Pancreas and Liver Histology

Question 1

Exocrine functions of Pancreas
What is a functional unit and what is it comprised of

Answer 1

Functional unit: pancreatic acinus (acini if plural)
Comprised of 40-50 acinar cells with 3-4 centroacinar cells (beginning of duct system)

Question 2

Exocrine functions of Pancreas
Acinar cell roles

Answer 2

Stimulated by secretin to produce fluid high in HCO3-
Stimulated by cholecystokinin to secrete proenzymes
Parasympathetic innervation stimulates acinar and centroacinar cells

Question 3

Exocrine functions of Pancreas
Pancreatic enzymes

Answer 3

Pancreatic amylase
Pancreatic lipase
Ribonuclease and DNase
Trypsinogen, chymotrypsinogen, procarboxypeptidase, elastase

Question 4

Exocrine functions of Pancreas
Centroacinar cell features

Answer 4

Stimulated by secretin

Question 5

Endocrine Functions of Pancreas
B- cells

Answer 5

produce insulin and amylin (assists insulin in its job)

Question 6

Endocrine Functions of Pancreas
A-cells

Answer 6

produce glucagon
Activates glycogenolysis and gluconeogenesis on hepatocytes

Question 7

Endocrine Functions of Pancreas
Delta (o)-cells

Answer 7

produce somatostatin
Somatostatin inhibits secretion of insulin and glucagon (hormones of a and b cells)
Suppresses exocrine secretion of pancreas

Extra: Stops motility of smooth muscle in digestive tract, affects growth hormone
Stop gall bladder as well

Question 8

Endocrine Functions of Pancreas
G cells

Answer 8

produce gastrin

Extra: Affects stomach function
Released by G cells
Gastric release of G cells
Gastric motility
Cell division

Question 9

Endocrine Functions of Pancreas
Pancreatic polypeptides (PP cells or F cells)

Answer 9

Produce pancreatic polypeptide
Released by PP cells
Regulates endocrine and exocrine function of the pancreas

Question 10

Pancreatic hormones
- insulin

Answer 10

Produced as pre-proinsulin in RER
Converted to proinsulin in RER cisternae
converted to insulin in golgi, packaged for export
insulin released due to INCREASE in blood glucose***. when insulin levels go up, glucose levels go up too.

Question 11

Pancreatic hormones
glucagon

Answer 11

released in response to LOW blood glucose
wants to increase blood glucose levels (gluconeogenesis in liver, glycogenolysis on hepatocytes)

Question 12

Pancreatic hormones
Somatostatin

Answer 12

Inhibits release of hormones by a and B cells
Suppresses exocrine secretion of pancreas
Reduce motility of smooth muscle in digestive tract and gallbladder.
Released due to increase in blood glucose. (like from glucagon)

Question 13

Pancreatic hormones
Gastrin

Answer 13

Released by G cells
Stimulates release of HCl, gastric motility and emptying

Question 14

Liver:
Classic Hepatic Lobule
Function Shape Boundary Center

Answer 14

Function: Drains blood from portal vein and hepatic artery to hepatic or central vein. Shape: Hexagonal, normal
Boundaries: 6 portal vein/hepatic artery/ bile duct components.
Center: Central Vein

Question 15

Liver:
Portal Lobule
Function Shape Boundary Center

Answer 15

Function: Drains bile from hepatocytes to the bile duct.
Shape: Triangular
Boundaries: 3 central veins
Center: 1 portal vein/hepatic artery/bile duct component.

Extra: Describes flow of bile. Anything inside of triangle drains to the bile duct.

Question 16

Liver:
Portal Acinus (lobule)
Function Shape Boundary Center

Zones

Answer 16

Function: Supplies oxygenated blood to hepatocytes.
Shape: Weird diamond/rhombus shaped
Boundaries: 2 portal vein/hepatic artery/bile duct components, as well as 2 central veins.
Center: Distributing artery in-between two classic lobules.

Important: In middle of this diamond shaped structure, there is a distributing artery that is a branch between two of the hepatic artery, running between two classic lobules.

Cells closest to distributing artery will receive most oxygen. If there is toxic in blood, cells further will be least damaged. 3 zones. Zone 1 = closest to artery, zone 3 = closest to central vein.

Question 17

Liver:
Sinusoids

Answer 17

Surrounded by plates of hepatocytes
Contain kupffer cells: macrophage-like phagocytes

Perisinudoisal space (disse space): inbetween sinusoids and hepatocytes. Allows for plasma to leak through. Microvilli bath in plasma of blood.
- hepatic stellate cells (ito cells) react to alcohol, make fibrosis of liver. located within perisinudoisal space.

Question 18

Roles of Liver

what they manufacture, metabolism of lipids, carbohydrates, proteins

Answer 18

Manufacture bile
Bile salts reabsorbed from lumen of small intestine, or made de novo in SER of hepatocytes

Metabolism of organic substances:
lipids: chylomicrons from digestion enter lymphatic system, reach liver via hepatic artery
Carbohydrates: Maintains blood glucose levels
Proteins: hepatocytes manufacture 90% of blood proteins: blood clotting factors like complement proteins, transport proteins, albumins

Question 19

Roles of Liver: what do hepatocytes do?

Answer 19

Hepatocytes manufacture globulins (except gamma globulins-these activated by plasma cells aka activated b cells), and also non-essential amino acids
hepatocytes convert ammonia to UREA

Question 20

Roles of liver: vitamins / hormones / toxins

Answer 20

Vitamin storage : A, D, B12
degradation of hormones by lysosomal enzymes
degradation of drugs / toxins (in SER or peroxisomes)

Methylation, Conjugation, Oxidation

Question 21

Roles of liver: immune function

Answer 21

release IgA in bile
Kupffer cells phagocytose foreign particulate matter