Lecture 3 - Carbohydrate Metabolism

Question 1

what is the basic principle of the fed state

Answer 1

where your body is breaking down something that you have eaten

Question 2

what happens with blood glucose and insulin in the fed state

Answer 2

release of insulin from pancreatic islet B cells

interaction of insulin with receptors

Question 3

what are the fates of glucose in the fed state

Answer 3

• glycogenesis and storage
• glycolysis and utilisation

Question 4

what is the basic principle to the fasted state

Answer 4

once the gut and last meal is no longer contributing to any nutrients in your circulatory system

Question 5

what depends how long it will take your body to enter the fasted state after eating

Answer 5

depends on the size of the meal and the individual

Question 6

after the direct effects of a meal have finished and you enter the fasted state, what happens

Answer 6

• decline in liver glycogen
• blood glucose maintained

Question 7

what is a key hormone in the fasted state

Answer 7

glucagon

Question 8

what is secreted in response to a decrease in blood glucose

Answer 8

glucagon

Question 9

where is glucagon synthesised and released from

Answer 9

pancreatic islet a cells

Question 10

what is gluconeogenesis

Answer 10

making glucose from amino acids and keto acids

Question 11

wh can only use what we have stored of glucose, so how can we make more

Answer 11

by gluconeogenesis (synthesis of glucose from precursors)

Question 12

what do enzymes in the lumen of the small intestine do

Answer 12

break down foods

Question 13

pyruvate can be used to make certain things such as …. or …

Answer 13

amino acids or glucose

Question 14

fats can not be used to make

Answer 14

can not be used to make glucose

Question 15

liver is a insulin what tissue

Answer 15

liver is an insulin insensitive tissue

Question 16

the primary driver of glycolysis and glycogenesis is what

Answer 16

increase in glucose

Question 17

the brain relies on ….. and is insulin ….

Answer 17

the brain relies on glucose and is insulin insensitive

Question 18

why can we not fuel the brain from fat

Answer 18

because fatty acids can not cross the blood brain barrier

Question 19

red blood cells do not have a mitochondria, what does this mean in terms of metabolism (and what do they produce even at rest)

Answer 19

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

Question 20

in the presence of insulin, glucose-6-phosphate is converted to what

Answer 20

glucose-6-phosphate is converted to glucose-1-phosphate and then to glycogen

Question 21

what are the linkages in glycogen

Answer 21

1-6 and 1-4 linkages

Question 22

when glycogen stores are being replenished in the liver from glucose what is the first step

Answer 22

the formation of glucose-6-phosphate

Question 23

what is glycogen synthase involved in

Answer 23

the synthesis of glycogen

Question 24

what is glycogen phosphorylase involved in

Answer 24

the breakdown of glycogen

Question 25

what is glycogenin

Answer 25

a ‘kernel’ molecule made from protein and carbohydrate

Question 26

what is the function of glycogenin

Answer 26

serves as a primer for glycogen synthesis

Question 27

what are the two stages of glycogen synthesis

Answer 27

• chain extension
• branching

Question 28

what is involved in the breakdown of glycogen

Answer 28

• chain shortening
• debranching (removing branches)

Question 29

what is gluconeogenesis basically the opposite of

Answer 29

glycolysis

Question 30

how are amino acids sources for gluconeogenesis

Answer 30

amino acids can be used to make things such as pyruvate and oxaloacetate which can be used to form glucose

Question 31

what is the primary site for synthesis of glucose from gluconeogenesis

Answer 31

liver

Question 32

gluconeogenesis can also occur in the kidneys (lesser extent tho) how does this happen

Answer 32

lactate produced by the body can be taken up by the kidneys and converted to pyruvate which can be used to make glucose