Biochemical aspects of liver metabolism Flashcards Preview

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Flashcards in Biochemical aspects of liver metabolism Deck (54):
1

Where is bile produced?

Liver

2

Name a plasma protein which is secreted in the liver

Albumin

3

What important molecules are stored in the liver?

Fuels, Iron, Vitamins

4

By what 2 processes are unwanted molecules eliminated?

Metabolism
Excretion into the biliary tree and faecal excretion

5

What is the importance of carbohydrate and lipid metabolism

Fuel storage

6

What is the importance of the amino acid metabolism

Urea cycle

7

What is electrophoresis

It allows the separation of proteins by size

8

Name 5 functions of plasma proteins

Maintenance of oncotic or colloid osmotic pressure
Transport of hydrophobic substancces
pH bufferring
Enzymatic
Immunity

9

What is the purpose of maintaining osmotic pressure

Prevents the loss of plasma proteins

10

Name some hydrophobic substances transported by plasma proteins

Steroid hormones
Free fatty acids
bilirubin
cholesterol

11

Name an ezymatic function of plasma proteins

Blood clotting

12

What are the 2 main substances secreted through plasma protein secretion

Albumin and alpha globulins

13

What do alpha globulins do?

Transport lipoproteins, lipids, hormones and bilirubin

14

What does retinol binding protein do?

Transports vitamin A

15

Name the main two beta globulins

Transferrin and fibrinogen

16

What is the function of Transferrin

Transports Fe3+
Indicator or iron deficiency

17

What is the function of fibrinogen

Inactive for of fibrin
Involved in the clotting of blood

18

What is Albumin and what is its main roll

Most abundant plasma protein
Small, negatively charge, water soluble protein
It is the main determinant of plasma oncotic pressure

19

How much albumin does the liver synthesise per day

14g

20

What stimulates the synthesis of albumin

Insulin

21

What causes low levels of albumin

Liver disease
Starvation / low protein diet

22

What is iron? How is it transported? and how is it stored?

It is a component of haemoglobin, myoglobin and cytochromes
Transported as ferric ion Fe3+ bound to transferrin
Stored in cells bound to ferritin

23

How is copper transported in the blood

Bound to ceruloplasmin

24

What is the roll of copper

Essential for regulation of redox reactions, transport and use of iron

25

What is the disease called where there is a copper deficiency

Wilson's disease

26

What 2 groups of hormones are hydrophobic

Steroid hormones
T3/T4 thyroid hormones

27

How are hormones transported

In the circulation bound to specific transport molecules

28

What is thyroxine bound to?

Thyroid-binding globulin
What is cortisol bound to

29

What is cortisol bound to

Cortisol binding globulin

30

What is the purpose of hormone transport

They extend biological half life and increase plasma concentration

31

Describe a lipoprotein

Hydrophobic
surrounded by a shell
Free cholesterol dispersed throughout

32

What is the roll of a lipoprotein

To transport fat between organs and tissues

33

What is the function of cholesterol transport

It removes excess cholesterol from cells

34

Where is cholesterol metabolised and excreted

Liver

35

How is cholesterol degraded

Esterified with fatty acids
Transported back to the liver
Excreted as bile salts via biliary system or faceces

36

What 3 vitamins are stored in the liver ?

Vitamin A,D and B12

37

What does cholesterol do in terms of mammalian cell membranes

Increases the rigidity of them

38

What 3 classes of compounds is cholesterol a precursor for

Bile acids
Steroid hormone
Vitamin D

39

Why is the metabolism of cholesterol important?

Etiology of cardiovascular disease
Major component of gall stones

40

How is the majority of cholesterol transported

Esterified to a wide range of long-chain fatty acids

41

How is cholesterol stored?

In lipid droplets

42

What 2 places is cholesterol synthesised

Cytoplasm, some enzymes bound to ER membrane

43

What 3 compounds are required to synthesis cholesterol

AcH
NADPH
ATP

44

What is the function of HMG-CoA reductase

Catalyses the irreversible formatin of mevalonic acid
It is a rate limiting enzyme

45

What is the effect of dietary cholesterol on HMG-CoA reductase activity

It reduces its activity

46

What is the function of Vitamin D

Regulation of calcium and phosphorus metabolism

47

What is the most abundant for of vitamin D

D3

48

Name the 3 types of synthesised by cholesterol-steroid hormones

Corticosteroids
Androgens
Oestrogens

49

What is the site of corticosteroid synthesis

Adrenal cortex

50

What is the site of androgen synthesis

Testis

51

What is the site of Oestrogen synthesis

Ovary

52

What is the main product from cholesterol

Bile salts

53

What does bile act as and for what

A detergent for emulsifying ingested lipids

54

How is bile recycled

Enterohepatic circulation

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