Gastric Acid Secretion – Regulation & Output

GASTRIC ACID SECRETION – REGULATION & OUTPUT

Q. 1

Intrinsic factor of Castle is secreted by

 A

Chief cells

 B

Parietal cells

 C

Mucous cells

 D

β cells

Q. 1

Intrinsic factor of Castle is secreted by

 A

Chief cells

 B

Parietal cells

 C

Mucous cells

 D

β cells

Ans. B

Explanation:

Parietal cells [Ref: Guyton 11/e, p 797; Ganong 23/e, p 431-433; Gray’s Anatomy 40/e, p 1121-1122] The ‘intrinsic factor of castle’ is secreted by the parietal cells of gastric glands. It is essential for absorption of vitamin /312 in the ileum.

Gastric glands can be divided into three groups on the basis of site:

Gastric glands

_                       .,

Cells

Function/secretion

(1) Principal gastric

glands (body &

fundus)

•  Mucous neck cells

•  Chief/peptic cells

•  Parietal/oxyntic cells

-Mucous

-Pepsinogen &lipase

-HCL & intrinsic

Factor

 

•  Stem cells

-Differentiation into

other cell types

 

•Neuroendocrine/enteroendocrine

 

 

– G. cells

– Gastrin

 

– D. cells

– Somatostatin

 

– ECL (enterochromatin like

cells)

– Histamine

(2) Cardiac glands

•  Mucous secreting cells

– Mucous

(near cardiac orifice)

•  Few parietal and chief cells

– HCL, Intrinsic factor,

pepsinogen lipase

(3) Pyloric glands

•  Mucous secreting cells

-Mucous

(pyloric antrum)

•  G. cells

-Gastrin



Q. 2 Acid secretion in stomach is increased in all of the following conditions, except:
 A Decreased Histamine
 B Decreased Acetyl choline
 C Food in stomach
 D Decreased Gastrin
Q. 2 Acid secretion in stomach is increased in all of the following conditions, except:
 A Decreased Histamine
 B Decreased Acetyl choline
 C Food in stomach
 D Decreased Gastrin
Ans. C

Explanation:

Food in stomach


Q. 3 Parietal cells secrets:
 A Pepsinogen
 B HCI
 C Mucous
 D Pepsin
Q. 3 Parietal cells secrets:
 A Pepsinogen
 B HCI
 C Mucous
 D Pepsin
Ans. B

Explanation:

HCI


Q. 4

Which type of cells are NOT found in stomach?

 A

Chief cells

 B

Parietal cells

 C

Enterochromaffin cells

 D

Goblet cells

Q. 4

Which type of cells are NOT found in stomach?

 A

Chief cells

 B

Parietal cells

 C

Enterochromaffin cells

 D

Goblet cells

Ans. D

Explanation:

Goblet cells are interspersed between the absorptive cells. They are less abundant in the duodenum and more numerous in the ileum. These cells produce glycoprotein mucins that are hydrated and cross-linked to form mucus, whose main function is to protect and lubricate the lining of the intestine.

 
The cells of the gastric glands are parietal (oxyntic) cells, chief (zymogenic) cells, mucous cells, enterochromaffin cells secreting a variety of hormones mainly serotonin.

Q. 5

All of the following statements are correct about stomach, EXCEPT:

 A

Pylorus has more acid secreting cells

 B

A high number of goblet cells are present in mucous lining

 C

Chief cells secrete pepsinogen

 D

Parietal cells secrete intrinsic factor

Q. 5

All of the following statements are correct about stomach, EXCEPT:

 A

Pylorus has more acid secreting cells

 B

A high number of goblet cells are present in mucous lining

 C

Chief cells secrete pepsinogen

 D

Parietal cells secrete intrinsic factor

Ans. A

Explanation:

In the cardiac and pyloric regions, these are called the cardiac and pyloric glands, respectively, secrete mucus only.Parietal cells secrete hydrochloric acid and intrinsic factor; chief cells secrete rennin and lipase in infancy and pepsinogen throughout life; and enteroendocrine cells secrete hormones and paracrine messengers that regulate digestion.


