Hepatic pearls part 2

Question 1

Hepatic arterial blood flow is dependent on

Answer 1

metabolic demand- autoregulation

Question 2

Hepatic blood flow promotes sufficient time for the blood to be in contact with

Answer 2

Kupffer cells & hepatocytes

Question 3

Describe bridging fibrosis.

Answer 3

fibrous tissue contracts around the blood vessels & greatly impedes portal vein blood flow

Question 4

Sympathetic activation results in

Answer 4

hepatic artery & mesenteric vessel vasoconstriction & decreased hepatic blood flow

Question 5

Kupffer cells that line the hepatic venous sinusoids

Answer 5

cleanse the blood as it passes through the sinuses

Question 6

Pores in the sinusoids are very permeable and allow easy passage of

Answer 6

fluid & protein into the spaces of Disse–> permits large amounts of lymph to form

Question 7

A 10 to 15 mmHg increase in hepatic venous pressure can increase

Answer 7

lymph flow to 20x normal

-produces “sweating” from the liver surface with large amounts of free fluid entering the abdominal cavity= ascites

Question 8

The liver has the following metabolic functions:

Answer 8

carbohydrate, fat, protein, drug, & miscellaneous metabolism

Question 9

Specific liver functions associated with CHO metabolism:

Answer 9

1. conversion of galactose & fructose to glucose
2. storage of large amounts of glycogen
3. gluconeogenesis
4. formation of many chemical compounds from intermediate products of CHO metabolism

Question 10

Glycogen is a readily available source of glucose that does

Answer 10

not contribute to intracellular osmolality

Question 11

Describe the glucose buffer function:

Answer 11

storage of glycogen allows the liver to remove excess glucose from the blood, store it, & return it to the blood when BG concentration decreases

Question 12

Hepatic glycogen stores are depleted after

Answer 12

a 24 hour fast

after this period we need gluconeogenesis to supply glucose

Question 13

____ enhances glycogen storage

Answer 13

insulin

Question 14

___ enhances glycogen breakdown

Answer 14

epinephrine & glucagon

Question 15

Specific liver functions associated with fat metabolism:

Answer 15

1. oxidation of fatty acids to supply energy for other body functions
2. synthesis of large amounts of cholesterol, phospholipids & lipoproteins
3. synthesis of fat from CHO & proteins

Question 16

To derive energy from fat (triglycerides):

Answer 16

they must be split into glycerol & FAs
FAs are then split by beta oxidation into 2 carbon acetyl radicals that form acetyl coenzyme A
Acetyl Co-A enters the citric acid cycle & yields energy

Question 17

Since the liver cannot use all of the acetyl co-A it produces:

Answer 17

it is converted to acetoacetic acid (combination of 2 acetyl co-A enzymes)
highly soluble and enters the blood & is absorbed by other tissues
reconverted back into acetyl co-A & enters the citric acid cycle
this is the way the liver is responsible for a major part of fat metabolism

Question 18

Specific liver functions associated with protein metabolism:

Answer 18

1. deamination of proteins
2. formation of urea for removal of ammonia from the body fluids
3. formation of plasma proteins
4. synthesis of amino acids & synthesis of other compounds from amino acids

Question 19

Deamination of _____ plays a major role in hepatic gluconeogenesis

Answer 19

alanine

Question 20

All of the plasma proteins with the exception of the

Answer 20

immunoglobulins are formed by hepatocytes

Question 21

Quantitatively the most important plasma proteins are

Answer 21

albumin

& alpha 1 anti-trypsin

Question 22

Qualitatively the most important plasma proteins are

Answer 22

coagulation factors

Question 23

Among one of the most important functions of the liver is the

Answer 23

synthesis of AAs and synthesis of other compounds from AAs

Question 24

Describe transamination

Answer 24

• keto acid is formed & similar to AA but has keto oxygen

- amino radical is transferred from an available AA to the keto acid to take the place of the keto oxygen

