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Metabolism > Intergration > Flashcards

Intergration Flashcards

1
Q

Consequences of high blood glucose on kidneys (4)

A

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

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2
Q

Which tissues is glut 2 located (4)

A

Liver
Kidney
Intestine
Pancreas

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3
Q

Explain glut 2 km and activity

A

Km-7-20 mmol/l - high

Activity dependant on extracellular concentration of glucose

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4
Q

Which tissues is glut 3 located

A

Brain

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5
Q

Explain glut 3 km and activity

A

Km-1.6 mmol/l

Constant activity due to low km

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6
Q

Which tissues is glut 4 located (2)

A

Muscle

Adipose tissue

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7
Q

Explain glut 4 km and activity

A

Km-5 mmol/l

Activity dependent on insulin

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8
Q

Fate of glucose once it reaches cells (4)

A

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

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9
Q

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

A

Glucose 6 phosphate

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10
Q

Fructose and galactose metabolism (2)

A

Majority converted to glucose in liver

Excess fructose may be converted into FAs

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11
Q

Major precursors of gluconeogenesis (3)

A

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

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12
Q

Why is TAG broken down and resynthesised?(2)

A

TAG is too hydrophobic to cross membranes

Re-esterification helps maintain conc gradient

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13
Q

Chylomicron pathway (4)

A

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

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14
Q

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

A

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

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15
Q

TAG synthesis in the liver (4)

A

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

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16
Q

Transport of TAG from the liver (2)

A

Assembled into VLDL in hepatocytes

VLDL directly secreted into blood stream

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17
Q

Give some examples of ketone bodies (3)

A

Acetoacetate
3-hydroxybutyrate
Acetone

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18
Q

Why are FAs converted to ketone bodies?(3)

A

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

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19
Q

Enzyme that breaks down TAG to FAs in adipose tissue

A

Hormones sensitive lipase

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20
Q

Fed state and insulin effect (6)

A 
Glucose uptake 
Increased LPL
Increased FA uptake 
Increase synthesis of FA and glycerol 3 phosphate 
Increased TAG synthesis
Decreased HSL
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21
Q

Fasted state glucagon and adrenalin effects (6)

A 
Increase HSL
Increased TAG breakdown 
Decreased glucose uptake 
Decreased FA and glycerol 3 phosphate synthesis
Decreased LPL
Decreased FA uptake
22
Q

Which are the branched chain AAs (3)

A

Valine
Leucine
Isoleucine

23
Q

How much of dietary AA uptake comes from branched chain AAs

A

20%

24
Q

Oxidation of branched chain AAs (3)

A

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

25
Q

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

A

2-oxo-acid dehydrogenase

26
Q

AA inter-conversions in muscle (5)

A

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

27
Q

Glucose-alanine cycle (5)

A

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

28
Q

Glucose liver uptake (3)

A

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

29
Q

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

A

Hexokinase

Glucokinase

30
Q

Hexokinase (2)

A

Located in most tissues

Inhibited by glucose 6 phosphate

31
Q

Glucokinase (3)

A

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

32
Q

Dietary lipids (3)

A

TAG
glycerophospholipids
Cholesterol

33
Q

Components of a chylomicron (4)

A

Re-esterified lipids
Free cholesterol
Lipid soluble vitamins
ApoB48

34
Q

Components of VLDL (4)

A

TAG
Phospholipid
Free and esterified cholesterol
ApoB100

35
Q

Which organ receives the highest glucose concentration?

A

Liver

36
Q

Which tissues does gluconeogenesis occur?(2)

A

Liver

Kidney cortex

37
Q

Endogenous lipoprotein pathway (6)

A

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

38
Q

What inhibits glycogen synthase?

A

Phosphorylation of the enzyme

39
Q

Glycogen synthase is active when it is _______

A

Dephosphorylated

40
Q

What activates glycogen phosphorylase?

A

Phosphorylation of enzyme

41
Q

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

A 
High insulin and low counter regulatory enzymes decrease kinase activity
And increase phosphatase activity 
This activated glycogen synthase 
Inactivates glycogen phosphorylase
Increases glycogen storage
42
Q

Hormones that stimulates protein degradation (2)

A

Cortisol

T3

43
Q

Hormones that stimulate protein synthesis (3)

A

Insulin
Growth hormone
Testosterone

44
Q

What is the purpose of glucose-alanine cycle

A

Get rid of excess nitrogen

45
Q

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

A

70%

46
Q

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

A

Liver

Adipose tissue

47
Q

Ketogenesis (3)

A

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

48
Q

Glycogen synthesis (6)

A 
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
49
Q

Glycogenolysis (4)

A

Glycogen to G1P
By glycogen phosphorylase
G1P to G6P
By phosphoglyceromutase

50
Q

Glycogenolysis liver (3)

A

G6P converted to glucose
Via G6 phosphatase
Glucose then enters blood

51
Q

Glycogenolysis muscle (3)

A

G6P to pyruvate
Via glycolysis
Pyruvate is transaminated to alanine

Metabolism (6 decks)

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