Lecture 28

Question 1

Exocrine Pancreatic Structure

Answer 1

Acini: secrete enzymes

Question 2

Endocrine Pancreatic Structure

Answer 2

Islets of Langerhans

Question 3

Pancreatic Duct Cells

Answer 3

Secrete bicarbonate

Question 4

Cholecystokinin (CCK)

Answer 4

Hormone from SI mucosa (stimulates)

Question 5

Secretin

Answer 5

Hormone from SI mucosa (stimulates)

Question 6

Annulus

Answer 6

Flat band of pancreatic tissue completely encircling the second portion of the duodenum

Question 7

Fusion of the ventral and dorsal pancreatic buds

Answer 7

• May occur during embryologic development
• Newborns: projectile vomiting in the first few days of life
• Adults: very rare cause of chronic pancreatitis

Question 8

Acinar Secretions

Answer 8

Enzyme-rich secretions that provide the enzymes necessary for digestion

Question 9

Ductal Secretions

Answer 9

Bicarbonate rich and neutralize acidic chyme

Question 10

Explain the process of bicarbonate secretion by pancreatic ducts.

Answer 10

• H ions (derived from carbonic anhydrase reaction between CO2 and water) are actively transported out of the duct cells by an H+/K+-ATPase pump and released into the blood
• Bicarbonate ions are secreted into the duct lumen

Question 11

Cystic fibrosis and pancreatic secretions

Answer 11

Thick secretions into the pancreatic duct may obstruct the duct and cause pancreatic insufficiency

Question 12

What are the three isoforms of trypsinogen?

Answer 12

1. Cationic (23.1%)
2. Anionic (16%)
3. Meso (0.5%)

Question 13

Trypsin Inhibitor

Answer 13

Tightly bound to the active site of trypsin

Question 14

What is the cause of autodigestion of pancreatic acini?

Answer 14

• Premature activation of pancreatic enzymes (trypsinogen to trypsin)
• Inactivation of trypsin inhibitor

Question 15

Explain the process that causes acute pancreatitis.

Answer 15

1. Mutations in cationic trypsinogen (hereditary pancreatitis)
2. Intracellular activation of trypsinogen
3. Intracellular activation and retention of other proenzymes
4. Acinar cell injury
5. Acinar cell injury response (-> Interstitial inflammation) OR proteolysis, fat necrosis (lipase, phospholipase), and hemorrhage (elastase)
6. Acute pancreatitis

Question 16

Acute Pancreatitis

Answer 16

• Acute hemorrhagic pancreatitis
• Heavy meals or excessive alcohol ingestion
• 80% of cases associated with gall stones and alcohol abuse
• Clinical features: severe abdominal pain, nausea, vomiting, rapid elevation of amylase and lipase in serum

Question 17

What structures are impacted with acute pancreatitis?

Answer 17

1. Vessel wall: necrosis, hemorrhage, enzymes in bloodstream (Increased amylase and lipase)
2. Enzymatic fat tissue necrosis
3. Acinus: necrosis and leakage of enzymes

Question 18

Chronic Pancreatitis

Answer 18

• Ischemia (perpetuates cycle): necrosis, fibrosis, calcifications (recurrent acute states)
• Oxidative stress (idiopathic)

Question 19

Pancreatic Ductal Adenocarcinoma

Answer 19

• Most common form
• 5% of cases are alive 5 years after diagnosis
• Carcinoma cells frequently spread to the liver via the portal vein
• Close association of pancreas with large blood vessels and the extensive and diffuse abdominal drainage to lymph nodes -> ineffectiveness of surgical removal

Question 20

CD40 and Pancreatic Ductal Adenocarcinoma (PDA)

Answer 20

• CD40 activation can reverse immune suppression and drive antitumor T cell response
• Tumor regression required macrophages but not T cells or gemcitabine
• CD40 activated macrophages rapidly infiltrated tumors -> tumoricidal -> depletion of tumor stroma

Question 21

What defects in the GI tract cause malabsorption?

Answer 21

1. Deficient intraluminal digestion
2. Inadequate digestion on the luminal cell membrane of the enterocytes
3. Impaired transcellular transport in the enterocytes
4. Blocked passage of nutrients from the enterocytes to the lymphatics

Question 22

Example of deficient intraluminal digestion.

Answer 22

Achlorhydria (atrophic gastritis), Steatorrhea (chronic pancreatic insufficiency, bile duct obstruction, cirrhosis)

Question 23

Example of inadequate digestion on the luminal cell membrane of the enterocytes.

Answer 23

Lactose intolerance: lactase deficiency

Question 24

Example of impaired transcellular transport in the enterocytes.

Answer 24

Defective chylomicron assembly (abeta-lipoproteinemia)

Question 25

Example of blacked passage of nutrients from the enterocytes to the lymphatics.

Answer 25

Lack of lipoproteins in circulation (amyloidosis, scleroderma)

Question 26

Why do malabsorption syndromes develop?

Answer 26

Due to disease involving stomach, pancreas, hepatobiliary system, or intestines

Question 27

What do the symptoms of malabsorption result from?

Answer 27

Deficiency of proteins, lipids, carbs, vitamins, and minerals