ANP 1107 Lecture Notes - Lecture 1: Gastric Inhibitory Polypeptide, Motilin, Vitamin K
22 May 2018
School
Department
Course
Professor
Friday, May 5, 2017
ANP1107
Lecture 1: The Digestive System Part 1
• Main functions of the digestive system:
• take in food
• break it down into nutrient molecules
• absorb molecules into the bloodstream
• rid body of any indigestible remains
• Nutrient Production
• Synthesis of vitamins by bacteria that lives in the intestine ex) Vit. K,
biotin, and other Vitamin B’s
• Production of neurotransmitters, hormones, and hormone-like compounds
• hormones: Gastrin, ghrelin, cholecystokinin, secretin, VIP, motilin, GIP
(gastric inhibitory peptide)
• NTs: acetylcholine, serotonin, histamine, nitric oxide
Two Groups of Organs
• 1. Alimentary Canal (Gastrointestinal or GI tract)
• digests and absorbs food through lining (mucus) into blood
• Organs: mouth, pharynx, esophagus, stomach, small intestine, large
intestine, anus
• reduce friction and aid movement: important role in protecting
stomach with mucous
• 2. Accessory digestive organs/structures
• mechanical and chemical digestion of food
•teeth
•tongue
!1
find more resources at oneclass.com
find more resources at oneclass.com
Friday, May 5, 2017
•gallbladder
• digestive glands: produces secretions that help break down food
• salivary glands
• liver
• pancreas (produces digestive juices)
Major Digestive Processes
• 1. Ingestion
• 2. Mechanical breakdown (chewing, mixing, churning, segmentation) *Most
mechanical breakdown occurs in the stomach*
• 3. Propulsion (swallowing, peristalsis)
• 4. Digestion (catabolism: enzymatic breakdown of food into molecules to be
absorbed—chemical digestion)
• 5. Absorption (passage of digested food from the
• 6. Compaction and defecation (dehydration, compression and elimination of
indigestible substances (feces) from the GI tract
• *Digestive juices spills into furthest part of small intestine. Breaks down carbs, fat,
prepare for absorption as it moves along.
• *Chemical breakdown of nutrients is metabolism*
• *Ilium is the most distal part*
• *Once passes through ilium, moves into colon (large intestine. Typically food
residues).
• *Small amounts of complex carbs. Here you're going to GAIN water. Mostly chemical
absorption in this area.
Peristalsis vs Segmentation
• Peristalsis
• Adjacent segments of alimentary tract organs alternatively contract and relax
• Some mixing MAY occur
!2
find more resources at oneclass.com
find more resources at oneclass.com
Friday, May 5, 2017
• Contractions start at the esophagus and food is moved forward (distally
along tract) and therefore contract behind to push it
• Segmentation
• Nonadjacent segments of alimentary tract organs alternately contract and
relax
• Food mixing and breakdown; slow food propulsion occurs
• Food is moved forward AND BACKWARDS—therefore it mixes.
• Takes place at junction between stomach and duodenum. There’s a valve
there that regulates type of food that gets through (only allows small
molecules and water) and the volume of it
• Mainly in small intestine, but also large intestine
Relationship of the Digestive Organs to the Peritoneum
• Peritoneum
• Serous membranes (layer of membrane that lines cavity) of abdominal cavity
that consists of
• Visceral peritoneum: membrane on external surface of most digestive
organs
• Parietal peritoneum: membrane that lines body wall
• Peritoneal cavity
• Fluid-filled space between two peritoneums
• Fluid lubricates mobile organs
• Mesentery
• double layer of peritoneum fused together that extends to the organs from
the body wall mostly posterior
• provides support for the organs; holds them in place
• provides support for vessels & nerves supplying the organs
• stores fat
!3
find more resources at oneclass.com
find more resources at oneclass.com
