Transcript Digestive system notes

13
The Digestive System and Nutrition
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Chapter 13: The Digestive System and Nutrition
Lesson 13.1
Nutrition
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Energy
• measuring the body’s energy use
– calories
– kilocalories
• basal metabolic rate
– energy required for one day at rest
– varies by individual
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Vitamins
• chemicals needed for proper metabolism
• types of vitamins
– fat-soluble
• may be stored in the body
– water-soluble
• are not stored in the body
• vitamin deficiency
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Minerals
• elements needed for proper body function
• examples
–
–
–
–
calcium
potassium
iron
phosphorus
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Water-Soluble Vitamins
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Fat-Soluble Vitamins
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Minerals
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DIET
• Deficiency diseases if you don’t eat a well
balanced diet
• Vegetarians: 20 amino acids - 12 we can make, 8
we need to eat (essential amino acids)
– Grains have 6 aa
– Beans have 6 aa
– Mix beans and grains for complete aa
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Fun facts
• 25ft long intestines in humans
• 89ft long intestines in horses
• Food drying up in large intestine can be there 18
hours-2 days
Final destination
• Starch = blood
• Fat = lymph vessels
• Protein = blood
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Chapter 13: The Digestive System and Nutrition
Anatomy and Physiology
Lesson 13.2
of the Digestive System
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Activities/functions of Digestion
• (1) ingestion- take in food
• (2) propulsion
– moving food along GI tract
– peristalsis
• (3) mechanical breakdown
– breaks food into smaller pieces
– increases surface area of food
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Activities of Digestion
• (4) chemical breakdown
– digestion
– enzymes
• (5) absorption
– digested food particles absorbed & moved into blood
• (6) elimination
– expulsion of food not absorbed
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Activities of
Digestion
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Layers of the
Alimentary Canal
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Digestive Organs and Their Functions
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Oral Cavity-Mechanical & Chemical
digestion
Mechanical digestion 
– Chew, tear, grind, mush, mix
Chemical digestion (saliva)
• Amylase digest starch
• Mucus -protect lining of
stomach GI tract; lubricate
• Buffers -neutralize acid to
prevent tooth decay
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Oral cavity- chem digestion
• Anti-bacterial chemicals
- kill unwanted
bacteria from food
• Epiglottis- flap in back
of mouth; closes
trachea, prevents food
from entering lungs
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Esophagus
• Esophagus
– connects pharynx to stomach
– 10-12 inches long
• Secretes mucus
• Acid from stomach gets in here = heart burn
– Acid reflux
– Diaphragm prevents, along w/ esophageal sphincter
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Stomach
• Storage of food
– Up to 2 Liters
• Disinfects food HCl (pH
= 2)
• Mucus-secreting
– To not digest itself
• Protein-digesting:
pepsin enzyme
• Chyme formation
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Stomach (cont.)
• Rugae - folds in lining allow for expansion
• Pyloric sphincter - regulates food from stomach to
intestine
• Ulcers: not caused by stress
– Bacterial infection of stomach
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Small Intestines
• About 6 meters long
• Duodenum (25cm) receives
stomach content
– Pancreatic juice &
bile/neutralize acid/pepsin
• Jejunum (2.5m)
• Ileum (3.6m) reabsorb bile
– Digests carbs (amylase)
– Digest protein (trypsin)
– Digest lipids (bile and lipase)
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Small Intestines…big absorption
• Absorb nutrients (diffusion & active transport)
– from capillaries to blood vessels
• Microvilli (projections) increase surface area
• 80% ingested water, vitamins, minerals
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Large intestines
• Colon: ascending, transverse,
descending, sigmoid
• Rectum & anus
• Elimination
• Undigested materials
– Cellulose (roughage)
– Keeps everything moving & clean
MASSES of bacteria
• Appendix: vestigial organs
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The Liver and Gallbladder
• functions of liver
– maintains nutrients in blood
– nutrient conversion and storage
– filters toxins
• functions of gallbladder
– stores bile made by liver
– releases bile when fat-containing chyme is in duodenum
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Liver and Gallbladder
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Pancreas
• pancreatic juices
– contain digestive enzymes
• Trypsin, amylase, lipase & buffers
• glucose regulation
– beta cells–insulin
– alpha cells–glucagon
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Chapter 13: The Digestive System and Nutrition
Lesson 13.3
Disorders and Diseases
of the Digestive System
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Disorders and Diseases of the Digestive
System
• gingivitis and periodontal disease
– plaque forms tarter
• cardiovascular disease
• gastroesophageal reflux disease
– heartburn
• ulcers
– Helicobacter pylori
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Disorders and Diseases of the Digestive
System
• gastroenteritis
– inflammation of stomach or intestine
• inflammatory bowel syndrome
– chronic inflammation
– ulcerative colitis
– Crohn’s disease
• constipation and diarrhea
– infrequent or too frequent defecation
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Disorders and Diseases of the Digestive
System
• hepatitis
– inflammation of liver
• pancreatitis
– inflammation of pancreas
• gallstones
– bile forms crystals
– Cholecystectomy
• (bye, gb!)
• cancer
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– digestive system cancers
are common
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