Exocrine Pancreas and Salivary Gland Physiology

Question 1

Salivary Glands

Answer 1

3 pairs of glands: parotid, submandibular and sublingual

Produce a serous (proteinaceous) or mucus product, or both

Question 2

Constituents of Saliva and their Functions

Answer 2

Water: Facilitates taste and dissolution of nutrients; aids in swallowing and speech

Bicarb: Neutralizes refluxed gastric acid

Mucins: Lubrication

Amylase: Strach digestion

Lysozyme, lactoferrin, IgA: innate and acquired immune protection

Epidermal and nerve growth factors: Assumed to contribute to mucosal growth and protection

Question 3

What is the secretory unit of the Salivary Gland

Answer 3

Acinus

Acinar cells make the saliva and striated duct cells modify its ionic content

Question 4

Salivary Secretion Regulation by ANS

Answer 4

Parasympathetic – increased acinar cell secretion and vasodilation of blood vessels surrounding the acini (results in protein rich & fluid/ion rich solution)

Sympathetic – increased acinar cell secretion (results in high protein/low fluid solution); less water (think gross, crusty running mucus)

Question 5

Myoepithelial cells

Answer 5

help squeeze acinar cells and force them to secrete into the acinus

Pancreatic gland DONT have them

Question 6

What downregulates salivary secretions

Answer 6

Sleep
Fatigue
Fear

Question 7

What upregulates salivary secretion

Answer 7

Smell, taste, sound, and sight of food

Pressure in mouth

Question 8

Which system primarily facilitates salivary secretion?

Answer 8

Parasympathetic through octic gangion (parotid gland) and submandibular ganglion (submandibular gland)

Question 9

Saliva formation

Answer 9

Formation by passive filtration

Content and secretion rate is dependent on blood flow

Question 10

Mechanism of Salivary Secretion: Fast vs. Slow Flow Rate

Answer 10

Low flow rate: duct cells absorb Na+ and Cl- and secrete K+ and HCO3-

High flow rt: Don’t have time to modify it so much more NaCl present in the secretions and less K Bicarb

Question 11

Are acinar secretions hypertonic, hypotonic, or isotonic?

Answer 11

Close to isotonic

Question 12

What allow movement of ions and water from the blood into saliva?

Answer 12

Tight junctions

Question 13

Movement of water in salivary ducts

Answer 13

is restricted by TJs, leaving the saliva hypotonic

Question 14

What establishes a concentration gradient in salivary duct cells?

Answer 14

Na+/K+ ATPase

Question 15

Pancreas and Pancreatic Secretions

Answer 15

Acinar cells produce a variety of enzymes (proteases, lipases and amylases)

Ductal cells produce a bicarbonate solution to help liquefy and neutralize acidic chyme in the duodenum

Endocrine organ

Question 16

Secretory Products of the Pancreas

Answer 16

Proteases: Trypsinogen, Chymotrypsinogen, Proleastase, Procarboxypeptidase A, Procarboxypeptidase B*

Amylases: Amylase

Lipases: Lipase, Nonspecific esterase, Prophospholipase A2*

Nucleases: Deoxyribonuclease, Ribonuclease

Others: Procolipase*, Trypsin inhibitors, Monitor peptide,
*= stored and secreted in inactive forms

Question 17

Regulation of Pancreatic Secretion

Answer 17

Acetylcholine (ACh) – released from the vagus and ENS nerves; stimulates the release of digestive enzymes from acinar cells (mostly cephalic stage)

Secretin – released from endocrine cells in the proximal small intestines in response to acid; stimulates the release of a bicarbonate rich solution from pancreatic duct cells

Cholecystokinin (CCK) – released from endocrine cells in the proximal small intestines in response to fats & proteins; stimulates the release of digestive enzymes from acinar cells but has other effects in the duodenum

Question 18

Structure of the Exocrine Pancreas

Answer 18

Acinar cells make the enzymes and duct cells secrete a water/bicarbonate rich solution

Question 19

Effects of Cholecystokinin Cluster Unit in the Duodenum

Answer 19

Gallbladder contraction, pancreatic acinar secretion, reduced emptying of stomach, relaxation of sphincter of Oddi

Protein, carbohydrate, lipid absorption and digestion
Matching of nutrient delivery to digestive and absorptive capacity

Question 20

cAMP and Ca2+ have what eddect on pancreatic acinar cell secretion?

Answer 20

Phosphorylation of structural and regulatory proteins causing fusion of granules with with apical membrane and discharge of contents

Question 21

Trypsin

Answer 21

The bulk of the enzymes released by the pancreas are proteases

Trypsin is secreted from the pancreas in an inactive, pro-enzyme form called trypsinogen. Also released is a trypsin inhibitor.

