Week 16 / GI system 3 Flashcards
Q: What are the three main subdivisions of the small intestine?
A: The three main subdivisions are:
Duodenum (including hepatopancreatic organs)
Jejunum
Ileum
Q: What is the main function of the jejunum?
A: The jejunum is the primary site for nutrient absorption.
Q: What is the primary role of the duodenum in the small intestine?
A: The duodenum is where most chemical digestion begins with the help of bile from the liver and digestive enzymes from the pancreas.
Q: What is the primary role of the ileum?
A: The ileum absorbs vitamin B12, bile salts, and remaining nutrients before passing the chyme to the large intestine.
Q: How long is the duodenum?
A: The duodenum is the first 10 inches of the small intestine.
Q: What is the primary function of the duodenum?
A: The duodenum is the first site of intensive digestion and receives bile and pancreatic juice.
Q: How do bile and pancreatic juice reach the duodenum?
A: They are delivered via the common bile duct and the main pancreatic duct.
Q: What happens when fatty chyme enters the duodenum?
A: The duodenum releases cholecystokinin (CCK), which triggers the release of bile and pancreatic enzymes.
Q: What is the duodenum’s response to acidic chyme?
A: Acidic chyme stimulates the release of secretin, which promotes the release of pancreatic bicarbonate to neutralize the acidity.
Q: What are the two functional divisions of the pancreas?
A: Exocrine and Endocrine.
Q: What do duct cells in the pancreas secrete?
A: An aqueous bicarbonate solution.
Q: What do acinar cells in the pancreas secrete?
A: Pancreatic juice containing proteases, amylase, and lipase.
Q: What cells make up the endocrine pancreas?
A: Islets of Langerhans, including β-cells and α-cells.
Q: What do β-cells in the pancreas secrete?
A: Insulin.
Q: What do α-cells in the pancreas secrete?
A: Glucagon.
Q: What are the endocrine cells of the pancreas, and what do they secrete?
A: Endocrine cells include β-cells (secrete insulin) and α-cells (secrete glucagon).
Q: What do exocrine cells in the pancreas secrete?
A: Digestive enzymes, including proteases, amylase, and lipase.
Q: What do duct cells in the pancreas secrete?
A: Bicarbonate solution.
Q: What does the gallbladder contribute to digestion?
A: It stores and releases bile into the common bile duct.
Q: How do the pancreas and gallbladder release their secretions into the duodenum?
A: Through the common bile duct and the pancreatic duct.
Q: What is the liver’s main digestive function?
A: The liver’s main digestive function is the production of bile.
Q: What is the liver composed of?
A: The liver is composed of ‘plates’ of liver cells called hepatocytes.
Q: What is bile, and what is its main function?
A: Bile is a yellow-green, alkaline solution that acts as a fat emulsifier.
Q: What does bile contain?
A: Bile contains bile salts, bile pigments, cholesterol, neutral fats, phospholipids, and electrolytes.
Q: What are the main sites of absorption in the small intestine?
A: The duodenum and jejunum.
Q: Where is bile stored and released from?
A: Bile is stored and released from the gallbladder.
Q: What do the duodenum and jejunum freely absorb?
A:
Products of carbohydrate, protein, and fat digestion.
Most ingested electrolytes, vitamins, and water.
Q: Which nutrients’ absorption is adjusted to the body’s needs in the duodenum and jejunum?
A: Calcium and iron.
Q: What does the ileum absorb?
A:
Bile salts
Vitamin B12
Electrolytes and water
Q: How are large fat globules emulsified in the small intestine?
A: Bile salts emulsify large fat globules into smaller fat droplets, increasing the surface area for pancreatic lipase action.
Q: What does pancreatic lipase do to triglycerides?
A: It hydrolyzes triglycerides into monoglycerides and free fatty acids.
Q: What carries water-insoluble products of fat digestion to the epithelial cells of the small intestine?
A: Water-soluble micelles formed by bile salts and other bile constituents.
Q: How do monoglycerides and fatty acids enter small-intestine epithelial cells?
A: They leave the micelle and passively diffuse through the lipid bilayer of the luminal membranes.
Q: What happens to monoglycerides and fatty acids inside epithelial cells?
A: They are resynthesized into
triglycerides.
Q: How are triglycerides made water-soluble inside epithelial cells?
A: They aggregate and are coated with a layer of lipoprotein to form chylomicrons.
Q: How do chylomicrons leave the epithelial cells?
A: By exocytosis through the basal membrane.
Q: Why do chylomicrons enter lymphatic vessels instead of capillaries?
A: They are too large to cross the basement membrane of capillaries, so they enter the central lacteals.
Q: What are the components of the large intestine?
A: The colon, caecum, appendix, and rectum.
Q: What are the primary functions of the large intestine?
A: It acts as a drying and storage organ.
Q: What does the large intestine absorb?
A: Water, electrolytes, several vitamin B complexes, vitamin K, and folic acid.
Q: How many species of beneficial bacteria are found in the large intestine?
A: Approximately 500–1000 species.
Q: What is the role of beneficial bacteria in the large intestine?
A: They produce vitamin K and folic acid, and ferment indigestible molecules to produce short-chain fatty acids.
