Secretions of GI Tract and Pancreas

Question 1

Saliva is produced by what?

Answer 1

Salivary glands - parotid, submandibular and sublingual

Question 2

What glands secrete the most saliva?

Answer 2

Submandibular and sublingual

Question 3

Describe the salivary gland structure

Answer 3

Acinar cells with myoepithelial cells surrounding

• Connected to intercalated duct
• Connected to striated duct
• Connected to excretory duct

Question 4

The acinar cells secrete an _____ solution

Answer 4

isotonic

Question 5

What type of cells contract to help eject saliva from the gland?

Answer 5

Myoepithelial cells

Question 6

What part of the salivary gland and what type of cells modify the initial saliva?

Answer 6

The striated duct and its ductal cells

Question 7

The striated duct creates a _____ solution

Answer 7

hypotonic

Question 8

Striated ductal cells are ______ to water

Answer 8

IMPERMEABLE = helps to create the hypotonic solution

Question 9

Describe the electrolyte concentrations in the hypotonic saliva

Answer 9

INCREASED K+ and HCO3-

DECREASED Na+ and Cl-

Question 10

The striated ductal cells _______ more Na+ and Cl-

Answer 10

Absorb

Question 11

The striated ductal cells _____ less K+ and HCO3- into the lumen

Answer 11

Secrete

Question 12

Describe the net absorption of the salivary ductal cells

Answer 12

The cells absorb MORE Na+ and Cl- than they secrete of K+ and HCO3-

Question 13

What controls the salivary secretions?

Answer 13

Autonomic Nervous System (ANS)

Question 14

Why is the control of salivary secretions unusual?

Answer 14

The parasympathetic system and the sympathetic system BOTH ACTIVATE the salivary secretions (normally oppose eachothers actions)

Question 15

Parasympathetic or sympathetic.. which one dominates salivary secretion control?

Answer 15

Parasympathetics

Question 16

What stimuli activates the Parasympathetics to increase saliva secretions?

Answer 16

Conditioning
Food, smell
Nausea

Question 17

What stimuli inhibits the Parasympathetics to decrease saliva secretions?

Answer 17

Dehydration

Sleep, fear

Question 18

CN ___ and ___ activate release of ____ to acinar or ductal cells in the salivary glands (parasymp.)

Answer 18

CN 7 and 9 activate release of Ach

Question 19

Sympathetics T1-T3 activate release of ____ to acinar or ductal cells in the salivary glands

Answer 19

NE

Question 20

What inhibits the parasympathetic release of Ach to the acinar or ductal cells in the salivary glands?

Answer 20

Atropine

Question 21

What are the cells in the body of the stomach that secrete components of gastric juice?

Answer 21

Parietal cells

Chief cells

Question 22

What do parietal cells release in the stomach?

Answer 22

HCl and Intrinsic factor

Question 23

Why is it important for the parietal cells to release HCl?

Answer 23

Creates a very acidic environment which is required for pepsinogen to be converted to pepsin

Question 24

Why is it important for the parietal cells to release Intrinsic factor?

Answer 24

For the absorption of Vitamin B12

Question 25

What do chief cells release in the stomach?

Answer 25

Pepsinogen

Question 26

What are the cells in the antrum of the stomach that secrete components of gastric juice?

Answer 26

G cells | Mucous cells

Question 27

What do G cells release into circulation from the stomach?

Answer 27

Gastrin

Question 28

What is secreted and absorbed from a parietal cell in the stomach?

