Section 3B

Question 0

Where is glycogen found in the most concentration? Muscles or liver?

Answer 0

Most concentration in liver but because there is more muscle in the body it has larger total amount. Muscle stores up to 1-3% of its mass in glycogen and liver is up to 8%

Question 1

Liver cells can typically store up to what percent of their weight as glycogen?

Answer 1

8%

Question 2

Amino acid degradation occurs with what process?

Answer 2

Deamination - removal of amine groups from amino acids

Question 3

What enzymes are required for deamination reactions?

Answer 3

Aminotransferases (also known as transaminases)

Question 4

What two specific aminotransfersases are needed to degrade amino acids?

Answer 4

Aspartate transaminase (AST) - also called SGOT (serum glutamate-oxaloacetate transaminase)
Alanine transaminase (ALT) - also called SGPT (serum glutamate-pyruvate transaminase)

Question 5

What are the dual purposes of AST and ALT?

Answer 5

1. They are involved amino acid degradation in deamination reactions
2. They are also used to synthesize non-essential amino acids within liver hepatocytes

Question 6

High blood levels of AST and ALT are indicative of what?

Answer 6

Liver disease

Question 7

What happens to the amine groups that are cleaved from the amino acids?

Answer 7

Amine groups are converted into ammonia (NH3) or ammonium ions (NH4+) which are then converted into urea.

Question 8

Where is all the urea formed in the body synthesized?

Answer 8

The liver

Question 9

In serious liver disease, ammonia can often accumulate in the blood and lead to a state called what?

Answer 9

Hepatic coma or hepatic encephalopathy

Question 10

A build up of urea in the blood can lead to a state of what?

Answer 10

Azotemia or Uremia in which high levels of urea can become toxic to a variety of tissues.

Question 11

Uremia is often a symptom of what disease?

Answer 11

Renal failure.

Question 12

What is the normal range of blood urea nitrogen (BUN)?

Answer 12

5-26 mg/dL

Question 13

Elevated BUN can occur with what four things?

Answer 13

1. Impaired renal function
2. Increased protein intake or catabolism
3. GI bleeding (due to intestinal flora creating nitrogenous wastes)
4. Dehydration

Question 14

Where does amino acid degradation almost entirely occur?

Answer 14

Liver

Question 15

How can the body eliminate excess cholesterol?

Answer 15

via the bile

Question 16

When is ketogenesis occuring?

Answer 16

Primarily in fasting states or poorly controlled type 1 diabetes mellitus

Question 17

What 3 hormones does the liver degrade?

Answer 17

1. Steroid hormones
2. T3
3. T4

Question 18

Iron is stored in the liver as what?

Answer 18

Ferritin

Question 19

Liver stores what vitamins?

Answer 19

Vitamin A
Vitamin B12
Vitamin D

Question 20

Liver is by the far the most important organ in this type of metabolism?

Answer 20

Drug metabolism

Question 21

Why does drug metabolism occur in the liver?

Answer 21

Because of the many enzyme systems. The cytochrome P450 system being most important

Question 22

Cytochrome P450 enzymes can be found predominantly in the liver but also in what other places?

Answer 22

Intestines
Lungs
Other organs

Question 23

How are Cytochrome P450 enzymes named?

Answer 23

CYP followed by an arabic number, letter, and another arabic number

Question 24

What is the purpose of conjugation reactions/

Answer 24

To make metabolites more polar or hydrophilic sometimes after they've been created by cytochrome p450 enzymes

Question 25

Conjugation reactions involve an endogenous substrate such as what being added to a metabolite?

Answer 25

Glucuronic acid Glutathione Acetyl CoA or an Amino acid

Question 26

What is the most common and important conjugation reaction?

Answer 26

Glucuronidation

Question 27

CP450 inhibition leads to what?

Answer 27

Decreased metabolic activity of CP450 enzymes leading to decreased metabolism of drugs

Question 28

3 major types of plasma proteins

Answer 28

Albumin Fibrinogen Globulin

Question 29

Where are the major plasma proteins formed?

Answer 29

All of fibrinogen and albumin as well as 50-80% of globulin are formed in the liver

Question 30

Where is the plasma protein globulin formed?

Answer 30

50-80% in the liver | Remaining is in the lymphoid tissues

Question 31

What blood clotting factors are synthesized in the liver?

Answer 31

I, II, V, VII, VIII, IX, X, XI, XII | not III, IV or VI

Question 32

What is the organic recipe for bile?

Answer 32

Bile salts (50%) Phospholipids (40%) Cholesterol (4%) Bile pigments such as bilirubin (2%)

Question 33

Other than the 4 constituents of bile, what else does it contain and where are they secreted from?

Answer 33

Electrolytes and water which are secreted by cells lining the bile ducts

Question 34

Hepatocytes synthesize what two primary bile acids?

Answer 34

Cholic acid and chenodeoxycholic acid

Question 35

What are the two secondary bile acids and how are they made?

Answer 35

- Deoxycholic acid - Lithocholic acid They are made as intestinal bacteria convert primary bile acids into secondary bile acids

Question 36

The liver conjugates the bile acids with what two amino acids to form bile salts?

Answer 36

Glycine or Taurine

Question 37

What is the most common phospholipid in the bile

Answer 37

Lecithin

Question 38

T or F, phospholipids are Amphipathic

Answer 38

True

Question 39

Hepatic synthesis of bile acids accounts for the majority of the breakdown of what?

Answer 39

Cholesterol

Question 40

How much cholesterol is converted to bile acids and eliminated in bile each day

Answer 40

500 mg

Question 41

What is bilirubin?

Answer 41

A waste product of hemoglobin degradation

Question 42

What are the two different types of bilirubin and their many different names?

Answer 42

1. Free or unconjugated or indirect bilirubin | 2. Conjugated or direct bilirubin

Question 43

As bilirubin passes into the liver and is released from albumin, hepatocytes has three functions.

Answer 43

1. Uptake of bilirubin from circulation 2. Conjugation of bilirubin 3. Excretion of bilirubin into bile

Question 44

What is attached to bilirubin during conjugation and what enzyme carries out this function?

Answer 44

Glucuronic acid is attached | Enzyme: Glucuronyl transferase

Question 45

T or F, Conjugated bilirubin is much more water-soluble than free or unconjugated bilirubin

Answer 45

Treu

Question 46

Synthesis of bile occurs in what three steps?

Answer 46

1. Hepatocytes actively secrete bile into the bile canals (canaliculi) 2. Intrahepatic and Extrahepatic ducts not only transport this bile but the cells that line these ducts also secrete a watery, HCO3- rich fluid 3. Between meals, approx 1/2 the hepatic bile is diverted to the gallbladder, which stores and removes salts and water

Question 47

So during meals, the bile that actually reaches the duodenum has what makeup?

Answer 47

It has diluted hepatic bile and concentrated bile from the gallbladder

Question 48

Bile has what 2 important functions?

Answer 48

1. Bile provides the sole excretory route for many solutes that are not excreted by the kidneys 2. Secreted bile salts and lecithin are required for normal lipid digestion and absorption in the small intestine