16 Questions
What is the major reaction involved in the digestion of all macromolecules?
Hydrolysis
What is the first organ in the digestive tract where digestion begins?
Mouth
What is the function of saliva in the mouth?
To lubricate the food
What is the movement of food through the digestive tract called?
Peristalsis
What is the name of the enzyme that breaks down carbohydrates in the mouth?
Amylase
What is the result of chewing food in the mouth?
Increased surface area of food
What is the name of the clump of food formed in the mouth?
Bolus
In which part of the digestive tract does no digestion occur?
Esophagus
What is the primary function of mucous cells in the stomach?
To secrete mucus
What is the term for the semifluid mass of food that is produced in the stomach?
Chyme
Which type of cell is responsible for synthesizing pepsinogen?
Chief cell
What is the pH of a full stomach?
2
What is the function of the proton gradient in parietal cells?
To secrete HCl
Which cell type is responsible for secreting gastrin?
G cell
What is the function of the lower esophageal sphincter?
To allow food to enter the stomach
What is the primary function of the stomach?
To mix and store food, and begin protein digestion
Study Notes
Anatomy of the Digestive System
- The digestive tract consists of: mouth, esophagus, stomach, small intestine (duodenum, jejunum, ileum), large intestine (ascending colon, transverse colon, descending colon, sigmoid colon), rectum, and anus.
- The pancreas, liver, and gallbladder are also part of the digestive system.
Mouth and Esophagus
- Digestion begins in the mouth with the breakdown of carbohydrates by amylase in saliva.
- Chewing increases the surface area of food, allowing more enzymes to act on it.
- A bolus is formed in the mouth, which is pushed into the esophagus by swallowing, and then moved down the esophagus via peristaltic action.
- Peristalsis is a wave-like motion of smooth muscle that moves food through the digestive tract.
- No digestion occurs in the esophagus.
Stomach
- The stomach is a flexible pouch that mixes and stores food, reducing it to a semifluid mass called chyme.
- The stomach contains exocrine glands with gastric pits, and begins protein digestion with the enzyme pepsin.
- The low pH of the stomach (pH 2) assists protein digestion and helps kill ingested bacteria.
- There are four major cell types in the stomach: mucous cells, chief cells, parietal cells, and G cells.
- Mucous cells secrete mucus, which lubricates the stomach wall.
- No absorption occurs in the stomach.
Learn about the different parts of the digestive system, including the digestive tract and accessory organs, and their roles in digestion.
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