Histology Digestive Glands 2

Front 1

Liver:

Back 1

= 2nd largest organ
- composed of a single type of parenchymal cell = hepatocyte
*IGF-I
*Angiotensionogen
*Thrombopoietin

Front 2

Hepatocyte..

Back 2

possess a myriad of both endocrine and exocrine functions

Front 3

What is a Glisson's Capsule?

Back 3

composed of thin CT that subdivides the liver into lobes and lobules

Front 4

Blood supply to the liver:

Back 4

Derived from 2 sources:
1. Abdominal aorta, via the hepatic artery (=branch of celiac trunk)
2. Portal vein --> brings nutrient-laden blood from the alimentary tract and the spleen

Front 5

Porta Hepatis:

Back 5

the region where:
- the hepatic artery and portal vein ENTER liver
- the hepatic ducts LEAVE the liver

Front 6

Drainage of blood of the liver is via:

Back 6

Hepatic vein
- hepatic vein is formed by the union of numerous sublobular veins
- sublobular veins collect blood from the central vein of each classical liver lobule

Front 7

Transportation of bile:

Back 7

- leaves the liver via hepatic ducts
- delivered to the gallbladder

Front 8

Portal triad consists of:

Back 8

Hepatic artery
Bile duct
Hepatic vein

Front 9

3 types of liver lobules are:

Back 9

1. classical (hexagonal)
2. portal lobule (triangular)
3. liver acinus of Rappaport (liver acinus - diamond-shaped)
*nutrient-rich blood towards central vein --> out of liver
*bile towards peripheral to portal canals --> intestine

Front 10

Features of the classical lobule:

Back 10

- based on the pig's liver, where CT elements clearly delineate it
- portal area (portal canal; triad) is present at each corner of the lobule
- portal area contains branches of the portal vein, hepatic artery, bile duct, lymph vessel*

Front 11

Structure of the Liver:

Back 11

Kupffer cells (=marophages) within the sinusoid
-hepatocytes (plate-like) arranged in columns separated by sinusoides

Front 12

The liver lobule is surrounded by:

Back 12

Portal space

Front 13

What occupies the portal spaces?

Back 13

Arteries
Veins
bile ducts
Nerves
CT
lymphatic vessels

Front 14

What forms the radial disposition of the plates in the lobule?

Back 14

Hepatocytes
- plates are separated by the Sinusoidal capillaries
- Bile canaliculi seen between the hepatocytes

Front 15

What drains the blood from the live lobules?

Back 15

Sublobular (intercalated) veins

Front 16

What type of tissue is this?

Back 16

Liver
- purple: hepatocytes
- white spaces: sinusoids

Front 17

What type of tissue is seen in this slide?

Back 17

Collagen type 3 reticular fibers in the lobule --> forming a scaffold for the hepatic tissue
Stain: silver impregnation

Front 18

Plates of Hepatocytes:

Back 18

- compose the bulk of the lobule
- arranged in a radial fashion, radiating from the region of a central vein
- blood flows from the periphery of the lobule forward the central vein

Front 19

Portal triad is composed of:

Back 19

Portal vein
Hepatic artery
Bile duct
*lymphatics

Front 20

Bile Canaliculi:

Back 20

= slender intercellular spaces between neighboring hepatocytes
- convey bile to canals of Herring
- canals of Herring deliver bile ducts in the portal area at the periphery of the classical lobule

Front 21

Flow of bile and blood is...

Back 21

in Opposite direction

Front 22

Hepatocytes are jointed by...

Back 22

Tight (occluding) junctions
where bile cannot leak

Front 23

What is show in this micrograph?

Back 23

Bile canaliculus (rat liver)
-microvilli in lumen
-junctional complexes (yellow arrows) =[tight junction]

Front 24

The junction of bile and canaliculi and bile ductules are lined by...

Back 24

Cuboidal epithelium
- the ductules merge with bile ducts in the portal spaces

Front 25

What are sinusoids?

Back 25

= endothelial-lined spaces between neighboring plates of hepatocytes
- receive blood from the vessels in the portal area and deliver it to the central vein

Front 26

Endothelial cells lining the sinusoids are:

Back 26

NOT continuous, have large fenestrations
- display discontinuous between neighboring cells

Front 27

What type of tissue is this?

Back 27

Liver
sinusoidal capillary with large fenestrations (red circle)

Front 28

What are Kupffer cells?

Back 28

= phagocytic cells that are derived from monocytes
- they are also present outside/within the endothelial lining

Front 29

What are the structures circled in red?

