9-Digestive system-III-Liver, galbladder, pancreas

Question 1

Gross features of the liver

Answer 1

-Located between ribs 7-11 mainly on the right side
-2 main lobes R>L and two accessory lobes( caudate and quadrate)
-Both exocrine and endocrine function
Covered by Glisson’s capsule
-Plates of hepatocytes separated by sinusoids which carry blood

Question 2

Hepatocytes

Answer 2

• Large polygonal cells with up to 6 surfaces
• Two basal surfaces face sinusoids and contain microvilli
• up to 4 sides facing neighboring cells- tight junctions seal off intercellular spaces called bile canaliculi

Question 3

Hepatocytes(organelles)

Answer 3

• Rough and smooth ER ae abundant
• Golgi is by bile cannaliculi and packages bile for excretion
• Numerous mitochndria
• Peroxisomes and lysosomes present

Question 4

Sinusoids

Answer 4

Endothelial cells that line the sinusoids are discontinuous and fenestrated.
Hepatocyte microvilli extend into the Space of Disse

Question 5

Space of Disse

Answer 5

Space between the hepatocytes and the endothelial cells

Question 6

Biliary tree(list)

Answer 6

1) Bile canaliculi
2) Biles cutules (canal of Hering)
3) Bile ducts

Question 7

Bile canaliculi

Answer 7

Small extra cellular canal between adjacent hepatocytes

Question 8

Bile ductules (Canal of hering)

Answer 8

• Cuboidal shaped epithelium(changiocytes)

- Carry bile to the portal triad

Question 9

Bile ducts

Answer 9

Cuboidal to columnar epithelium

-Join to form right and left hepatic ducts which join the common hepatic ducts

Question 10

Hepatic stellate cells(Ito cells)

Answer 10

• In the perisinusoidal space
• store Vitamin A in cytoplasmic lipid droplets
• With chronic inflammation they can differntiate ino myofibroblasts and deposit type I and III collagen. Causing fibrosis then cirrhosis

Question 11

Kupffer cells

Answer 11

• Macrophages in the liver
• derived from monocyte
• located in sinusoids

Question 12

Main vessels of hepatic circulation

Answer 12

Portal vein
Hepatic vein
Hepatic artery

Question 13

Portal vein

Answer 13

Collects poorly oxygenated blood but nutrient(and toxic) rich blood from the GI tract and carries it to the liver

Question 14

Hepatic vein

Answer 14

Carries the filtered blood from the liver to the inferior vena cava ending up in the right atrium

Question 15

Parenchyma

Answer 15

Tissue of the liver

Question 16

Hepatic artery

Answer 16

Supplies oxygenated blood to the liver

Question 17

Blood flow in the liver

Answer 17

Portal vein and hepatic artery blood mix in the sinusoids and drain to the central vein

Question 18

portal “triad” canals

Answer 18

-Terminal portal vein, Terminal hepatic artery, bile ducts and lymphatic vessels run together.

Question 19

Classic liver lobule

Answer 19

In a hexagon the corners are portal canals, the blood drains into the sinusoids. Blood is modified and drains into the central vein which is at the center of the hexagon

Question 20

Portal lobule

Answer 20

A triangle around the portal canal. The bile moves from the corners(central vein) to the portal canal.

Question 21

Functions of the liver(summary list)

Answer 21

1. Secretion of bile
2. Excretion of waste(bilirubin) conjugated to bile
3. Secretion of blood-borne substances into sinusoid
4. detoxification/metabolism of natural or exogenous substances
5. Immune response

Question 22

Bile secretion

Answer 22

Bile is secreted by hepatocytes into bile canaliculi then through a series of duct and accumulates into the gall bladder. It is excreted into the duodenum then reabsorbed by enterocytes and into portal blood. bile salts get reabsorbed by heptocytes and re-released

Question 23

Bile function

Answer 23

Emulsifies fats for absorption

Question 24

Excretion of waste by the liver

Answer 24

Excretes bilirubin into the bile which is a toxic product of degradation of RBCs

Question 25

Secretion of blood-borne substances

Answer 25

- Stores extra glucose as glycogen and releases glucose when needed. - secreets plasma proteins like Albumin, clotting proteins, complement cascade proteins, lipoproteins, all non-essential AA.

Question 26

Detoxification/metabolism

Answer 26

SER of hepatocytes can metablizes fat soluble toxins.

Question 27

Enterohepatic cirulation

Answer 27

It is where drugs can be excreted with bile into the intestine and reabsorbed. It then goes back into systemic circulation. Can amplify bioavailability of drugs

Question 28

First pass efffect

Answer 28

Since all thing absorbed by the intestine go thorugh the liver it can lower the bioavailabilty of drugs before even entering systemic circulation.

Question 29

Grapefruit juice affect on liver

Answer 29

It inhibits first pass drug metabolism prolonging bioavailabilty of drugs

Question 30

Immune response/ protecction

Answer 30

Kupffer cells remove harmful materials from the sinusoids

Question 31

Sphincter of Oddi

Answer 31

Sphincter that closes off the cystic duct(carries bile) from liver and gall bladder into the duodenum.

Question 32

Gall bladder(function)

Answer 32

It fills up with bile when the sphincter of Oddi is closed and the cystic duct backs up into the gall bladder. Cholecystokinin,released by enteroendocrine cells, stimulates galbladder contraction and sphincter relaxation allowing bile release.

Question 33

Gall bladder (structure)

Answer 33

Simple columnar epithelium which absorbs water and keeps bile concentrated. - Lamina propria/submucsa may contain lymphoid tissue - No muscularis mucosa - Oblique bundles of SM make the muscularis

Question 34

Pancreas

Answer 34

``` 25cm x 5cm x 2cm behind the stomach at the bottom of the liver. Both exocrine(into duodenum) and endocrine(into blood) ```

Question 35

Exocrine pancreas

Answer 35

Made up of acini and ducts. Excretory cells produce digestive proenzymes, stored in zyogen granules apical side of the cell -Centroacinar cells start the duct in the acini -Aqueous portion is secreted by the duct