Question 25

The most common cause of postoperative jaundice is

Answer 25

over-production of bilirubin due to reabsorption of a large hematoma or RBC breakdown following transfusion

Question 26

All opioids can potentially cause spasm

Answer 26

of the sphincter of Oddi & increase biliary pressure | order of effect: fentanyl, morphine, meperidine, butorphanol, nalbuphine

Question 27

The endocrine stress response may be at least partially blunted by

Answer 27

``` regional anesthesia (blocks afferent signals to the brain so the body doesn't release catecholamines) ```

Question 28

All _____ decrease portal blood flow

Answer 28

volatile agents--> greatest with halothane, least with isoflurane

Question 29

Spinal & epidural anesthesia (effects on hepatic blood flow)

Answer 29

decrease hepatic blood flow by decreasing blood pressure

Question 30

General anesthesia (effect on hepatic blood flow)

Answer 30

usually decreases hepatic blood flow by decreasing blood pressure & CO & resulting SNS stimulation

Question 31

Describe lab values that are changed in pre-haptic liver dysfunction

Answer 31

bilirubin overload increased unconjugated bilirubin (no change to other values)

Question 32

Describe lab values that are change in intrahepatic liver dysfunction:

Answer 32

``` parenchymal/hepatocellular dysfunction increased- conjugated bilirubin increased aminotransferase prolonged PT decreased albmin slightly increased alk phosph ```

Question 33

Describe the lab values that are changed in post-hepatic liver dysfunction:

Answer 33

cholestasis increased-conjugated bilirubin slightly increased aminotransferase increased alk phosph

Question 34

PT measures the activity of

Answer 34

factors II, V, VII, & X

Question 35

Factor VII has

Answer 35

a short half-life & therefore the PT is useful in evaluating hepatic synthetic function

Question 36

In the presence of biliary obstruction, more

Answer 36

alk phos is synthesized & released into the circulation

Question 37

Which is the more specific of the serum aminotransferases?

Answer 37

ALT- primarily located in the liver

Question 38

Serum aminotransferases are

Answer 38

enzymes that are released into the circulation as a result of hepatocellular injury

Question 39

Which bilirubin is toxic to cells?

Answer 39

conjugated

Question 40

A primarily unconjugated hyperbilirubinemia may be seen with

Answer 40

hemolysis or with congenital or acquired defects in bilirubin conjugation

Question 41

A predominantly conjugated hyperbilirubinemia is associated with

Answer 41

an increased urobilinogen & may reflect: intrahepatic cholestasis extrahepatic biliary obstruction a & b may lead to hepatocellular dysfunction

Question 42

Generally liver "function" tests are

Answer 42

not very sensitive or specific

Question 43

Tests that measure the liver synthetic function include:

Answer 43

serum albumin, PT, cholesterol, & pseudocholinesterase

Question 44

Describe phase I reactions

Answer 44

modify substances through CYP450 enzymes & mixed function oxidases oxidation & reduction

Question 45

Describe cross-tolerance

Answer 45

enzyme induction can promote tolerance to other drugs metabolized by the same enzymes

Question 46

Products of phase 1 reactions may be

Answer 46

more active than the parent compound or may be rendered cytotoxic

Question 47

For drugs that have a high rate of hepatic extraction from the circulation,

Answer 47

a decrease in metabolic clearance is a product of reduce hepatic blood flow (not hepatocyte dysfunction)

Question 48

Describe phase II reactions.

