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Phase 1 Cards > Liver and Friends > Flashcards

Liver and Friends Flashcards

1
Q

What is another name for vitamin A?

A

retinol

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2
Q

Where is vitamin A/ retinol stored and what is it stored as?

A

stored in stellate cells as retinyl ester

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3
Q

How is vitamin A made active?

A

retinyl ester activated to retinol by lecithin retinol acyltransferase (LRA)

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4
Q

What is the function of retinol?

A

helps maintain healthy teeth, skeletal and soft tissue, mucus membranes, and skin

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5
Q

What is another name for vitamin D?

A

cholecalciferol

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6
Q

How is vitamin D found in food?

A

found in food as ergocalciferol

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7
Q

Where is ergocalciferol metabolised?

A

liver

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8
Q

What is vitamin E a collective term for?

A

vitamin E is a family of 8 fat soluble compounds

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9
Q

What is the main function of vitamin E?

A

antioxidant

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10
Q

Where is vitamin E stored?

A

either liver or adipose tissue

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11
Q

What are the forms of vitamin K and where are they found?

A

two forms acquired from plant or meat sources

phylloquinone = green leafy vegetables
menaquinones= animal sources
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12
Q

What us another name for vitamin B12?

A

cobalamin

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13
Q

How much vitamin B12 is stored in the body?

A

2-5mg

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14
Q

Where is vitamin B12 stored?

A

liver

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15
Q

Which vitamins are fat/ water soluble

A 
ADEK= fat soluble
B12= water soluble
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16
Q

What is the distribution of iron in the body?

A

50% haemoglobin
25% haem-containing proteins
25% liver ferritin

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17
Q

How is iron stored?

A

iron is bound to transferrin after being absorbed by duodenal epithelial cells

most of stored iron is in the Kupffer cells of liver as ferritin

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18
Q

Where is iron absorbed?

A

duodenum

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19
Q

What organ maintains blood glucose levels?

A

liver

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20
Q

What is excess glucose stored as?

A

glycogen

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21
Q

How much glycogen do different muscles store?

A

liver stores 100mg

skeletal muscles stored 300g

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22
Q

What stimulates formation/ breakdown of glycogen?

A

formation: insulin release
breakdown: glucagon release

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23
Q

What are xenobiotics?

A

a foreign chemical substance not normally found or produced in the body which cannot be used for energy requirements

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24
Q

What are microsomes?

A

fragments of endoplasmic reticulum with attached ribosomes that contain microsomal enzymes

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25
Q

Define lipophilic

A

able to pass through plasma membranes

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26
Q

What happens in phase 1 reactions?

A

make drugs more hydrophilic to be excreted by kidneys
introduce/ expose hydroxyl (OH) and other polar groups
carried out via oxidation, reduction and hydrolysis
facilitated by microsomal enzymes

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27
Q

What are some properties of pharmacologically active compounds?

A

lipophilic
non-ionised at pH 7.4
bound to plasma proteins to be transported

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28
Q

What enzymes carry out phase 2 reactions?

A

most are done by non-microsomal enzymes except glucuronidation which is done by microsomal enzymes (UGT)

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29
Q

What is UGT?

A

microsomal enzymes- uridine diphosphate glucuronosyltransferase

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30
Q

What us UDPGA?

A

urine diphosphate- glucaronic acid

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31
Q

What are the 3 types of protein?

A

plasma proteins
clotting factors
complement proteins

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32
Q

What is the most common plasma protein and its function?

A

albumin

maintains osmotic pressure
binding + transporting large/ hydrophobic molecules

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33
Q

What is vitamin K essential for?

A

synthesis of clotting factors 10,9,7,2

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34
Q

What are two phase 2 reactions?

A

conjugation

glucuronidation

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35
Q

What occurs in conjugation reactions?

A

attachment of substituent groups
inactive products
catalysed by transferases
increases hydrophilicity

36
Q

What occurs in glucuronidation reactions?

A

adding glnucaronic acid groups
increases hydrophilicity
done by glucoronosyltransferase
UDPGA is an essential coenzymes for glucuronidation reactions

37
Q

What are phase 1 and phase 2 reactions concerning?

