10 Questions
What is the primary function of the stomach's parietal cells?
To secrete gastric juices
Which hormone is responsible for signaling the pancreas to secrete bicarbonate ions?
Secretin
In which part of the digestive system does most water absorption occur?
Large intestines
What is the role of bile produced by the liver?
It emulsifies fats.
Where are villi and microvilli found in the digestive system?
Small intestines
What enzyme secreted in the mouth is responsible for the breakdown of carbohydrates?
Amylase
What substance protects the walls of the stomach from its acidic environment?
Mucus
Which structure in the digestive system prevents food from entering the trachea?
Epiglottis
What process moves food through the esophagus?
Peristalsis
What are the products of lipase activity on lipids?
Fatty acids and glycerol
Study Notes
Digestive System Structures
-
Mouth (Oral Cavity)
- Contains salivary glands that secrete saliva, amylase enzymes, and lipase
- Teeth enable physical digestion
- Tongue increases surface area, and the mouth pH is neutral
Pharynx (Throat)
+ Leads to the trachea and esophagus for breathing and eating
+ Epiglottis separates trachea and esophagus
Esophagus
+ A straight muscular tube with involuntary contractions (peristalsis)
Stomach
+ Composed of rigid muscle with physical and chemical digestion
+ Releases gastrin hormone and secretes gastric juices
+ Has sphincters that relax to let food in and contract to stop food or stomach acid from leaving
Liver
+ Produces bile stored in the gallbladder
+ Bile emulsifies fats and contains bile salts, bile pigments, and cholesterol
Gallbladder
+ Stores bile and can develop gallstones (cholesterol binds solid crystals in bile, resulting in jaundice)
Pancreas
+ Secrete secretin hormone, which stimulates the release of:
- Bicarbonate ions to neutralize HCl in the stomach
- Carbohydrases (amylase) for poly/disaccharides to monosaccharides
- Proteases (trypsin, erepsin) for polypeptides to amino acids
- Lipase for lipids to glycerol and fatty acids
Small Intestines
+ Completes digestion and absorption of nutrients into blood vessels
+ Villi and microvilli increase surface area for absorption
+ Composed of duodenum, jejunum, and ileum
Large Intestines
+ Absorbs most water and has bacteria that produce vitamins B and K
+ Needs cellulose and has a rectum for feces storage and an anus with a voluntary sphincter for defecation
Gastric Juices
+ Mucus protects the stomach walls
+ Hydrochloric acid kills bacteria, aids physical digestion, and has a pH of 2
+ Pepsinogen is activated at low pH, becoming pepsin, which breaks down peptides to amino acids
Stomach Ulcers
+ Caused by HCl acid and enzymes breaking down the mucus lining
+ Treatment involves antibiotics for early detection or laser therapy for later detection
Fat Emulsification
+ Bile breaks down large fat globules
+ Lipase breaks down smaller fat globules into fatty acids and glycerol
Liver Functions
+ Synthesis and breakdown/conversion of various molecules
This quiz covers the structures of the digestive system, including the mouth, pharynx, and their components, as well as their functions in the digestion process.
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