20: Upper Digestive Flashcards
Where does the GI tract begin and end?
Begins at the mouth, ends at the anus
What is peristalsis?
Involuntary muscle contractions that propel food through the GI tract
What two types of mechanical digestion happen after ingestion?
Churning in the stomach
Segmentation in the small intestine
What are the four layers of the GI tract, from deep to superficial?
mucosa, submucosa, muscularis, and serosa or adventitia
What is the histological difference between the mucosa of the mouth, pharynx, and anal canal and the mucosa of the stomach and intestines?
In the mouth, pharynx, and anal canal the epithelium is stratified squamous epithelium. In the stomach and intestines, it is a simple columnar epithelium.
What is the submucosa and what does it do?
A broad layer of dense connective tissue connecting the mucosa to the muscularis. It includes blood and lymphatic vessels as well as submucosal glands to release digestive secretions. It also houses the submucosal plexus
What is the muscularis and what does it do?
The third layer of the GI tract. In the small intestine it is a double layer of smooth muscle that promote mechanical digestion. At the mouth and anal sphincter, it is skeletal (voluntary) muscle.
What is the serosa or adventitia and what does it do?
These hold the GI tract in place
What are deciduous teeth and how many do we have?
Baby teeth, 20
How many permanent teeth do we have (of each type)
8 incisors
4 canines (or cuspids)
8 premolars (or bicuspids)
12 molars
32 total
What is the dentin of a tooth covered by in the root?
Cementum
What does the esophagus pass through to access the stomach?
Esophageal hiatus
What structure controls the movement of food from the pharynx into the esophagus?
Superior esophageal sphincter
At what point does food pass from the esophagus into the stomach?
Inferior esophageal sphincter
What is deglutition?
Swallowing
What happens in the pharyngeal phase of deglutition?
The uvula and soft palate move upward and close off the nasopharynx
What happens during the esophageal phase of deglutition?
Peristalsis propels the food through the esophagus toward the stomach
What is the name of the ball of food made in the oral cavity?
Bolus
When the stomach deflates inward, it falls into folds called ______
Rugae
Each gastric gland secretes through the _____
Gastric pit
What cells secrete mucin that protect the stomach from its own acid juice?
Mucous neck cells
What do parietal cells do in the stomach?
Produce HCl and intrinsic factor
Why does the pH of the stomach need to be so low?
This is needed to activate the protein-digesting enzyme called pepsin
What do chief cells do in the stomach?
Secrete pepsinogen, which forms pepsin
What do enteroendocrine cells do in the stomach?
Secrete hormones from the stomach into the bloodstream
