4. Secretions of the Gastrointestinal Tract and the Pancreas Flashcards Preview

12. GI Test 2 > 4. Secretions of the Gastrointestinal Tract and the Pancreas > Flashcards

Flashcards in 4. Secretions of the Gastrointestinal Tract and the Pancreas Deck (70)
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1

What would be the effect of atropine on the salivary glands?

Which branch of the autonomic nervous system is affected?

Atropine decreases production of saliva, bicarbonate, enzymatic secretions, and constriction of myoepithelial cells.

Atropine is a muscarinic acetylcholine receptor antagonist, and therefore affects the parasympathetic nervous system.

2

Why might cystic fibrosis lead to pancreatitis?

Patients with cystic fibrosis may develop acute and chronic pancreatitis due to an absent/defective CFTR channel (cystic fibrosis transmembrane conductance regulator). When CFTR is absence/defective, chloride has difficulty reentering the lumen of the duct, which can inhibits bicarbonate secretion into the lumen. This may result in a diminished ability to "flush active enzymes out of the duct" and pancreatitis may develop.

3

A vagotomy abolishes which phase of HCl secretion?

The cephalic phase.

4

What controls the cephalic phase of gastric HCl secretion?

The vagus nerve.

5

What is the enzymatic target of omeprazole?

The H+-K+ ATPase on the luminal side of gastric parietal cells.

This is the "proton pump" we are talking about.

6

Which of the major salivary glands produces the enzymes for the early digestion of food?

 

What type of secretory cells predominate in this gland?

The parotid gland.

Serous cells.

7

Between parasympathetic and the sympathetic nervous system, which has the more significant control over the major salivary glands?

The parasympathetic nervous system.

8

What are the primary damaging factors of the gastric mucosa?

Acid.

Pepsin.

Bile.

NSAIDs.

Helicobacter pylori.

Alcohol.

Stress.

9

What component of gastric juice is required for the absorption of vitamin B12?

Intrinsic factor

10

What are the primary methods by which chief cells are stimulated to produce pepsinogen?

Vagal nerve stimulation during the cephalic and gastric phases of gastric HCl secretion.

Local reflexes responding to H+ directly.

11

Which secretory cells are unique to the oxyntic glands?

Enterochromaffin like cells.

Chief cells.

Parietal cells.

12

What cells do we find in the oxyntic glands?

Parietal cells.

Enterochromaffin like cells.

Chief cells.

D cells.

Enterochromaffin cells.

(As well as the mucous / mucous neck cells)

13

What are the differences between nonparietal gastric juice and parietal gastric juice?

Non-parietal gastric juice can be considered the "tone" of gastric juice. It is an alkaline solution of constant and low volume, is made of sodium, chloride, potassium, and bicarbonate.

Parietal gastric juice is slightly hyperosmotic, contains a great deal of hydrogen, less potassium, and a great deal of chloride. As this secretion rate of the parietal cells increases, the more the total gastric juice appears to become pure parietal cell secretion.

14

What is secreted by D cells?

Somatostatin.

15

What is of the optimal pH for pepsin?

1.8 to 3.5

16

What is unique about the interface of the parietal cell and the lumen it secretes its product into?

The lumen extends into the parietal cells as a structure called a canaliculus. That canaliculus is lined with microvilli which increase the surface area for HCl secretion.

17

Besides production of Gi, how do prostaglandins inhibit H+ secretion by H+-K+ ATPase?

Inhibition of enterochromaffin like cells.

18

What is the effect of histamine on H+ secretion?

What is the pathway used to affect the target enzyme?

What is the target enzyme?

Histamine increases H+ secretion.

Histamine activates the H2 receptor, which causes the production of Gs, which increases available cAMP, which upregulates H+-K+ ATPase.

19

What enzyme is key in the creation of bicarbonate in the pancreatic ductal cells?

Carbonic anhydrase.

20

How does the sympathetic nervous system produce an effect on the ductal cells of the salivary glands?

Sympathetic nerve fibers release norepinephrine, and activates Beta adrenergic receptors, which increases cAMP to produce an effect.

21

What controls the gastric phase of gastric HCl secretion?

Local nervous secretory reflexes.

Vagal reflexes.

Gastrin-histamine.

 

22

Which of the enzymatic secretions of the pancreatic acinar cells are secreted in their inactive forms?

Pancreatic proteases.

23

What hormone can inhibit both gastrin release and histamine release?

Somatostatin

24

What are the primary protective factors of the gastric mucosa?

HCO3-.

Mucus.

Prostaglandins.

Mucosal blood flow.

Gastrin (trophic effect).

Other growth factors.

25

What type of cell releases cholecystokinin?

I cells

26

What transporter is responsible for the "alkaline tide" in the bloodstream after eating?

The HCO3- / Cl- exchanger on the basolateral side of gastric parietal cells, which releases bicarbonate into the bloodstream.

27

What controls of the intestinal phase of gastric HCl secretion?

Nervous and hormonal mechanisms.

28

Ulcers typically form due to either a defective mucosal barrier or increased acid secretion. Which of those two causes is more common in the case of the gastric ulcer?

Defective gastric mucosal barrier.

29

In general, what is absorbed by the ductal cells of the salivary gland, and what is secreted?

The ductal cells of the salivary glands secrete K+ and HCO3-.

The ductal cells of the salivary glands absorb Na+ and Cl-.

(There is also a net absorption of solutes here, leading to an overall hypotonic solution.)

30

Where do the sympathetic nerves which innervate the major salivary glands originate?​

T1-T3