Exam 3 – Dr. Sullivant Hepatic Physiology Flashcards
1
Q
What is ascites?
A
Fluid accumulation in peritoneal cavity
2
Q
What are the different types of ascites?
A
Transudate
Modified transudate
Exudate
3
Q
What is icterus?
A
Elevated bilirubin levels
4
Q
What is cirrhosis?
A
Condition in which normal cells are replaced by scar tissue
5
Q
What is portal hypertension?
A
Hypertension in the portal vein and its branches
6
Q
What is metabolism?
A
Sum of all anabolic and catabolic reactions as it related to use of all nutrients
7
Q
What are the functions of the liver?
A
Filtering and storage of blood Metabolism of CHOs, proteins, and fats Metabolism of hormones, drugs, and toxins Formation of cholesterol and bile Storages of vitamins and iron Production of coagulation factors Production of plasma proteins Lymph formation
8
Q
What is the liver lobule?
A
Basic functional unit of the liver
9
Q
Where do most of the liver functions occur?
A
In the lobules
10
Q
Where does the liver make lymph?
A
In the sinusoids
11
Q
Where does the major supply to the liver come from?
A
Portal vein
12
Q
What do hepatocytes do?
A
Clean and detoxify blood to make sure it does not go into systemic circulation
13
Q
What happens once everything that goes to the liver gets cleaned up?
A
It moves to the central vein where it is released to the jugular vein, the heart, and then goes through it all again
14
Q
Look at liver anatomy
A
Look at liver anatomy
15
Q
Describe the liver anatomy
A
Largest internal organ
2-5% total body weight
Receives 30% of cardiac output
16
Q
How many lobes does the liver consist of? What are they?
A
6 Right and left medial Right and left lateral Quadrate Caudate
17
Q
What are venous sinusoids lined by?
A
Endothelial cells with large pores to allow movement of plasma proteins
Large Kupffer cells
18
Q
What are Kupffer cells?
A
Macrophages
19
Q
Describe Kupffer cells
A
Keeps less than 1% of GI bacteria from entering systemic circulation
Defense mechanism
20
Q
What percentage of lymph in the body is made in the liver?
A
50%
21
Q
What do sinusoidal endothelial cells do in the lymph formation the liver?
A
Leak fluids and proteins into “space of Disse”
22
Q
What happens if lymph leaks out into the body?
A
There is a protein concentration of 6g/dl (slightly less than plasma protein)
23
Q
What does increased sinusoidal pressure cause?
A
Increase in lymph production
24
Q
What happens if the liver is losing a lot of lymph?
A
Any disease of the liver can occur, especially chronic disease such as fibrosis and cirrhosis
25
What happens once sinusoidal pressure rises enough?
The liver sweats lymph which leads to ascites
26
What does the liver have a high capacitance for?
Lymph
27
What can lymph cause the liver volume to do?
Increase by 1 liter or more
28
What can the liver perform for blood?
Vast storage
| Extramedullary hematopoiesis
29
What is extramedullary hematopoiesis?
Making blood cells outside of the bone marrow
30
When can the liver make blood cells?
Cytokine stimulation
| Hypoxia
31
What is the blood flow break down of the liver?
20% from hepatic artery
| 80% from portal vein
32
What is the oxygen supply breakdown of the liver?
50% from hepatic artery
| 50% from portal vein
33
What do portosystemic shunts do?
Shunting of blood from portal circulation to systemic circulation without passing through the liver
34
What are the types of portosystemic shunts?
Congenital
| Acquired
35
What does an extrahepatic shunt do?
Goes around the liver
36
What does an intrahepatic shunt do?
Go through the liver, but it is not the correct path
37
What makes up the portal vein?
Spleen
Pancreas
GI tract
38
Look at blood flow picture
Look at blood flow picture
39
What are congenital shunts?
Intrahepatic or extrahepatic anomalous vessels that does not allow the blood to take a normal course through the liver
40
What is an examples of a congenital shunt?
Portocaval shunt: portal vein empties directly into caudal vena cava
41
What are consequences of congenital shunts?
Impaired liver development
Liver dysfunction
Liver failure
End stage cirrhosis without repair
42
What does impaired liver development cause?
Stunted growth
43
What does liver dysfunction cause?
Build up of toxins, especially ammonia
| Poor ability to metabolize anesthetics/sedatives
44
What is the pressure in portal vein?
9 mmHg
45
What is the pressure in the hepatic vein leading to the vena cava?
0 mmHg
46
Why is the 0 mmHg pressure in the hepatic vein good?
It is the perfect low pressure gradient to get blood from the intestines and spleen, throughout the liver, into vena cava and back into the right atrium
47
What can ascites do?
It can leak from the portal vessels or from the liver tissue itself
48
What are causes of portal hypertension?
Cirrhosis
Severe infection
Chronic biliary tract obstructions
Portal vein thrombosis
49
What are the consequences of portal hypertension?
Gastrointestinal edema/ulceration
Severe GI signs and protein loss
Ascites
Acquired portosystemic shunts
50
What does cirrhosis cause?
Fibrous tissue to contract around blood vessels
51
Describe acquired shunts
Multiple tortuous vessels outside of the liver develop due to high pressure in the liver (acts as a relief valve for portal vasculature)
All throughout abdomen
Often near the kidney
Worsens liver function
52
What are causes of congestion?
Right sided congestive heart failure
Heartworm disease
Congenital diseases
Cor pulmonale
53
What are the consequences of congestion?
