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Questions and Answers
What primarily governs the delivery of chyme to the duodenum?
What primarily governs the delivery of chyme to the duodenum?
- Gastric motility and pyloric sphincter opening (correct)
- Neuronal signals from the duodenum
- Consistency of food before reaching the stomach
- Hormonal regulation from the pancreas
What effect does distension of the stomach have on motility?
What effect does distension of the stomach have on motility?
- Decreases motility due to increased pressure
- Increases motility by stimulating intrinsic nerve plexuses (correct)
- Has no effect on gastric emptying
- Increases motility only when the pyloric sphincter is closed
What role do enterogastrones play in gastric emptying?
What role do enterogastrones play in gastric emptying?
- Stimulate gastric contractions to enhance emptying
- Increase the volume of chyme in the stomach
- Inhibit stomach contractions to delay emptying (correct)
- Facilitate digestion of fats in the stomach
Which factor is NOT considered a gastric factor affecting stomach emptying?
Which factor is NOT considered a gastric factor affecting stomach emptying?
Which of the following substances in the duodenum most effectively delays gastric emptying?
Which of the following substances in the duodenum most effectively delays gastric emptying?
What is the consequence of hypertonicity in the duodenum on gastric emptying?
What is the consequence of hypertonicity in the duodenum on gastric emptying?
What triggers the enterogastric reflex that slows gastric emptying?
What triggers the enterogastric reflex that slows gastric emptying?
What role does somatostatin play during the gastric phase of digestion?
What role does somatostatin play during the gastric phase of digestion?
Which hormone is primarily responsible for promoting the secretion of pancreatic and biliary HCO3-?
Which hormone is primarily responsible for promoting the secretion of pancreatic and biliary HCO3-?
Which hormone inhibits gastric emptying and also stimulates the release of insulin from pancreatic β-cells?
Which hormone inhibits gastric emptying and also stimulates the release of insulin from pancreatic β-cells?
What is the effect of the hormone glucose-dependent insulinotropic peptide (GIP) on gastric motility?
What is the effect of the hormone glucose-dependent insulinotropic peptide (GIP) on gastric motility?
Which hormone is released from M cells during the fasting state to initiate the migrating motor complex?
Which hormone is released from M cells during the fasting state to initiate the migrating motor complex?
What effect does the binding of histamine to H2 receptors have on adenylyl cyclase?
What effect does the binding of histamine to H2 receptors have on adenylyl cyclase?
What is the role of somatostatin in gastric acid secretion?
What is the role of somatostatin in gastric acid secretion?
During the resting state of the parietal cell, where is the majority of the H+/K+ATPase located?
During the resting state of the parietal cell, where is the majority of the H+/K+ATPase located?
Which factor primarily stimulates the trafficking of H+/K+ATPase to the apical membrane?
Which factor primarily stimulates the trafficking of H+/K+ATPase to the apical membrane?
What ions are primarily involved in the processes described in the gastric lumen?
What ions are primarily involved in the processes described in the gastric lumen?
Which pathway does NOT contribute to the trafficking of H+/K+ATPase to the apical membrane?
Which pathway does NOT contribute to the trafficking of H+/K+ATPase to the apical membrane?
What happens to cAMP levels when somatostatin binds to its receptor?
What happens to cAMP levels when somatostatin binds to its receptor?
Which receptor is associated with the action of acetylcholine (ACh) in the parietal cells?
Which receptor is associated with the action of acetylcholine (ACh) in the parietal cells?
In the stimulated state, what structural change occurs in the parietal cell?
In the stimulated state, what structural change occurs in the parietal cell?
What triggers the cephalic phase of gastric acid secretion?
What triggers the cephalic phase of gastric acid secretion?
Which statement correctly describes the gastric phase of gastric acid secretion?
Which statement correctly describes the gastric phase of gastric acid secretion?
During which phase of gastric acid secretion does the body prepare to receive food?
During which phase of gastric acid secretion does the body prepare to receive food?
What are the main controls of gastric secretion during the intestinal phase?
What are the main controls of gastric secretion during the intestinal phase?
What role do prostaglandins play in gastric acid secretion?
What role do prostaglandins play in gastric acid secretion?
Which cranial nerve is primarily involved in the cephalic phase of gastric acid secretion?
Which cranial nerve is primarily involved in the cephalic phase of gastric acid secretion?
Which of the following best describes the intestinal phase?
Which of the following best describes the intestinal phase?
What does the presence of food in the stomach primarily stimulate?
What does the presence of food in the stomach primarily stimulate?
What is NOT a function of the cephalic phase in gastric acid secretion?
