GI Liver and bilirubin metabolism

Question 1

Where is Ammonia formed and what is the rout it takes for first pass metabolism?

Answer 1

formed within intestines from nitrogenous substances (proteins) → sent to liver via portal vein → converted to urea → enters systemic circulation → excreted in urine

Question 2

Where is Estrogen formed and what is the rout it takes for first pass metabolism?

Answer 2

formed in tissues throughout body → sent to liver via hepatic artery proper → broken down into metabolites → excreted in urine, feces and bile

Question 3

Result of excess estrogen on
local arterioles
Hypothalamus: levels of GnRH, FSH, and LH

Answer 3

Cirrhosis → excess estrogen

(1) Localized arteriole dilation → spider angiomas
(2) Gynecomastia
(3) Negative feedback on hypothalamus → decreased GnRH, FSH, and LH release → testicular atrophy (males) or amenorrhea (females)

Question 4

1. A male patient with known hepatic cirrhosis develops gynecomastia. Why?

Answer 4

Liver dysfunction leads to excess estrogen which can lead to gynecomastia.

Question 5

2. A patient with chronic liver failure demonstrates purpura and petechiae. Why?

Answer 5

Decreased TPO–> decreased platelet formation in bone marrow leading to these.

Could also be a decrease in coagulation factors produced in the liver.

Question 6

How does copper get to the liver?

How is this process altered in a patient with Wilson’s Disease?

Answer 6

Copper–>bsorbed in the small intestine–> Albumin carries TO the liver thorug the portal vein.

From liver–> carried via Ceruloplasmin

Wilsons: Low Ceruloplasmin

Question 7

4. A statin drug inhibits an enzyme to decrease cholesterol synthesis. Where in the body does it directly act?

Answer 7

inhibit HMG-CoA reductase in liver

Question 8

5. A female patient with type II diabetes injects insulin. What would happen to glycogenolysis and gluconeogenesis?

Answer 8

Insulin inhibits while glucagon up-regulated it.

Question 9

6. An infant is jaundiced at birth. Serum analysis shows elevated unconjugated bilirubin. Will the urine of the infant appear dark?

Answer 9

High indirect bilirubin. This can occur either bc the liver is overwhelmed or because of immature UGT enzymes. Bilirubin has to be water soluble to enter water so urine will not be dark.

Question 10

7. It is determined that this infant has normal physiological jaundice. Will this patient have clay-colored stool?

Answer 10

No because there is still a small about of UCB that is making it to the intestines to be converted to stercobilin.

Question 11

8. A 60 year old male with a history of alcoholism and pancreatitis presents with painless jaundice and epigastric pain. What is the most likely diagnosis?

Answer 11

Pancreatitis–> obstructs bile duct–> obstructive jaundice due to inability to release bile.

Clay colored stool dt inability for CB to get to intestines.

Pancreatic adenocarcinoma

Question 12

3 metabolic pathways for carb metabilism that occurs in the liver.

Answer 12

A. Gluconeogenesis
B. Glycogen storage
C. Glycogenolysis → glucose released into bloodstream

Question 13

Rate limiting enzyme in lipid metabolism

Answer 13

HMG-CoA reductase

Question 14

Describe the breakdown of RBC and how it leads to bilirubin metbolism.

Answer 14

Macrophages break down RBC–> heme is broken down into iron and protoporphyrin → iron is recycled, protoporphyrin is converted to unconjugated bilirubin (UCB)–> carried by Albumin

Question 15

Enzyme that converts UCB to CB

Answer 15

Uridine glucuronyl transferase (UGT)