Physiology

Physiology Poster

Mechanism of acid Secretion:

• HCl is produced by the parietal cells of the stomach. • H2O and CO2 combine to produce carbonic acid which is catalyzed by carbonic anhydrase then dissociates into H+ and HCO3–. • The H+ is transported into the stomach lumen via the H+– K+ ATPase ion pump which uses ATP to exchange K+ ions into the parietal cells of the stomach with H+ ions. • The bicarbonate ion is transported out of the cell into the blood in exchange for Cl–. • This results in both hydrogen and chloride ions to associate with each other due to their opposing charges to form HCL in stomach lumen

HCL

Stimulated By:

Functions:

Acetylcholine, Histamine & Gastrin

• acidifying stomach content
• Prevents infections
• Activates pepsinogen to pepsin
• Provides optimum pH for the action of pepsin
• Helps in digestion of food
• Stimulates the flow of bile

Pepsinogen Secretions:

-Secreted by cheif cells in gastric glands, & mucous cells. -Pepsinogen: Aspartic proteinases, endopeptidases -Two types 1- Group I (cheif cell od corpus ) 2- Group II (cheif cells + mucous nech cells in all parts) -Zymogen granule compound exocytosis pepsinogen -Intrinsic factor is secreted by parietal cells of the gastric glands in the stomach, where it binds with the vitamin. Thus bound, intrinsic factor protects vitamin B12 from digestion as it passes through the gastrointestinal tract and facilitates the vitamin's absorption in the ileum of the small intestine.

Gastric Secretion Phases:

Three phases: 1-cephalic phase occurs in response to stimuli received by the senses—that is, taste, smell, sight, and sound. 2-Gastric phase set in motion by local neural and hormonal mechanisms triggered by the entry of food into the stomach. 3- Intestinal phase elaborated by the jejunum, has both excitatory and inhibitory elements.

Mucous Secretion:

The production of mucous inside the stomach is done by the surface epithelium and foveolar cells. Considering the composition mucous is mainly water with a remaining glycoprotein part that gives its Gel-like consistency. The viscosity is a production secretion rate limited depending on glandular cells and proteolytic enzymes. Bicarbonate ions are formed in the mucus-secreting cells by reacting carbon dioxide with water, using the enzyme carbonic anhydrase. The bicarbonate ions are then pumped into the mucus layer by exchanging them with chloride ions. This provides an increased pH to protect the stomach from digesting itself by Hcl

1. Omar Hawary 191070103
2. Abu Bakr Essam 191070227
3. Marwan Atef 191070014
4. Abdelrahman Abdelqaawy 191070172
5. Mostafa mohamed 191070250
6. Mohamed Abdallah 191070251
7. Ahmed Maher 191070234
8. Ahed Mokhtar 191070195
9. Mostafa Mohamed 191070072

10. Shahy Saleh 19107026011. Madonna Ezzat 19107006612. Raghad Maher 19107025913. Reem Ayman 192070010