Final Exam GI Physiology: Liver Flashcards Preview

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Flashcards in Final Exam GI Physiology: Liver Deck (44):
1

Most of the hepatic blood supply is ____________ and delivered by the hepatic portal vein.

hypoxygenated

2

The hepatic artery delivers ________ blood to the liver.

oxygenated

3

How does the liver metabolize carbohydrates?

Uses carbs for glycogenesis, glycogenolysis, and GLUconeogenesis

4

How does the liver metabolize lipids?

Beta-oxidation of fatty acids
FA and TAG synthesis
Synthesis and export of: ketones, cholesterol, and lipoproteins

Converts carbs and AAs into triacylglycerol

5

How does the liver metabolize proteins?

Deamination and transamination

Plasma protein synthesis of:
Albumin, a & B globulins, coagulation factors, complement proteins, plasma antiproteases

NH3 uptake, urea and glutamine synthesis

6

What does the liver do with vitamins?

Stores them! A, D, and B12

7

What does the liver do with iron?

Stores it!

8

What is a Phase I Transformation reaction?

A biotransformation that provides polar groups for reactions.

9

What is a Phase II Transformation reaction?

A reaction that conjugates the products of Phase I reactions to produce a strong acid.

10

What do Phase I reactions do to the toxicity of a compound?

Increases OR decreases the toxicity

11

Bile is produced by which organ?

The liver

12

What are the 4 functions of bile?

1. Emulsification of lipids
2. Excretion of wastes (bilirubin, drugs, hormones)
3. Protection (IgA)
4. Protection (bile acids kill bacteria)

13

What are the 6 components of bile?

1. Electrolytes (with water)
2. Phospholipids (mostly lecithans)
3. Cholesterol
4. Bile acids
5. IgA
6. Biotransformation waste products

14

How does the liver make primary bile acids?

It conjugates cholesterol and amino acids to make bile acids

15

Where are primary bile acids converted into secondary bile acids?

In the small intestine

16

What does high plasma [bile acids] indicate?

Liver disease, compromised bile flow, accumulation of bile, and backflux of bile into circulation

17

Where are bile acids reabsorbed?

Ileum (99% absorbed here)

18

How do bile acids get to the liver?

Through the portal vein

19

Describe the route of bile acids

Liver--> Bile duct --> Intestine --> Portal vein --> Liver

20

What is enterohepatic circulation?

The route that bile acids take starting and ending at the liver

21

What cells are majorly responsible for the degradation of red blood cells and where are they found?

Macrophages found in the spleen degrade RBCs

22

After an RBC is degraded, what happens to the hemoglobin?

It is reduced to biliverdin and reduced further by macrophages, then released as unconjugated bilirubin

23

Is unconjugated bilirubin toxic?

YES!

24

Can unconjugated bilirubin diffuse through cell membranes?

YES!

25

What plasma protein has a high affinity for unconjugated bilirubin?

Albumin

26

Why is it advantageous that albumin has a high affinity for unconjugated bilirubin?

Because unconjugated bilirubin is toxic and can pass through cell membranes. When albumin binds to it, a complex is formed. This complex CANNOT pass through cell membranes.

27

Hepatocytes have albumin receptors which allows for rapid uptake of _________ ________.

unconjugated bilirubin

28

How does unconjugated bilirubin become conjugated bilirubin?

It is acted on by glucuronyl transferase (a conjugating enzyme that performs a Phase II rxn). This produces conjugated bilirubin.

29

Is conjugated bilirubin able to diffuse across cell membranes?

NO, it's water soluble and not bound by albumin

30

Conjugated bilirubin is also known as ________ bilirubin.

DIRECT

31

Unconjugated bilirubin is also known as _____ bilirubin.

INdirect

32

Both forms of bilirubin are colorful _________.

pigments

33

What happens when plasma [bilirubin] rises?

A yellow color is imparted and Jaundice or Icterus occurs

34

What substance is secreted into the bile canaliculi and becomes a component of bile?

Conjugated bilirubin

35

How does conjugated bilirubin get into the small intestine?

Through the bile duct

36

What happend to conjugated bilirubin when it is in the lumen of the small intestine?

Acted on by bacteria that cleave off the glucuronide residue to make free bilirubin.

37

What is free bilirubin reduced to?

Urobilinogen and Stercobilinogen (these terms refer to the ultimate route of excretion- urinary or fecal)

38

How does yellow bile pigment end up in the urine?

Intestinal bacteria removes the gluconuride conjugate residue making the molecule MORE lipid soluble. This allows urobilinogen to be absorbed by the terminal ileum and large intestine. During transfer to the liver via the hepatic portal vein, some urobilinogen escapes and is excreted by the urinary route.

39

How do bile acids enter the bile canuliculi?

By using membrane pumps that use ATP

40

The presence of bile acids in the canuliculi draws water by __________ and electrolytes by _________.

Osmosis; solvent drag

41

What are cholangiocytes?

bile ductular cells

42

How are bile ductular cells like pancreatic ductular cells? What is the result?

They both exchange HCO3- for Cl- which increases the pH of bile (makes it more basic)

43

What stimulates bile and pancreatic ductular cells?

Secretin

44

What are choleliths?

Gall stones