Q. 6

Somatostatin is secreted by:

 A

Alpha cells

 B

Beta cells

 C

Delta cells

 D

Intestinal endothelial cells

Q. 6

Somatostatin is secreted by:

 A

Alpha cells

 B

Beta cells

 C

Delta cells

 D

Intestinal endothelial cells

Ans. C

Explanation:

The alpha cells, about 25 per cent of the total, secrete glucagon. The beta cells, constituting about 60 per cent of all the cells of the islets, lies mainly in the middle of each islet and secrete insulin and amylin, a hormone that is often secret in parallel with insulin, although its function is unclear. The delta cells, about 10 per cent of the total, secret somatostatin. In addition, at least one other type of cell, the PP cell, is present in small numbers in the islets and secretes a hormone of uncertain function called pancreatic polypeptide.

Ref: Ganong 23/e, page 316, 328-30


Q. 7

Intrinsic factor of Castle is secreted by?

 A

Chief cells

 B

Mucous cells

 C

Parietal cells

 D

p cells

Q. 7

Intrinsic factor of Castle is secreted by?

 A

Chief cells

 B

Mucous cells

 C

Parietal cells

 D

p cells

Ans. C

Explanation:

Intrinsic factor, a mucoprotein secreted by the parietal cells, binds with vitamin B12 of dietary origin and greatly enhances absorption of the vitamin. Absorption occurs by an active process in the terminal ileum. Intrinsic factor secretion is enhanced by stimuli that evoke H+ output from parietal cells. Pernicious anemia is characterized by atrophy of the parietal cell mucosa, deficiency in intrinsic factor, and anemia. Subclinical deficiencies in vitamin B12 have been described after operations that reduce gastric acid secretion, and abnormal Schilling tests in these patients can be corrected by the administration of intrinsic factor.
 
Ref: Doherty G.M., Way L.W. (2010). Chapter 23. Stomach & Duodenum. In G.M. Doherty (Ed), CURRENT Diagnosis & Treatment: Surgery, 13e.

Q. 8

All of the following factors increased acid secretion in the stomach, EXCEPT:

 A

Histamine

 B

Acetylcholine

 C

Food in stomach

 D

Gastrin

Q. 8

All of the following factors increased acid secretion in the stomach, EXCEPT:

 A

Histamine

 B

Acetylcholine

 C

Food in stomach

 D

Gastrin

Ans. C

Explanation:

Factors which increase the acid secretion in stomach are vagal stimulation(acetyl choline), gastrin and histamine. Gastrin and acetylcholine promote secretion by elevating cytosolic free calcium concentrations, whereas histamine increases intracellular cAMP.
 
Factors that inhibit HCl secretion are:
  • Low pH in the stomach by negative feedback mechanism
  • Intestinal influences
  • Somatostatin
  • Prostaglandins, epidermal growth factor transforming growth factor
Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. (2012). Chapter 25. Overview of Gastrointestinal Function & Regulation. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks (Eds), Ganong’s Review of Medical Physiology, 24e.

 


Q. 9

Intrinsic Factor of Castle is secreted by which of the following cells in gastric glands:

 A

Chief cells

 B

Parietal cells

 C

Enterochromaffin cells

 D

B cells

Q. 9

Intrinsic Factor of Castle is secreted by which of the following cells in gastric glands:

 A

Chief cells

 B

Parietal cells

 C

Enterochromaffin cells

 D

B cells

Ans. B

Explanation:

B i.e. Parietal Cells

Intrinsic factor of Castle is secreted by parietal (oxyntic) cellsQ and is essential for absorption of vitamin 1312Q; in its absence, Addison’s pernicious (megaloblastic) anemiaQ results.

Cells with in Principal Gastric Glands in body & fundus

Gastric glands are simple branched tubular glands which usually open in group of 4 into a short common channel (or gastric pit), through which they discharge their secretions into the lumen. Each gland has 3 zones containing 4 main cell types (& secrete)


Q. 10

Which of these statements are correct regarding acid secretion in stomach:

 A

Gastrin increases acid secretion

 B

Secretin decreases acid secretion

 C

H2 blockers decrease acid secretion

 D

All

Q. 10

Which of these statements are correct regarding acid secretion in stomach:

 A

Gastrin increases acid secretion

 B

Secretin decreases acid secretion

 C

H2 blockers decrease acid secretion

 D

All

Ans. D

Explanation:

A i.e. Gastrin increases acid secretion; B i.e. Secretin decreases acid secretion; C i.e. H2 blocker decreases acid secretion


Q. 11

True about gastric acid secretion:

 A

Secretion ,l,ses with secretin

 B

H2 blockers prevent release

 C

Total acid output indicates parietal cell mass activity

 D

All

Q. 11

True about gastric acid secretion:

 A

Secretion ,l,ses with secretin

 B

H2 blockers prevent release

 C

Total acid output indicates parietal cell mass activity

 D

All

Ans. D

Explanation:

A i.e. Secretion decreases with secretin B i.e., H2 blocker prevents relapse C i.e., Total acid output indicates parietal cell mass activity


Q. 12

Which of the following statements, regarding ‘secretin’ is least correct?

