4. Swallowing
• Food is pushed into the back of the mouth by
the tongue
• When food reaches the fauces, sensory
receptors initiate swallowing reflex
(involuntary)
5. Swallowing
• Food is pushed into the pharynx by the tongue
• When food reaches the fauces, sensory
receptors initiate swallowing reflex
(involuntary)
• Uvula is elevated to prevent food from
entering nasopharynx. Epiglottis drops down
to prevent food from entering the larynx.
6. Swallowing
• Food is pushed into the pharynx by the tongue
• When food reaches the fauces, sensory
receptors initiate swallowing reflex
(involuntary)
• Uvula is elevated to prevent food from
entering nasopharynx. Epiglottis drops down
to prevent food from entering the larynx.
• Peristaltic movements propel food from
pharynx into the esophagus
9. Esophagus: collapsible muscular tube,
about 25cm long, passageway between
pharynx and stomach
• Posterior to trachea
• Passes through an opening in diaphragm
called the esophageal hiatus
10. Esophagus: collapsible muscular tube,
about 25cm long, passageway between
pharynx and stomach
• Posterior to trachea
• Passes through an opening in diaphragm
called the esophageal hiatus
• Upper and lower esophageal sphincters
control movement of food into and out of
esophagus
13. Stomach Structure
4 regions:
1. Cardiac - small region around the opening from
esophagus
2. Fundus- most superior. Expands to provide
temporary storage
14. Stomach Structure
4 regions:
1. Cardiac - small region around the opening from
esophagus
2. Fundus- most superior. Expands to provide
temporary storage
3. Body- main portion
15. Stomach Structure
4 regions:
1. Cardiac - small region around the opening from
esophagus
2. Fundus- most superior. Expands to provide
temporary storage
3. Body- main portion
4. Pyloric- at exit of stomach
16. Stomach Structure
Wall- contains three layers of muscle:
• Innermost (oblique), Middle (circular), Outer
(longitudinal)
• Contains folds (rugae) that allow for expansion
18. Gastric Secretions (pg 6)
• Lining of stomach contains numerous tubular
gastric glands. Produce 2-3 liters of gastric
juice per day
19. Gastric Secretions (pg 6)
• Lining of stomach contains numerous tubular
gastric glands. Produce 2-3 liters of gastric
juice per day
• Chyme = Food + Gastric juice
20. Gastric Secretions (pg 6)
• Lining of stomach contains numerous tubular
gastric glands. Produce 2-3 liters of gastric
juice per day
• Chyme = Food + Gastric juice
• 4 Types of Cells in gastric glands
1. Mucous Cells: Produce thick alkaline mucus to
protect stomach lining and thin watery mucus to
mix with food
21. Gastric Secretions (pg 6)
• Lining of stomach contains numerous tubular
gastric glands. Produce 2-3 liters of gastric
juice per day
• Chyme = Food + Gastric juice
• 4 Types of Cells in gastric glands
1. Mucous Cells: Produce thick alkaline mucus to
protect stomach lining and thin watery mucus to
mix with food
2. Parietal Cells: Produce Hydrochloric acid (kills
bacteria) and Intrinsic factor (for absorption of
Vitamin B12)
22. Gastric Secretions (pg 6)
• 4 Types of Cells in gastric glands
1. Mucous Cells: Produce thick alkaline mucus to
protect stomach lining and thin watery mucus to
mix with food
2. Parietal Cells: Produce Hydrochloric acid (kills
bacteria) and Intrinsic factor (for absorption of
Vitamin B12)
3. Chief Cells: Produce enzyme pepsin for protein
digestion
23. Gastric Secretions (pg 6)
• 4 Types of Cells in gastric glands
1. Mucous Cells: Produce thick alkaline mucus to
protect stomach lining and thin watery mucus to
mix with food
2. Parietal Cells: Produce Hydrochloric acid (kills
bacteria) and Intrinsic factor (for absorption of
Vitamin B12)
3. Chief Cells: Produce enzyme pepsin for protein
digestion
4. Endocrine Cells: Produce gastrin (stimulates
gastric gland secretion)
24. Regulation of Gastric Secretions
1. Cephalic phase: Begins when you see, smell,
taste, or think about food. Medulla oblongata
sends signal to stomach to increase secretion
of gastric juice and the hormone gastrin.
Prepares stomach to receive food.
25. Regulation of Gastric Secretions
1. Cephalic phase: Begins when you see, smell,
taste, or think about food. Medulla oblongata
sends signal to stomach to increase secretion
of gastric juice and the hormone gastrin.
Prepares stomach to receive food.
2. Gastric phase: Begins when food reaches
stomach. Stretching of stomach wall
stimulates more gastrin secretion, which
leads to more production of hydrochloric acid
and pepsin
26. Regulation of Gastric Secretions
1. Cephalic phase: Begins when you see, smell,
taste, or think about food. Medulla oblongata,
sends signal to stomach to increase secretion of
gastric juice and the hormone gastrin. Prepares
stomach to receive food.
2. Gastric phase: Begins when food reaches
stomach. Stretching of stomach wall stimulates
more gastrin secretion, which leads to more
production of hydrochloric acid and pepsin
3. Intestinal phase: Begins when chyme passes
from stomach into duodenum of small intestine.
Decrease in pH in duodenum inhibits gastric
secretion.
27. Stomach Emptying
• Pyloric sphincter opens and lets a small
amount of chyme into small intestine. Then
closes, pauses, and repeats
28. Stomach Emptying
• Pyloric sphincter opens and lets a small
amount of chyme into small intestine. Then
closes, pauses, and repeats
• Takes about 4 hours for stomach to empty
after a meal, but time depends on the type of
food eaten (carbohydrates faster, fat slower)
