Liver

Question 1

name the three types of proteins made by the liver

Answer 1

albumin
most clotting factors
complement proteins - mark pathogens in the immune response

Question 2

function of albumin

Answer 2

carry unconjugated bilirubin
plasma protein

Question 3

are proteins stored as they are?

Answer 3

no, always have a function
if no function, used for energy or stored as fat

Question 4

how are faulty proteins degraded?

Answer 4

ubiquitin
- in cell cytoplasm
- small protein ubiquitin selectively binds to defective protein
signals to proteases that protein needs breakdown

lysosomal
- reticuloendothelial system (liver)
- sinusoid endothelial cells remove protein from blood
- protein fused into lysosomes
- phagocytosed by Kuppfer cells

Question 5

name functions of the liver

Answer 5

storage
- vitamins
- fats
- carbohydrates
- minerals such as iron and copper

synthetic
- produces proteins such as clotting factors, plasma proteins and complement proteins

immune
- resident macrophages: Kuppfer cells

hormonal regulation
- oestrogen

digestion
- produces bile

metabolism
- carbohydrate
- fat
- protein
- hormone

toxin/ drug metabolism and excretion

Question 6

which clotting factor is not produced by the liver?

Answer 6

Von Willebrand - produced by endothelial cells

Question 7

what is the reticuloendothelial system?

Answer 7

resident macrophages residing in tissues systemically
e.g liver Kuppfer cells and alveolar macrophages

Question 8

in which quadrant is the liver found?

Answer 8

right upper quadrant

Question 9

why is the liver important with regards to vitamin K?

Answer 9

bile salts produced in the liver are necessary to absorb vitamin K
vitamin K is required to produce clotting factors 10, 9, 7, 2

Question 10

fate of amino acids

Answer 10

catabolised for energy breakdown - enters Krebs
excreted as urea

Question 11

when metabolising amino acids for energy, which is the key intermediate we always start with?

Answer 11

alpha ketoglutarate

Question 12

mechanism of amino acid catabolism

Answer 12

transamination then oxidative deamination

Question 13

describe transamination
include the fate of the products

Answer 13

alpha ketoglutarate accepts amine from alanine
forms glutamate and pyruvate
catalysed by alanine transferase
alphaketoglutarate + alanine —> glutamate + pyruvate

pyruvate for
- gluconeogenesis
- aerobic respiration

Question 14

describe oxidative deamination

Answer 14

glutamate hydrolysed to reform alphaketoglutarate and ammonia
catalysed by glutamate dehydrogenase
glutamate + water –> alpha ketoglutarate + ammonia

toxic ammonia is removed to enter urea cycle

Question 15

what is a negative nitrogen balance?

Answer 15

catabolism
more nitrogen out than in

Question 16

what is a positive nitrogen balance?

Answer 16

anabolism
more nitrogen in than out

Question 17

what determines nitrogen balance?

Answer 17

protein intake
loss or gain of total body protein

Question 18

draw the urea cycle

Answer 18

.

Question 19

major amino acids in the urea cycle

Answer 19

arginine, ornithine, citrulline
‘CITARGORN’

Question 20

why is ammonia harmful?

Answer 20

neurotoxic, can cross blood brain barrier

Question 21

what is the glucose alanine cycle?

Answer 21

involves muscle protein being degraded to provide more glucose to generate additional ATP for muscle contraction

Question 22

describe the glucose alanine cycle

Answer 22

1. reverse transamination in muscles
   glutamate + pyruvate –> alanine + alphaketoglutarate
2. alanine to liver (in blood)
3. transamination in liver
   alanine + alphaketoglutarate —> glutamate + pyruvate
   glutamate is oxidatively deaminated to remove excess ammonia in the urea cycle
   pyruvate is converted to glucose in the liver (gluconeogenesis)
4. glucose back to muscle cells
5. glycolysis (to pyruvate)

Question 23

which are the fat soluble vitamins?

Answer 23

A,D,E,K

Question 24

functions of lipids

Answer 24

energy reserve - fatty acid beta oxidation
shock absorber
cell membrane components - phospholipids and cholesterol
hormones, metabolism

Question 25

energy content of lipids

Answer 25

9kcal/g

Question 26

structure of lipoproteins

Answer 26

outer glycoprotein, inner lipid

Question 27

what is 'good' cholesterol and why?

Answer 27

HDLs - high density lipoproteins highest protein to lipid ratio

Question 28

where are HDLs synthesised?

Answer 28

liver

Question 29

function of HDLs

Answer 29

remove cholesterol from cells to take to the liver

Question 30

where are LDLs produced?

Answer 30

plasma

Question 31

function of LDLs

Answer 31

deposit cholesterol in cells

Question 32

what are VLDLs

Answer 32

very low density lipoproteins carry triglycerides to adipose tissue

Question 33

what are IDLs?

Answer 33

VLDL intermediates converted to LDL

Question 34

when does beta oxidation of fatty acids occur?

Answer 34

in the fasted state high glucagon and low insulin

Question 35

name types of beta oxidation of fatty acids

Answer 35

peroxisomal mitochondrial - main

Question 36

what is a xenobiotic?

