Week 1- Intergration of Metabolism Flashcards
Describe the metabolic features of skeletal muscle
Can oxidize both fatty acids and carbohydrates, high ATP requirement during activity, during light contraction ATP is supplied by oxidative phosphorylation and during high contraction ATP is supplied by glycogen stores
Describe the metabolic features of the brain
Continuously requires ATP, cannot metabolise fatty acids, too much sugar (hyperglycemia) causes irreversible damage, too little sugar (hypoglycemia) causes coma, ketone bodies can be temporarily substituted for glucose as a metabolite
Describe the metabolic features of the heart
Continuously requires ATP, can oxidize both fatty acids and sugars, only aerobic respiration, uses TCA cycle substrates eg fatty acids and ketone bodies
Describe the metabolic features of the liver
Undertakes lots of metabolic processes eg gluconeogensis, glycogenlysis etc, maintains blood glucose at 4/5.5 mM, plays a key role in lipoprotein metabolism (triglycerides and cholesterol)
What can the body do when blood glucose falls below 3mM
Breakdown glycogen stores in liver, release fatty acids from adipose tissue, convert acetyl coA to ketone bodies, and eventually gluconeogenesis
Describe the process of gluconeogenesis
Pyruvate (3C) goes to oxaloacetate (4C) via pyruvate decarboxylase
Oxaloaceteate goes to phosphophenol pyruvate (4C) via phosphophenol pyruvate carboxylique kinase
Phosphophenol pyruvate goes to G3P (3C) NOTE: G3P comes from DHAP
G3P goes to fructose 1,6 bisphosphate (6C)
Fructose 1,6 bisphosphate goes to fructose 6 phosphate (6C) via fructose 1,6 bisphosphotase
Fructose 6 phosphate goes to glucose 6 phosphate (6C)
Glucose 6 phosphate goes to glucose (6C) via glucose 6 phosphatage
For gluconeogenesis where does pyruvate come from
From lactate that’s converted to pyruvate after anaerobic respiration
For gluconeogenesis where does oxaloacetate come from?
From some amino acids that come from the diet or skeletal muscle breakdown
For gluconeogenesis where does DHAP (that makes G3P) come from?
From glycerol (arising from triglyceride hydrolysis)
Where does gluconeogenesis take place?
1st reaction (pyruvate to oxaloacetate) in the mitchondria, rest of the process in the cytosol
What are glucogenic amino acids?
Amino acids that can be converted to glucose via gluconeogenesis
What are ketogenic amino acids?
Amino acids that give rise to skeletal bodies that can be made to ketones or fatty acids
Can fatty acids be converted to glucose? Explain why
No because 2C enter TCA cycle as CoA and 2 leave as CO2 so fatty acids can instead be converted to ketone bodies and used by the muscle/brain
How is rising demand for ATP met by muscles during aerobic respiration?
Increased number of glucose transporters on muscle cell membranes
Release of adrenaline which increases rates of glycolysis, gluconeogensis and release of fatty acids in adipose tissues
What happens during anaerobic respiration?
Glycogen is muscles is brocken down to give glucose
Pyruvate is converted to lactate via lactate dehydrogenase in order to replenish NAD+, lactate can then be used by the liver to generate glucose via gluconeogenesis