Whitney & Rolfes – Understanding Nutrition, 12th Edition
Digestion, Digestion, Absorption, and Absorption, and
TransportTransportChapter 3
Whitney & Rolfes – Understanding Nutrition, 12th Edition
DigestionDigestion
Breaking down foods into nutrients Prepare for absorption
Challenges of digestion Tasks of the mouth Diaphragm Steady movement Lubrication of food Digestive enzyme functions
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Anatomy of the Digestive Anatomy of the Digestive TractTract
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Anatomy of the Digestive Anatomy of the Digestive TractTract
Gastrointestinal (GI) tract Flexible and muscular Path
Mouth → esophagus → stomach → small intestine → large intestine → rectum → anus
LumenContinuous
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Anatomy of the Digestive Anatomy of the Digestive TractTract
Mouth Process of digestion begins
Mastication Four basic taste sensations
SavoryAroma, texture, and temperature
Pharynx Bolus
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Anatomy of the Digestive Anatomy of the Digestive TractTract
Esophagus Two sphincters
Upper esophageal sphincterLower esophageal sphincter
Stomach Movement of bolus Chyme Pyloric sphincter
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Anatomy of the Digestive Anatomy of the Digestive TractTract
Small intestine Common bile duct
Pancreas and gall bladder Three segments
Large intestine (colon) Ileocecal valve Withdrawal of water Rectum and anus
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Anatomy of the Digestive Anatomy of the Digestive TractTract
Transverse colon
Ascending colon
Descending colon
Sigmoid colonAnus
Rectum
Appendix
Opening from small intestine to large intestine
End of small intestine
Stepped Art
Fig. 3-2, p. 72
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Muscular Action of Muscular Action of DigestionDigestion
Peristalsis Circular and longitudinal muscles working
togetherRate and intensity of contractions varyFactors that may interfere with peristalsis
Stomach action Circular, longitudinal, and diagonal muscles Timing the release of chyme
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Muscular Action of Muscular Action of DigestionDigestion
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Muscular Action of Muscular Action of DigestionDigestion
Segmentation Contraction of circular muscles in small
intestineMix chymePromote contact with absorption cells
Sphincter contractions Periodically open and close Control pace of GI tract contents
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Muscular Action of Muscular Action of DigestionDigestion
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Muscular Action of Muscular Action of DigestionDigestion
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Secretions of DigestionSecretions of Digestion
Five organs Salivary glands, stomach, pancreas, liver,
small intestine Secretions
Water Enzymes
Protein facilitator of chemical reactionsHydrolysis
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Secretions of DigestionSecretions of Digestion
Saliva Moisten food for easy passage Protective role Carbohydrate digestion
Gastric juice Protein digestion Mucus pH units
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Secretions of DigestionSecretions of Digestion
Pancreatic juice Released via ducts into duodenum Enzymes act on all three energy nutrients Sodium bicarbonate Bile
LiverGallbladder
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Secretions of DigestionSecretions of Digestion
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The Final StageThe Final Stage
Vitamin and mineral absorption Undigested residues
Exercise intestinal muscles Retention of water
Colon Intestinal bacteria Recyclable materials
Water and dissolved salts
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Whitney & Rolfes – Understanding Nutrition, 12th Edition
AbsorptionAbsorption
Small intestine Majority of absorption Ten feet long
Surface area Absorption techniques
Simple diffusionFacilitated diffusionActive transport
Whitney & Rolfes – Understanding Nutrition, 12th Edition
AbsorptionAbsorption
Carrier loads nutrient on outside of cell . . .
Carrier loads nutrient on outside of cell . . .
Outside cell
Cell membrane
. . . and then releases it on inside of cell.
. . . and then releases it on inside of cell.Inside
cellFACILITATED
DIFFUSION
Some nutrients (such as the water-soluble vitamins) are absorbed by facilitated diffusion. They need a specific carrier to transport them from one side of the cell membrane to the other. (Alternatively, facilitated diffusion may occur when the carrier changes the cell membrane in such a way that the nutrients can pass through.)
