NUTR 200 Lecture Notes - Lecture 6: Protease, Thoracic Duct, B Vitamins
31 May 2018
School
Department
Course
Professor
NUTR 200 Nutrition for Today 4/6/18
MJ Gunnarson, MS, RD 1
Digestion and Absorption 1
Reading:
p 49-66
Chapter 3 – Introduction, Oerie of the Digestie Process, Oerie of the Mechanical…, The Path…,
The Role of Bacteria…
Learning Objectives:
• Define digestion and absorption and highlight the differences between the two processes.
• Name and locate the organs involved in digestion and absorption.
• Describe the function of each organ.
• Name hormones and enzymes required to digest food and their origin and action.
• Name the cell types involved in absorption and the 2 types of circulation that transport absorbed
nutrients.
Are digestion and absorption equivalent?
Digestion = the process of converting food into absorbable nutrients
• Large food molecules are broken down to smaller molecules, mechanically and chemically
Absorption = moving nutrients from the lumen of the intestine into the interior of the body
• Moving digestive products through the intestinal wall into the body
Elimination: process whereby solid waste is removed
Where does digestion happen? Gastrointestinal tract--a continuous tube from mouth to anus
Lumen= inner cavity
Accessary organs
• Salivary glands
• Liver
• Gallbladder
• pancreas
Cephalic phase = First thought of food (nervous system) stimulates the release of digestive juices
Mouth - Mechanical disruption of food (Chewing) - moistens the food and mechanically breaks it into
smaller pieces
Salivary glands-produce saliva
-produce ~1L/day
Saliva – water, mucus, enzymes--helps you taste your food
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NUTR 200 Nutrition for Today 4/6/18
MJ Gunnarson, MS, RD 2
Salivary ___amylase___________ – hydrolyzes starch molecules
__lysosome__________ – kills bacteria
Bolus = the mass of chewed food mixed with saliva
Swallowing = moving food into esophagus from the mouth
Esophagus
Peristalsis = wavelike muscular contraction and relaxation that propels food forward though the GI tract
(forward propulsion)
Segmentation = mixing of intestinal contents with digestive fluids by contractions of circular muscles in
small intestine
Peristalsis and segmentation are the processes called gastric motility (contractions of the GI tract’s
smooth muscles that mix food with digestive fluids and propel food along the length of the tract)
Stomach – mixing and storing--food mixes with HCl (pH 1) and some enzymes in the stomach
Surface and neck cells
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find more resources at oneclass.com
NUTR 200 Nutrition for Today 4/6/18
MJ Gunnarson, MS, RD 3
Mucus--protects the stomach lining from stomach acid
Endocrine cells
Gastrin – hormone produced when food
present in stomach
Parietal cells
Hydrochloric acid (pH1)
Chief cells
Pepsinogen--a protein digesting pro-enzyme made by chief cells, activated by HCl to for pepsin
Chyme= mixture of partially digested food
Pyloric sphincter = a gateway between stomach and small intestine
Small intestine = ~20 ft
Duodenum--first section of small intestine
• Chyme enters into the duodenum
Jejunum--4-8 ft up to 10ft
Ileum--5-8 ft
Pancreatic secretions
(bicarbonate and digestive enzymes)
• Enters duodenum via the common bile duct
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Document Summary
Chapter 3 introduction, o(cid:448)er(cid:448)ie(cid:449) of the digesti(cid:448)e process, o(cid:448)er(cid:448)ie(cid:449) of the mechanical , the path , Digestion = the process of converting food into absorbable nutrients. Large food molecules are broken down to smaller molecules, mechanically and chemically. Absorption = moving nutrients from the lumen of the intestine into the interior of the body: moving digestive products through the intestinal wall into the body. Gastrointestinal tract--a continuous tube from mouth to anus. Cephalic phase = first thought of food (nervous system) stimulates the release of digestive juices. Mouth - mechanical disruption of food (chewing) - moistens the food and mechanically breaks it into smaller pieces. Saliva water, mucus, enzymes--helps you taste your food. Bolus = the mass of chewed food mixed with saliva. Swallowing = moving food into esophagus from the mouth. Peristalsis = wavelike muscular contraction and relaxation that propels food forward though the gi tract (forward propulsion)
