Additional GI Notes Flashcards
(31 cards)
describe the events in glycogenesis
glucose phosphorylated to glucose-6-phosphate (uses ATP and hexokinase catalyst)
G6P then stores as glycogen or broekn down by glycolysis
G6P converted to glucose-1-phosphate
G1P converted to UDP-glucose by UDP glucose phosphorylase
Glycogen synthase adds the new UDP-glucose to the end of the existing glycogen chain
describe the events in glycogenolysis
catalysed by glycogen phosphorylase
glycogen has one glucose cleaved
glucose is combined with a phosphate
G1P then converts to G6P by phosphoglucomutase
G6P is phosphorylated in the liver and released into the blood by glucose-6-phosphatase
what bonds link glucose molecules
alpha-1,4-glycosidic bonds
what is glycogenin and where is it found
found at the centre of a glycogen molecule
it allows for a glycogen starting point as glycogen synthase cant make glycogen from scratch
what does transglycosylase allow
branches to be added to a glycogen molecule
what GLUT transported transports glucose produced by glycogen to the blood
2
what are the three classic precursors of gluconeogenesis
Lactate
Glucogenic Amino acids (not ketogenic)
Glycerol
what is rewuired to start gluconeogenesis
4ATP and 2 GTP
what stimulates glycolysis
what inhibits glycolysis
high AMP, ADP or ATP
High citrate, alanine, acetyl-CoA (these also promote gluconeogenesis)
how many carbons can the body synthesise into its fatty acids - after which the others are essential fatty acids
9
what must fatty acids be broken down into to join the TCA cycle
CoA derivatives
fatty acid + CoA –> acyl-CoA
NOT ACETYL
how is acyl-CoA transferred into the mitochondria
carnitine shuttle
what is the P/O ratio
the amount of ATP produced from the movement of 2 electrons through the transport chain donated by the reduction of oxygen to water
what are the three ketone bodies
acetoacetate
acetone
hydroxy-butyrate
what happens during periods of starvation
lots of oxaloacetate is used up for gluconeogenesis and so ketone bodies are produced from excess acetyl-CoA and ketone levels rise leading to acidosis
describe lipogenesis
occurs in the liver
acetyl-CoA produced in matric
acetyl-CoA carboxylase regulates how much fatty acid is synthesised at once
fatty acid synthesis requires acetyl-CoA, manolyl-CoA and NADPH
palmitoyl-CoA can antagonise acteyl-CoA carboxylase if the levels get too high
steps in urea synthesis
transamination - amino group transferres to a keto acid
deamination - amino group is removed from the glutamic acid and reforms the keto acid - the free ammonium ion can now enter the urea cycle which needs 3ATP –> produces urea, 2 phosphate, 2 ADP, AMP and fumarate
urea cycle - ammonium ions converted to urea along with aspartic acid
what are ketogenic vs glucognic amino acids broken down into
K = acetyl-CoA G = pyruvate
what do alpha4-beta7 integrin on T cells and MADCAM-1 on the endothelium do
aid the transport of T cells out of the gut
what do paneth cells secrete and where are they from
defensins and they are found in the small intestine
what Ig is present in bile
IgA
what analgesia cant be given in gallstones and why
morphine because it constricts the sphincter of Oddi and increases intrabiliary pressure
what substances act on the CTZ to enduce vomiting
substance P opiates dopamine ACh 5-HT Histamine
what are the side effects of severe vomiting
excessive acid loss
leading to hypochloraemic metabolic alkalosis
loss of K - hypokalaemia
