6: Jaundice & The Liver

Question 1

what separates the left and right lobes of the liver

Answer 1

the falciform ligament

Question 2

lobes divided into

Answer 2

segments (8 in total)

Question 3

segments comprise of

Answer 3

Hepatic Lobules

Question 4

what’s the functional unit of the liver

Answer 4

Hepatic Lobules

Question 5

describe Hepatic Lobule

Answer 5

Hexagonal arrangement
Around a CENTRAL VEIN
At each 6 corners:
-a branch of the HEPATIC ARTERY
-a branch of the HEPATIC PORTAL VEIN
-a BILE DUCT

Question 6

blood flows from hep artery and hep portal vein via…

Answer 6

sinusoids

Question 7

sinusoids lined by

Answer 7

Kupffer cells - engulf old RBCs and bacteria from the blood

Question 8

cells of the liver

Answer 8

80% Hepatocytes.
10% Sinusoidal endothelial cells
9% Immune Cells
1% Bile Duct Endothelial Cells

Question 9

name for spaces between hepatocytes, cells found there and what they store

Answer 9

a. Spaces of Disse
b. Stellate cells
c. Store Vitamin A

Question 10

Blood Supply

Answer 10

75% - Hepatic Portal Vein
-formed by veins draining the GIT
-these contain all the absorbed nutrients
25% - Hepatic Artery
-arises directly off the Aorta
Blood then LEAVES Liver via Hepatic VEIN

Question 11

what does the Hepatic Artery provide to the liver

Answer 11

1. metabolites

2. oxygen supply

Question 12

what vein converge to form the Hepatic Vein (leaving liver)

Answer 12

The Central Veins

Question 13

where does the Hepatic Vein flow

Answer 13

Inferior Vena Cava

Question 14

what is the driving force of bile flow

Answer 14

Osmotic gradient of bile salts and sodium created by hepatocytes

Question 15

describe the pathway of bile

Answer 15

hepatocytes –> bile canaliculi –> INTRAhepatic Bile Ducts –> Left/Right Hepatic Duct –> Common Hepatic Duct –> Common BILE Duct (formed also by CYSTIC DUCT from gallbladder joining it)

Question 16

Sphincter of Odi

Answer 16

maintains the pressure within Common BILE Duct by rhythmic contraction and relaxation

Question 17

how is gallbladder bile

Answer 17

10x more concn due to reabsorption of water and electrolytes

Question 18

role of gallbladder contraction

Answer 18

force out bile into duodenum by applying pressure to the Common Bile Duct

Question 19

Functions of Liver (first 3)

Answer 19

1. Metabolism of carbs, amino acids and lipids after their absorption
2. Detoxification and degradation of:
   - body wastes
   - hormones
   - drugs
3. Synthesis of Plasma Proteins
   - needed for Blood Clotting
   - Angiotensinogen (important in RAAS)
   - Transport of Cholesterol, Thyroid Hormones and Steroids

Question 20

Functions of Liver (next 3)

Answer 20

4.Storage of Glycogen, Fats, Iron, Copper, Large amounts Vit A, D & B12
5.Removal of BACTERIA
-old RBCs
due to its resident macrophages
6.Activation of Vit D (7-dehydrocholesterol) to 25-OH Vitamin D. Activation is done in conjunction w kidneys

Question 21

Functions of Liver (last 3)

Answer 21

7. Secreting Hormones
8. Secreting Acute Phase Proteins
9. Excreting Cholesterol and Bilirubin

Question 22

List hormones secreted

Answer 22

1. THROMBOPOIETIN - stimulates platelet production
2. Insulin-like Growth Factor I (stimulates growth)
3. HEPCIDIN - stimulates iron uptake from the intestine

Question 23

Coagulation factors produced

Answer 23

1. Clotting Factors:
II
VII
IX
X
2.Proteins involved in Clotting Cascade
*synthesis of these impaired when deficiency of Vit K as these are post-translationally modified by Vit K-dependent ENZYMES

Question 24

Role of plasma protein Albumin

Answer 24

1. transport of Bilirubin

2. transport of hormones throughout body & drugs

Question 25

Bilirubin a product of

Answer 25

Heme catabolism

Question 26

Bilirubin form in the blood

Answer 26

Unconjugated - bound to albumin.

This form is taken up by hepatocytes at the sinusoidal mebrane & conjugated

Question 27

Fate of conjugated bilirubin

Answer 27

exported into Bile Canaliculus by Specific Carriers and excreted in Bile into the bowel lumen

Question 28

name of product to which colonic bacteria metabolize bilirubin & fate

Answer 28

StercoBILINOgen which may be further oxidised into STERCObilin
both are excreted in faeces (gives dark colour)