Biochemical aspects of liver metabolism

Question 1

Where is bile produced?

Answer 1

Liver

Question 2

Name a plasma protein which is secreted in the liver

Answer 2

Albumin

Question 3

What important molecules are stored in the liver?

Answer 3

Fuels, Iron, Vitamins

Question 4

By what 2 processes are unwanted molecules eliminated?

Answer 4

Metabolism

Excretion into the biliary tree and faecal excretion

Question 5

What is the importance of carbohydrate and lipid metabolism

Answer 5

Fuel storage

Question 6

What is the importance of the amino acid metabolism

Answer 6

Urea cycle

Question 7

What is electrophoresis

Answer 7

It allows the separation of proteins by size

Question 8

Name 5 functions of plasma proteins

Answer 8

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

Question 9

What is the purpose of maintaining osmotic pressure

Answer 9

Prevents the loss of plasma proteins

Question 10

Name some hydrophobic substances transported by plasma proteins

Answer 10

Steroid hormones
Free fatty acids
bilirubin
cholesterol

Question 11

Name an ezymatic function of plasma proteins

Answer 11

Blood clotting

Question 12

What are the 2 main substances secreted through plasma protein secretion

Answer 12

Albumin and alpha globulins

Question 13

What do alpha globulins do?

Answer 13

Transport lipoproteins, lipids, hormones and bilirubin

Question 14

What does retinol binding protein do?

Answer 14

Transports vitamin A

Question 15

Name the main two beta globulins

Answer 15

Transferrin and fibrinogen

Question 16

What is the function of Transferrin

Answer 16

Transports Fe3+

Indicator or iron deficiency

Question 17

What is the function of fibrinogen

Answer 17

Inactive for of fibrin

Involved in the clotting of blood

Question 18

What is Albumin and what is its main roll

Answer 18

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

Question 19

How much albumin does the liver synthesise per day

Answer 19

14g

Question 20

What stimulates the synthesis of albumin

Answer 20

Insulin

Question 21

What causes low levels of albumin

Answer 21

Liver disease

Starvation / low protein diet

Question 22

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

Answer 22

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

Question 23

How is copper transported in the blood

Answer 23

Bound to ceruloplasmin

Question 24

What is the roll of copper

Answer 24

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

Question 25

What is the disease called where there is a copper deficiency

Answer 25

Wilson's disease

Question 26

What 2 groups of hormones are hydrophobic

Answer 26

Steroid hormones | T3/T4 thyroid hormones

Question 27

How are hormones transported

Answer 27

In the circulation bound to specific transport molecules

Question 28

What is thyroxine bound to?

Answer 28

Thyroid-binding globulin | What is cortisol bound to

Question 29

What is cortisol bound to

Answer 29

Cortisol binding globulin

Question 30

What is the purpose of hormone transport

Answer 30

They extend biological half life and increase plasma concentration

Question 31

Describe a lipoprotein

Answer 31

Hydrophobic surrounded by a shell Free cholesterol dispersed throughout

Question 32

What is the roll of a lipoprotein

Answer 32

To transport fat between organs and tissues

Question 33

What is the function of cholesterol transport

Answer 33

It removes excess cholesterol from cells

Question 34

Where is cholesterol metabolised and excreted

Answer 34

Liver

Question 35

How is cholesterol degraded

Answer 35

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

Question 36

What 3 vitamins are stored in the liver ?

Answer 36

Vitamin A,D and B12

Question 37

What does cholesterol do in terms of mammalian cell membranes

Answer 37

Increases the rigidity of them

Question 38

What 3 classes of compounds is cholesterol a precursor for

Answer 38

Bile acids Steroid hormone Vitamin D

Question 39

Why is the metabolism of cholesterol important?

Answer 39

Etiology of cardiovascular disease | Major component of gall stones

Question 40

How is the majority of cholesterol transported

Answer 40

Esterified to a wide range of long-chain fatty acids

Question 41

How is cholesterol stored?

Answer 41

In lipid droplets

Question 42

What 2 places is cholesterol synthesised

Answer 42

Cytoplasm, some enzymes bound to ER membrane

Question 43

What 3 compounds are required to synthesis cholesterol

Answer 43

AcH NADPH ATP

Question 44

What is the function of HMG-CoA reductase

Answer 44

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

Question 45

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

Answer 45

It reduces its activity

Question 46

What is the function of Vitamin D

Answer 46

Regulation of calcium and phosphorus metabolism

Question 47

What is the most abundant for of vitamin D

Answer 47

D3

Question 48

Name the 3 types of synthesised by cholesterol-steroid hormones

Answer 48

Corticosteroids Androgens Oestrogens

Question 49

What is the site of corticosteroid synthesis

Answer 49

Adrenal cortex

Question 50

What is the site of androgen synthesis

Answer 50

Testis

Question 51

What is the site of Oestrogen synthesis

Answer 51

Ovary

Question 52

What is the main product from cholesterol

Answer 52

Bile salts

Question 53

What does bile act as and for what

Answer 53

A detergent for emulsifying ingested lipids

Question 54

How is bile recycled

Answer 54

Enterohepatic circulation