What is NOT a function of the cephalic phase in gastric acid secretion?
What mechanism primarily inhibits gastric acid secretion?
What mechanism primarily inhibits gastric acid secretion?
What triggers the activation of G cells in the stomach?
What triggers the activation of G cells in the stomach?
In the context of gastric acid secretion, what role does vagal activation play?
In the context of gastric acid secretion, what role does vagal activation play?
How does the buffering of pH by food affect gastrin release?
How does the buffering of pH by food affect gastrin release?
Which neurotransmitter is primarily responsible for stimulating acid secretion in the stomach?
Which neurotransmitter is primarily responsible for stimulating acid secretion in the stomach?
Which of the following best describes the role of ECL cells in gastric physiology?
Which of the following best describes the role of ECL cells in gastric physiology?
What is the primary effect of gastric distension on gastric secretion?
What is the primary effect of gastric distension on gastric secretion?
What happens to gastrin levels when somatostatin is released from D cells?
What happens to gastrin levels when somatostatin is released from D cells?
What effect does increased pH have on gastrin secretion?
What effect does increased pH have on gastrin secretion?
Which component is primarily activated by enteric neurons to stimulate parietal cells?
Which component is primarily activated by enteric neurons to stimulate parietal cells?
Which of the following statements about the roles of neurotransmitters in gastric physiology is accurate?
Which of the following statements about the roles of neurotransmitters in gastric physiology is accurate?
Flashcards
Stomach Emptying
Stomach Emptying
The process of chyme (partially digested food) leaving the stomach and entering the duodenum (small intestine).
Gastric Factors
Gastric Factors
Factors within the stomach that influence how quickly food empties.
Duodenal Factors
Duodenal Factors
Factors within the duodenum (the first part of the small intestine) that influence stomach emptying.
Enterogastric Reflex
Enterogastric Reflex
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Enterogastrones
Enterogastrones
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Chyme Consistency
Chyme Consistency
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Gastric Motility
Gastric Motility
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Histamine
Histamine
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H2 receptor
H2 receptor
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Secretagogues
Secretagogues
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H+/K+ATPase
H+/K+ATPase
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Parietel Cell
Parietel Cell
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Enterochromaffin-like cell
Enterochromaffin-like cell
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Somatostatin
Somatostatin
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cAMP
cAMP
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Gastrin
Gastrin
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Gastric Acid Inhibition
Gastric Acid Inhibition
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Secretin Hormone
Secretin Hormone
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Cholecystokinin (CCK)
Cholecystokinin (CCK)
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Glucose-dependent insulinotropic peptide (GIP)
Glucose-dependent insulinotropic peptide (GIP)
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Motilin Hormone
Motilin Hormone
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Cephalic phase
Cephalic phase
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Gastric phase
Gastric phase
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Intestinal phase
Intestinal phase
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Gastric acid secretion
Gastric acid secretion
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CNS
CNS
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Vagus nerves
Vagus nerves
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Stimulatory mechanisms
Stimulatory mechanisms
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Inhibitory mechanisms
Inhibitory mechanisms
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Prostaglandins
Prostaglandins
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Chyme
Chyme
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Gastric Acid Secretion
Gastric Acid Secretion
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Vagal Pathway
Vagal Pathway
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Enteric Neurones
Enteric Neurones
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G Cells
G Cells
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Parietal Cells
Parietal Cells
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pH Buffering
pH Buffering
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Amino Acid Stimulation
Amino Acid Stimulation
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Somatostatin
Somatostatin
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Enterogastric Reflex
Enterogastric Reflex
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Distension of Stomach
Distension of Stomach
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Study Notes
Hormonal Regulation of the Gastrointestinal Tract
- The gastrointestinal system is hormonally regulated.
- There are different types of cells involved (e.g., parietal cells).
- The stomach contains glands that secrete gastric juice.
- The stomach has different regions (e.g., fundus and antrum).
- Stomach emptying is controlled by the strength of antral waves and the pyloric sphincter.
- The rate is proportional to the volume of chyme in the stomach.
- Factors affecting emptying (e.g., consistency of chyme, duodenal factors).
Learning Objectives
- Students should be able to outline the gross anatomy and mechanical functions of the stomach.
- Describe the process of gastric emptying and its controls.
- List the gastric gland secretions and their functions.
The Stomach
- J-shaped, with capacity ranging from 50 to 1000ml.
- Accommodates food from the esophagus.
- Starts protein digestion (pepsin and HCI).
- Continues carbohydrates digestion (salivary amylase).