ACTIVE TRANSPORT
Some nutrients (such as glucose and amino acids) must be absorbed actively. These nutrients move against a concentration gradient, which requires energy.
Stepped Art
Some nutrients (such as water and small lipids) are absorbed by simple diffusion. They cross into intestinal cells freely.
SIMPLE DIFFUSION
Fig. 3-9, p. 78
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Anatomy of the Anatomy of the Absorptive SystemAbsorptive System
Villi Select and regulate nutrients absorbed
Microvilli Enzymes and “pumps”
Crypts Secretion of intestinal juices
Goblet cells Mucus secretion
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Preparing Nutrients for Preparing Nutrients for TransportTransport
Transport pathways Bloodstream
Water-soluble nutrients and smaller products of fat digestion
Liver Lymphatic system
Larger fats and fat-soluble vitaminsChylomicronsBypass liver at first
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The Vascular SystemThe Vascular System
Closed system of vessels Heart pump
Blood Delivers oxygen and nutrients Removes carbon dioxide and wastes Blood flow
Special routing for digestive system Liver
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The Vascular SystemThe Vascular System
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The Vascular SystemThe Vascular System
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The Lymphatic SystemThe Lymphatic System
One-way route No pump Circulation between cells
Entry into bloodstream Subclavian vein
Nutrients in lymphatic vessels Bypass liver at first
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Health and Regulation of Health and Regulation of GI TractGI Tract
Gastrointestinal bacteria – flora Most are not harmful
Benefits of gastrointestinal bacteria Factors influencing bacteria presence
Diet – probioticsOthers
Digestion of fibers and complex proteins Vitamin production
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Health and Regulation of Health and Regulation of GI TractGI Tract
Endocrine and nervous systems Homeostatic regulation
Hormones and nerve pathwaysStimulation and inhibition of digestive
secretions Feedback mechanisms
Examples GI hormones
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Health and Regulation of Health and Regulation of GI TractGI Tract
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Health and Regulation of Health and Regulation of GI TractGI Tract
Whitney & Rolfes – Understanding Nutrition, 12th Edition
The Digestive System at The Digestive System at Its BestIts Best
Sensitive and responsive to environment Immunity against intestinal diseases Defense against foreign invaders
Health of digestive system Healthy supply of blood Lifestyle factors Types of foods eaten
Balance, moderation, adequacy, and variety
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Highlight 3Highlight 3
Common Digestive Problems
Whitney & Rolfes – Understanding Nutrition, 12th Edition
ChokingChoking
Food slips into trachea Cuts off breathing
International sign for choking Heimlich maneuver
Foods commonly associated with choking Prevention of choking
Whitney & Rolfes – Understanding Nutrition, 12th Edition
ChokingChoking
Whitney & Rolfes – Understanding Nutrition, 12th Edition
ChokingChoking
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Vomiting and DiarrheaVomiting and Diarrhea
Vomiting Adaptive mechanism of the body Medical treatment
Dehydration and projectile vomiting
Diarrhea Symptom of medical conditions & treatments
Irritable bowel syndrome (IBS) Colitis
Treatment
Whitney & Rolfes – Understanding Nutrition, 12th Edition
ConstipationConstipation
Not a disease Symptoms of constipation Causes
Lifestyle Side effect of medications
Prevention Fiber and water Physical activity
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Belching and GasBelching and Gas
Belching Swallowed air Prevention
Intestinal gas Consumption of certain foods
Individually determined
Hiccups
Whitney & Rolfes – Understanding Nutrition, 12th Edition
Heartburn and “Acid Heartburn and “Acid Indigestion”Indigestion”
Gastroesophageal reflux (heartburn) Causes Prevention
Indigestion Causes Antacids and acid controllers
Damage to esophagus Barrett’s esophagus
Whitney & Rolfes – Understanding Nutrition, 12th Edition
UlcersUlcers
Peptic ulcers Gastric ulcers Duodenal ulcers
Causes Bacterial infection Anti-inflammatory drugs Excessive gastric acid secretion
Ulcer treatment regimen
Whitney & Rolfes – Understanding Nutrition, 12th Edition
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