Physio - Digestion In The Stomach And Peptic Ulcers Flashcards
Describe the control of the gastric motility in the stomach.
- Parasympathetic stimulations and Gastrin increase the force of gastric smooth muscles contractions.
- Sympathetic stimulations and secretin and cholecystokinin decrease the force of gastric smooth muscle contractions.
List the factors that support the reservoir function of the proximal part of the stomach
Tonic contractions
Rugae- allow stomach to expand
Receptive relaxation - induced via the vagovagal reflex and increase the stomach volume.
List the types of phasic contractions of the stomach.
Propulsion - when food moves down to the antrum
Retropulsion - when food is forced back into the body of the stomach
Gastric emptying - food is move down to the duodenum
Gastric emptying involves what two events?
- Phasic contractions of the stomach antrum
- Relaxation of the pyloric sphincter.
State the regulation of gastric emptying.
- Fatty acids stimulate the release of CCK and inhibits gastric contraction.
- Low pH stimulates the release of secretin and inhibits gastric contraction.
Facts that inhibits gastric emptying.
List the three types of exocrine cells in the gastric glands.
- Mucous cells - mucus
- Parietal cells - hydrochloric acid and intrinsic factor
- Chief cells - pepsinogen and gastric lipase.
What does gastrin stimulate? State what its secretion is increases and reduced by.
A. Parietal cells - secrete HCL acid
B. Gastrin secretion is increased by vagal stimulation and presence of amino acids
- Gastrin secretion is decreased by high amount of HCL acid in the stomach.
Describe the process of secretion of hydrochloric acid.
- Carbonic anhydrate catalyzed the formation of carbonic acid.
- Carbonic acid is dissociated into H+ and HCO3- ions
- The proton pump pumps the H+ into stomach lumen and brings K+ into the parietal cell.
- The increase K+ concentration causes K+ to diffuse back into the gastric lumen
- HCO3- exits the cell into the blood steam in exchange for the CL-
- The Cl- ion diffuse from the cell into the gastric lumen via the channel and form HCl acid.
Hydrochloric acid is stimulated and inhibited by what agents?
Stimulates-
AcH, Gastrin, Histamine, secretin and Cholecystokinin
Inhibited-
Somatostatin and prostaglandin E2.
State the roles of hydrochloric acids.
- Kills microbes
- Denatures proteins
- Converts pepsinogen
- Creates optimum pH
- Stimulates the release of enteric hormones.
Pepsin is derived from and what is its function?
Pepsinogen which was derived from the chief cells.
It acts as an endopeptidase which acts on peptide bonds.
What is pepsin stimulated by?
ACh
Gastrin
Histamine
CCK
Secretin
What stimulates Gastric acid?
Secretin and cholecystokinin.
What is the most frequent site for peptic ulcers?
Duodenum
Lesser curvature of antral part of the stomach
Lower end of the esophagus
State the significance of Gastric lipase.
- Produced by the chef cells
- Breaks down triglycerides into fatty acids and glycerol
- Significant in newborn infants
- Is deactivated by pancreatic proteases once contents of the stomach move into the duodenum.
Note: The continued action of gastric lipase is permitted when there is an issue with pancreatic proteases.