Digestive System and NutritionDigestive System and Nutrition

OrgansOrgansProcess of DigestionProcess of Digestion

NutritionNutrition

Path of Food through the Digestive SystemPath of Food through the Digestive System

mouth

pharynx

esophagus

stomach

small intestine

large intestine

anal canal

Produces peptidases,

maltase,lactase

Produces pepsin, HCl

Peristalsis: Muscular contractions that move food through the digestive systemPeristalsis: Muscular contractions that move food through the digestive system

Accessory Organs and Glands Accessory Organs and Glands

salivary glands

liver

pancreasgallbladder

Produce salivary amylase Produces

pancreatic amylase, trypsin, lipaseProduces

bile

Stores bile

Process of Digestion and AbsorptionProcess of Digestion and Absorption• MouthMouth

– Teeth chew food Teeth chew food into smaller piecesinto smaller pieces

– Salivary amylase Salivary amylase (enzyme in saliva) (enzyme in saliva) begins starch begins starch digestiondigestion

– Tongue mixes food Tongue mixes food with saliva to form with saliva to form bolus to be bolus to be swallowedswallowed

Starch in bun has been broken into smaller chains of

sugars

Process of Digestion and AbsorptionProcess of Digestion and Absorption

• StomachStomach– HCl acid unfolds HCl acid unfolds

proteinsproteins

– Pepsin (enzyme) Pepsin (enzyme) begins protein begins protein digestion, breaking digestion, breaking some peptide bondssome peptide bonds

Protein in beef has been broken into smaller chains of

amino acids

gastric pit

gastric gland

esophagus

sphincter

pyloricsphincter

cells thatsecretegastricjuice

muscularis layer has three layersof muscle

mucosa layerhas rugae

Contains pepsin, HCl, mucus

Process of Digestion and AbsorptionProcess of Digestion and Absorption• Small IntestineSmall Intestine

– Large surface area due Large surface area due to numerous villito numerous villi

– Bile emulsifies lipidsBile emulsifies lipids– Pancreatic and intestinal Pancreatic and intestinal

enzymes digest enzymes digest carbohydrates, lipids, carbohydrates, lipids, proteinsproteins

– Amino acids and sugars Amino acids and sugars absorbed into bloodabsorbed into blood

– Lipids absorbed into Lipids absorbed into lymphatic systemlymphatic system

Carbohydrate, Protein and Fat

have been digested and absorbed

lacteal

venule

arteriole

villus

lymphaticvessel

bloodcapillaries

Digestion occurs by Hydrolysis of MacromoleculesDigestion occurs by Hydrolysis of Macromolecules

carbohydrate

pancreatic amylase

maltase

glucose

pH = basic pH = basicpH = basic

protein

trypsin

peptides

lipasepeptidase

amino acids

blood capillaryblood capillary

bile salts fat globules

Carbohydrate digestionCarbohydrate digestion Protein digestionProtein digestion Fat digestionFat digestion

+

emulsificationdroplets

cell ofintestinalvillus

lymphaticcapillary

Hydrolysis:chemical

separation of subunits

hydrolysisHydrolysis

Emulsification: physical dispersion of lipids into

smaller droplets

Process of Digestion and AbsorptionProcess of Digestion and Absorption

• Large IntestineLarge Intestine– Absorbs water Absorbs water

– Absorbs salts (minerals)Absorbs salts (minerals)

– Absorbs some vitaminsAbsorbs some vitamins

– Stores waste for later Stores waste for later eliminationelimination

Calcium from cheese has been absorbed. Fiber

from tomatoes and lettuce remains.

Distribution and Use of NutrientsDistribution and Use of Nutrients• LiverLiver

– regulates nutrient entry into regulates nutrient entry into blood blood

– detoxifies blooddetoxifies blood

– stores iron and fat-soluble stores iron and fat-soluble vitaminsvitamins

– makes plasma proteinsmakes plasma proteins

– stores and releases glucosestores and releases glucose

– produces urea from amino acidsproduces urea from amino acids

– produces bileproduces bile

– destroys old red blood cellsdestroys old red blood cells– helps regulate blood cholesterolhelps regulate blood cholesterol

Applying Your KnowledgeApplying Your Knowledge

A.A. Where are fats digested? Where are fats digested?

B.B. Where do proteins unfold?Where do proteins unfold?

C.C. Where does starch digestion begin?Where does starch digestion begin?

D.D. Where is water absorbed? Where is water absorbed?

