Exocrine Pancreas and Salivary Gland Physiology Flashcards Preview

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Flashcards in Exocrine Pancreas and Salivary Gland Physiology Deck (37)
1

Salivary Glands

3 pairs of glands: parotid, submandibular and sublingual

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

2

Constituents of Saliva and their Functions

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

3

What is the secretory unit of the Salivary Gland

Acinus

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

4

Salivary Secretion Regulation by ANS

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)

5

Myoepithelial cells

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

Pancreatic gland DONT have them

6

What downregulates salivary secretions

Sleep
Fatigue
Fear

7

What upregulates salivary secretion

Smell, taste, sound, and sight of food
Pressure in mouth

8

Which system primarily facilitates salivary secretion?

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

9

Saliva formation

Formation by passive filtration

Content and secretion rate is dependent on blood flow

10

Mechanism of Salivary Secretion: Fast vs. Slow Flow Rate

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

11

Are acinar secretions hypertonic, hypotonic, or isotonic?

Close to isotonic

12

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

Tight junctions

13

Movement of water in salivary ducts

is restricted by TJs, leaving the saliva hypotonic

14

What establishes a concentration gradient in salivary duct cells?

Na+/K+ ATPase

15

Pancreas and Pancreatic Secretions

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

16

Secretory Products of the Pancreas

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

17

Regulation of Pancreatic Secretion

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

18

Structure of the Exocrine Pancreas

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

19

Effects of Cholecystokinin Cluster Unit in the Duodenum

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

20

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

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

21

Trypsin

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

22

Effect of Secretin

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

23

Pancreatic secretion regulation

ANS and hormones

**Salivary is just ANS**

24

Pancreatic acini compared to salivary acini

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.

25

Saliva vs pancreatic juice

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

26

Salivary Gland Diseases

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

27

Benign Neoplasms

Mixed Tumor (pleomorphic adenoma)
Monomorphic Adenomas
Ductal papilloma

28

Endocrine Pancreatic Cancer

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

29

Pleomorphic Adenoma

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.

30

Warthin’s Tumor

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

31

Monomorphic Adenoma

Similar to Pleomorphic Adenoma except no mesenchymal stromal component

32

Basal Cell Adenoma

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.

33

Malignant Neoplasms

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

34

Features Suggestive of Malignancy

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

35

Mucoepidermoid Carcinoma

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

36

Adenoid Cystic Carcinoma

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.

37

Exocrine Pancreatic Cancer

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