Transcript digestion - GLLM Moodle 2

“I Am Smart” Quiz
• Where digestion first begins?
• What glands secrete hydrochloric acid?
• What is the length of the small intestine?
• The name of the projections on the villi?
• The name of small lymphatic vessels?
• What organ produces bile?
• What organ secretes bile?
• What is the name of the portion of large
intestine that contains no villi?
What You Need to Know
Mouth
• Where digestion begins
• Name of structure at back of the mouth?
Esophagus
• Circular and longitudinal bands of muscle
• Peristalsis = rhythmic contractions
• esophageal sphincter
What You Need to Know
Stomach
• Volume ranges from 50 ml to 6.0 L
• Parietal glands secrete HCl
• Mucos secreted from mucos neck cells
• Chief cells secrete pepsinogen
• Little absorption occurs except for alcohol
• Chyme is slushy, acidic mixture
What You Need to Know
Small Intestine
• 90% of digestion occurs first two sections
• Duodenum, jejunum, ileum
• Villi = highly vascularized; contain
small projections called microvilli;
increase absorptive surface up to 600-fold
• Large surface area facilitates speed
• Villi contain lymphatics called lacteals
• Lacteals transport fatty materials (from the
liver) to lymphatic system
What You Need to Know
Small Intestine
• Segmentation contractions
• Peristalsis
• Bile, produced in the liver and stored and
secreted by the gallbladder, helps to
increase solubility and digestibility of
lipid droplets by emulsifying them
• Pancreas secretes bicarbonates (alkali) to
help buffer HCl from stomach that
remains in the chyme
What You Need to Know
Large Intestine
• Final pathway for digestion
• Absorption of water, electrolyes, storage
of digestive residue (fecal matter)
• Terminal portion of GI tract contains no
villi and is known as the colon
• Ascending, transverse, descending,
sigmoid colon, rectum, and anal canal
• Bacterial fermintation produces gas (flatus)