Intergration

Question 1

Consequences of high blood glucose on kidneys (4)

Answer 1

Rate of glomerular filtration (GFR) exceeds tubular reabsorption
And glucose appears in the urine
Results in osmotic diuresis
Which results in excessive urination and excessive thirst

Question 2

Which tissues is glut 2 located (4)

Answer 2

Liver
Kidney
Intestine
Pancreas

Question 3

Explain glut 2 km and activity

Answer 3

Km-7-20 mmol/l - high

Activity dependant on extracellular concentration of glucose

Question 4

Which tissues is glut 3 located

Answer 4

Brain

Question 5

Explain glut 3 km and activity

Answer 5

Km-1.6 mmol/l

Constant activity due to low km

Question 6

Which tissues is glut 4 located (2)

Answer 6

Muscle

Adipose tissue

Question 7

Explain glut 4 km and activity

Answer 7

Km-5 mmol/l

Activity dependent on insulin

Question 8

Fate of glucose once it reaches cells (4)

Answer 8

Metabolised to provide energy in all cells (little in liver)
Converted to glycogen in muscle and liver
Converted to FAs and the TAG in liver and adipose tissue
Converted to ribose 5 phosphate and NADPH in all tissue

Question 9

What is glucose first converted to when it enters a cell?

Answer 9

Glucose 6 phosphate

Question 10

Fructose and galactose metabolism (2)

Answer 10

Majority converted to glucose in liver

Excess fructose may be converted into FAs

Question 11

Major precursors of gluconeogenesis (3)

Answer 11

Lactate from muscle and erythrocytes
Glycerol from adipose tissue
AAs (alanine) from muscle

Question 12

Why is TAG broken down and resynthesised?(2)

Answer 12

TAG is too hydrophobic to cross membranes

Re-esterification helps maintain conc gradient

Question 13

Chylomicron pathway (4)

Answer 13

Travel from lymph to blood
TAG broken down by LPL
FAs taken up by cells
Chylomicron remnant taken up by liver

Question 14

Where do FAs which are taken up by the liver come from?(3)

Answer 14

Newly synthesised by from carb precursors
Chylomicron remnants or escaped from tissue uptake
Released from adipose tissue

Question 15

TAG synthesis in the liver (4)

Answer 15

Fatty acyl CoA + Glycerol 3 phosphate -> Lysophosphatidate
FA added to make phosphatidate
Phosphate removed to make DAG
FA added to make TAG

Question 16

Transport of TAG from the liver (2)

Answer 16

Assembled into VLDL in hepatocytes

VLDL directly secreted into blood stream

Question 17

Give some examples of ketone bodies (3)

Answer 17

Acetoacetate
3-hydroxybutyrate
Acetone

Question 18

Why are FAs converted to ketone bodies?(3)

Answer 18

Ketones can be used by tissues which can’t use FAs
FAs not very soluble so conc kept low
Ketones are freely soluble

Question 19

Enzyme that breaks down TAG to FAs in adipose tissue

Answer 19

Hormones sensitive lipase

Question 20

Fed state and insulin effect (6)

Answer 20

Glucose uptake 
Increased LPL
Increased FA uptake 
Increase synthesis of FA and glycerol 3 phosphate 
Increased TAG synthesis
Decreased HSL

Question 21

Fasted state glucagon and adrenalin effects (6)

Answer 21

Increase HSL
Increased TAG breakdown 
Decreased glucose uptake 
Decreased FA and glycerol 3 phosphate synthesis
Decreased LPL
Decreased FA uptake

Question 22

Which are the branched chain AAs (3)

Answer 22

Valine
Leucine
Isoleucine

Question 23

How much of dietary AA uptake comes from branched chain AAs

Answer 23

20%

Question 24

Oxidation of branched chain AAs (3)

Answer 24

Uptake of BCAAs by muscle specifically increased by insulin
Transaminated to 2-oxo acids
2-oxo-acids oxidised to CO2 and produces ATP

Question 25

What enzyme in the muscle initiates the oxidation of 2-oxo-acid to CO2

Answer 25

2-oxo-acid dehydrogenase

Question 26

AA inter-conversions in muscle (5)

