Week #13 Flashcards
What are the two types of digestion?
Mechanical and Chemical
What is Mechanical Digestion?
Mastication: Mouth
Peristalsis: Esophagus
Maceration: Stomach
Segmentation: Small intestine
What is Chemical Digestion?
Enzymatic activity: Salivary amylase (Carbohydrates, starts in mouth)
What happens during swallowing?
Saliva:
- Helps prevent mouth from drying-out / lubricates mouth (oral cavity)
- Helps prevent cavities
- 1st line of defense against disease-causing microorganisms entering mouth
- Coats food
- With tongue, helps form bolus
Describe what happens with the muscles of stomach and what they are?
Longitudinal, Oblique, Circular; churn predigested food; about 1- 2 hours; mixes food with gastric juices creating chyme
What chemicals help digest in the stomach?
- HCL (Hydrochloric acid): activates pepsinogen into pepsin
- Pepsinogen: inactive form of pepsin
- Pepsin: active form of enzyme, breaks protein down into polypeptides (amino acids)
How much does the stomach absorb?
~10% absorption (caffeine, aspirin, tiny amount of water “if dehydrated”), 10% - 20% of alcohol
What is the pyloric sphincter?
Stomach to the small intestine (duodenum); controls the flow of chyme, from the stomach into the small intestine
How long is the small intestine?
~20 feet long
How much FOOD absorption does the small intestine?
90%
What are the three parts of the small intestine?
Duodenum, Jejunum, and Ileum (DJ Eye “I”)
What does the duodenum do?
Protein digestion; Fat breakdown - bile salts emulsify fat globule into tiny droplets, which increases surface area on which pancreatic lipase digest fatty acids (lipids) and glycerol
How much absorption does the jejunum do?
90%
How much absorption does the ileum do?
90%
What is the key absorption structure?
Microvilli (Brush border) !!
How long is the large intestine/colon?
~5 feet long (1.5 m)
How much WATER does the large intestine absorb?
90%
How much water is needed for digestion?
~1.8 gallons or ~7 liters
What is the ascending colon?
Cecum (“Dead end pouch” bacteria); Appendix (Vestigial organ but Duke says bacterial garden especially important w/ diarrhea)
What is the transverse colon?
Goes across
What is the descending colon?
Rectum
- ~4.7 inches to anal canal
- Defecation (removing waste material)
- Fecal matter/Feces/Stool (undigested material, 60% bacteria, mucus, cellulose “bulk flow”)
- Constipation (fecal impact)
- Diarrhea (loss of water/irritate intestinal lining leading to bacterial infection)
Where does digestion of carbohydrates start?
Starts in mouth w/ salivary amylase
Where does digestion of proteins to amino acids occur?
Starts in stomach w/ pepsin
Where does digestion of lipids start?
Small intestines w/ pancreatic lipase, bile salts (duodenum)
