Transcript Nutrition & Digestion - Regional School District 17

Nutrition & Digestion
Ch.18
Nutrition
• Nutrition – process by which we obtain food
• Nutrients – substances used in metabolism.
• Nutrients obtained thru major food groups.
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Bread/Cereal
Fruit/Vegetable
Meat/Fish/Poultry
Dairy
Oils/Fats
Types of Nutrition
• Autotrophs – can make their own food
• Heterotrophs – can’t make their own food
Types of Digestion
• Mechanical
– Break food into smaller pieces.
– Increases surface area for digestion.
• Chemical
– Breaks down food molecules into their basic
building blocks. Ex) Carbs to monosaccharides
• Intracellular – within the cell
• Extracellular – outside the cell
Adaptations for Nutrition
• Protozoan – intracellular diges, osmosis
• Hydra – osmosis, tentacles, stinging cells,
gastro-vascular cavity.
• Earthworm – alimentary canal, typhlosole
• Grasshopper – gizzard/teeth, diges glands
Basic Nutrients
• Carbohydrates – monosacchrides
• Proteins – amino acids
• Lipids – glycerol + fatty acids
• Vitamins – organic cmpds needed in small amts
• Minerals – inorganic ions needed in small amts
• Water – most basic & important nutrient
Balanced Diet
• 2000 – 4000 Calories/day
• Diet should supply more than just the
energy needed for that day.
Human Digestive System
• 9 meters long w/ specialized sections
• Duct glands – secrete to specific location
• Ductless glands – individual cell secretions
• Mucus protects most surfaces
Mouth
• Teeth – mechanical digestion
• Tongue – tastes food, assists swallowing
• Saliva – lubricates food for swallowing,
– Mostly Water (90%)
– Amylase digests Carbs to Disaccahrides
Esophagus
• Connects mouth to stomach.
• Epiglottis – covers trachea so food enters
the esophagus when you swallow.
• Composed of circular muscles.
• Peristalsis pushes food along with a wave
of muscle contractions.
Stomach
• Stores food 3-4 hours
• Churns food – mechanical digestion
• Gastric juice – chemical digestion
– Pepsin digests proteins to large peptides
– Hydrochloric acid
• activates enzyme
• kills bacteria
• curdles milk
– Ulcers are holes in stomach lining
Liver
• Accessory Digestive Organ
• Produces Bile – emulsifies fats
• Gall Bladder stores bile & excretes
cholesterol
Pancreas
• Juices digest all 3 food groups
– Amylase: Carbs to disacchrides
– Lipase: Fats to glycerol & fatty acids
– Trypsin: Proteins to small peptide chains
• Sodium Bicarbonate – neutralizes acids
• Insulin – regulates sugar absortion
Small Intestine
• Digestion is completed here
– Maltase, Sucrase, Lactase digest disaccharides
– Lipase digests remaining lipids
– Eripsin completes protein digestion to AA’s
• Absorption of all nutrients occurs here
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Villi increase surface area of intestine
Microvilli are extensions of villi cells
Blood vessels absorb water soluble nutrients
Lacteals absorb fat soluble nutrients
Large Intestine
• Undigestible materials pass thru here
• Water is reabsorbed
• Feces is concentrated remains
• Bacteria feed on remains and produce…
– Vitamin K
– Vitamin B12
• Appendix is a vestigial organ (no function)
Rectum
• Feces is stored here for elimination