Digestive System Flashcards
What are the four stages of the digestive system?
- Ingestion
- Digestion
- Absorption
- Egestion
How long is the digestive tract of adults?
6-9m
What is the digestive system responsible for?
Taking in, storing, breaking down, and absorbing food as well as removing waste materials
How does food move through the digestive system?
Peristalsis; a contractile motion
In order; how does food travel through the digestive system?
- Mouth
- Esophagus
- Stomach
- Small intestine
- Large intestine
- Rectum
- Anus
What happens in the mouth?
The start of sugar/carb breakdown
What is the esophagus?
A connector
What does the liver do?
Makes bile
What does the gallbladder do?
Stores the bile
What does the stomach do?
Starts protein breakdown (HCl)
What is the pancreas?
An enzyme factory
What does the small intestine do?
90% of absorption and digestion
What does the large intestine do?
Site of water absorption
What is ingestion?
The taking in of nutrients by the mouth
What occurs in the mouth?
The early stages of chemical and mechanical digestion
What is food that is taken in called?
Bolus
What is saliva?
A watery, slippery fluid produced by the salivary glands, dissolves food particles and lubricates the food bolus; responsible for chemical digestion
What enzyme does saliva contain?
Amylase
What does amylase do?
Breaks down complex carbohydrates into simpler sugars
What are teeth needed for?
Mechanical breakdown
What is the esophagus?
A long muscular tube that contracts in a rhythmic motion called peristalsis. These contractions push the food bolus towards the stomach and the remainder of the gi tract
What is the epiglottis?
A tissue flap that shuts the trachea when eating so food does not go down that tube causing you to choke
What is the stomach?
A J-shaped sac that is the site of food storage and digestion
What is the stomachs capacity?
1.5L
What part of the stomach contracts and closes preventing the the stomach contents from moving back into the esophagus?
The cardiac sphincter
What is at the bottom of the stomach and regulates the exit of digested food in the into the small intestine?
The pyloric sphincter
What does the stomach secrete?
A number of digestive enzymes and gastric juices that help in the digestion of food particles
In what order, are items released into the stomach?
- Mucus
- Hydrochloric acid (HCl)
- Pepsin
What does mucus do?
Coats the inner lining of the stomach, protecting it from its own digestive juices; comes from mucous cells
What does hydrochloric acid do?
Kills harmful bacteria in the stomach. HCl is also important in activating the protein digesting enzyme pepsinogen to become pepsin, as a result the pH of the stomach is about 1-2. Comes from parietal cells
What does pepsin do?
The enzyme responsible for the digestion if proteins. Pepsin, secreted as pepsinogen, is activated by the presence of HCl. In the active form, pepsin breaks down long chain amino acids into shorter chain polypeptides. Comes from chief cells
What does rennin do?
An enzyme that causes milk to curdle which allows its nutrients to be properly absorbed
What else is absorbed in the stomach?
Alcohol, some drugs and vitamin B
What is food known as when it exits the stomach and enters the small intestine?
Chyme
What is acid reflux?
“heartburn”; caused by the movement of gastric juices (acidic) back into the esophagus, usually caused by failure of the cardiac sphincter to close
What are peptic ulcers?
Lesions or sores on the stomach lining that are irritated by the acidic secretions in the stomach. Caused by the breakdown of the protective mucus lining in the stomach. Induced by stress, diet and the bacteria Heliobacter pylori