Lecture 3 - Carbohydrate Metabolism Flashcards
what is the basic principle of the fed state
where your body is breaking down something that you have eaten
what happens with blood glucose and insulin in the fed state
release of insulin from pancreatic islet B cells
interaction of insulin with receptors
what are the fates of glucose in the fed state
- glycogenesis and storage
- glycolysis and utilisation
what is the basic principle to the fasted state
once the gut and last meal is no longer contributing to any nutrients in your circulatory system
what depends how long it will take your body to enter the fasted state after eating
depends on the size of the meal and the individual
after the direct effects of a meal have finished and you enter the fasted state, what happens
- decline in liver glycogen
- blood glucose maintained
what is a key hormone in the fasted state
glucagon
what is secreted in response to a decrease in blood glucose
glucagon
where is glucagon synthesised and released from
pancreatic islet a cells
what is gluconeogenesis
making glucose from amino acids and keto acids
wh can only use what we have stored of glucose, so how can we make more
by gluconeogenesis (synthesis of glucose from precursors)
what do enzymes in the lumen of the small intestine do
break down foods
pyruvate can be used to make certain things such as …. or …
amino acids or glucose
fats can not be used to make
can not be used to make glucose
liver is a insulin what tissue
liver is an insulin insensitive tissue
the primary driver of glycolysis and glycogenesis is what
increase in glucose
the brain relies on ….. and is insulin ….
the brain relies on glucose and is insulin insensitive
why can we not fuel the brain from fat
because fatty acids can not cross the blood brain barrier
red blood cells do not have a mitochondria, what does this mean in terms of metabolism (and what do they produce even at rest)
they can not use oxidative metabolism, they use anaerobic metabolism
- means even at rest we will have some lactate in our blood due to this being produced in red blood cells
in the presence of insulin, glucose-6-phosphate is converted to what
glucose-6-phosphate is converted to glucose-1-phosphate and then to glycogen
what are the linkages in glycogen
1-6 and 1-4 linkages
when glycogen stores are being replenished in the liver from glucose what is the first step
the formation of glucose-6-phosphate
what is glycogen synthase involved in
the synthesis of glycogen
what is glycogen phosphorylase involved in
the breakdown of glycogen
what is glycogenin
a ‘kernel’ molecule made from protein and carbohydrate
what is the function of glycogenin
serves as a primer for glycogen synthesis
what are the two stages of glycogen synthesis
- chain extension
- branching
what is involved in the breakdown of glycogen
- chain shortening
- debranching (removing branches)
what is gluconeogenesis basically the opposite of
glycolysis
how are amino acids sources for gluconeogenesis
amino acids can be used to make things such as pyruvate and oxaloacetate which can be used to form glucose
what is the primary site for synthesis of glucose from gluconeogenesis
liver
gluconeogenesis can also occur in the kidneys (lesser extent tho) how does this happen
lactate produced by the body can be taken up by the kidneys and converted to pyruvate which can be used to make glucose