Trypsin becomes activated in the duodenal lumen when trypsinogen is cleaved by enzymes (enterokinases) located on the surface of enterocytes

Activated trypsin then autoactivates more trypsinogen along with most of the other pancreatic enzymes

Question 22

Effect of Secretin

Answer 22

Secretin acts by increasing cAMP levels in the duct cells. The release of secretin is enhanced by CCK

Question 23

Pancreatic secretion regulation

Answer 23

ANS and hormones

Salivary is just ANS

Question 24

Pancreatic acini compared to salivary acini

Answer 24

Pancreatic acini are not as vascular and respond to ACh and CCK. Ductal cells actively secrete a water and a bicarbonate rich solution in response to secretin.

The salivary acinus is very vascular and increased blood flow results in a dilute saliva that is modified by duct cells. Salivary ducts, on the other hand, are fairly impermeable to water.

Question 25

Saliva vs pancreatic juice

Answer 25

Saliva is rich in KHCO3 whereas pancreatic juice is rich in NaHCO3.

Question 26

Salivary Gland Diseases

Answer 26

``` Mumps Cytomegaloviral Sialadenitis Bacterial Sialadenitis Sarcoidosis Sjögren’s Syndrome Salivary Lymphoepithelial Lesion Xerostomia or dry mouth Halitosis ```

Question 27

Benign Neoplasms

Answer 27

Mixed Tumor (pleomorphic adenoma) Monomorphic Adenomas Ductal papilloma

Question 28

Endocrine Pancreatic Cancer

Answer 28

Gastrinoma (Zollinger-Ellison Syndrome) Glucagonoma – usually large, often mets, 70% malignant Insulinoma – the most common pancreatic neuroendocrine tumors Nonfunctional islet cell tumors (NICT) – Usually malignant and hard to detect Somatostatinoma – occur anywhere in the pancreas or doudenum VIP-Releasing Tumor – usually in the body and tail of the pancreas

Question 29

Pleomorphic Adenoma

Answer 29

The diverse microscopic pattern of this lesion is one of its most characteristic features. Islands of cuboidal cells arranged in ductlike structures is a common finding.

Question 30

Warthin’s Tumor

Answer 30

Warthin's tumor (benign papillary cystadenoma lymphomatosum) the second most common benign tumor of the parotid gland It accounts for 2-10% of all parotid gland tumors Bilateral in 10% of the cases may contain mucoid brown fluid in FNA Oncotic epithelial Component (fronds) and Lymphoid Component BOTH must be present to diagnose

Question 31

Monomorphic Adenoma

Answer 31

Similar to Pleomorphic Adenoma except no mesenchymal stromal component

Question 32

Basal Cell Adenoma

Answer 32

A monomorphic adenoma is composed of uniform basaloid epithelial cells with a monomorphous pattern. Histologically, these tumors are distinguished from pleomorphic adenomas by their absence of stroma and the presence of a uniform epithelial pattern.

Question 33

Malignant Neoplasms

Answer 33

``` Mucoepidermoid Carcinoma (mucin+) Polymorphous Low-grade Adenocarcinoma Adenoid Cyctic Carcinoma Clear Cell Carcinoma Acinic Cell Carcinoma (no glycogen, fat & mucin, 3% maligant and bilateral) ```

Question 34

Features Suggestive of Malignancy

Answer 34

``` Induration (hardness) Fixed to Overlying Skin or mucosa Ulceration of skin or mucosa Rapid Growth; Growth Spurt Short Duration Pain, often severe Facial N. Palsy ```

Question 35

Mucoepidermoid Carcinoma

Answer 35

MECs contain two major elements: mucin-producing cells and epithelial cells (Epidermoid and Mucinous components)

Question 36

Adenoid Cystic Carcinoma

Answer 36

Adenoid cystic carcinoma with Swiss cheese pattern. It is the second-most common malignant tumor of the salivary glands. ACC is the most common malignant tumor found in the submandibular, sublingual, and minor salivary glands.

Question 37

Exocrine Pancreatic Cancer

Answer 37

Acinar Cell Carcinoma – Rare, leads to overproduction of lipase Adenocarcinoma – 90% of all pancreatic cancer starts in duct Adenosquamous carcinoma - forms glands that flatten as it grows Intraductal Papillary-Mucinous Neoplasm – fingerlike projections into the duct, prelude to malignancy Mucinous Cystadenocarcinoma – rare malignant spongy cystic tumor Pancreatoblastoma – Rare, occurs in kids