Physiology of liver, pancreas and gallbladder Flashcards
1
Q
What is Fe2+ stored in the liver as?
A
ferritin
2
Q
Iron is transported bound to which protein?
A
transferrin
3
Q
How much glycogen is stored in the liver?
A
100g
4
Q
What are the fat soluble vitamins?
A
ADEK
5
Q
How long can the liver’s glycogen stored last for?
A
12 hours
6
Q
How long can the liver’s fat stores last for?
A
3 months
7
Q
What is the aim of liver detoxification?
A
Aims to either make the substance less toxic or increase solubility to allow the substance to be excreted
8
Q
Describe phase 1 reactions
A
oxidation or hydrolysis reactions
9
Q
Describe phase 2 reactions
A
Glucoronidation
Conjugation
Excretion
10
Q
What is glucaronidation?
A
addition of glucaronic acid to a substance
11
Q
What is conjugation?
A
addition of a chemical group to a substance
12
Q
What does Gilbert’s syndrome cause?
A
Mild jaundice as a result of inefficiant UDPGT
13
Q
What can colloid osmotic pressure also be referred to as?
A
oncotic pressure
14
Q
What is oncotic pressure?
A
form of osmotic pressure induced by proteins in the vessel
15
Q
What are the main functions of albumin?
A
maintaining oncotic pressure
binding and transporting large/hydrophobic molecules
16
Q
All but which clotting factors are produced in the liver?
A
All but 4 and 7
17
Q
What are the vitamin K dependent clotting factors?
A
10, 9, 7, 2
18
Q
What is produced by the liver that is important for the absorption of vitamin K and other fat soluble vitamins?
A
bile salts
19
Q
What three types of protein are produced by the liver?
A
Plasma protein e.g albumin
Clotting proteins
Complement proteins (part of immune response)
20
Q
What is the purpose of the glucose-alanine cycle?
A
to move proteins from the muscle to the liver when glycogen stores are low
21
Q
What is an important enzyme involved in the glucose-alanine cycle? Its concentration in serum is used to measure liver health.
A
Alanine aminotransferase (ALT)
22
Q
In the glucose-alanine cycle, what does is glucose converted into in the muscle?
A
pyruvate
23
Q
In the glucose-alanine cycle, what is pyruvate converted into in the muscle. What enzyme is required for this step?
A
pyruvate is converted into alanine
alanine aminotransferase is required for this step
24
Q
Apart from pyruvate and alanine aminotransferase, what other substance is required to produce alanine at the muscle?
A
glutamate
25
What is glutamate converted into at the muscle in the glucose-alanine cycle?
alpha-ketoglutarate
26
What is the next step of the glucose-alanine cycle after alanine has been produced in the muscle?
alanine travles in the blood to the liver
27
What is alanine converted to in the liver?
pyruvate
28
In the glucose-alanine cycle, what is pyruvate converted into at the liver?
glucose
29
Where does glutamate come from initially in the glucose-alanine cycle?
muscle proteins
30
Which cycle is similar in function to the glucose-alanine cycle except more productive?
the Cori cycle
31
Describe what happens to glucose in the muscle in the Cori cycle
Glucose is converted to 2 pyruvate
| 2 pyruvate is converted to 2 lactate
32
In the Cori cycle, what is used to produce glucose from in the liver
2 lactate
33
In the Cori cycle, what is 2 lactate converted to in the liver?
2 lactate is converted to 2 pyruvate
| 2 pyruvate is converted to glucose
34
What is NH3?
ammonia
35
What neurotoxic substance does the urea cycle remove?
ammonia
36
In the urea cycle, what is added to ornithine to form citrulline?
ammonia and CO2
37
In the urea cycle, what is added to citrulline to form arginine?
ammonia
38
What does arginine release to regenergate ornithine?
Urea
39
In the urea cycle, the release of urea from arginine forms what substance?
ornithine
40
what does LDL stand for?
low density lipoproteins
41
what does HDL stand for?
high density lipoproteins
42
What does VLDL stand for?
very low density lipoproteins
43
What type of lipoprotein is used to transport lipids from the liver to adipose tissue?
VLDL
44
What cell is the main store of lipids?
adipocytes
45
When VLDLs reach adipocytes, how does the fat enter the adipocyte?
VLDLs release their triglycerides
| triglycerides diffuse into adipocytes
46
Emulsification of fatty acids by bile forms what ?
micelles
47
Where in the GI tract does lipid digestion primarily occur?
the small intestine (but some occurs in the mouth and stomach)
48
Lipase converts triglycerides into?
monoglyercide +2 fatty acids
49
Describe the solubility of pancreatic lipase?
water soluble
50
Why can pancreatic lipase only act on the surface of fat droplets?
It is water soluble
51
Which enzyme holds lipase to the surface of the lipid droplet?
colipase
52
How do the fatty acids + monoglycerides get into the epithelial cells?
via diffusion
53
Where in the intestinal epithelial cells are monoglycerides and fatty acids resynthesised into triglycerides?
smooth endoplasmic reticulum
54
What are triglycerides packaged into after their resynthesis in the intestinal epithelial cells?
chylomicrons
55
What type of vessel do chylomicrons pass into from the intestinal epithelial cells?
lacteals
56
Where are LDLs formed and what is their function?
formed in plasma
| deliver cholesterol to cells
57
Where are high density lipoproteins formed and what do they do?
formed in the liver
| remove excess cholesterol from blood and tissues via excretion in bile
58
Where are VLDLs formed and what do they do?
formed in liver (hepatocytes)
| deliver triglycerides from liver to adipocytes
59
Which type of lipoprotein delivers cholesterol to cells?
low density lipoproteins
60
Which type of lipoprotein removes excess cholesterol from the blood and tissues via excretion in bile?
