Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

DRS > Secretions of the stomach > Flashcards

Secretions of the stomach Flashcards

1
Q

What are the functions of the stomach?

A

Secretions of different cell types
Motility - peristalsis
Digestion - carbohydrate, protein and fat
Absorption - alcohol, drugs - aspirin

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

What is bolus?

A

Food is called bolus when it enters the stomach, up until the small intestine - then it is called chyme.

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

What are the parts of the stomach?

A

Cardia - beginning, near gastroesophageal sphincter
Oxyntic mucosa - fundus and body (corpus)
Pyloric - antrum and pyloric sphincter

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

What are the general functions of the stomach?

A

First part - corpus, is for storage
Bottom part - antrum and pylorus, is for enhancing digestion

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

What is the structure of the stomach?

A

There are infoldings of epithelial tissue to create a larger surface area to increase absorption.
Holes on the surface are the openings into the gastric pit.
The cell types changes as it travels down the pit.

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

What are the layers of the stomach?

A

At top:
Mucosa
Muscularis mucosa
Submucosa
Oblique muscle
Circular muscle
Longitudinal muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the function of the layers of the stomach?

A

Protects the stomach so it is not destroyed by the acid.

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

What are the parts of the stomach?

A

after the gastroesophageal junction:
cardia
fundus
antrum
pylorus
then goes to the duodenum
see picture

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

What are the cell types of the stomach?

A

At top:
Mucous neck cell
Parietal cell
EC like cell
Chief cell
D cell
G cell

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

What is the mucous neck cell?

A

Secretes mucous and bicarbonate HCO3-

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

What is the parietal cell?

A

Secretes acid and intrinsic factor

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

What is the EC cell?

A

Enteric Chromaffin
Secretes histamine

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

What is the chief cell?

A

Secretes pepsinogen and lipase

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

What is the D cell?

A

Produces somatostatin, which inhibits acid secretion

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

What is the G cell?

A

Secretes gastrin which stimulates acid production via the parietal cells.

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

How does the cell proportions change in the stomach?

A

The corpus has predominantly parietal and chief cells, and contains some ECL and D cells.
The antrum and pylorus have no parietal cells, and contain G-cells and D cells.

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

Why does the bottom of the stomach have different cells?

A

The antrum and pylorum are concerned with the pathway of the bolus when it exits the stomach.
It has more G and D cells for somatostatin production which inhibits acid.

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

How does the tissue structure of the stomach change?

A

The pit of the corpus is smaller than the antrum.
This is because the antrum produces more mucous, so produces more HCO3-, to neutralise the acid before entering the intestine.

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

How does acid secretion occur by Cl-?

A

Cl- enters the parietal cell against the loss of HCO3-.
This is paired with Na+ entry, which then exits back through the Na+/K+ pump.
The Cl- then enters the lumen.

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

How does acid secretion occur through H+?

A

H2O + CO2 <–carbonic anhydrase–> H2CO3 <–> H+ + HCO3-
H+ enters the lumen via a proton pump H+/K+ ATPase, against K+ entry into the parietal cell.
HCO3- then exits into the interstitial space by antiporter with Cl-.

21
Q

How does acid secretion occur?

A

The H+ and Cl- in the lumen of the stomach combine to form HCl.

22
Q

What does the HCO3- do?

A

HCO3- formed goes into the interstitial space then into the blood.
This increases the alkalinity - ‘alkaline tide’ - so more acid is produced, and this can be detected in a blood test that someone has just eaten.

23
Q

How does the vagus nerve regulate acid secretion through ACh?

A

The vagus nerve acts directly by producing Acetylcholine which binds to the muscarinic receptor on the parietal cells, which increases HCl secretion.

24
Q

How does the vagus nerve act on G cells to regulate acid secretion?

A

The vagus nerve acts indirectly on G cells by releasing gastrin releasing peptide, which secretes gastrin, then acts on the CCKB receptor of the parietal cells, and increases HCl secretion.