 A

Increases bicarbonate rich secretion

 B

Inhibit gastric acid secretion

 C

Increases gastric acid secretion

 D

Causes contraction of pyloric sphincter

Q. 12

Which of the following statements, regarding ‘secretin’ is least correct?

 A

Increases bicarbonate rich secretion

 B

Inhibit gastric acid secretion

 C

Increases gastric acid secretion

 D

Causes contraction of pyloric sphincter

Ans. C

Explanation:

C i.e. Increase gastric acid secretion


Q. 13

All of the following are associated with Gastric Ulcer’s Except:

 A

H. Pylori infection

 B

High Acid output

 C

Smoking

 D

Bile Reflux

Q. 13

All of the following are associated with Gastric Ulcer’s Except:

 A

H. Pylori infection

 B

High Acid output

 C

Smoking

 D

Bile Reflux

Ans. B

Explanation:

Answer is B (High Acid Output)

Gastric ulcers are associated with normal or decreased gastric acid output. High Acid output is a feature of Duodenal Ulcers.

`Gastric acid output (basal and stimulated) tend to be normal or decreased in Gastric Ulcer Patient’s’- Harrison

Aetiological factors in peptic ulceration:

Causal factor

Gastric ulcer

Duodenal ulcer

Hellicobacter pylori

Important

Very important

NSAIDs and aspirin

Important

Important

Acid

Normal or low acid output

High or normal acid output

Bile reflux

Important

Unimportant

Smoking

Important

Important

Stress

Evidence for head injuries and burns only

Family history

Uncommon

Common


Q. 14

Amount of gastric juice secreted per day ‑

 A

500-1000 ml

 B

1000-1500 ml

 C

2000-2500 ml

 D

3000-3500 ml

Q. 14

Amount of gastric juice secreted per day ‑

 A

500-1000 ml

 B

1000-1500 ml

 C

2000-2500 ml

 D

3000-3500 ml

Ans. C

Explanation:

Ans. is ‘c’ i.e., 2000-2500 ml


Q. 15

Gastric acid secretion is stimulated by all except-

 A

Gastric distension

 B

Gastrin

 C

Smell of food

 D

Somatostatin

Q. 15

Gastric acid secretion is stimulated by all except-

 A

Gastric distension

 B

Gastrin

 C

Smell of food

 D

Somatostatin

Ans. D

Explanation:

There are following phases of gastric acid secretion : ‑

 

  1. The cephalic phase :- Just as salivary secretion may start before food enters the mouth, gastric secretion is also intitiated before food enters the stomach. Sight, smell or even thought of food stimulate gastric acid secretion. It is by parsympathetic system through vagus. This phase accounts for 20% of acid secretion.
  2. The gastric phase :- This phase of acid secretion comes into play when food makes contact with the gastric mucosa. Acid secretion in this phase is brought about two factors :- (i) Hormonal stimulation due to gastrin release and (ii) Stretch of stomach wall due to gastric distension which activates a vago-vagal reflex as well as a local intragastric reflex. This phase accounts for 72-80% of acid secretion.
  3. The intestinal phase :- Once the food enters upper portion of small intestine (i.e., duodenum) it causes small amounts of gastric juice secretion because of gastrin released from dudenal mucosa. While the intestinal phase play only a minor role in stimulation of gastric secretion, presence of food in the intestine plays a major role in its inhibition. With the entry of food into the duodenum, gastric secretion starts slowing down. The presence of acid, fats, and products of protein digestion; and increased osmolarity in the duodenum inhibit gastric secretion by :- (i) Hormonal mechanism : These mentioned stimuli cause the release of several intestinal hormones like secretin, cholecystokinin (CCK), vasoactive intestinal peptide (VIP), gastric inhibitor polypeptide (GIP) and somatostatin. These local hormones inhibit the gastric secretion as well as gastric motility. (ii) Neural mechanism (enterogastric reflex) : The above mentioned stimuli inhibit gastric secretion and motility by intrinsic neural reflex.


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