Answer 28

``` Secreted = H+ and Cl- Absorbed = HCO3- ```

Question 29

What can inhibit the secretion of H+ from parietal cells?

Answer 29

Omeprazole

Question 30

Agents that can stimulate H+ secretion from gastric parietal cells

Answer 30

Vagus - ACh G cells - Gastrin ECL cells - Histamine

Question 31

Agents that can inhibit H+ secretion from gastric parietal cells

Answer 31

Somatostatin | Prostaglandins

Question 32

What are the 2 ways the Vagus nerve can stimulate H+ secretion from gastric parietal cells?

Answer 32

1. Direct - release Ach to parietal cells | 2. Indirect - release GRP to G cells, which then release Gastrin into circulation, which then activates parietal cells

Question 33

Somatostatin can inhibit G cells from releasing Gastrin. When the pH falls to low (too much H+ secretion from parietal cells), what will activate somatostatin to inhibit them more?

Answer 33

Gastrin itself! (negative feedback)

Question 34

Atropine can block which vagus nerve pathway for stimulation of H+ secretion from parietal cells?

Answer 34

The direct pathway because it releases ACh | -- The indirect pathway releases GRP which cannot be inhibited by Atropine

Question 35

What are the 3 phases of Gastric HCl secretion?

Answer 35

Cephalic phase Gastric phase Intestinal phase

Question 36

What can abolish the cephalic phase of gastric HCl secretion?

Answer 36

Vagotomy

Question 37

Which phase of gastric HCl secretion accounts for the majority of secretion control?

Answer 37

Gastric phase

Question 38

What drink can stimulate Gastric HCl secretion?

Answer 38

Coffee

Question 39

What can inhibit H+ secretion from parietal cells?

Answer 39

Omeprazole

Question 40

What can inhibit ECL cells from releasing Histamine (Histamine normally activates H+ secretion)?

Answer 40

Cimetidine

Question 41

What stimulation is the most important stimulus for pepsinogen secretion?

Answer 41

Vagus nerve

Question 42

H+ triggers local _____ reactions to stimulate chief cells to release _____

Answer 42

Cholinergic | Pepsinogen

Question 43

What converts more pepsinogen to pepsin?

Answer 43

Pepsin

Question 44

What does pepsin do?

Answer 44

Degrades food proteins into peptides

Question 45

Parietal cells also release intrinsic factor. What is it required for and where does this take place?

Answer 45

Vitamin B12 absorption in the distal ileum

Question 46

Pernicious anemia

Answer 46

Stomach does NOT produce enough intrinsic factor = decreased vitamin B12 absorption

Question 47

Common causes/disruptions of pernicious anemia/absorption of B12

Answer 47

Causes: atrophic gastritis or autoimmune - loss of parietal cells or immune attacking IF/parietal Disruptions: Gastrectomy or Gastric bypass

Question 48

What makes up the mucosal barrier that protects the gastric epithelium?

Answer 48

Mucous + HCO3-

Question 49

What will damage the mucosal barrier that normally protects the gastric epithelium?

Answer 49

Acid, pepsin, NSAIDs, helicobacter pylori, alcohol, bile, stress

Question 50

What is the purpose of the mucosal barrier in the stomach?

Answer 50

To protect the gastric epithelium from HCl and pepsin

Question 51

Zollinger - Ellison Syndrome

Answer 51

Large secretion of gastrin by duodenal/pancreatic tumors (gastrinomas)

Question 52

Zollinger - Ellison Syndrome causes an _____ in H+ and Gastrin secretion

Answer 52

INCREASE

Question 53

How do you diagnose a gastinoma/Zollinger - Ellison Syndrome?

Answer 53

Secretin stimulation test

Question 54

Under normal conditions, secretin will do what to gastrin release?

Answer 54

INHIBIT

Question 55

With gastrinomas, secretin will do what to gastrin release?

Answer 55

Cause an INCREASE = ACTIVATE

Question 56

What are the 2 types of peptic ulcers?

Answer 56

Gastric ulcer | Duodenal ulcer

Question 57

What is a main cause of a peptic ulcer?

Answer 57

Helicobacter pylori or NSAIDs

Question 58

A peptic ulcer results in the loss of?

Answer 58

Mucosal barrier loss with excessive acid and pepsin

Question 59

Gastric ulcer levels of H+ and gastrin

Answer 59

DECREASED H+ and increased gastrin

Question 60

Duodenal ulcer levels of H+ and gastrin

Answer 60

INCREASED H+ and gastrin

Question 61

Zollinger - Ellison syndrome levels of H+ and gastrin

Answer 61

MAJORLY INCREASED H+ and gastrin

Question 62

2 main things the pancreatic juice contains?

Answer 62

HCO3- aqueous solution | Enzymes

Question 63

What is the purpose of the pancreas secreting HCO3-?

Answer 63

Neutralize the H+ acid from stomach

Question 64

What do pancreatic enzymes do?

Answer 64

Digest food

Question 65

_____ activity increases pancreatic secretions

Answer 65

Parasympathetic

Question 66

______ activity decreases pancreatic secretions

Answer 66

Sympathetic

Question 67

What cells in the pancreatic duct synthesize and secrete enzymes?

Answer 67

Acinar cells

Question 68

What cells in the pancreatic duct secrete HCO3- solution?

Answer 68

Centroacinar and ductal cells

Question 69

Pancreatic acinar cells can secrete enzymes in their active or inactive form. What is an example of enzymes they secrete in the inactive form?

Answer 69

Proteases

Question 70

For a pancreatic ductal cell, it secretes and absorbs what?

Answer 70

Secretes HCO3- and absorbs H+

Question 71

Cystic fibrosis associated with a mutation of what?

Answer 71

CFTR Cl- channel in the pancreatic ductal cell

Question 72

Cystic fibrosis mutation of the pancreas leads to what?

Answer 72

Impaired HCO3- secretion from ductal cells

Question 73

What are the pancreatic secretion phases?

Answer 73

Cephalic - enzyme secretion Gastric - enzyme secretion Intestinal - enzyme AND HCO3- secretion

Question 74

What molecule activates the release of pancreatic enzymes?

Answer 74

CCK

Question 75

What molecule activates the secretion of HCO3- from the pancreas?

Answer 75

Secretin