Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

GI Exam 2 > Secretions of the GI tract and pancreas > Flashcards

Secretions of the GI tract and pancreas Flashcards

(59 cards)

Start Studying
1
Q

Functions of saliva

A

initial digestion of starches and lipids, dilution and buffering of ingested food, lubrication of food with mucus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

composed of serous cells, secreted fluid composed of water, ions and enzymes, secrete 25% of daily output of saliva

A

parotid glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

composed of serous and mucous cells, secretes aqueous fluid and mucin glycoprotein for lubrication, secrets most of the daily output of saliva (75%)

A

submaxillary glands and sublingual glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is saliva composed of?

A

H2O, electrolytes, alpha-amylase, lingual lipase, kallikrein and mucus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is saliva compared to plasma?

A

Saliva is hypotonic. High concentrations of K+ and HCO3- and low concentrations of Na+ and Cl-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the 2 main steps in the formation of saliva?

A
  1. Formation of isotonic plasma-like solution by acinar cells
  2. Modification of the isotonic solution by the ductal cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Mechanism of salivary secretion:

A

Combined action is absorption of Na+ and Cl- and secretion of K+ and HCO3-, there is a net absorption of solute (more NaCl is absorbed than KHCO3 secretion)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the transport mechanisms in the luminal side?

A

Na+/H+ exchange
Cl-/HCO3- exchange
H+/K+ exchange

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the transport mechanisms on the basolateral/blood side?

A

Na+/K+ ATPase

Cl- channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does HCO3- leave the cell?

A

HCO3- leaves the cell to the lumen via the cAMP activated CFTR Cl- channel or the Cl-/HCO3- exhchanger

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does saliva become hypotonic as it flows through the ducts?

A

Ductal cells are H2O impermeable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Parasympathetic innervation of the salivary glands

A

presynaptic nerves originate at facial and glossopharyngeal nerves, postsynaptic fibers in autonomic ganglia innervate individual glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Sympathetic innervation of salivary glands

A

preganglionic nerves originate at the cervical ganglion, whose postganglionic gibers extend to the glands in prearterial spaces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What part of the ANS dominates in the regulation of salivary secretion?

A

Parasympathetic NS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Results of salivary cell stimulation:

A

increased saliva production, increase HCO3- and enzyme secretions, contraction of myoepithelial cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Salivary is exclusively under the control of what?

A

Autonomic NS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What increases salivary secretion?

A

Both parasympathetic and sympathetic stimulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

HCl (H+)

A

-initiates protein digestion together with pepsin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Pepsinogen

A

Inactive precursor to pepsin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Mucus

A

Lines the walls of the stomach and protects it from damage, lubricant, together with HCO3- it neutralizes acids and maintains the surface of the mucosa at a neutral pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Intrinsic factor

A

absorption of vitamin B12 in the ileum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Oxyntic gland

A

located in the proximal 80% of the stomach (body and fundus), secretes acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

pyloric gland

A

located in the distal 20% of the stomach (antrum), synthesizes and releases gastrin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Parietal cells

Study These Flashcards
A

located in the body of the stomach, secretes intrinsic factor and HCl, # of parietal cells determines the maximal secretory rate

