008 An Overview of Metabolism Flashcards
What are the four metabolic states?
Fed state
Fasting state
Starvation state
Exercise state
What occurs during the fed state to the liver, brain, muscles, adipose tissue, glucose and fat?
Brain uses glucose for fuel
Glucose and amino acids immediately drain into the liver, which uses products for fuel or stores it as glycogen or fat.
Excess glucose is taken in by adipose tissue and made into triglyceride.
Fat soluble products enter the lymph and don’t enter circulation for a few hours.
What occurs during the fasting state to the liver, muscles, brain, adipose tissue, glucose and fat?
Brain still uses glucose for fuel.
Low insulin levels stimulate skeletal muscles to stop using glucose and switch to fat.
Liver stabilises glucose by using glucagon to release it from glycogen.
Gluconeogenesis also supplies glucose.
Adipose tissues release fatty acids into blood for other tissues to use.
What occurs during the starvation state to the liver, muscles, brain, adipose tissue, glucose and fat?
Brain uses ketone bodies for fuel.
Skeletal muscles use fat and ketone bodies, whilst also releasing some amino acids.
Gluconeogenesis gradually decreases because it requires the supply of proteins, but using too much will cause us to die.
Fatty acids are converted into ketone bodies and are released.
Adipose tissues continue to release fatty acids into blood for other tissues.
What occurs during the exercise state to the liver, muscles, brain, adipose tissue, glucose and fat?
Brain uses glucose for fuel.
Skeletal muscles increase glucose or fat from stores.
Adipose tissues release fatty acids into the blood for muscle use.
Liver converts lactate from muscles back into glucose and releases glucose from stores of glycogen.
What is Gibbs free energy and the significance of its value?
Gibbs free energy is the free energy that is available to do work. When it is a negative value, the reaction is able to occur spontaneously without inputting work.
How does Gibbs free energy allow reactions to pair together?
Enzymes and its pathways can link pairs of exergonic and endogernic reactions, as long total value is negative.
What is gluconeogenesis?
Generation of glucose from non-carb substance e.g. lactate, glycerol, amino acids.
Where does gluconeogenesis occur?
In the liver and small amounts in the kidney.
What compound is present in urea?
Ammonia
