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Neural and Endocrine Control of Digestive Processes
                             Production of Saliva

Salivary Glands are stimulated to produce and release saliva.
Text Box: Salivary Glands are stimulated to produce and release saliva.

Efferent messages are sent via PNS fibers in cranial nerves VII and IX)

Text Box: Efferent messages are sent via PNS fibers in cranial nerves VII and IX)
Contractions of Masseter and Temporalis muscles in chewing stimulates Pressoreceptors .  Afferent messages of chewing are sent to the salivatory nuclei.
Text Box: Contractions of Masseter and Temporalis muscles in chewing stimulates Pressoreceptors .  Afferent messages of chewing are sent to the salivatory nuclei.
Chemoreception with Taste Buds.  Afferent messages of taste via the Facial, Glossopharyngeal and Vagus nerves (CN VII, IX and X) are sent to the salivatory nuclei.
Text Box: Chemoreception with Taste Buds.  Afferent messages of taste via the Facial, Glossopharyngeal and Vagus nerves (CN VII, IX and X) are sent to the salivatory nuclei.
Presence of Food in the Mouth
Text Box: Presence of Food in the Mouth
Salivatory Nuclei in the Pons and Medulla
Text Box: Salivatory Nuclei in the Pons and Medulla
Hypothalamus - Low Blood Sugar Produces Hunger Drive
Text Box: Hypothalamus - Low Blood Sugar Produces Hunger Drive
Cerebral Cortex
Text Box: Cerebral Cortex
SIght, Smell or Thought of Food
Text Box: SIght, Smell or Thought of Food

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Cerebrum
Text Box: Cerebrum
Sight, smell, taste or thought of food
Text Box: Sight, smell, taste or thought of food

   

 

 

 

 

 

Gastric Phase
Text Box: Gastric Phase

 

Neural and Endocrine Regulation of Digestion in the Stomach and Small Intestine  - 3 Phases
Text Box: Neural and Endocrine Regulation of Digestion in the Stomach and Small Intestine  - 3 Phases

 


 

Submucosal plexi of the stomach wall are stimulated
Text Box: Submucosal plexi of the stomach wall are stimulated
  
       

 

 

 

 

 

 

 

 

 

   
   

 

 

 

 

 

 

 

The overall effect of a, b and c above is to lower the pH of the stomach chyme and reduce the distention of the stomach wall due to the passage of acid chyme through the pyloric sphincter into the duodenum.  The entrance of chyme into the small intestine brings on the last component of the control of gastric digestion, namely, the Intestinal Phase.

Text Box: The overall effect of a, b and c above is to lower the pH of the stomach chyme and reduce the distention of the stomach wall due to the passage of acid chyme through the pyloric sphincter into the duodenum.  The entrance of chyme into the small intestine brings on the last component of the control of gastric digestion, namely, the Intestinal Phase.

 

 

 

 

 

 

 

 

III.  Intestinal Phase of Gastric Digestion - Duration is several hours
    The combined result of the hormonal and neural portions of the intestinal phase is to insure that the stomach doesn't empty more chyme into the small intestine than can be processed by the duodenum at one time.

 

Text Box: III.  Intestinal Phase of Gastric Digestion - Duration is several hours
    The combined result of the hormonal and neural portions of the intestinal phase is to insure that the stomach doesn't empty more chyme into the small intestine than can be processed by the duodenum at one time.
 

 

 

 

 

 

 

 

 

 

 

 

   

 

 

 

 

Cephalic Phase
Text Box: Cephalic Phase

 


 

The release of secretin and cholecystokinin by duodenal enterendocrine cells coordinates the functions of the small intestine and the accessory organs of digestion with the stomach as see in the table below.

Digestive organ Effects of Secretin Effects of Cholecystokinin
Stomach Inhibits gastric secretion and peristalsis Inhibits gastric secretion and peristalsis
Pancreas Release of pancreatic juice rich in sodium bicarbonate Release of pancreatic juice rich in enzymes
Liver Release of bile to the small intestine by way of the hepatic ducts No significant effect
Gall Bladder No significant effect Contraction of gall bladder and relaxation of the sphincter of Oddi
Intestinal Mucosa Release of digestive juice and Brunner's gland mucous Same as secretin

 

           

 

Stimulates the duodenum due to distension and the entrance of chyme containing glucose and fatty acids
Text Box: Stimulates the duodenum due to distension and the entrance of chyme containing glucose and fatty acids

 

 

 

 

cholecystokinin
Text Box: cholecystokinin
secretin
Text Box: secretin

Duodenal enteroendocrine cells release two hormones
Text Box: Duodenal enteroendocrine cells release two hormones
Entrance of acid chyme into the duodenum
Text Box: Entrance of acid chyme into the duodenum

Inhibits the emptying of the stomach by reducing peristalsis and closing the pyloric sphincter
Text Box: Inhibits the emptying of the stomach by reducing peristalsis and closing the pyloric sphincter
Inhibits the release of gastric juice
Text Box: Inhibits the release of gastric juice
Directly stimulates
Text Box: Directly stimulates

a. Increased gastric juice secretion

Text Box: a. Increased gastric juice secretion

3.  Presence of proteins and amino acids in incoming food stimulates enteroendocrine (G) cells releasing the hormone gastrin.  This results in

Text Box: 3.  Presence of proteins and amino acids in incoming food stimulates enteroendocrine (G) cells releasing the hormone gastrin.  This results in

2.  An increase in the pH of the stomach contents as foods buffer the gastric juice.

Text Box: 2.  An increase in the pH of the stomach contents as foods buffer the gastric juice.

1.  Distension of the stomach as food enters.
 

Text Box: 1.  Distension of the stomach as food enters.
 
       
Neural enterogastric reflex
Text Box: Neural enterogastric reflex

 

c. Relaxation of the pyloric sphincter

Text Box: c. Relaxation of the pyloric sphincter

b. Increased peristalsis of the stomach wall

Text Box: b. Increased peristalsis of the stomach wall
Parasympathetic impulses via the vagus nerve
Text Box: Parasympathetic impulses via the vagus nerve
Medulla Oblongata
Text Box: Medulla Oblongata