Histology 2

Question 1

development of the liver and pancreas

Answer 1

develop as outgrowth of gut

parenchyma of liver and pancreas composed of glandular epithelial cells

Question 2

liver capsule

Answer 2

liver covered by collagenous connective tissue capsule

capsule covered by layer of mesothelial cells (simple squamous epithelium) derived from peritoneum

Question 3

structure of the liver

Answer 3

made up of lobules

main cells of the liver are hepatocytes

Question 4

structure of lobule

Answer 4

hexagonal
has a branch of hepatic vein called the centrolobular vein (central vein) as its centre
has portal triads at each corner

Question 5

hepatocytes

Answer 5

polyhedral epithelial cells

form plates/sheets of cells with spaces in between for blood to flow through - sinusoids

Question 6

contents of portal triads

Answer 6

hepatic artery
portal vein
bile duct (lined by simple cuboidal cells - cholangiocytes)
(and lymphatic vessels)

Question 7

sinusoids

Answer 7

lined by endothelial cells, endothelium is fenestrated - liquid component of blood generally has free access to hepatocyte but blood cells do not
narrow spaces between the endothelial cells and hepatocytes - space of Disse (perisinusoidal space)
microvilli of hepatocytes project into the space of Disse

Question 8

connective tissue of the liver

Answer 8

portal tracts accompanied by collagenous connective tissue
parenchyma of liver is supported by reticular fibres (Type III collagen) and type I collagen - found in space of Disse
hepatic stellate cells (Ito cells) are found scattered in space of Disse

Question 9

hepatic stellate cells

Answer 9

modified fibroblasts and make connective tissue
store vitamin A within fat droplets in their cytoplasm
in cirrhosis they transform into myofibroblasts and produce scar tissue in the liver

Question 10

macrophages located within sinusoids

Answer 10

Kupffer cells;

remove particulate matter from blood and help remove worn out red blood cells

Question 11

contents of bile

Answer 11

alkaline solution;
water
ions
phospholipids
bilirubin
bile salts

Question 12

bilirubin

Answer 12

pigment from the breakdown of hemoglobin in the spleen

when excreted in bile, it is cause of the brown colour of faeces

Question 13

bile salts

Answer 13

essential for emulsification of fats in digestive tract

Question 14

modification of bile

Answer 14

addition of bicarbonate ions and water by cholangiocytes (cells lining the biliary tree)

Question 15

production of bile

Answer 15

produced by hepatocytes

bile flows via bile canaliculi towards bile ducts in portal tracts and then to the hepatic ducts

Question 16

bile canaliculi

Answer 16

small channels

formed via tight junctions in cell membranes of adjacent hepatocytes

Question 17

epithelium of gall bladder

Answer 17

simple columnar epithelium with brush border

Question 18

structure of gallbladder

Answer 18

muscular sac
lined by epithelium backed by lamina propria of loose connective tissue rich in;
blood vessels
lymphatic vessels 
smooth muscle 
outer collagenous layer of adventitia 

folded mucosa when empty - flattens when distended

Question 19

function of bile

Answer 19

stores bile via actively pumping sodium and chloride ions from bile into spaces between adjacent epithelial cells
water then follows due to increase in osmotic pressure in these spaces, which becomes distended with fluid when the gall bladder is actively concentrating bile
water is carried away largely by lymphatic vessels of the lamina propria
gall bladder is stimulated to contract and deliver bile to duodenum via nervous (vagal) and hormonal (cholecystokinin release by endocrine cells of duedenum) control

modifies bile stored within it

Question 20

cholecystitis

Answer 20

inflammation of gallbladder
common
can be caused by gallstones obstructing the cystic duct - expanding the gall bladder and thickening the muscle layers and inflammation

Question 21

function of exocrine pancreas

Answer 21

produces digestive juices containing; 
proteases (break down proteins)
lipases (break down lipids)
nucleases (break down DNA/RNA)
amylase (break down starch)

enter duodenum via pancreatic duct

Question 22

function of endocrine pancreas

Answer 22

produces hormones;
insulin
glucagon

Question 23

structure of endocrine pancreas

Answer 23

small scattered islands of tissue - islets of langherhans

Question 24

activation of exocrine pancreas enzymes

Answer 24

enzymes produced as inactive proenzymes
as they arrive at duodenum an enteropeptidase converts inactive proteolytic enzyme trypsinogen into an active form - trypsin
this begins cascade of activation of enzymes

Question 25

structure of exocrine pancreas

Answer 25

thin connective tissue capsule continuous with connective tissue septa that divide the gland into lobules

Question 26

cells of pancreatic acinus

Answer 26

typically basophilic due to extensive RER

Question 27

cells of pancreatic apical

Answer 27

eosinophilic due to presence of zymogen (pre-enzyme) granules

Question 28

centroacinar cells

Answer 28

intercalated duct cells within the acini

nuclei and cytoplasm do not stain well

Question 29

hepatopancreatic ampulla (of Vater)

Answer 29

formed by the union of the pancreatic duct and the common bile duct. The ampulla is specifically located at the major duodenal papilla