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DDS LAB -ED EXAM STUDY GUIDE
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DS LAB -ED EXAM STUDY GUIDE- Digestive system
- Digestive glands
The digestive system consists of:
Digestive Tract (Alimentary canal)
Oral cavity to nus
Digestive glands
TWO TYPES:
(1) embedded directly to digestive organs,
(2) form accessory glands outside digestive organs (ex: pancreas)
DIGESTIVE SYSTEM
Function:
○ Digestion of food (mechanical or chemical)
○ Absorption of digested substances (food)
○ Excretion of undigested materials (in anus in the form of feces)
DIGESTION
involves the mechanical action of the digestive tract and the chemical
action of substances and enzymes
Mechanical action
(in mouth) cut food in smaller particles
Chemical action
divide into smaller size with the use of substances and enzymes present
- Mechanical action
- Chemical action
2 actions in digestion:
- Mucosa
- Submucosa
- Muscularis
- Serosa
4 layers- well defined in esophagus to anus:
Mucosa
Innermost layer in the histologic organization of digestive tract
Muscularis
,Muscle tissue layer in the histologic organization of digestive tract
Serosa
Outermost layer in the histologic organization of digestive tract
1. Mucosa
2. Submucosa
3. Muscalaris
4. Serosa
- Mucous epithelium
- Lamina propria
- Muscularis mucosae
3 layers of Mucosa
Mucous epithelium
- in the lumen of organ / colon
■ Visible / well-defined in esophagus up to anus
■ Not observable in oral cavity to pharynx
■ Non-keratinized in esophagus
■ Simple columnar in stomach
Lamina propria
- where mucous epithelium is attached
- Loose CT with blood vessels
Muscularis mucosae
- outer part
■ Muscularis interna
■ Smooth muscle tissue located in the outermost part of mucosa layer
■ Separates mucosa from submucosa
Submucosa
● Consist of glands and blood vessels
● Dense Irregular CT
Submucosal plexus
nerve between submucosa and inner circular layer of muscularis externa
MUSCULARIS EXTERNA
● Muscularis layer - smooth muscle cells with 2 types of orientation
○ Inner Circular
, ○ Outer Longitudinal
● Myenteric plexus - nerve between 2 layers of muscularis externa
Muscularis layer
smooth muscle cells with 2 types of orientation
○ Inner Circular
○ Outer Longitudinal
Myenteric plexus
nerve between 2 layers of muscularis externa
INTRAMURAL PLEXUS
for contraction of muscle for peristalsis (move bolus from one organ to
another)
● Myenteric plexus
● Submucosal plexus
SEROSA
● Outermost layer
● Directly attached to visceral peritoneum
● Loose connective tissue usually seen in peritoneum
Serosa
- areas of digestive tract covered by peritoneum
○ ___ of small and large intestines is continuous with portions of
mesentery that suspends the intestines and continuous with peritoneum
○ Covers organs that freely move inside a cavity
Adventitia
- no peritoneal covering
○ Esophagus is not suspended in a cavity but bound directly to adjacent
structures
○ Covers organs that should be bound with the surrounding structures
for support
1. Lumen
2. Villi
3. Mucosa
4. Muscularis mucosae
5. Submucosa
6. Muscularis externa
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