Lecture 19

Question 1

What is the structure of the pancreas that is involved in endocrine function?

Answer 1

Islets of Langerhans

Question 2

What is the appearance of Islets of Langerhans?

Answer 2

Pale-staining
Clusters
Embedded in exocrine cells

Question 3

What is the function of Islets of Langerahans?

Answer 3

Production of hormone (insulin)

Question 4

What is the structure of the pancreas that is involved in exocrine function?

Answer 4

Pancreatic acini

Question 5

What is the appearance of pancreatic acini?

Answer 5

Dark staining

Zymogen granules - granular appearance

Question 6

What are the functions of pancreatic acini?

Answer 6

Production of digestive enzymes
Fluid secretion
Electrolyte secretion
Ductal cells of pancreas secrete bicarbonate

Question 7

Describe the exocrine pancreas

Answer 7

A tubulo-acinar gland with highly branched ducts. Acinar cell has large spherical nucleus in basal position. Mitochondria oriented perpendicular to the basal surface.

Question 8

Where are protein secretory products synthesised in the acini? Where are they packaged? Where do they accumulate?

Answer 8

Basal rER, packaged in the golgi, and accumulated as zymogen granules in the apical cytoplasm.

Question 9

Acini produce a small volume of __________-_____ ________. What does this contribute to?

Answer 9

Enzyme-rich fluid

Contributes to pancreatic juice

Question 10

What do ducts of the pancreas begin with? What do duct cells produce?

Answer 10

The smallest intercalated ducts which are inserted into the acini. Duct cells produce bicarbonate and a large volume of alkaline fluid.

Question 11

How much alkaline fluid do duct cells produce?

Answer 11

1 litre/day

Question 12

What are centro-acinar cells?

Answer 12

Intercalated duct cells which penetrate the lumen of the acini

Question 13

List the sequential ducts that extend from the acini.

Answer 13

Intercalated ducts - intralobular ducts - interlobular ducts -pancreatic duct - hepatopancreatic ampulla of vater - duodenum

Question 14

What lies in the junction between hexagonal lobules of the liver?

Answer 14

Connective tissue septa containing collagen, blood vessels, nerves, lymphatics

Question 15

What lies between the hepatocytes of the liver?

Answer 15

Sinusoids

Question 16

What is each hepatocyte in contact with?

Answer 16

Blood vessels

Question 17

What is the arrangement of hepatocytes?

Answer 17

Radiating columns of hepatocytes. Columns can branch quite freely but have a radiating pattern

Question 18

What is the classical/anatomical classification of a portion of the liver?

Answer 18

Hepatic lobule

Question 19

What type of blood do sinusoids contain? What happens to the blood in the sinusoids?

Answer 19

Mixed blood. Nutrients and O2 diffuse out of sinusoids and into hepatocytes according to gradient. Mixed blood is eventually drained into central vein.

Question 20

Describe the concentration of Zone 1 and 3

Answer 20

Zone 1: High nutrient and oxygen concentration

Zone 3: Low nutrient and oxygen concentration

Question 21

Describe the hepatic portal vein

Answer 21

Thin walled, large lumen, low pressure
Carries nutrient rich blood
Contributes 75% blood supply going to liver

Question 22

Describe the hepatic artery

Answer 22

Thick wall
Relatively small lumen
High pressure
Contributes 25% blood supply going to liver
Carries oxygen rich blood

Question 23

What is the functional way of describing a unit of the liver?

Answer 23

Liver acinus

Question 24

What does a portal lobule describe?

Answer 24

The flow of bile

Question 25

What is the usual shape of a hepatocyte?

Answer 25

Polygonal

Question 26

What are sinusoids?

Answer 26

A special type of capillary

Question 27

What is another name for sinusoid?

Answer 27

Lumen of sinusoidal capillary

Question 28

What is the difference between a sinusoid and a normal capillary?

Answer 28

Much wider than capillary. More than one RBC can pass through (up to 10). Leads to increased flow and increased rate of diffusion. Endothelium has intercellular openings as well as being fenestrated. Leads to leakiness, which is good for substrate diffusion.

Question 29

What lines the sinusoids?

Answer 29

Endothelium

Question 30

Where are stellate cells found?

Answer 30

In Space of Disse

Question 31

What is the Space of Disse?

Answer 31

Lymphatic space between endothelium and microvilli of hepatocytes

Question 32

What are the functions of the stellate cells?

Answer 32

Fat-storing | Role in vitamin A metabolism

Question 33

Where are the Kupferr cells found?

Answer 33

In the lumen of the sinusoidal capillary

Question 34

What are the functions of the Kupffer cells?

Answer 34

Macrophage-like Prevent obstruction Antibacterial

Question 35

What is special about the nucleus of hepatocytes?

Answer 35

Because they undergo a high rate of replacement, there is increased level of cell division and regeneration. It is normal to see binucleate or polypoid nuclei.

Question 36

What is meant by a polyploid nucleus?

Answer 36

Multiple copies of DNA material contained in a big nucleus

Question 37

What are bile canaliculi?

Answer 37

Membranous in-foldings that create a channel-like structure. Proteins help form an occluding junction that seals off the bile canaliculus so that it doesn't leak. Circular structures found between adjacent hepatocytes.

Question 38

What do canaliculi feed into?

Answer 38

Canaliculi from adjacent hepatocytes all converge and feed into bile ductules, which then feed into the bile duct