25
What is CCKB receptor?
cholecystokinin B receptor
26
How does the vagus nerve act on ECL to regulate acid secretion?
Acts on Enteric Chromaffin Like cells which secretes histamine. Histamine then acts on the H2 receptor of the parietal cells which increases HCl secretion.
27
What is paracrine regulation of acid secretion?
This acts on cells close by, not directly. Histamine is produced, which acts on the H2 receptor of parietal cells, and increases HCl secretion.
28
What are enterogastrones?
Hormones secreted by the duodenum that inhibits peristalsis and secretions in the stomach. This hormone is stimulated by fat. Somatostatin, CCK, prostaglandins and secretin.
29
What is secretin?
Secretin is released by S cells in the duodenum. It is stimulated by acid and fat in the duodenum and can inhibit acid secretion by inhibiting antral gastrin and somatostatin release by the D cells. Gastrin therefore cannot act on parietal cells to secrete acid.
30
How does CCK inhibit acid secretion?
CCK is produced by I-cells in the duodenum and jejenum in response to fat. It directly reduces parietal cell acid secretion.
31
How does prostaglandins inhibit acid secretion?
Produces HCO3- from mucous cells to produce mucous.
32
What is omeprazole?
Proton pump inhibitor. This directly acts on the H+/K+ ATPase pump to prevent H+ going into the lumen, so HCl isn't produced.
33
What are H2 antagonists?
H2 receptor antagonists cimetidine and ranitidine are competitive antagonists of histamine at the paritetal cell H2 receptor.
34
What are the phases of gastric secretion?
Basal Cephalic Gastric Intestinal
35
What is the basal phase?
Follows a circadium rhythm. Acid secretion is low at am and high at pm.
36
What is the cephalic phase?
30% of acid secretion. Initiated by smell, sight, taste, thought and swallowing of food. Mediated by vagus nerve which causes acid secretion.
37
What is the gastric phase?
50-60% of acid secretion. Stimulated by distention of the stomach, detected by mechanoreceptors, and partially digested proteins. The pepsin is partially digested and goes past the antrum, which targets G cells to secrete gastrin.
38
What is the intestinal phase?
5-10% of acid secretion. Stimulated by digested peptides in the duodenum. Causes quick digestion by releasing gastrin from duodenal G cells, which acts on the parietal cells to stimulate acid production.
39
What is pepsin?
Another gastric secretion which initiates protein digestion. Pepsin is the active form of pepsinogen, which is secreted by chief cells, and triggered by ACh. Triggers antral G-cell gastrin secretion.
40
What is mucous?
Mucous is a gastric secretion containing trapped HCO3-, and is secreted by mucous cells. The mucous layer protects the stomach from the acid, by preventing direct contact between the acid and the wall. The HCO3- neutralises hte acid.
41
How does prostaglandin regulate mucous?
Prostaglandins maintain mucosal diffusion barrier, by inhibiting acid secretion, stimulating HCO3- secretion and mucous secretion. The importance is exemplified by the effects of NSAIDS on gastric mucosa.
42
What is intrinsic factor?
IF is produced by parietal cells and is required for the absorption of vitamin B12 in the terminal ileum. IF binds to vitamin B12 and protects it from degradation by acid. This is because vitamins are very sensitive to pH.
43
What does damaged parietal cells cause?
Prevents production of IF, so vitamin B12 cannot enter the body, and red blood cells are not synthesised. This also affects DNA synthesis and nerve function. This leads to pernicious (megaloblastic) anaemia.
44
What is the cause of damaged parietal cells?
Pernicious anaemia is an autoimmune atrophic gastritis, where auto-antibodies are directed against parietal cells and causes their destruction.
45
What are peptic ulcers?
Lesions in the stomach or duodenum, mainly caused by Helicobacter pylori. H.pylori, which can survive in the stomach - produces urease which neutralises the gastric acid. Causes acid production and barrier damage - mucosal injury so stomach is not protected.
46
How does H pylori act in the antrum?
H.pylori infection causes G cells to hypersecrete gastrin nad decrease antral D-cell somotastatin release. This increases acid secretion which the duodenum cannot neutralise enough and causes hypergastrinaemia, and can lead to duodenal cancer.
47
How does H.pylori act in the corpus?
H.pylori infection leads to reduced acid secretion, causing hypochlorhydria, and leads to gastric ulcers. Urease is produced by HP converts. Urease cause Urea --> NH3 + CO2 + H2O --> NH4+ + HCO3-, which neutralises stomach acid.
48
What is the treatment of H.pylori?
Triple therapy of antibiotics. Amoxicillin affects the cell wall. Clarithromycin affects protein synthesis. Proton pumps affects the H+, affecting HCl formation. It must be triple so the bacteria cannot adapt against it.

DRS (13 decks)

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