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What are the 3 phases?
Cephalic
Gastric
Intestinal
How is the cephalic phase activated?
Activated by the taste of food, smell, and when you see and think of the food.
How long does the cephalic phase lasts
few seconds to minutes
How much of Gastric juices is released during the cephalic phase?
1/3
Where does the sight and thought of food goes to?
Cerebral cortex then hypothalamus
Where does the smell and taste of food goes to?
Goes directly to hypothalamus
What kind of fibers does the vagus nerve have and where does it go?
Parasympathetic fibers
goes to the submucosal plexus
Where does submucosal plexus send signals to?
Sends signals to the mucus glands which then secretes mucus.
The parietal cell will produce the HCI and Intrinsic factor which helps absorb vitamin B12
How do you make pepsin?
Pepsinogen mixes with HCI
What is pepsin responsible for?
Responsible for breaking down proteins
What else does the submucosa plexus also activates?
Activates the endocrine cells called g cells.
What do g cells secrete?
Secretes a hormone called gastrin
How does the Gastric phase start?
Starts when a bolus enters the stomach
How long does it the gastric phase last?
Can last for hours
How much of gastric juices are released?
2/3
What is Distension?
When the bolus enters the stomach and causes the stomach to stretch out
What happens when the bolus enters the stomach?
It becomes more base
What happens when there is change in the pH of your stomach?
Change in pH is sensed by chemoreceptors
What receptors sense when there is distension and where does it send signals to?
Stretch and chemoreceptors, it sends signals to the myentric plexus
Where is the myenteric plexus located ad what does it contain ?
Located in the muscularis externa and contains the lonitudunal and circular muscles
What muscle is in the stomach?
Oblique muscle
What will happen if the myenteric plexus stimulates the muscle to contract?
It will cause mixing waves so the bolus mixes w/ ACID and cause peristalsis. Which moves the bolus toward the end of stomach
What are partially digested proteins called?
peptones
…
Peptones-→sensed by g cells-→release of gastrin →pariatal, chief cells, and myentric plexus →
Where will the Gastrin go once it is released?
It will go to the bloodstreams and then to the parietal calls causing more HCI, pepsinogen, and chief cells to be released.
Where does cephalic phase take place?
Takes place before the stomach
Where does the Gastric phase take place?
takes place in the stomach
Where does the intestinal takes place?
takes place in the intestines
How does the intestinal phase start?
Starts when chyme enters the intestine
What happens to chyme when it is in the stomach?
It is pushed toward the pyloric sphincter
How much can the pylorus region of the stomach can hold?
30 ml of chyme
What is the pylorus made up of?
It is made up of the antrum and pyloric canal
Why does 3 ml of chyme pass through the duodenum?
So the body can test to see what’s in it
What happens when pep tones are present?
G- cells in the duodenum secrete Gastrin ( G34 Gastrin)
…..
Gastrin will go to chief cells and cause the release of pepsinogen. It will mix with HCI and make pepsin which will break pep tones in the duodenum.
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