Anatomy and Cell Biology 3309 Lecture Notes - Lecture 19: Lobules Of Liver, Portal Vein, Hepatic Veins
22 May 2018
School
Department
Professor
Histology 3309
Liver
Learning Objectives
1. Explain the main functions of the liver.
2. Summarize the blood supply of the liver.
3. Describe the features of the classic liver lobule.
4. Describe two other ways how liver lobules are organized.
5. Describe the course of hepatic blood vessels and bile ducts.
6. List the structures found in the portal area.
7. Explain the structure and function of the Space of Disse.
8. Outline the location and function of Kupffer cells.
9. Explain the structure and function of the bile canaliculus
Question: the mucosa of the small intestine contains…
a) Gastric glands
b) Surface mucous cells
c) Goblet cells
d) Chief cells
e) Rugae
Question: the production of HCl in the stomach involves…
a) Cells with abundant zymogen granules
b) Intracellular canaliculi
c) Goblet cells
d) Secretion of gastrin by parietal cells
e) Membrane bound enterokinases
Transport of Nutrients From the Intestine to the Liver
- The food that comes from the stomach is called chyme
- It enters the small intestine, where enterocytes will absorb the nutrients and most of our
proteins, amino acids, sugars and some fatty acids will enter the capillary bed through post
capillary venules and is carried into the liver
- In the liver, it is processed (things will be taken out and stored)
- Most of our lipids are packaged into chylomicrons and travel through the lymphatic system by
entering the lacteal in the intestinal villus
- Here, the fat is put in the systemic circulation and goes throughout the body and eventually
reaches the liver
find more resources at oneclass.com
find more resources at oneclass.com
The Liver
- High magnification
- Liver is mostly made of hepatocytes
- Hepatocytes are epithelial cells which form plates (rows)
- Amongst those cells, you will find spaces that don’t stain
- The spaces are capillaries (they are lined by endothelial
cells and you might find RBCs in there)
- These capillaries are highly leaky and called hepatic
sinusoids
- Each hepatocyte has direct access to at least 1 sinusoid
- Some of the hepatocytes have an extremely large nucleus
while others have binucleated
o this shows that the DNA is being made and makes the cell bigger
o so the large nucleus is a polyploid cell and it expresses the genes in abundance
Major Functions of Hepatocytes
- Metabolism and storage →smooth ER and Cytoplasm
o Lipid soluble drugs
o Steroids
o Storage of carbohydrates as glycogen
o Detoxification
- Bile formation and secretion →smooth ER
o Synthesis and recycling of bile acids to and from intestine
- Synthesis and secretion of… →smooth ER, Rough ER and golgi
o Plasma proteins (albumin, prothrombin, fibrinogen)
o Cholesterol
o Lipoproteins
Venous Portal system
- We want to send all the diff nutrients that we absorb in a capillary network in the small intestine
first right to the liver before it goes to the rest of the body
- So the capillaries coming from the small intestine form veins that merge into a large vein called
the portal vein
- The portal vein then breaks up into a secondary capillary network in the liver that allows
hepatocytes to have access to those components in the blood
- This is a venous portal system
o Portal system means a capillary network that forms a vein that forms another capillary
network
o This can also happen with an artery (capillary network forms an artery which forms
another capillary network which them goes on to form another artery) →called an
arterial portal system
find more resources at oneclass.com
find more resources at oneclass.com
Blood and Bile Flow Through the Liver
- Hepatocytes are organized in hexagonal substructures – called classic hepatic lobules
- The hepatocytes form rows that are perfused by blood coming from the small intestine through
the portal vein
- 70% of blood that flows through the portal vein into the liver is nutrient rich and oxygen poor
(bc it has already been depleted by going through diff organs)
- this blood enters the portal lobules through small portal venules
- these venules form the thin wall sinusoids that perfuse the hepatocytes
- each hepatic lobule has a central venule in the center
o the central venule can be used to signify the location of a hepatic lobule
o the central venule is where the blood leaves the lobule (it drains the lobule into the
hepatic vein which drains into the inferior vena cava)
- since this is oxygen poor blood that flows through the portal vein and the liver also needs an
oxygen source – it has its own arterial supply
o the hepatic artery delivers oxygen rich blood (30% of the blood is oxygen rich through
the arterial system)
o this enters the hepatic lobule througha hepatic arterial found at the periphery of the
hepatic lobule
- the arterial blood and the venous blood mix at the periphery as it enters the sinusoids
- so the sinusoids have input from 2 places: the portal vein and hepatic artery
- so the liver produces bile and the bile is excreted into a duct system that leaves the portal
lobules
o so you will find structures outside of the hepatic lobule that look like a duct (made of
epithelial cells)
o this is called the bile duct – it drains bile from the hepatocyte to the hepatic duct
- there will be certain lobules that supply blood from diff arteries and veins and certain arteries
and veins supply more than 1 lobule
The Classic Liver Lobule
- this is low magnification of pig liver
- there is a thin layer of connective tissue surrounding each lobule
o this is only seen in certain animals
o THE HUMAN LIVER DOES NOT HAVE THIS
- Central vein/venule (A) is in the center of the lobule while the periphery contains the portal
triad (B)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Question: the mucosa of the small intestine contains . Question: the production of hcl in the stomach involves : cells with abundant zymogen granules, intracellular canaliculi, goblet cells, secretion of gastrin by parietal cells, membrane bound enterokinases. Transport of nutrients from the intestine to the liver. The food that comes from the stomach is called chyme. It enters the small intestine, where enterocytes will absorb the nutrients and most of our proteins, amino acids, sugars and some fatty acids will enter the capillary bed through post capillary venules and is carried into the liver. In the liver, it is processed (things will be taken out and stored) Most of our lipids are packaged into chylomicrons and travel through the lymphatic system by entering the lacteal in the intestinal villus. Here, the fat is put in the systemic circulation and goes throughout the body and eventually reaches the liver. Hepatocytes are epithelial cells which form plates (rows)
