Nutrition and Digestion Chapter 41. Breaking It Down Major macromolecules: polymers monomers?
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Transcript of Nutrition and Digestion Chapter 41. Breaking It Down Major macromolecules: polymers monomers?
Nutrition and Digestion
Chapter 41
Breaking It Down
Major macromolecules: polymers monomers?
Today We Are Serving Autotrophs
HeterotrophsConsumers
Herbivores Carnivores Omnivores
Decomposers
No Hands or ‘Utensils’
Baleen whales, oysters, and spongesMosquitoes, hummingbirds, and aphids
Most animals
Catepillars, earthworms, and maggots
Breaking It Down
Compartmentalizing Digestion Prevents self digestion Intracellular digestion
No digestive tract Individual cells and sponges
Extracellular digestion Incomplete digestive tract
Cnidarians and flatworms
Complete digestive tract Most animals
No Digestive Tract
Digestion is completely intracellular
Phago- or pinocytosis form food vacuoles
Broken down by lysosomes
Incomplete Digestive Tract
Single opening to a gastrovascular cavity
Starts extracellularly, but ends intracellularly
Complete Digestive Tract
Mouth and anus
Digestion is extracellular
Specialized organs
Mammalian Digestive Tract
Alimentary canal
Accessory organs (green)
Food moved by peristalsis
Regulated by sphincters
Time varies
Comparative Digestive Tracts Length related to diet
Herbivores & omnivores longer than carnivores
Cellulose in plants
Herbivores lose many nutrients to feces Recycle feces to regain
Ruminants have 4 chambered stomachs Regurgitate food from 1 to
another = chew cud
Mouth Mechanical digestion
Bite, tear, grind and crush Increase SA
Chemical digestion Salivary glands release saliva
Neural signal from food or association Amylase for carb digestion, bicarbonate to neutralize, and
mucins to lubricate
Tongue manipulates Evaluates food via taste and olfaction Forms a bolus
Pharynx Esophagus and
trachea Epiglottis and larynx
regulation Heimlich maneuver if
fails
Esophagus Peristalsis moves bolus Length varies b/w
species Cell types
Stomach Stores and mixes bolus Gastric juices convert to chyme (ph=2) Chemical digestion
Parietal cells: H+ & Cl-
Chief cells: pepsinogen Both inactive until lumen Protects gastric glands Positive feedback
Mucus & epithelial cells Gastric ulcers (Helicobacter pylori)
Sphincter regulation
The Final Breakdown Chyme and digestive juices mix in the
duodenum (SI)Pancreas: enzymes and bicarbonate solutionLiver/gallbladder: bile, emulsifier (2107 lab?)
Detoxifies and maintains homeostasis
Hormonal controlPositive and negative feedbackEnsures juices present only when necessaryFig 41.4
Summary of Chemical Digestion
Sucrase, maltase, and lactase
Breaking It Down
Small Intestine
3 folded regions Duodenum Jejunum Ileum
Increased SA increases absorption Circular folds contain villi covered in microvilli Diffusion or active transport to blood, lymph, and liver
Large Intestine Cecum for plant material; dead ends
Appendix Colon recovers water by osmosis
Remnants = fecesPeristalsis moves along, reclaiming more water
Irritation limits absorption = diarrhea Move too slowly = constipation
Rectum stores until eliminationTwo sphincters (voluntary and involuntary)
control
Breaking It Down
Nutritional Needs
Chemical energy Organic building
blocks Carbohydrates Proteins Lipids
Essential nutrients
Essential Nutrients Essential amino acids
8* of 20 can’t be made, must be consumed Lacking = protein deficiency (malnutrition) Eggs, meat, and cheese are complete; plants
are incomplete
Essential fatty acids Unsaturated fatty acids Seeds, grains, and
vegetables supply
plenty
Essential Nutrients (cont.) Vitamins
Organics needed in small amounts
13 (0.01-100 mg/day)
Water soluble Fat soluble
Benefits of supplements
Table 41.1
Minerals Inorganics needed
in small amounts Vary among species
(1mg-2500mg/day)
Excess can cause imbalances and toxic effects
Table 41.2
Imbalances in Energy Intake
Undernourishment Deficient calories Droughts and wars
Overnourishment Excess calories Evolution of food hording
Malnourished Deficient nutrients Eating habits