Gastrointestinal edema/ulceration
Severe GI signs and protein loss
Ascites
54
How can ascites happen in liver disease?
Obstruction of lymph flow/congestion (right sided heart failure)
Portal hypertension (increases resistance to blood flow through the liver)
Increased sinusoidal pressure in the liver
Hypoalbuminemia
55
How is the liver forgiving?
There are insults and then there is a repair process
Great ability to repair and regenerate
Transforming growth factor B can stop liver cell proliferation
56
When the liver does not repair, what happens?
Insults turn into fibrosis which turns into cirrhosis
57
What does the liver store?
Vitamins (A, D, B12)
| Iron
58
What is iron stored as?
Ferritin in hepatic cells by combining with the protein "apoferritin"
It is released from storage in times of need
59
What is the livers role in coagulation?
Makes most of proteins needed in the process–fibrinogen, prothrombin, and clotting factors 2, 7,9, and 10
60
Describe clotting factors 2, 7, 9, and 10
Vitamin K dependent
| The liver activates vitamin K so that it can be used to make these factors
61
What is the role of the liver in drug, hormone, and toxin metabolism?
```
Detoxify/activate antibiotics
Excrete antibiotics into bile
Chemical alteration of hormones
Excrete hormones
Calcium excretion
```
62
What is bilirubin?
Greenish, yellow pigment that is the major end product of hemoglobin degradation
63
Where does bilirubin come from?
Old, sick, and tired RBCs that get phagocytosed by macrophages
Hgb is split into globin and heme which releases free iron and a substrate from which bilirubin will be formed
64
What is biliverdin?
Free bilirubin released from macrophages into circulation
65
What is the formation of bilirubin?
Senescent RBCs have Hgb which splits into iron and biliverdin by heme oxygenase. Biliverdin becomes bilirubin by biliverdin reductase
66
What does free bilirubin do?
Joins albumin and is transported throughout the body
67
What happens when the bilirubin/albumin combo reaches the liver?
They are absorbed through the hepatocyte membrane
68
What happens to bilirubin inside the hepatocyte?
Conjugation with glucuronide, sulfate, and others (conjugated bilirubin)
It is excreted into bile canaliculi and then into intestines
69
What is the fate of bilirubin?
Converted via bacteria to urobilinogen
70
What happens to urobilinogen?
It is reabsorbed through intestinal mucosa back into blood
Most goes back to liver for re-excretion into gut and is oxidized to stercobilin
5% is excreted by kidneys and is oxidized to the urobilin
71
Where is stercobilin excreted?
Feces
72
Where is urobilin excreted?
Urine
73
Look at bilirubin metabolism
Look at bilirubin metabolism
74
What is increased bilirubin known as?
Hyperbilirubinemia, icertus, or jaundice
75
What is the yellowish tint to body tissues due to?
Excessive build up of conjugated or unconjugated bilirubin
76
What is the normal range of bilirubin? What is the range of bilirubin with jaundice?
0.2-0.6 mg/dl
| 2 mg/dl
77
What occurs with hyperbilirubinemia?
Bilirubinuria, which is often the first sign of liver disease
78
What can cause hyperbilirubinemia?
Hemolytic anemia
Liver failure/dysfunction
Obstruction of biliary tracts in the lover
Obstruction of posthepatic biliary system
79
What happens with liver failure/dysfuction?
Bilirubin is not processed/conjugated properly by sick liver cells
80
What happens with obstruction of biliary tracts in the liver?
Bilirubin can't get out of the liver due to obstructed bile flow
81
Where does obstruction of postheptaic biliary system?
Gallbladder
Common bile duct
Pancreas
82
Describe hepatic metabolism
High rate of metabolism
Shares substrates with other organs
Processing and transportation to other organs
83
What are manifestations of liver disease?
```
Decreased albumin
Decreased glucose
Increased bilirubin
Decreased protein metabolism
Increases ammonia
```
84
What does decreased albumin cause?
Decreased colloidal osmotic pressure which leads to effusions and edema
85
What does decreased protein metabolism cause?
Decreased urea
86
What does increased ammonia cause?
Hepatic encephalopathy
87
What are coagulopathies involved in the manifestations of liver disease?
```
Increased prothrombin time
Increased partial thromboplastin
Platelet dysfunction
Decreased fibrinolysis
Excessive fibrinolysis
```
88
What is alanine aminotransferase (ALT)?
Leakage enzyme made inside hepatocytes
| Indicators of hepatic injury
89
What is aspartate aminotransferase (AST)
Leakage enzyme made inside hepatocytes mitochondria
| Indicators of hepatic injury
90
What is alkaline phosphorase (ALP)?
Induced enzyme made in lining of bile caniliculi
| Elevated with cholestasis
91
What is gamma glutamyltranspeptidase (GGT)?
Induced enzymes made in lining of bile caniliculi
Excellent marker for hepatobiliary disease especially biliary tract disease
Elevated with cholestasis
92
What do you look for on bloodwork?
```
Increased bilirubin
Decreased albumin
Decreased cholesterol
Decreased glucose
Decreased BUN
Increased ALT/AST
Increased ALP/GGT
```
93
What can be done to test liver function?
Bile acid assay
| Ammonia tolerance test
94
What are the pros of bile acid assay?
Can do in practice
95
What are the cons of bile acid assay?
Have to feed patient
| Cannot rely on results if bilirubin is elevated
96
What are the pros of ammonia tolerance test?
Can do if bilirubin is elevated
97
What are the cons of ammonia tolerance test?
Not able to do in practice
| Can cause hepatic encephalopathy/coma