- Mixes food with gastric secretions into chyme.
- Stores food before passing to the small intestine.
- Secretes approximately 2 liters of gastric juice daily from gastric glands.
Mechanical Activity of the Stomach
- Occurs in two types:
- Orad stomach (fundus and proximal body) – tonic.
- Caudad stomach (distal body and antrum) – phasic.
Control of Stomach Emptying
- Strength of antral waves and pyloric sphincter opening determine chyme delivery.
- Governed by gastric and duodenal factors.
- Rate of emptying proportional to chyme volume.
- Distension increases motility due to: stretch of smooth muscle, stimulation of intrinsic nerve plexuses, and increased vagus nerve activity and gastrin release.
- Empting facilitated by thin liquid chyme.
Duodenal Factors
- Duodenum must be ready to receive chyme.
- Delays emptying through enterogastric reflex.
- Enterogastrones (e.g., cholecystokinin CCK) inhibit stomach contraction.
- Stimuli in the duodenum (e.g., fat, acid, hypertonicity, distension) drive neural and hormonal responses.
Secretory Activity of the Stomach
- Mucosa is categorized into oxyntic gland area (proximal stomach) and pyloric gland area (distal stomach).
- Composed of a surface lining, pits, and glands at the base of the pits.
- These glands are responsible for various secretions.
Secretions of the Gastric Glands
- Secretion includes hormones (e.g., gastrin).
- Includes different types of cells (e.g., chief cells, parietal cells, G cells, D cells and ECL cells).
- Different secretions have specific roles, such as activating pepsinogen to pepsin, stimulating HCI secretion, and binding vitamin B12.
Functions of Gastric Secretions
- HCI activates pepsinogen and denatures proteins and kills microbes.
- Pepsinogen activates to pepsin and is involved in protein digestion.
- Intrinsic factor is crucial for Vitamin B12 absorption.
- Gastroferrin is critical.
- Histamine and other substances activate HCI secretion.
- Mucous protects the stomach lining.
HCI Secretion Mechanism
- Proton pumps actively secrete H+.
- Bicarbonate is exchanged for Cl-, which enters the stomach lumen.
Gastrin and other hormones (e.g. ACh, Histamine)
- Stimulate or inhibit HCl secretion.
- Hormone functions can cause HCl secretion or have other functions.
- Affect the H+/K+ATPase to promote HCl secretion.
Secretagogues Cause Trafficking of the H+/K+ATPase
- Resting state—H+/K+ATPase is within cytoplasmic tubulovesicles.
- Stimulated state—H+/K+ATPase moves to apical membrane.
Inhibition of Gastric Acid Secretion
- Cephalic, gastric, and intestinal phases involve different mechanisms to inhibit secretion.
- Vagus nerve activity decreases, and other factors (e.g., reduced pH) affect these phases.
- Prostaglandins and somatostatin play a role in decreasing acid secretion.
Secretions of the Small Intestine- Hormones (1 & 2)
- Small intestine secretes various peptide hormones (e.g., gastrin, secretin, CCK, GIP, GLP-1, Motilin, Ghrelin).
- These hormones play roles in regulating digestion, nutrient absorption, and gastric emptying.
Secretions of the Small Intestine (Juice)
- The small intestine secretes succus entericus, a juice with varying compositions.
- Its secretion regulated by mechanisms, including hormones (e.g., gastrin, CCK, secretin) nerve activity, and distension.
Pancreatic Secretions
- Contains both endocrine (e.g., insulin and glucagon) and exocrine (e.g., enzymes and bicarbonate) components.
- Exocrine is the aqueous NaHCO3- solution to the duodenum as pancreatic juice.
Secretion of the Pancreatic Duct Cells
- Pancreatic ducts secrete alkaline fluid (HCO3-) into the duodenum.
- This neutralizes stomach acid, optimizes pH for enzymes, and protects the mucosa.
- Mechanisms involve various transporters.
Pancreatic Enzymes
- Acinar cells release enzymes (e.g., proteases, amylases, lipases) to digest food.
- These enzymes are initially inactive to prevent premature activation.
- Enterokinase activates the enzymes in the duodenum.
Control of Pancreatic Secretion
- Cephalic, gastric, and intestinal phases regulate secretion.
- These phases involve various stimuli (e.g., presence of acid in the duodenum, fat) that activate different pathways.
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Description
This quiz focuses on the hormonal regulation of the gastrointestinal tract, particularly the function and anatomy of the stomach. Students will explore gastric emptying processes, gastric gland secretions, and factors affecting digestion. Enhance your understanding of how hormones interact with the GI system.