Answer 36

foreign substance to be excreted modified by the liver to be less lipophilic and more hydrophilic to increase solubility e.g drugs

Question 37

what are the phase 1 biotransformation reactions?

Answer 37

addition/ exposure of a functional group most commonly produces a hydroxyl group small increase in hydrophilicity oxidation, reduction or hydrolysis microsomal enzymes in endoplasmic reticulum - CYP450 enzymes

Question 38

what are phase 2 conjugation reactions?

Answer 38

conjugation to produce hydrophilic metabolites large increase in hydrophilicity glucoronidation - most common examples of conjugation molecules - glucaronic acid - sulphate non microsomal enzymes - enzyme UGT

Question 39

alcohol detoxification - a different type

Answer 39

metabolism of alcohol does not fit into type 1 or 2 detoxification does not need to be conjugated for excretion alcohol --> acetaldehyde --> acetate --> carbon dioxide and water enzymes for the first two steps: alcohol dehydrogenase, acetaldehyde dehydrogenase

Question 40

does alcohol need to be conjugated for excretion?

Answer 40

no

Question 41

constituents of bile

Answer 41

bile salts cholesterol xenobiotics electrolytes phospholipids bilirubin

Question 42

what is the portal triad?

Answer 42

hepatic portal vein, hepatic artery, bile duct

Question 43

where are portal triads found?

Answer 43

vertexes of hepatic lobules

Question 44

histological appearance of liver tissue

Answer 44

hexagonal lobules lobules have a central hepatic vein (not hepatic portal vein) in the corners of the lobules we find the portal triad

Question 45

what is the hepatoduodenal ligament and what does it contain?

Answer 45

part of the lesser omentum connects the porta hepatis of the liver to the duodenum contains - portal vein - hepatic artery (right and left) - common hepatic duct

Question 46

what percentage of bile is excreted?

Answer 46

about 5

Question 47

where is bile reabsorbed? what percentage?

Answer 47

ileum 95%

Question 48

function of CCK

Answer 48

relaxes the sphincter of Oddi gallbladder contraction chole, "bile"; cysto, "sac"; kinin, "move"

Question 49

how is bile reabsorbed?

Answer 49

into portal blood using apical Na+ bile acid transporter (ASBT)

Question 50

function of iron in body

Answer 50

muscle myoglobin erythrocytes

Question 51

what is directly proportional to the total iron stores in the body?

Answer 51

ferritin levels

Question 52

what causes low ferritin?

Answer 52

iron deficiency

Question 53

what amount of ferritin suggest depletion? and absence of stored iron

Answer 53

less than 20ug/L 12ug/L

Question 54

functions of vitamins

Answer 54

gene activators free radical scavengers coenzymes or cofactors in metabolic reactions

Question 55

vitamin a sources

Answer 55

retinol carotenoids

Question 56

functions of vitamin a

Answer 56

vision - used to form rhopsodin in the rod cells in the retina spermatogenesis prevention of foetal resorption

Question 57

vitamin a excess

Answer 57

joint and bone pain reversible yellowing of the skin abdominal pain

Question 58

function of vitamin d

Answer 58

calcium absorption

Question 59

vitamin d deficiency

Answer 59

demineralisation of bone - rickets in children - osteomalacia in adults

Question 60

function of vitamin e

Answer 60

antioxidant

Question 61

vitamin e requirements

Answer 61

4mg/ day in men 3mg/ day

Question 62

causes of vitamin e deficiency

Answer 62

fat malabsorption

Question 63

which vitamins does the liver store?

Answer 63

ADEK fat soluble

Question 64

which clotting factors are vitamin K dependent?

Answer 64

2, 7, 9, 10 1972

Question 65

deficiency of what substance causes neural tube defects?

Answer 65

folate

Question 66

which clotting factors are produced by the liver?

Answer 66

1, 2, 4, 5, 6, 7

Question 67

functions of fat

Answer 67

energy reserve hormone metabolism part of cell membranes inflammatory cascades steroid hormones - cholesterol

Question 68

where is cholesterol made?

Answer 68

liver

Question 69

what percentage of cholesterol is endogenous?

Answer 69

90%

Question 70

what percentage of cholesterol is dietary?

Answer 70

10%

Question 71

what is the only way cholesterol is exported?

Answer 71

through bile excretion

Question 72

what is enterohepatic circulation?

Answer 72

movement of bile acid molecules from the liver to the small intestine and back to the liver

Question 73

how are triglycerides and cholesterol carried through the circulatory system?

Answer 73

lipoproteins

Question 74

energy content of lipids

Answer 74

9kcal/g

Question 75

what carries lipids from the gut to muscle and adipose tissue?

Answer 75

chylomicrons

Question 76

order HDL VLDL LDL chylomicron in order of highest to lowest lipid to protein ratio

Answer 76

highest lipid to protein ratio means more lipid compared to protein chylomicron VLDL LDL HDL

Question 77

what happens to chylomicron remnants?

Answer 77

taken up by liver by receptor mediated endocytosis - recognition of ApoB by hepatocyte surface receptors