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Questions and Answers
Which of the following substances inhibits gastric secretions in the stomach?
Which of the following substances inhibits gastric secretions in the stomach?
What type of cells produce histamine in the stomach?
What type of cells produce histamine in the stomach?
What is the primary effect of secretin on gastric secretions?
What is the primary effect of secretin on gastric secretions?
Which of the following substances stimulates gastric acid secretion?
Which of the following substances stimulates gastric acid secretion?
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What neurotransmitter is secreted by cholinergic nerves to stimulate gastric acid secretion?
What neurotransmitter is secreted by cholinergic nerves to stimulate gastric acid secretion?
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Inhibition of gastric secretion occurs due to which of the following factors?
Inhibition of gastric secretion occurs due to which of the following factors?
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Which of the following is NOT a known inhibitor of gastric acid secretion?
Which of the following is NOT a known inhibitor of gastric acid secretion?
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What type of receptors do ECL cells utilize to stimulate acid secretion?
What type of receptors do ECL cells utilize to stimulate acid secretion?
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What protects the stomach from self-digestion?
What protects the stomach from self-digestion?
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What is the primary composition of chyme?
What is the primary composition of chyme?
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What is the primary role of acetylcholine in gastric secretion?
What is the primary role of acetylcholine in gastric secretion?
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Which cells in the stomach are responsible for producing gastrin?
Which cells in the stomach are responsible for producing gastrin?
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What triggers the cephalic phase of gastric secretion?
What triggers the cephalic phase of gastric secretion?
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How does the H+/K+ ATPase function in gastric acid secretion?
How does the H+/K+ ATPase function in gastric acid secretion?
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What type of cells produce histamine in the gastric gland?
What type of cells produce histamine in the gastric gland?
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What effect does chyme with a pH less than 2 have on gastric secretions?
What effect does chyme with a pH less than 2 have on gastric secretions?
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Which cells in the stomach are responsible for gastrin production?
Which cells in the stomach are responsible for gastrin production?
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During the gastric phase, which trigger activates parasympathetic reflexes?
During the gastric phase, which trigger activates parasympathetic reflexes?
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What is the primary mechanism of action for histamine in gastric secretion?
What is the primary mechanism of action for histamine in gastric secretion?
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Which hormone is secreted by the stomach in response to the cephalic phase?
Which hormone is secreted by the stomach in response to the cephalic phase?
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Which phase occurs when food initially enters the stomach?
Which phase occurs when food initially enters the stomach?
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What is the primary function of famotidine in acid secretion regulation?
What is the primary function of famotidine in acid secretion regulation?
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Which drug class works by irreversibly inhibiting the H+/K+-ATPase pump?
Which drug class works by irreversibly inhibiting the H+/K+-ATPase pump?
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Which receptors are involved in gastric acid secretion modulation?
Which receptors are involved in gastric acid secretion modulation?
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What effect does somatostatin have on gastric acid secretion?
What effect does somatostatin have on gastric acid secretion?
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What is the role of ACh in gastric acid secretion?
What is the role of ACh in gastric acid secretion?
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Which phase of gastric secretion is primarily influenced by the presence of food?
Which phase of gastric secretion is primarily influenced by the presence of food?
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What component is essential for the production of hydrochloric acid (HCl) in the stomach?
What component is essential for the production of hydrochloric acid (HCl) in the stomach?
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What is the outcome of using proton pump inhibitors?
What is the outcome of using proton pump inhibitors?
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What is the primary role of prostaglandins in the body?
What is the primary role of prostaglandins in the body?
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Which enzyme is responsible for the first step in prostaglandin synthesis?
Which enzyme is responsible for the first step in prostaglandin synthesis?
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What is the effect of antacids on gastric acid?
What is the effect of antacids on gastric acid?
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Which of the following is NOT a characteristic of alginates?
Which of the following is NOT a characteristic of alginates?
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What is the role of Histamine H2-receptor antagonists in acid secretion?
What is the role of Histamine H2-receptor antagonists in acid secretion?
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Which ion is primarily involved in the action of the proton pump in gastric acid secretion?
Which ion is primarily involved in the action of the proton pump in gastric acid secretion?
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What is the effect of PGE2 when it interacts with parietal cells?
What is the effect of PGE2 when it interacts with parietal cells?
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Which component does NOT play a role in gastric acid secretion?
Which component does NOT play a role in gastric acid secretion?
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Study Notes
Gastric Secretion Regulation
- Gastric secretion is regulated by neural and hormonal mechanisms.
- Three phases: cephalic, gastric, and intestinal.
Cephalic Phase
- Occurs before food enters the stomach.
- Taste, smell, or even thoughts of food stimulate the medulla oblongata.
- Stimulates parasympathetic action potentials through the vagus nerve to the stomach.
- Results in HCl and pepsin secretion by parietal and chief cells.
- Also stimulates gastrin secretion.
- Gastrin further stimulates HCl and pepsin secretion.
Gastric Phase
- Occurs once food enters the stomach.
- Stomach distension activates a parasympathetic reflex.
- Action potentials are carried by the vagus nerve to the medulla oblongata.
- This stimulates further secretions to the stomach.
- Distension also stimulates local reflexes that amplify stomach secretions.
Intestinal Phase
- Occurs as partially digested food enters the duodenum.
- Chyme in the duodenum with pH less than 2 or containing lipids inhibits gastric secretions.
- Three mechanisms involved:
- Sensory input from the duodenum inhibits motor input from the medulla to the stomach. This stops pepsin and HCl secretion.
- Local reflexes inhibit gastric secretion.
- Secretin, gastric inhibitory polypeptide, and cholecystokinin produced by the duodenum inhibit gastric secretions in the stomach.
Physiological Regulation of Gastric Acid Secretion
- Stimulatory factors: gastrin, acetylcholine, histamine
- Inhibitory factors: somatostatin, prostaglandins E2 and I2, intestinal hormones
Stimulation of Gastric Acid Secretion
- Mechanism: Cholinergic nerves release acetylcholine, which acts on muscarinic receptors on parietal cells and ECL cells.
- ECL cells release histamine.
- Histamine acts on H2-receptors on parietal cells.
- Gastrin also acts on parietal cells and ECL cells.
- Parietal cells release hydrogen ions (H+) through the proton pump (H+/K+ ATPase).
Inhibition of Gastric Acid Secretion
- Mechanism: Somatostatin (SSR) is secreted from D cells in the gastric gland.
- Somatostatin inhibits gastrin, histamine, and acetylcholine release.
- Prostaglandins E2 (PGE2) and I2 (PGI2) also inhibit gastric acid secretion by acting on parietal cells.
Drugs to Treat Disorders of Acid Secretion
- Antacids and alginates: buffer gastric acid, raising pH (e.g., Calcium carbonate and magnesium carbonate)
- Histamine H2-receptor antagonists: decrease acid secretion (e.g., famotidine)
- Proton pump inhibitors: irreversibly inhibit the H+/K+-ATPase pump, preventing acid secretion (e.g., omeprazole and lansoprazole)
Summary
- Gastric secretion is a complex process regulated by multiple factors.
- HCl production is a key element, stimulated by various factors and inhibited by others.
- Understanding the different phases of gastric acid secretion and its regulation is crucial for medical professionals.
- Various drugs target specific mechanisms to treat disorders of acid secretion.
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Description
Explore the intricate process of gastric secretion regulation, which involves neural and hormonal mechanisms across three key phases: cephalic, gastric, and intestinal. Learn how different stimuli affect the secretion of gastric acid and enzymes to aid digestion.
