Introduction to NutritionThe Adventure of Ingested Food

To obtain nutrients in food!

ENERGY••••••

CarbohydratesProteinsLipids (fats)WaterVitaminsMinerals

••••

SurviveGrowthPhysical activitiesMaintenance:- constant body temp.- biological processes

Metabolism: chemical reactions that the body needs to perform in order to stay aliveThere are two (2) types of chemical processes:

Catabolism – breaking down of materials in an organism (e.g. digestion of food)Anabolism – building of large and complex molecules from simpler ones

Factors determine how much an animal needs to eat: Body size: larger body needs more energy to stay alive Physical activity: muscle burns more energy when activity is more rigorous Gender: males typically are larger in size &have greater amount of muscle mass Age: metabolic rate decrease with age (loss of muscle mass) Heredity factors: some individual have a naturally high metabolic rate

Basal metabolic rate: the minimum amount of energy required to keep you alive

Male:BMR = [66 + (13.7 x mass in kilograms)

+ (5 x height in centimeters)– (6.8 x age in years)] x 4.18

BMR = unit is kJ1000 calories (C) = 4180 J

Female:BMR = [655 + (9.6 x mass in kilograms)

+ (1.8 x height in centimeters)– (4.7 x age in years)] x 4.18

To account for the level of activity:a. Little or not exerciseb. Some (1-3 days/week)c. Moderate (3-5 days/week)

BMR x 1.2BMR x 1.375BMR x 1.55

2007 StatisticsCanada

2007 StatisticsCanada

Carbohydrates: are sugars and their derivatives (i.e. other forms of sugars) main source of energy of the human body made up carbon, hydrogen and oxygen three main types: monosaccharides, disaccharides & polysaccharides

Monosaccharides: are simple sugars examples include glucose, fructose, galactose the molecular formula is C6H12O6 the molecular structure is either linear or ring form

glucose

Disaccharides: when simple sugars pair up forming sugar derivatives examples include maltose, sucrose, lactose

glucose + glucose = maltose + H2Oglucose + fructose = sucrose + H2Oglucose + galactose = lactose + H2O

amylose (some branching)

Polysaccharides: are long chains of sugar units example include cellulose, amylose (starch), glycogen

cellulose – very long chain of glucose units, provide structure for plant cell wallsstarch – polysaccharides of mostly glucose units, store energy in plant cellsglycogen – polysaccharides of glucose units, store energy in animal cells

glycogen(highly branched)

cellulose(no branching)

Proteins: are chains of amino acids; they are variable in shape, size, function examples include hormones, organelles, hemoglobin, antibodies there are 20 amino acids from which proteins are built human body can make twelve (12) of these amino acids, so we need to

obtain the other eight (8) from food sources

Animal sources: meat, eggs, fish, cheesePlant sources: beans, lentils, seeds, nuts

molecular structure:

Peptide bond – H2O is created/released

Lipids: are concentrated source of chemical energy

functions: insulate the body, absorb vitamins, form cell membranescommon types of lipids are fats and oilsmolecular structure: glycerol + 3 fatty acids = triglyceridethere are two (2) forms of triglyceride: saturated and unsaturated

triglyceride

Saturated:single bonds = straight chainsolid at room temperature

Unsaturated:double bonds = kinksliquid at room temperaturehealthier

Bolus

ChymeChemical Digestion Absorption

Food

Ingestion

Mechanical Digestion(physical breakdown of food)• chewing (mouth)• churning (stomach)• segmentation (intestine)

Propulsion

• swallowing (oropharynx)• peristalsis (esophagus &

intestines)

Via blood vessels (capillaries)• nutrients, vitamins• water

FecesDefecation / Egestion

(chemical breakdown of food)• lipids, starches• large molecules• proteinsare broken down furtherinto tiny molecules by

enzymes & body chemicals

mouth

tongue

Mechanical breakdown of food:• teeth, tongue

Chemical breakdown of food:• saliva, amylase

oral cavity

salivary glands

Function of your teeth:••••

incisors: slicing & grippingcanines: ripping & tearingpremolars: bitting & tearingmolars: grinding

lipgingiva

caninesincisors

wisdomtooth

crown

root

enameldentin

premolars

molars

uvula

periodontal membrane

tongue

frenulum

Swallowed Food bolus

Peristalsis pushes the bolustowards the stomach via musclecontraction of the esophagus

mouth

tongue

oral cavity

pharynx

esophagus

oral cavity

pharynxmouth

tongue

gastric pitsesophagus

stomach

Gastric glandsecrete mucus &gastric juices todigest bolus

mouth

tongue

oral cavity

pharynx

esophagus

stomach

small intestine

large intestine

mouth

tongue

oral cavity

pharynx

esophagus

stomach

small intestine

large intestine

anusrectum

oral cavity

pharynx

esophagus

stomach

small intestinelarge intestine

anusrectum

mouth

tongue

livergall bladder

Liver secretes bile• bile digest fat

commonbile duct

mouth

tongue

oral cavity

pharynx

esophagus

anus

livergall bladder

pancreas

rectum

stomachspleen

small intestine

large intestine

Pancreas- digest large molecules,- neutralize stomach acid

Spleen- removes old RBC- stores WBC that guardagainst invaders