Gastric secretion:-

Question 1

The volume of gastric secretion is about :

Answer 1

2 liters per day

Question 2

The pH of gastric secretion is

Answer 2

highly acidic (PH is about 2).

Question 3

Gastric mucosa contains many deep glands which open in a common chamber (gastric pits) that opens on ………….

Answer 3

On the surface of the mucosa

Question 4

Where is the glands secrete mucus ?

Answer 4

In the pyloric and cardiac regions

Question 5

In the funds and body of the stomach, the glands contain 2 types of cells:

Answer 5

1- Parietal (Oxyntic) cells
2- Peptic (Chief) cells

Question 6

Parietal (Oxyntic) cells secrete :

Answer 6

1- HCl
2- intrinsic factor

Question 7

Peptic (Chief) cells secrete :

Answer 7

pepsinogen

Question 8

The contents of the normal gastric juice:

Answer 8

1) Ions: H+ (100 mmol/L), Na+ (40 mmol/L), K+ (10 mmol/L) and Cl- (150 mmol/L).

2)Enzymes: Pepsinogen, amylase, lipase and gelatinase.

3)Mucous.

4)Gastric intrinsic factor.

5)Water

Question 9

Acid secretion (gastric HCl):

• In oxyntic cells CO2 combines with H2O forming …….. under the effect of……. then dissociate into………

Answer 9

H2CO3 , carbonic anhydrase enzyme , dissociate into H+ and HCO3-

Question 10

Acid secretion (gastric HCl):

•H+ is pumped into the……. in exchange with………by the activity of…..

Answer 10

lumens , K+ , H+ -K+ ATPase

• k+ from lumen to cell , H+ في الاتجاه العكس

Question 11

Acid secretion (gastric HCl):

• The HCO3- ion leaves the oxyntic cells through the basolateral border into the…………in exchange with…………. forming the…………… .

Answer 11

blood, Cl- , alkaline tide.

Question 12

Acid secretion (gastric HCl):

• Cl- ions is then pumped actively from the……. into the ……….to meet H+ forming ………

Answer 12

cell , gastric lumen , HCI

Question 13

The most important enzyme in the gastric HCL secretion is…………..

Answer 13

H+-K+ ATPase.

Question 14

Proton pump inhibitor drugs inhibit………..ATPase & so blocks …….

Answer 14

H+ - K+ ، blocks H+ secretion.

Question 15

Function of HCL:

Answer 15

1- Activating pepsinogen enzyme to active pepsin (important in protein digestion)

2- Helping ferrous and calcium absorption.

3- Killing bacteria in food into the stomach.

4- Promoting pancreatic, small intestinal and bile secretion.

Question 16

Regulation of HCl secretion by :

Answer 16

1. Stimulation of gastric acid secretion

2- Enzymes

3-Intrinsic factor

4- Mucous secretion

Question 17

Parietal cell is stimulated by:

Answer 17

1- Acetylcholine (ACh): Acts on Muscarinic receptors by increasing intracellular free Ca++.

2-Gastrin : Acts by by increasing intracellular free Ca++.

3- Histamine : Acts via H2 receptors by increasing cAMP.

Question 18

Acetylcholine (ACh) blocked by

Answer 18

Atropine

Question 19

Histamine blocked by

Answer 19

-cimitidine (Tagamet)

-ranitidine (Zantac)

-famotidine (Pepcid)

Question 20

Inhibition of gastric acid secretion by :

Answer 20

• -ve feedback inhibition of parietal cells by the HCl itself.

• Some GIT hormones: As GIP, CCK, secretin and VIP.

• Enterogastric reflex.

• Prostaglandins : by decreasing histamine effect .

Question 21

Pepsinogen:

1- It is secreted from:

2- Its secretion is stimulated by:

3- It is activated by:

4-It is activated in:

Answer 21

1- peptic (chief) cells , When it is secreted it is “inactive”

2- ACh, gastrin and histamine.

3- HCl into pepsin

4- In the stomach at PH 2 (highly acidic medium)

Question 22

Once the Pepsinogen is convert into pepsin the pepsin digest the proteins into:

Answer 22

polypeptides and peptones

Question 23

Gastric amylase: plays a very minor role in ?

Answer 23

digestion of starch

Question 24

Gastric lipase:

Answer 24

digestion of Lipid

Question 25

Gelatinase:

Answer 25

liquefies gelatin

Question 26

Gastric urease:

Answer 26

abnormally released in the presense of bacteria that are normally killed by HCl

Question 27

The Intrinsic factor: • It is a glycoprotein secreted by the…… • It combines with vitamin……… to allow its …… from the terminal ileum. • Vit. B12 is a maturation factor in………. and in absence of oxyntic cells, the patient develops ……….

Answer 27

• Parietal (oxyntic) cells. • vit. B12 , absorption • erythropoisis , pernicious anemia “ vit. B2 عامل خارجي مانصنعه في الجسم "

Question 28

phases of gastric secretion:

Answer 28

1. Cephalic phase (nervous) 2. Gastric phase (nervous and hormonal) 3. Intestinal phase (nervous and hormonal)

Question 29

Cephalic phase (nervous):

Answer 29

• It accounts for about 20% of gastric secretion associated with eating a meal.

Question 30

Cephalic phase (nervous): Food simulate gastric secretion through:

Answer 30

• a) Conditioned reflex: Seeing, smell, hearing or even thinking of food • b) Unconditioned reflex: Presence of food in the mouth .

Question 31

2. Gastric phase (nervous and hormonal):

Answer 31

• This phase begins when the food enters the stomach. • It accounts for about 70% of gastric secretion

Question 32

Intestinal phase (nervous and hormonal):

Answer 32

stimulation of gastric secretion through the release of gastrin hormone from duodenal mucosa in response to the digestive breakdown products of protein.

Question 33

Gastric (gastroduodenal) mucosal barrier:

Answer 33

• Protects the gastric mucosa from damage, irritation by gastric HCl or auto-digestion by pepsin enzyme.

Question 34

The protective factors of Gastric (gastroduodenal) mucosal barrier:

Answer 34

• Thick, viscid alkaline mucous layer •Tight junctions between adjacent epithelial cells. • Neutralization of the gastric acid by the alkaline secretions (pancreatic secretion, bile secretion • Continuous regeneration of gastric mucosa.