24.13 Three Phases of Gastric Secretion Slide number 1 Copyright © The McGraw-Hill Companies, Inc....
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24.13 Three Phases of Gastric Secretion Slide number 1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1. The taste or smell of food, tactile sensations of food in the mouth, or even thoughts of food stimulate the medulla oblongata (green arrow). 2. Parasympathetic action potentials are carried by the vagus nerves to the stomach (pink arrow). 3. Preganglionic parasympathetic vagus nerve fibers stimulate postganglionic neurons in the enteric plexus of the stomach. 4. Postganglionic neurons stimulate secretion by parietal and chief cells and stimulate gastrin secretion by Cephalic Phase Gastrin Circulation Secretions stimulated Taste or smell of food Tactile sensation in mouth Medulla oblongata Vagus nerves Stomach 1 2 3 5 4
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Transcript of 24.13 Three Phases of Gastric Secretion Slide number 1 Copyright © The McGraw-Hill Companies, Inc....
24.13 Three Phases of Gastric SecretionSlide number 1
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
1. The taste or smell of food, tactile sensations of food in the mouth, or even thoughts of food stimulate the medulla oblongata (green arrow).
2. Parasympathetic action potentials are carried by the vagus nerves to the stomach (pink arrow).
3. Preganglionic parasympathetic vagus nerve fibers stimulate postganglionic neurons in the enteric plexus of the stomach.
4. Postganglionic neurons stimulate secretion by parietal and chief cells and stimulate gastrin secretion by endocrine cells.
5. Gastrin is carried through the circulation back to the stomach (purple arrow), where it stimulates secretion by parietal and chief cells.
Cephalic Phase
Gastrin
Circulation
Secretionsstimulated
Taste or smell of foodTactile sensation in mouth
Medulla oblongata
Vagus nerves
Stomach
1
2 3
5
4
24.13 Three Phases of Gastric SecretionSlide number 2
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
The taste or smell of food, tactile sensations of food in the mouth, or even thoughts of food stimulate the medulla oblongata (green arrow).
Taste or smell of foodTactile sensation in mouth
Medulla oblongata
Cephalic Phase
24.13 Three Phases of Gastric SecretionSlide number 3
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Parasympathetic action potentials are carried by the vagus nerves to the stomach (pink arrow).
Vagus nerves
Cephalic Phase
24.13 Three Phases of Gastric SecretionSlide number 4
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Preganglionic parasympathetic vagus nerve fibers stimulate postganglionic neurons in the enteric plexus of the stomach.
Vagus nerves
Cephalic Phase
24.13 Three Phases of Gastric SecretionSlide number 5
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cephalic Phase
Postganglionic neurons stimulate secretion by parietal and chief cells and stimulate gastrin secretion by endocrine cells.
Gastrin
Stomach
24.13 Three Phases of Gastric SecretionSlide number 6
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cephalic Phase
Gastrin is carried through the circulation back to the stomach (purple arrow), where it stimulates secretion by parietal and chief cells.
Gastrin
Circulation
Secretionsstimulated
24.13 Three Phases of Gastric SecretionSlide number 7
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Stomach
Local reflexesstimulated bystomach distention
Distention
Secretionsstimulated
Vagus nervesMedulla oblongata
1. Distention of the stomach activates a parasympathetic reflex. Action potentials are carried by the vagus nerves to the medulla oblongata (green arrow).
2. The medulla oblongata stimulates stomach secretions (pink arrow).
3. Distention of the stomach also activates local reflexes that increase stomach secretions (purple arrow).
Gastric Phase
1
2
3
24.13 Three Phases of Gastric SecretionSlide number 8
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Local reflexesstimulated bystomach distention
Distention
Vagus nervesMedulla oblongata
Distention of the stomach activates a parasympathetic reflex. Action potentials are carried by the vagus nerves to the medulla oblongata (green arrow).
Gastric Phase
Stomach
24.13 Three Phases of Gastric SecretionSlide number 9
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Gastric Phase
Secretionsstimulated
The medulla oblongata stimulates stomach secretions (pink arrow).
Vagus nerves
Stomach
Decreasedgastricsecretions
24.13 Three Phases of Gastric SecretionSlide number 10
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Gastric Phase
Local reflexesstimulated bystomach distention
Distention of the stomach also activates local reflexes that increase stomach secretions (purple arrow).
Stomach
Distention
24.13 Three Phases of Gastric SecretionSlide number 11
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
1. Chyme in the duodenum with a pH less than 2 or containing fat digestion products (lipids) inhibits gastric secretions by three mechanisms.
2. Sensory vagal action potentials to the medulla oblongata (green arrow) inhibit motor action potentials from the medulla oblongata (pink arrow).
3. Local reflexes inhibit gastric secretion (orange arrows).
4. Secretin, gastric inhibitory polypeptide, and cholecystokinin produced by the duodenum (brown arrows) inhibit gastric secretions in the stomach.
Intestinal Phase
Secretin, gastric inhibitorypeptide, cholecystokinin
Circulation
pH<2or lipids
Localreflexes
Decreasedgastricsecretions
Medulla oblongata
Vagusnerves
Vagusnerves
12
3
4
24.13 Three Phases of Gastric SecretionSlide number 12
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Chyme in the duodenum with a pH less than 2 or containing fat digestion products (lipids) inhibits gastric secretions by three mechanisms.
pH<2or lipids
Intestinal Phase
24.13 Three Phases of Gastric SecretionSlide number 13
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Intestinal Phase
Sensory vagal action potentials to the medulla oblongata (green arrow) inhibit motor action potentials from the medulla oblongata (pink arrow).
pH<2or lipids
Medullaoblongata
Vagusnerves
Vagusnerves
Mechanism One
Decreasedgastricsecretions
24.13 Three Phases of Gastric SecretionSlide number 14
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Intestinal Phase
Local reflexes inhibit gastric secretion (orange arrows).
pH<2or lipids
Localreflexes
Decreasedgastricsecretions
Mechanism Two
24.13 Three Phases of Gastric SecretionSlide number 15
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Secretin, gastric inhibitory polypeptide, and cholecystokinin produced by the duodenum (brown arrows) inhibit gastric secretions in the stomach.
Secretin, gastric inhibitorypeptide, cholecystokinin
pH<2or lipids
Decreasedgastricsecretions
Circulation
Mechanism Three
Intestinal Phase