A

drug metabolism

38
Q

What is the function of the glucose-alanine cycle?

A

muscle protein being degraded to provide more glucose to generate additional ATP for muscle contraction when stores are low

39
Q

What is ALT and what is it’s clinical significance?

A

alanine aminotransferase

it’s concentration in serum is used to measure liver health

40
Q

Describe the steps of the urea cycle.

A
  1. ammonia and carbon dioxide added to ornithine
  2. another ammonia is added to citrulline to make arginine
  3. arginine is cleaved by arginase into urea and ornithine and the cycle goes round again
41
Q

What is the only compound generated in the urea cycle?

42
Q

What are high levels of ammonia associated with?

A

neurotoxicity

43
Q

Where are the enzymes for the urea cycle found?

A

all found in hepatocytes

44
Q

Where is body fat stored?

A

mostly in adipocytes

some stored in hepatocytes

45
Q

What forms are fats stored in and in what distribution?

A

triglycerides- 78%
protein- 21%
carbohydrates- 1%

46
Q

Where are LDLs formed?

47
Q

Where are HDLs formed?

48
Q

Where are VLDLs formed?

A

hepatocytes

49
Q

What is the function of LDLs?

A

main cholesterol carrier- carries cholesterol to all cells in body
essential for cell membrane and steroid hormone production

50
Q

What is the function of HDLs?

A

removes excess cholesterol from blood and tissues delivering it to the liver to be secreted into bile

51
Q

What is the function of VLDLs?

A

deliver triglycerides from liver to adipocytes

52
Q

What happens if there is a high density of LDLs?

A

high levels of LDL will be taken up by cell via endocytosis and deposition will increase risk for heart attack

53
Q

What are the types of lipoproteins?

A

LDL- low density lipoproteins
HDL- high density lipoproteins
VLDL- very low density lipoproteins

54
Q

What is the general function of lipoproteins?

A

lipid metabolism

55
Q

What 2 enzymes are involved in hepatic metabolism of lipids and what do each do?

A

lipoprotein lipase:
-hydrolyses triglycerides in lipoproteins into 2 free fatty acids and 1 monoglyceride

hepatic lipase:

  • found in liver and adrenal glands
  • converts IDL (intermediate density lipoprotein) into LDL thereby packaging it with more triglycerides to be released into the body
56
Q

What are the main functions of the gallbladder?

A
  1. production and concentration of bile

2. bilirubin and enterohepatic secretion of bile salts

57
Q

What is the function of bile?

A

to emulsify fats

58
Q

Where is bile produced?

A

liver hepatocytes

59
Q

What stimulated secretion of bile

A

cholecystokinin (CCK)

60
Q

What causes release of CCK?

A

released in response to increased fatty acid concentration in duodenum

61
Q

How is bile concentrated?

A

concentrated in the gallbladder by absorption of NaCl and H2O

62
Q

What are the constituents of bile?

A 
bile salts 
lecithin (a phospholipid)
carbonate ions (HCO3-)
cholesterol
bile pigments (e.g. bilirubin)
63
Q

Describe the duct system between the liver, gallbladder and pancreas.

A

right and left hepatic duct merge to form common hepatic duct

cystic duct (from gallbladder) joins common hepatic duct to form common bile duct

pancreatic duct merges with common bile duct at the ampulla of vater where secretions enter the duodenum, flow controlled by sphincter of odd

64
Q

What percentage of bile salts are recycled?

65
Q

Describe process of enterohepatic circulation.

A
  • bile salts enter intestinal tract via bile
  • reabsorbed via Na+ coupled transporters
  • majority of reabsorption in terminal ileum, some in jejunum
  • returned to liver via hepatic portal vein (HPV) to be used again in bile
  • 5% of bile salts lost to faeces
66
Q

What is enterohepatic circulation?

A

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

67
Q

How are new bile salts made?

A

new bile salts synthesised by liver from cholesterol

68
Q

How are old erythrocytes broken down?

