Week 18 - GI Tract Flashcards
(20 cards)
Where does the majority of chemical digestion and absorption occur?
Small intestine (mainly jejunum and ileum).
What are the two main types of motility in the small intestine?
Segmentation and peristalsis.
What hormone stimulates segmentation in the small intestine?
Cholecystokinin (CCK).
What is the main function of segmentation?
Mix chyme and expose it to absorptive surfaces and enzymes.
What hormone triggers the migrating motor complex (MMC)?
Motilin.
What is the function of peristalsis in the small intestine?
Propels intestinal contents toward the large intestine.
What enzymes complete digestion in the small intestine?
Pancreatic and brush border enzymes.
What do brush border enzymes digest?
Carbohydrates, proteins, and nucleic acids.
Into what are carbohydrates broken down for absorption?
Monosaccharides (glucose, galactose, fructose).
Into what are proteins broken down for absorption?
Amino acids and small peptides.
Into what are lipids broken down for absorption?
Fatty acids and monoglycerides.
How are long-chain fatty acids transported after absorption?
Packaged into chylomicrons and transported via lacteals.
What structure increases absorptive surface area in the small intestine?
Villi and microvilli (brush border).
What triggers the defecation reflex?
Distension of the rectum.
What muscle relaxes involuntarily during defecation?
Internal anal sphincter.
What part of the pancreas secretes digestive enzymes?
Exocrine pancreas (pancreatic acini).
What part of the pancreas secretes hormones?
Endocrine pancreas (Islets of Langerhans).
What enzyme activates trypsinogen in the duodenum?
Enteropeptidase (enterokinase).
What stimulates the secretion of bicarbonate from the pancreas?
Secretin.
What is the function of pancreatic bicarbonate in the duodenum?
Neutralizes stomach acid and creates optimal pH for enzymes.