Back 29

Kupffer cells (present towards the sinusoid)
- sinusoid capillaries close to hepatocytes
- Disse = thin slit between the hepatocytes and the endothelium

Front 30

Space of Disse are located at:

Back 30

visualized by EM as a subendothelial space between the liver cells (hepatocyts) and the lining cells of the sinusoids

Front 31

Space of Disse contains:

Back 31

-stellate-shaped fat storing cells (preferentially store vit. A)
- reticular fibers (maintains the architecture of the sinusoids)
- NON-myelinated nerve fibers
- short, blunt microvilli of hepatocytes (increase S.A.)

Front 32

Functions of the Space of Disse?

Back 32

exchange of material between the bloodstream and the hepatocytes (which do not contact the
bloodstream)

Front 33

Is Basal Lamina present in the Space of Disse?

Back 33

NO!

Front 34

Where is the portal lobule located?

Back 34

-it is based on the liver's exocrine function; in many exocrine glands, the ducts is in the center of a lobule

Front 35

Portal Lobule:

Back 35

a triangular region whose 3 apices are neighboring central veins
-Has a portal canal in a central position and central veins at the edges of the cross-sectioned lobule

Front 36

Liver Acinus (of Rappaport):

Back 36

= another interpretation of lobulation in the liver
- based on blood flow
- diamond-shaped structure
- distributing vessels in the center & central veins at each pole
- portal area shared by the 2 neighboring classical lobules

Front 37

What is Zonation?

Back 37

blood enters the sinusoids from vessels located in the interface between the two neighboring classical lobules (bases of the equilateral triangles)

Front 38

Hepatocytes:

Back 38

- first to be "exposed" to the entering blood
- near the central vein, they are the last to be "exposed"

Front 39

Three zones within each acins of Rapport:

Back 39

1: in the immediate vicinity of the blood supply
3: in the area of the central vein
2: in between zone 1 & 3

Front 40

Structure of Hepatocytes:

Back 40

- large, polyhedral cells that stain light pink with Hematoxylin & eosin (H&E)
- usually possess 1 or 2, centrally placed round nucleus (polyploid)
- frequently >2 nuclei may be present in a single cell
- bile canaliculi are between neighboring hepatocytes

Front 41

Organelles within the liver cells:

Back 41

Under EM
- rich in RER & SER
- rich in mitochondira
- several golgi regions
- lysosomes
- peroxisomes
- lots of lipid droplets
- lots of glycogen

Front 42

Carbohydrate stored in the liver in the form of:

Back 42

glycogen
- usually associated with SER, when glucose is needed, glycogen is degraded

Front 43

Proteins produced by hepatocytes are synthesized in...

Back 43

RER

Front 44

Hepatocyte lesions or starvation lead to ...

Back 44

decrease in amounts of albumin, fibrinogen, prothrombin in a pt's blood
--> imp for blood's osmotic pressure and for coagulation

Front 45

10% of bile acids are made in the liver, how are they made?

Back 45

by conjugation of cholic acid with the amino acids glycine and taurine
- this process occurs in the SER

Front 46

Secretion of bilirubin:

Back 46

the Water-insoluble form of bilirubin is derived from the metabolism of hemoglobin in macrophages
*Bilirubin can be "conjugated" with a molecule of glucuronic acid which makes it soluble in water
*Bilirubin diglucuronide is a conjugated form of bilirubin

Front 47

2 types of the surfaces (liver cells):

Back 47

1. those that border the space of Disse
2. those that are adjacent neighboring hepatocytes

Front 48

What takes place in the adjacent space of Disse?

Back 48

Microvilli assist in the transfer of materials to and from hepatocytes. It is here that the endocrine secretion of the liver also take place.
*microvilli extend into the bile canaliculus from each hepatocyte

Front 49

What do the adjacent neighboring hepatocytes form?

Back 49

- Form small, tunnel-like bile canaliculi that represent intercellular spaces
- Form occluding junctions at each surface of the bile canaliculus

Front 50

Bile Canaliculi:

Back 50

Receive the exocrine secretion of the liver (bile)
--> representing the beginning of the duct system

Front 51

Neighboring hepatocytes contact one another via?

Back 51

Gap Junctions

Front 52

Intrahepatic Bile ducts consists of:

Back 52

1. bile canaliculi
2. cholangioles
3. canals of Herring (bile ductules), lined by a layer of low cuboidal cells
4. bile ducts, lined by a single layer of cuboidal cells