A

liver- by kupffer cells (a type of macrophages)

spleen- by macrophages

69
Q

What colour is bilirubin?

70
Q

Describe the full process of bilirubin metabolism.

A
  1. RBCs ingested by macrophages/ kupffer cells
  2. haemoglobin broken down into haem and globin
  3. globing broken down into amino acids (used to make new RBCs in bone marrow)
  4. haem further broken down into biliverdin and Fe2+ and CO. This is catalysed by haem oxygenase (HO)
  5. biliverdin is reduced by biliverdin reductase to make unconjugated bilirubin
  6. unconjugated bilirubin is bound to albumin and transported to liver
  7. undergoes glucuronidation to make conjugated bilirubin, catalysed by UDP glucuronyl transferase
  8. conjugated bilirubin is now soluble and dissolved in bile
  9. excreted into duodenum with rest of bile
  10. intestinal bacteria in terminal ileum reduce conjugated bilirubin into urobilinogen
  11. urobilinogen is lipid-soluble so 10% is reabsorbed into blood, bound to albumin, transported to liver, oxidised to urobilin
  12. urobilin is recycled into bile or transported to kidneys and excreted in urine- responsible for yellow colour of urine
  13. remaining 90% of urobilinogen is oxidised by a different intestinal bacteria into stercobilin
  14. stercobilin is excreted in faeces (responsible for brown colour)
71
Q

What does unconjugated bilirubin need to be removed?

A

it is toxic

72
Q

What colour is biliverdin?

73
Q

What is the predominant pigment in haemoglobin?

74
Q

What are the types of jaundice?

A
  1. Pre-hepatic- excessive RBC breakdown, leads to overwhelming of liver to deal with bilirubin. Unconjugated bilirubin in bloodstream.
  2. Hepatic/ intrahepatic- dysfunction of hepatic cells. Both conjugated and unconjugated bilirubin in blood.
  3. Post-hepatic/ obstructive- obstruction of biliary drainage.
75
Q

What are the 2 broad functions of the pancreas?

A

exocrine

endocrine

76
Q

What are the exocrine secretions of the pancreas?

A

bicarbonate
digestive enzymes
zymogens

77
Q

What is the function of pancreatic bicarbonate?

A

protects duodenum from gastric acid

buffers chyme to a suitable pH

78
Q

How is bicarbonate secreted from the pancreas?

A
  • secretion stimulated by secretin
  • pancreatic duct cells secrete HCO3- into duct lumen via Cl-/HCO3- exchanges
  • HCO3- for this comes from dissociation of carbonic acid
  • Cl- is recycled back into lumen via CFTR channel
79
Q

What is a CFTR channel?

A

cystic fibrosis transmembrane conductance regulator

80
Q

What stimulated release of pancreatic enzymes into the duodenum?

81
Q

What active enzymes does the pancreas secrete? What do each of them do?

A

alpha amylase- converts starch to maltose

lipase- converts triglycerides into monoglyceride + fatty acids

82
Q

What does the pancreas secrete zymogens?

A

protects the pancreas from auto digestion

83
Q

What activates pancreatic zymogens?

A

enterokinase in intestinal epithelial cells

84
Q

What are 2 examples of pancreatic zymogens and what do they become after activation?

A

trypsinogen –> trypsin

chymotrypsinogen –> chymotrypsin

85
Q

What is the most common pancreatic exocrine inhibitor? What else does this substance inhibit?

A

somatostatin

gastric acid secretion

86
Q

Where is somatostatin made?

A

D cells in islets of langerhans

87
Q

What are the phases of gastric juice secretion and what occurs in each stage?

A
  1. cephalic phase
    - sensory experience: seeing and chewing food
    - parasympathetic vagus nerve stimulation to acinar cells
    - produce digestive enzymes
  2. gastric phase
    - prescience of food in stomach causes further parasympathetic vagus nerve stimulation to acing cells- produces digestive enzymes
  3. intestinal phase
    - duodenum responds to arriving chyme and moderates gastric activity through hormones and nervous reflexes

Phase 1 Cards (9 decks)

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