High density lipoproteins
61
What essentially is fatty acid beta oxidation?
breaking down lipids to release energy
| Each cycle shortens the fatty acid chains by 2 carbons until the fatty acid is only 2 carbons long
62
Where does fatty acid beta oxidation occur?
the mitochondria of hepatocytes
63
What type of cell continuously secretes bile?
hepatocytes
64
What components are in bile?
```
bile salts
lecithin (a phospholipid)
HCO3-
Cholesterol
Bile pigments e.g bilirubin
```
65
What is lecithin?
a phospholipid
66
Bile is released from the gallbaldder in response to which hormone?
CCK
67
Which type of bilirubin is toxic and lipid soluble?
unconjugated bilirubin
68
Which type of bilirubin is water soluble?
conjugated bilirubin
69
Which cells phagocytose red blood cells? what is hemoglobin broken down into?
macrophages
| hemoglobin is broken down into heme and globin
70
What happens to the globin from the breakdown of hemoglobin?
globin is hydrolysed to from amino acids and these are used to make new proteins
71
Which enzyme breaks down heme into biliverdin and Fe2+?
heme oxygenase
72
What are the products of the breakdown of heme by heme oxygenase?
biliverdin and Fe2+
73
Biliverdin results from the breakdown of what substance?
heme
74
What colour is biliverdin?
green
75
What is biliverdin converted into by the enzyme biliverdin reductase?
unconjugated bilirubin
76
Which enzyme converts biliverdin into unconjugated bilirubin?
biliverdin reductase
77
What colour is unconjugated bilirubin?
yellow
78
Where is unconjugated bilirubin converted into conjugated bilirubin + glucaronic acid ?
the liver
79
What does the liver convert unconjugated bilirubin into?
conjugated bilirubin and glucaronic acid
80
How is conjugated bilirubin excreted from the liver?
In bile
81
What is conjugated bilirubin converted into in the ileum and the beginning of the large intestine?
urobilinogen
82
What converts conjugated bilirubin into urobilinogen?
bacteria
83
How do bacteria convert unconjugated bilirubin into urobilinogen ?
remove glucaronic acid
84
Describe the solubility of urobilinogen?
lipid soluble
85
What is the majority of urobilinogen oxidised to form?
stercobilin
86
What colour is stercobilin?
brown
87
What chemical is responsible for the brown colour of feces?
stercobilin
88
What percentage of urobilinogen is reabsorbed and bound to albumin in the blood?
10-15%
89
What is urobilinogen converted into at the kidneys?
urobilin
90
Which chemical is primarily responsible for the yellow colour of urine?
urobilin
91
What happens to the reabsorbed urobilinogen that does not go to the kidneys ?
enters the enterohepatic urobilinogen cycle and is resecreted into the bile
92
What is the cause of jaundice?
increased bilirubin in the blood
93
What are the different types of jaundice?
pre hepatic
hepatic
post hepatic
94
Describe post hepatic jaundice
impaired excretion due to mechanical obstruction to bile flow
elevated conjugated bilirubin in serum
95
Describe pre hepatic jaundice
excessive hemolysis
| elevated unconjugated bilirubin in serum
96
How is unconjugated bilirubin transported to the liver?
via albumin
97
What enzyme is involved in the conversion of unconjugated bilirubin into conjugated bilirubin?
UDPGT
98
What colour is bilirubin in bile?
yellow/green
99
What are the exocrine secretions of the pancreas?
HCO3-
Zymogens
Digestive enzymes
100
What does the pancreas secrete that neutralises chyme in the duodenum?
HCO3-
101
Where are the zymogens secreted by the pancreas activated?
the duodenum
102
What part of small intestine releases secretin?
the duodenum
103
What hormone stimulates HCO3- secretion from the pancreas?
secretin
104
How is HCO3- secreted by pancreatic duct cells?
a Cl-/HCO3- exchanger
105
What is HCO3- exchanged for when it is secreted by the duct cells of the pancreas?
Cl-
106
Cl- brought into pancreatic duct cells are recycled back into the lumen by what channel?
CFTR channels
107
What is the function of CFTR channels?
movement of Cl- from inside the pancreatic duct cell into the lumen
108
Which channel is non-functional in cystic fibrosis?
CFTR
109
Give two examples of zymogens
trypsinogen
| chymotrypsinogen
110
Which enzyme is key for activating zymogens?
enterokinase
| trypsin also plays an important role in the activation of zymogens
111
What is the function of trypsin?
digests proteins
| activates zymogens
112
What is the function of alpha-amylase?
digests starch into maltose
113
What hormone inhibits the release of digestive enzymes?
somatostatin
114
What cell type produces pancreatic lipase, trypsin and alpha-amylase?
pancreatic acinar cells
115
What hormone stimulates the release of pancreatic digestive enzymes?
CCK
116
What do alpha cells in the pancreas secrete?
glucagon
117
What do beta cells in the pancreas secrete?
insulin
118
What do delta cells in the pancreas secrete?
somatostatin
119
What hormone inhibits pancreatic exocrine secretion as well as glucagon and insulin secretion ?
somatostain
120
What is CCK released by?
the duodenum