Answer 26

Amino group from branches chain AA is transferred to oxo acid Usual recipient of amino group is either pyruvate to form alanine Or 2-oxoglutarate to form glutamate Glutamate can be converted to glutamine by addition of NH2 group Major AAs to leave muscle are alanine and glutamine

Question 27

Glucose-alanine cycle (5)

Answer 27

Liver releases glucose which taken up by muscle Glycogen broken down to pyruvate Pyruvate is transaminated to alanine Alanine transported to liver This is then converted to pyruvate then glucose

Question 28

Glucose liver uptake (3)

Answer 28

Liver has a high number of glucose transporters with high Km Glucokinase has a high Km and is not inhibited by G6P Therefore uptake is related to glucose concentration in blood

Question 29

What enzymes are involved in the synthesis of glucose 6 phosphate?(2)

Answer 29

Hexokinase | Glucokinase

Question 30

Hexokinase (2)

Answer 30

Located in most tissues | Inhibited by glucose 6 phosphate

Question 31

Glucokinase (3)

Answer 31

Located in liver and pancreatic beta cells Not inhibited by glucose 6 phosphate Not insulin dependent

Question 32

Dietary lipids (3)

Answer 32

TAG glycerophospholipids Cholesterol

Question 33

Components of a chylomicron (4)

Answer 33

Re-esterified lipids Free cholesterol Lipid soluble vitamins ApoB48

Question 34

Components of VLDL (4)

Answer 34

TAG Phospholipid Free and esterified cholesterol ApoB100

Question 35

Which organ receives the highest glucose concentration?

Answer 35

Liver

Question 36

Which tissues does gluconeogenesis occur?(2)

Answer 36

Liver | Kidney cortex

Question 37

Endogenous lipoprotein pathway (6)

Answer 37

VLDL leaves liver and enters bloodstream Lipoprotein lipase hydrolyses TAG FA taken up by muscles and adipose tissue VDL becomes IDL IDL converted to cholesterol-rich LDL Most of LDL goes to liver, some goes to other tissues such as arteries

Question 38

What inhibits glycogen synthase?

Answer 38

Phosphorylation of the enzyme

Question 39

Glycogen synthase is active when it is _______

Answer 39

Dephosphorylated

Question 40

What activates glycogen phosphorylase?

Answer 40

Phosphorylation of enzyme

Question 41

How are glycogen phosphorylase and synthase regulated during fed state?(5)

Answer 41

``` High insulin and low counter regulatory enzymes decrease kinase activity And increase phosphatase activity This activated glycogen synthase Inactivates glycogen phosphorylase Increases glycogen storage ```

Question 42

Hormones that stimulates protein degradation (2)

Answer 42

Cortisol | T3

Question 43

Hormones that stimulate protein synthesis (3)

Answer 43

Insulin Growth hormone Testosterone

Question 44

What is the purpose of glucose-alanine cycle

Answer 44

Get rid of excess nitrogen

Question 45

Branch chain AAs makes up ____ of the AAs leaving the liver after a meal

Answer 45

70%

Question 46

In which tissues is there a high conversion of glucose to ribose 5 phosphate and NAPDH?(2)

Answer 46

Liver | Adipose tissue

Question 47

Ketogenesis (3)

Answer 47

Occurs in liver Acetyl CoA derived from oxidation of FAs are incorporated into ketone bodies Can be used as a source of energy by most aerobic tissues

Question 48

Glycogen synthesis (6)

Answer 48

``` G6P converted to G1P Using phosphoglucomutase G1P converted to UDP-glucose Using G1P uridyltranferase Glucose from UDP-glucose added to glycogen chain Using glycogen synthase UDP is released ```

Question 49

Glycogenolysis (4)

Answer 49

Glycogen to G1P By glycogen phosphorylase G1P to G6P By phosphoglyceromutase

Question 50

Glycogenolysis liver (3)

Answer 50

G6P converted to glucose Via G6 phosphatase Glucose then enters blood

Question 51

Glycogenolysis muscle (3)

Answer 51

G6P to pyruvate Via glycolysis Pyruvate is transaminated to alanine