1.1. StomachStomach

2.2. MouthMouth

3.3. Large IntestineLarge Intestine

4.4. Small IntestineSmall Intestine

Nutritional RecommendationsNutritional Recommendations

• MacronutrientsMacronutrients– CarbohydrateCarbohydrate– FatFat– ProteinProtein

• WaterWater• MicronutrientsMicronutrients

– VitaminsVitamins– MineralsMinerals

MIL

K

FR

UIT

S

GR

AIN

S

ME

AT

& B

EA

NS

VE

GE

TA

BL

ES

Use fats in small amounts

June 2011 RecommendationsJune 2011 Recommendations

Balancing CaloriesBalancing Calories•  Enjoy your food, but eat less. Enjoy your food, but eat less. • Avoid oversized portions.  Avoid oversized portions.  Foods to IncreaseFoods to Increase  • Make half your plate fruits and Make half your plate fruits and vegetables.  vegetables. • Make at least half your grainsMake at least half your grains whole grains.  whole grains. • Switch to fat-free or low-fat Switch to fat-free or low-fat (1%) milk.  (1%) milk.   Foods to ReduceFoods to Reduce•  Compare sodium in foods likeCompare sodium in foods like soup, bread, and frozen meals, soup, bread, and frozen meals,

and choose the foods with and choose the foods with lower numbers.  lower numbers. • Drink water instead of sugary Drink water instead of sugary drinks.      drinks.     

Carbohydrates: Dietary Carbohydrates: Dietary Recommendations Recommendations

• 58% of calories from carbohydrates58% of calories from carbohydrates• No more than 10% of calories from simple, No more than 10% of calories from simple,

refined sugars refined sugars • EmphasizeEmphasize

– Complex CarbohydratesComplex Carbohydrates• StarchStarch• Fiber (cellulose)Fiber (cellulose)

– Naturally-occurring simple carbohydratesNaturally-occurring simple carbohydrates• Fructose from fruitFructose from fruit• Lactose from milkLactose from milk

Fats: Dietary Recommendations Fats: Dietary Recommendations

• << 30% of calories from fats 30% of calories from fats

• << 10% of calories from saturated fats 10% of calories from saturated fats

• Limit cholesterol to 300 mg/dayLimit cholesterol to 300 mg/day

• Avoid “trans” fatty acids in partially Avoid “trans” fatty acids in partially hydrogenated productshydrogenated products

• EmphasizeEmphasize

– Unsaturated fatty acids from Unsaturated fatty acids from vegetables,vegetables, fish, legumes,fish, legumes, and nutsand nuts

– Oils: mono- or polyunsaturatedOils: mono- or polyunsaturated

Proteins: Dietary Proteins: Dietary Recommendations Recommendations

• 12% of calories from proteins12% of calories from proteins

• 8 essential amino acids obtained 8 essential amino acids obtained from from

–Lean sources of animal proteinLean sources of animal protein

–Complementary plant proteinsComplementary plant proteins• Beans + GrainsBeans + Grains

• Beans + SeedsBeans + Seeds

Vitamins Vitamins

• Organic compounds used in metabolic Organic compounds used in metabolic reactions as coenzymes or reactions as coenzymes or antioxidantsantioxidants

• Water Soluble: B vitamins, CWater Soluble: B vitamins, C• Fat Soluble: A, D, E, KFat Soluble: A, D, E, K• Adequate amounts come from a varied Adequate amounts come from a varied

diet that includes vegetables and fruits diet that includes vegetables and fruits • May prevent cancer and cardiovascular May prevent cancer and cardiovascular

diseasedisease

Minerals Minerals

• Inorganic substances required by the Inorganic substances required by the bodybody

• Macrominerals needed in large Macrominerals needed in large amounts, eg. calciumamounts, eg. calcium

• Microminerals needed in smaller Microminerals needed in smaller amounts, eg. ironamounts, eg. iron

• May need to emphasize certain foods May need to emphasize certain foods to obtain iron or calciumto obtain iron or calcium

• May need to limit foods high in sodiumMay need to limit foods high in sodium

Applying Your KnowledgeApplying Your Knowledge

A.A. Which one is a mineral? Which one is a mineral?

B.B. Which macronutrient should supply the Which macronutrient should supply the greatest number of calories in the diet? greatest number of calories in the diet?

C.C. Which one may protect against cancer? Which one may protect against cancer?

1.1. CalciumCalcium2.2. Vitamin CVitamin C3.3. LipidLipid4.4. CarbohydrateCarbohydrate5.5. Protein Protein

Reading a Reading a Nutrition LabelNutrition Label

More info atMore info athttp://www.fda.govhttp://www.fda.gov

Calorie Percentage CalculationsCalorie Percentage Calculations

5 x 4/250 = 0.080 x 100 = 8.0%5 x 4/250 = 0.080 x 100 = 8.0%

5 x 4/250 = 0.080 x 100 = 8.0%5 x 4/250 = 0.080 x 100 = 8.0%

31 x 4/250 = 0.496 x 100 = 49.6%31 x 4/250 = 0.496 x 100 = 49.6%

12 x 9/250 = 0.432 x 100 = 43.2%12 x 9/250 = 0.432 x 100 = 43.2%

3 x 9/250 = 0.108 x 100 = 10.8%3 x 9/250 = 0.108 x 100 = 10.8%

Number of grams

Caloric value

Total calories

The

se s

houl

d ad

d to

100

%.