
What are the 3 processes that occur in the fasting stage in the liver, muscle and adipose tissue?
Liver - glycogenolysis (releasing glucose)
Adipose tissue - lipolysis (releasing FA’s & glycerol)
Muscle - proteolysis (realising A.A)
What is the main function of the liver in carbohydrate metabolism?
Produce glucose by glcogenolysis and gluconeogenesis
What is the major energy source in liver tissue?
Fatty acid oxidation
How does a hyper catabolic state occur?
Injury: burns & septic stress
What happens in a hyper catabolic state? (3)
- Cortisol is the main mediator of response
- Amino acids are used in a prioritised fashion
- Glutamine efflux from skeletal muscle can provide an energy source
