Gi Week 4 Objective 2

Front 1

What are the 3 basic functions of the liver in glucose metabolism?

Back 1

1. Store glucose
2. Breakdown glucose
3. Make glucose from other organic molecules

Front 2

What is the name of the biochemical process the liver utilizes when storing glucose?

Back 2

Glycogen synthesis

Front 3

Name the enzyme responsible for “trapping” glucose within hepatocyts:

Back 3

glucose-6-phosphatase

Front 4

What chemical reaction does glucose-6-phosphatase catalyze?

Back 4

Glucose → glucose-6-phosphate

Front 5

What structural arrangement is glucose stored as glycogen?

Back 5

Glycogen is arranged in a tree-like branching structure

Front 6

Name the glucose linkages that give glycogen it’s branching structure:

Back 6

a-1,4 linkage and a-1,6 linkage

Front 7

What tissues/ organs rely on the liver storage of glucose?

Back 7

RBC, retina, renal medulla and brain

Front 8

Why do RBCs, the retina, the renal medulla and the brain rely on liver stores of glucose?

Back 8

These tissues do not have the capacity to store their own metabolic fuel

Front 9

What is the name of the biochemical process the liver utilizes to produce chemical energy in the form of ATP from glucose?

Back 9

Glycolysis

Front 10

What are the chemical products of glycolysis?

Back 10

Glucose → 2 ATP + pyruvate

Front 11

Describe the branching pattern of glycogen:

Back 11

Glucose monomers are linked together by -1,4 glycosicic bonds, with β-1,6-glycosidic branching occurring approximately every 10 units.

Front 12

What is the significance of glycogen’s branched structure?

Back 12

Branching increases the solubility of glycogen, and it also increases the rate at which glucose can be stored and mobilized from glycogen.

Front 13

What organs are dependent on glucose as their fuel source; where is this store located and in which form?

Back 13

The erythrocytes, retina, renal medulla, and brain are dependent on glucose for fuel, the liver and muscle both store glycogen as a reserve for these organs.

Front 14

True or false: the breakdown of glucose into pyruvate requires energy derived from ATP?

Back 14

True.
The catabolic enzyme hexokinase requires ATP to create one G6P from each glucose molecule.

Front 15

What is the starting point for glycolysis, what is the end product and what will happen to it next.

Back 15

Glucose
Pyruvate
Citric Acid Cycle

Front 16

What is the Cori Cycle?

Back 16

Front 17

What is the name of the biochemical process the liver utilizes to produce glucose from of the organic substrates?

Back 17

Gluconeogenesis

Front 18

What organic substrates can be used in gluconeogenesis?

Back 18

Pyruvate, amino acids, lactate

Front 19

Describe the Cori cycle:

Back 19

muscle lactate produced by anaerobic metabolism → transported to liver hepatocytes via blood → lactate is converted to glucose via gluconeogenesis → glucose is transported to muscles → repeat

Front 20

What is ammonia?

Back 20

Metabolic waste product from amino acid metabolism

Front 21

How is ammonia produced?

Back 21

When an amino group is released from an amino acid

Front 22

What is the chemical formula for ammonia?

Back 22

NH3

Front 23

What organ removes ammonia in the body?

Back 23

The liver

Front 24

How is ammonia removed from the body?

Back 24

Ammonia is combined with CO2 to produce urea (NOTE: there are several steps, substrates and enzymes involved in this process)

Front 25

What are the advantages of converting ammonia into urea?

Back 25

Urea is non-toxic and water-soluble

Front 26

What is the advantage of urea being water-soluble?

Back 26

Urea can be excreted via the kidneys

Front 27

Describe the production of unconjugated billirubin:

Back 27

1. With in phagocytes RBC are digested
2. Heme is released from RBC
3. Heme → Biliverdin (releasing iron and CO) via Heme oxygenase
4. Biliverdin → Bilirubin (water insoluble) via biliveriden reductase
5. Bilirubin binds to albumin and transported in the blood

Front 28

Describe the production of conjugated bilirubin:

Back 28

1. Unconjugated bilirubin → travel to sinusoid capillaries of liver → free bilirubin enter hepatocyte
2. Free bilirubin → bind to ligandin (prevent diffusing out of cell)
3. Bilirubin → conjucation with glucuronic acid via glucuronyl transferase
4. Conjugated bilirubin → bile via energy dependent excretion

Front 29

Describe the production and fate of urobilinogen:

Back 29

1. Conjugated bilirubin in bile → urobilinogen via intestinal bacteria
2. Urobilinogen absorbed into portal circulation or excreted as feces
3. Urobiligen → liver (excreted as bile again) or kidney (excreted in urine)

Front 30

Describe the fate of urobilinogen excreted as feces:

Back 30

1. Urobiligen → stereobilinogens via bacteria
2. Stereobilinogen → stercobilins via oxidation

Front 31

What process in the body generates ammonia?

Back 31

Amino acid catabolism releases amino groups which form ammonia.

Front 32

How does the body deal with the ammonia it creates?

Back 32

The primary mechanism for converting neuro-toxic ammonia into urea is through the hepatic urea cycle.

Front 33

How might you treat acute hyperammonemia?

Back 33

Hemodialysis or exchange trasfusions to lower the blood ammonia level.

Front 34

What lifestyle management schemes might you recommend to your patient who suffers from hyperammonia?

Back 34

Decrease dietary protein intake.

Front 35

You are a CC-3 on your pediatric rotation when you see a neonate presenting with mental retardation and convulsions. Your are a ken reviewer and had recetly looked over your GI-4 notes, what from GI-4 would you include in you DDx?

Back 35

A genetic deficiency in the urea cycle enzymes, inducing an ammonia toxicity, this X-linked trait are known to occur at a rate of 1/25000 live births.

Front 36

Define Bilirubin.

Back 36

Bilirubin is the yellow breakdown product of heme produced by the reticuloendothelial system.

Front 37

What are the components of the reticuloendothelial system?

Back 37

Spleen
Kupffer Cells
Bone Marrow
Connective Tissue
Lymph Nodes

Front 38

What is the function of the reticuloendothelial system?

Back 38

To recognize aging erythrocytes and to break them down into heme and globin.

Front 39

What is the result of a UDP-glucuronyl transferase deficiency?

Back 39

Bilirubin would remain uncongugated and which would present as intrahepatic induced jaundice.

Front 40

What is Gilbert’s Syndrome?

Back 40

Gilbert's syndrome is caused by approximately 30%-50% reduced glucuronidation activity of the enzyme UDP-glucuronyl transferase and presents as jaundice with elevated serum unconjugated bilirubin

Front 41

What is enterohepatic circulation of bilirubin?

Back 41

Conjugated bilirubin is converted by intestinal flora to urobinogen which is mostly absorbed in the terminal ileum and re-excreted by the liver, some is eliminated I the feces.