Histology: Liver and Gallbladder Flashcards
What is Glisson’s capsule? What is it covered by?
dense irregular CT that surrounds the liver’s 4 lobes
Covered by simple squamous epithelium from peritoneum
What do we mean when we say the liver has a dual blood supply?
What percent of cardiac output is bound for the liver?
The liver receives 75% of blood supply from the portal vein and the other 25% from the hepatic artery.
20 to 25% of cardiac output is to the liver.
What nutrients does the liver take up?
carbohydrates, amino acids, lipids, vitamins
What does the liver store and release? What does the liver synthesize?
Stores and releases: glucose, triglycerides, vitamins
What are some examples of products that are synthesized by the liver?
albumin, prothrombin & fibrinogen, a & b globulins,
glucose, fatty acids & triglycerides, cholesterol & phospholipids,
lipoproteins
Bile - secretes ~750 mL/day
What are examples of things the liver detoxifies?
metabolites, drugs, xenobiotics (foreign matter ingested w/ food)
bacteria, immunoglobulin complexes, “worn out” cells/proteins
What is the hepatic triad?
- Portal Vein
- Hepatic Artery
- Bile Ductule
(Slide also includes “lymph vessel” which would hose the whole “triad” thing, but whatev! (Kathleen asks if the lymph vessel is actually relevent to liver detoxor nutrient absorption, or just an artifact of blood flow?)
In the liver, what do the hepatocytes form?
A muralium (wall of cells) that radiate in a polyhedron from the central vein.
What is the path of blood through the lobule of the liver?
- Enters at periphery
- percolates via sinusoids
- leaves by central vein
How does bile travel in the liver lobule?
Counter-current to blood, leaves at periphery of lobule
Describe the structure of a hepatocyte
Most cells are mononuclear but many may be binucleate
most cells polyploid (tetraploid)
80% of cells in liver
What are the 3 surfaces hepatocytes possess?
- sinusoidal
- baso-lateral
- bile canalicular
What facilitates the access of blood to hepatocytes? What keeps blood cells out of the lymph?
Sinusoids with discontinuous wall and discontinuous basal lamina
supported by reticular fibers. Structure also keeps blood supply out of space of Disse (liver lymphatics).
What are Kupffer cells?
Liver macrophages
What is altered in diseases like hepatic fibrosis or hepatic cirrhosis?
The liver stroma - in disease, CT elements relate abnormally with parenchyma. Increase in CT alters normal fxn.
What are the three ways to describe liver lobules?
- classic
- portal
- portal acinus (acinar lobule)
What are the following based on?
- Classic lobule
- portal lobule
- portal acinus
- Endocrine nature
- exocrine nature
- metabolic zonation
What is the shape of a classic lobule? What does it make?
polygonal in shape
peripheral central canals and center vein emphasize endocrine nature
Makes fibrinogen, albumin, glucose that are used elsewhere.
What lies at the center of a classic lobule? At the periphery?
What does this structure emphasize about the function of the gland?
Vein in center and portal canals at periphery
emphasizes the endocrine function of the gland
What is the shape of a portal lobule?
Triangular in concept
What is in the center of a portal lobule? At the periphery? Why does it have this arrangement?
Portal canal in center
Central vein in peripheral apices
Arrangement due to exocrine function - bile is secreted into a duct.
What is the pictured lobulation?
portal acinus
Where are the central veins located in a portal acinus?
at apices of the lobule
The liver is zoned based on a gradient of metabolic activity. What are the zones?
Zone 1 - Periportal Zone
Zone 2 - mid-region
Zone 3 - centrolobular zone
What does the periportal zone recieve?
receives blood with highest concentration of nutrients/oxygen last to die and first to regenerate.
What does zone 2 (mid-region) recieve?
receives blood of intermediate “quality“ (from zone 1)
What does the centrolobular zone (zone 3) recieve?
receives blood with lowest nutrient/oxygen content (from zone 2) first cells to die in centrolobular necrosis
There are numerour differences in zones, what are four we covered?
carbohydrate metabolism
protein metabolism
lipid metabolism
drug metabolism
How does regeneration of hepatocytes differ in a diseased liver compared to a healthy liver?
Zonal damage, selective regeneration of damaged zones as opposed to regeneration in all zones.
What is different about hepatic regeneration in cirrhosis?
CT elements don’t cooperate, leading to
- Altered structure
- compromised parenchymal function
What are some examples of hormones that target the liver?
growth hormone
prolactin
insulin
glucagon
norepinephrine
What does Tay-Sachs disease result from?
A.K.A. Sphingolipidosis
-Absence of B-hexosaminidase (which degrades acidic fatty gangliosides)
What causes metachromatic leukodystrophy?
The absence of aryisulfatase causes accumulation of sulfated cerebrosides.
What causes type II glycogenolysis (not a good thing)?
acid maltase (acid alpha-glucosidase) is absent
Where are VLDL’s made? What do they do?
Made in the rER from chylomicrons converted by the sER.
VLDL’s transport apoprotein for lipoproteins
Where is glycogen preferentially laid down in gluconeogenesis?
The periportal area
Where is glucose preferentially laid down in the liver?
Perivenous area
What do we need to digest fats?
Lipase and bile
What do peroxisomes do?
- Oxidize substrates with O2 and H2O2, including lactate, D-amino acids and polyamines.
- Peroxidize alcohols, formate, nitrite, quinones
- Purine catabolism
What is a stellate cell for?
Storage break down and storage of fats.
What is being indicated here? When are these seen?
Mallory bodies.
Seen in a variety of hepatic diseases
Cholestatic conditions, cirrhosis
What do hepatic sinusoids do for hepatocytes?
- Allow easy access to blood
- exclude cellular elements from the space of Disse
What are Ito cells?
Another name for Stellate cells, which is another name for lipocyte
What are the functions of Kupffer cells?
(4)
- phagocytose immune complexes, bacteria, non-immune particulates via Fc and C’ receptors.
- Bind and degrade hemoglobin to bilirubin
- Can assume RBC destruction responsibilities of the spleen
- Process and present antigen
Identify cell type
Kuppfer cell
What vitamin is rapidly taken up and stored in the lipid droplet of Ito cells?
Vitamin A
What is bile necessary for?
- solubilization/absorption of intestinal fat
- provides main pathway for excretion of cholesterol
- eliminates many toxins, including bilirubin
Describe the submucosa in the gall bladder.
There is none
Describe the lamina propria of the gall bladder
- thin layer of dense irregular CT
- numerous small blood vessels
- numerous small lymphatic vessels
- no muscularis mucosa
Describe the surface of the gallbladder when empty and full.
- filled - surface is even
- empty - decussating folds or rugae
What is the secretory stimulus from the gut enteroendocrine cells for the gall bladder?
- secretin - induces biliary bicarbonate and H20 secretion
- cholecystokinin (CCK ) - induces gall bladder contraction
Describe the serosa of the gall bladder
- thick layer of dense irregular CT
- abundant arteries, veins & lymphatics
- mesothelium covers underlying CT