25
Chief cells
located in the body of the stomach, secretes pepsinogen
26
G cells
located in the antrum of the stomach, secretes gastrin into circulation
27
Mucus cells
located in the antrum of the stomach, secretes mucus, HCO3- and pepsinogen
28
What drug inhibits the H+/K+ on the luminal side of parietal cell?
omeprazole
29
Non-parietal gastric secretion
basal alkaline secretion of constant and low volume, primary constituents are Na+ and Cl-, K+ is present at the same concentration as in plasma
30
Parietal gastric secretion
slightly hyperosmotic, Cl- is the only anion present, as the secretion rate increases the concentration of electrolytes begin to approach those of pure parietal cell secretion
31
Receptor and function of Ach, Gastrin and Histamine
- ACh - M3 receptor, Gastrin - CCKB receptor, Histamine - H2 receptor - activate Gq which activates IP3/Ca2+ (ACh and gastrin) and activate Gs which activates cAMP (histamine) which activates H-K ATPase
32
Somatostatin and Prostaglandin
inhibitors that activate Gi and inhibit cAMP which inhibits H-K ATPase
33
Postive feedback mechanism regulating HCl secretion
as the pH falls (increase H+ concentration), gastrin release is inhibited and this leads to a decrease in HCl secretion
34
What does atropine block?
Atropine blocks the direct pathway of vagal stimulation. Atropine will not block the vagal effects on gastrin secretion because the NT at the synapse on G cells is GRP
35
What is the effect of gastrin on somatostatin?
Gastrin increases somatostatin release
36
What is the effect of somatostatin on G cells?
Inhibit gastrin release
37
What is the role of cimetidine?
antagonist of H2 receptors, used to treat duodenal and gastric ulcers, gastroesophageal reflux disease
38
Omeprazole
inhibits the H/K ATPase, used in the treatment of ulcers to reduce H+ secretion
39
Cephalic phase of gastric secretion
stimuli: smell, taste, chewing, swallowing and conditioning reflex mechanism: - vagus nerve --> parietal cell - vagus nerve --> gastrin --> parietal cell
40
What phase does vagotomy abolish?
Cephalic phase
41
Gastric phase
stimuli: distention of the stomach and presence of breakdown of proteins, amino acids and small peptides mechanism: -vagus nerve --> parietal cell -vagus nerve --> gastrin --> parietal cell -distension of the antrum -amino acids and small peptides
42
What other substances stimulate gastric HCl secretion?
coffee (caffeinated and decaf), wine and beer
43
Intestine phase
accounts for ~5-10% of the total HCl secreted in response to a meal, distention of the small intestine and digested protein stimulates acid secretion
44
Pepsinogen is secreted by chief cells and mucus cells in the oxyntic glands, what are the conditions it has to meet to be secreted?
required H+ secretion from parietal cells to lower pH of gastric contents (pH<5)
45
What is the most important stimulation for pepsinogen secretion?
Vagus nerve stimulation
46
What is the pH where pepsinogen conversion to pepsin is optimal, reversibly inactivated and irreversibly inactivated?
optimal pH = 1.8-3.5 reversibly inactivated at > pH 3.5 - 5.0 irreversibly inactivated > pH 7-8
47
What is required for the absorption of B12 in the ileum?
Intrinsfic Factor (IF)
48
Intrinsic Factor
mucoprotein secreted by parietal cells, binds to vitamin B12, only secretion by the stomach that is requires (essential)
49
Pernicious anemia
stomach does not produce enough IF, decreased levels of vitamin B12, common causes: atrophic gastritis and autoimmune metaplastic atrophic gastritis
50
What factors protect the gastric mucosa?
HCO3-, mucus, prostaglandins, mucosal blood flow, gastrin and growth factors
51
What damages the gastric mucosa?
Acid, pepsin, NSAIDs, H. pylori, alcohol, bile and stress
52
Zolinger-Ellison syndrome
H+ secretory rates are the highest in this disease, tumor usually in the pancreas that secretes large amounts of gastrin, High levels of H+ secretion by parietal cells, lead to low duodenal pH that inactivates pancreatic lipases
53
Secretin stimulation test
used to diagnose gastrin secreting tumors normal: secretin administration inhibits gastrin release gastrinomas: injection of secretin causes a paradoxical increase in gastrin release
54
Peptic ulcer disease
predominant cause: H. pylori infection and NSAID use | result of loss or protecting mucosal barrier, excessive H+ and pepsin secretions, 2 types: gastric and duodenal
55
Gastric ulcers
forms on the lining of the stomach, forms because gastric mucosal barrier is defective
56
Duodenal ulcers
form on the lining of the duodenum, usually do not become malignant, H+ secretion rates are higher than normal
57
Effect of parasympathetic and sympathetic innervation of the pancreas
Parasympathetic activity stimulates pancreatic secretion and sympathetic activity inhibits pancreatic secretion
58
2 components of pancreatic secretions
- enzymatic secretion by acinar cells - pancreatic proteases are secreted in inactive forms and converted to their active forms in the lumen of the duodenum - aqueous secretion by centroacinar and ductal cells - secrete HCO3- rich fluid that alkalinizes and hydrates protein rich primary secretion of acinar cells
59
Mutations in the cystic fibrosis transmembrane conductance regulator
- CFTR: regulated Cl- channel in the apical surface of the ductal cell - some CFTR mutations seem to be associated with a loss of HCO3- secretion

GI Exam 2 (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions