Pancreas and Liver microanatomy

Question 1

How do pancreas endocrine cells appear in histology?

Answer 1

The islets of langerhans are pale stainingclsuters that secret insulin and glucagon.

Question 2

How do pancreas exocrine cells appear in histology?

Answer 2

pancreatic acini are dark staining (due to zymogen granules) and they secrete digestive enzymes, fluids, electrolytes and bicarbonate

Question 3

How big are pancreatic acini, what do acini produce, and what do duct cells produce?

Answer 3

5-8 cells around a small lumen, acini produce a small volume of enzyme rich fluid and duct cells produce a large vol. of bicarbonate

Question 4

What are some liver functions?

Answer 4

endocrine and exocrine, synthesis of bile and proteins, detox and storage (eg gylcogen)

Question 5

Describe a hepatic lobule

Answer 5

Hexagonal shape, with a portal system in each corner. Radiating columns of adjacent heaptocytes and inbetween these columns are sinusoid (specialised capillary). Sinusoids drain to a central vein.

Question 6

Describe a portal lobule

Answer 6

Centre is a portal system, three adjacent hepatoocytes have bile canaliculi that drain into bile ductules that then drain into the bile duct of the portal triad. Think triangle

Question 7

Describe a liver/hepatic acinus

Answer 7

quadranglar in shape. between two portal systems (so splits two lobules) and is where poral vein and hepatic artery branches then branch into lobules to form sinusoid. Due to flow of blood towards central vein, splits the lobule into specific zones that have diff. enzyme profiles and function. (due to zone 1 getting nutrient and O2 rich blood and zone 3 poor supply)

Question 8

What are the three different cells found in lobules other than hepatocytes?

Answer 8

Stellate cells: are located in the space of disse, tore fat and has a role in vitamin A metabolism
Endothelial cells of sinusoid: fenestrated and intercellular openings making them leaky
Kupffer cells: Prevent obstruction of sinusoid and are in lumen. Are like macrophages

Question 9

What are some defining characteristics of sinusoid?

Answer 9

They are wider than normal capillaries and can thus take more than 1 RBC (up to 10)
are leaky due to fenestrations
have mixed blood from portal vein and hepatic artery