Answer 48

may or may not follow a phase 1 reaction involve conjugation of a substance with a H2O soluble metabolite glucuronide is the most common

Question 49

The liver stores large quantities of these vitamins:

Answer 49

A, B12, D, E, & K

Question 50

Describe how the liver stores iron

Answer 50

iron is stored in the liver as ferritin hepatic cells produce apoferritin which binds excess iron in body fluids apoferritin + iron= ferritin- stored in hepatocytes until iron is needed in body during low levels of iron in the circulation ferritin releases iron iron is carried in the blood by transferrin apoferritin-ferritin system therefore acts as an iron storage & buffer system

Question 51

Vitamin K is a required cofactor for the synthesis of factors

Answer 51

II, VII, IX, & X

Question 52

Hepatocytes secrete_____ into the bile canniculi

Answer 52

conjugated bilirubin

Question 53

Flow of bile from the common bile duct is controlled by

Answer 53

the sphincter of Oddi

Question 54

The gallbladder serves as a

Answer 54

reservoir for bile

Question 55

Cholecystokinin is a hormone

Answer 55

released from the intestinal mucosa in response to fat & protein that causes contraction of the gallbladder, relaxation of the Sphincter of Oddi & ejection of bile into the small intestine

Question 56

Bilirubin is the major end product of

Answer 56

end product of hemoglobin degradation

Question 57

Bilirubin provides a valuable tool for diagnosing

Answer 57

hemolytic blood disease & various types of liver disease

Question 58

Describe the formation of bilirubin

Answer 58

hemoglobin is split into globin & heme heme ring is opened and the Fe is released & transported by transferrin 4 pyrrole rings of the prophyrin structure are converted to biliverdin biliverdin is rapidly converted to free bilirubin free bilirubin combines with plasma albumin

Question 59

Describe the summary of conversion of hemoglobin to bilirubin.

Answer 59

hemoglobin--> globin + heme--> Fe + pyrrole rings--> biliverdin--> free bilirubin--> bilirubin + albumin

Question 60

Bilirubin bound to plasma albumin is called

Answer 60

"free bilirubin", unconjugated or indirect bilirubin

Question 61

Free bilirubin is absorbed by hepatocytes, released from albumin, and conjugated with:

Answer 61

glucuronide | or sulfate

Question 62

Conjugated bilirubin is excreted from

Answer 62

or direct bilirubin is excreted from hepatocytes by active transport into the bile canaliculi

Question 63

1/2 of the conjugated bilirubin in the intestines is converted by bacteria to

Answer 63

urobilinogen which is reabsorbed back into the blood | majority of urobilinogen is reexcreted by the liver back into the intestines & eliminated in the feces

Question 64

Excess bilirubin in the ECF produces

Answer 64

jaundice | -large quantities of unconjugated or conjugated bilirubin

Question 65

Common causes of jaundice include:

Answer 65

hemolytic jaundice- increased destruction of RBCs | obstructive jaundice- obstruction of bile ducts or damage preventing bilirubin from being excreted

Question 66

In hemolytic jaundice, RBCs are

Answer 66

hemolyzed rapidly -increased production of bilirubin by macrophages -increased unconjugated bilirubin in blood- hepatocytes cannot conjugate all of the bilirubin results in primarily an increase in unconjugated bilirubin in the blood -excretory function of the liver is not impaired

Question 67

Hemolytic jaundice results primarily in an increase in

Answer 67

unconjugated bilirubin

Question 68

With obstructive jaundice, unconjugated bilirubin enters

Answer 68

the hepatocytes & is conjugated in the usual way the rate of conjugated bilirubin formation is normal but it cannot pass from the liver into the intestines the conjugated bilirubin enters the blood via rupture of the bile canaliculi & direct emptying of bile into the lymph system

Question 69

Most of the bilirubin in the plasma in obstructive jaundice is in the

Answer 69

conjugated form

Question 70

The diagnostic differences between hemolytic & obstructive jaundice include

Answer 70

hemolytic jaundice--> unconjugated or free bilirubin form | obstructive jaundice--> conjugated form

Question 71

When there is total obstruction of bile flow, diagnostically we will see

Answer 71

test for urobilinogen in the urine is completely negative because: no conjugated bilirubin can reach the intestines to be converted to urobilinogen no urobilinogen is reabsorbed into the blood and excreted by the kidney