CarbohydratesCarbohydrates

Simple CarbohydratesSimple Carbohydrates

sugarssugars– monosaccharides – single sugarsmonosaccharides – single sugars– disaccharides – 2 monosaccharidesdisaccharides – 2 monosaccharides

Simple CarbsSimple Carbs monosaccharidesmonosaccharides

– all are 6 carbon hexesall are 6 carbon hexes6 carbons6 carbons12 hydrogens12 hydrogens6 oxygens6 oxygensarrangement differsarrangement differs

–accounts for varying accounts for varying sweetnesssweetness

– glucose, fructose, glucose, fructose, galactosegalactose

GlucoseGlucose

mild sweet flavormild sweet flavor known as blood sugarknown as blood sugar essential energy sourceessential energy source found in every found in every

disaccharide and disaccharide and polysaccharidepolysaccharide

FructoseFructose

sweetest sugarsweetest sugar found in fruits and honeyfound in fruits and honey added to soft drinks, added to soft drinks,

cereals, desertscereals, deserts

GalactoseGalactose

hardly tastes sweethardly tastes sweet rarely found rarely found

naturally as a single naturally as a single sugar sugar

DisaccharidesDisaccharides

pairs of the monosaccharidespairs of the monosaccharides– glucose is always presentglucose is always present– 22ndnd of the pair could be fructose, galactose of the pair could be fructose, galactose

or another glucoseor another glucose– taken apart by hydrolysistaken apart by hydrolysis– put together by condensationput together by condensation– hydrolysis and condensation occur with all hydrolysis and condensation occur with all

energy nutrientsenergy nutrients– maltose, sucrose, lactosemaltose, sucrose, lactose

CondensationCondensation

making a disaccharidemaking a disaccharide– chemical reaction linking 2 chemical reaction linking 2

monosaccharidesmonosaccharides

HydrolysisHydrolysis

breaking a disaccharidebreaking a disaccharide– water molecule splitswater molecule splits– occurs during digestionoccurs during digestion

MaltoseMaltose

2 glucose units2 glucose units produced when starch breaks downproduced when starch breaks down not abundantnot abundant

SucroseSucrose fructose and fructose and

glucoseglucose tastes sweettastes sweet

– fruit, vegetables, fruit, vegetables, grainsgrains

table sugar is table sugar is refined sugarcane refined sugarcane and sugar beetsand sugar beets

brown, white, brown, white, powderedpowdered

LactoseLactose

glucose and galactoseglucose and galactose main carbohydrate in main carbohydrate in

milkmilk– known as milk sugarknown as milk sugar

Complex CarbohydratesComplex Carbohydrates

starches and fibersstarches and fibers polysaccharidespolysaccharides

– chains of monosaccharideschains of monosaccharides

Complex CarbohydratesComplex Carbohydrates

polysaccharidespolysaccharides– glycogen and starchglycogen and starch

built entirely of glucosebuilt entirely of glucose– fiberfiber

variety of monosaccharides and other variety of monosaccharides and other carbohydrate derivativescarbohydrate derivatives

GlycogenGlycogen limited in meat and not found in plantslimited in meat and not found in plants

– not an important dietary source of not an important dietary source of carbohydratecarbohydrate

BUTBUT– all glucose is stored as glycogenall glucose is stored as glycogen– long chains allow for long chains allow for hydrolysis and releasehydrolysis and release of energyof energy

CarbohydratesCarbohydrates

glucose provides energy for the brain and ½ glucose provides energy for the brain and ½ of energy for muscles and tissuesof energy for muscles and tissues

glycogen is stored glucoseglycogen is stored glucose glucose is immediate energyglucose is immediate energy glycogen is reserve energyglycogen is reserve energy

StarchesStarches

stored in plant cellsstored in plant cells body hydrolyzes plant starch to glucosebody hydrolyzes plant starch to glucose

FiberFiber

structural parts of plantsstructural parts of plants– found in all plant derived foodfound in all plant derived food

bonds of fibers cannot be broken down bonds of fibers cannot be broken down during the digestive processduring the digestive process– minimal or no energy availableminimal or no energy available

Fiber typesFiber types

cellulosecellulose pectinspectins ligninslignins resistant starchesresistant starches

– classified as fibersclassified as fibers– escape digestion and escape digestion and

absorptionabsorption

Fiber CharacteristicsFiber Characteristics soluble fibers, viscous, fermentablesoluble fibers, viscous, fermentable

– easily digested by bacteria in coloneasily digested by bacteria in colon– associated with protection against heart associated with protection against heart

disease and diabetesdisease and diabetes lower cholesterol and glucose levelslower cholesterol and glucose levels

– found in legumes and fruitsfound in legumes and fruits

Carbohydrate MetabolismCarbohydrate Metabolism 1/3 of body’s glycogen is stored in liver1/3 of body’s glycogen is stored in liver

– released as glucose to bloodstreamreleased as glucose to bloodstream1.1. eat – intake glucoseeat – intake glucose2.2. liver condenses extra glucose to glycogenliver condenses extra glucose to glycogen3.3. blood glucose fallsblood glucose falls4.4. liver hydrolyzes glycogen to glucoseliver hydrolyzes glycogen to glucose

Glycogen is bulky, so we store only so much: Glycogen is bulky, so we store only so much: short term energy supplyshort term energy supply

Fat is the long term energy supply.Fat is the long term energy supply.

Glucose for EnergyGlucose for Energy enzymes break apart glucose – yielding enzymes break apart glucose – yielding

energyenergy inadequate supply of carbohydratesinadequate supply of carbohydrates

– ketone bodies (fat fragments) are an ketone bodies (fat fragments) are an alternate energy source during starvationalternate energy source during starvation

– excess ketones can lead to ketosis: excess ketones can lead to ketosis: imbalance of acids in bodyimbalance of acids in body

minimum of 50 – 100 grams of carbs/day are minimum of 50 – 100 grams of carbs/day are needed to avoid ketosisneeded to avoid ketosis

Glucose HomeostasisGlucose Homeostasis

maintaining an even balance of glucose is maintaining an even balance of glucose is controlled by insulin and glucagoncontrolled by insulin and glucagon– insulininsulin

moves glucose into the bloodmoves glucose into the blood– glucagonglucagon

brings glucose out of storagebrings glucose out of storage

maintaining balancemaintaining balance– balanced meals at regular intervalsbalanced meals at regular intervals

fiber and some fat slow the digestive fiber and some fat slow the digestive process downprocess down

glucose gets into the blood slow and glucose gets into the blood slow and steadysteady

Maintaining Blood

Glucose Homeostasis

IntestineWhen a person eats,blood glucose rises.

1

2

Insulin stimulates the uptake of glucose into cells and storageas glycogen in the liver andmuscles. Insulin also stimulatesthe conversion of excessglucose into fat for storage.

3

4

5

6

7 Blood glucose begins torise.

a The stress hormoneepinephrine and other hormonesalso bring glucose out of storage.

GlucoseInsulinGlucagonGlycogen

Glucagon stimulates livercells to break down glycogenand release glucose into theblood.a

Liver

Low blood glucose stimulatesthe pancreas to releaseglucagon into the bloodstream.

As the body's cells useglucose, blood levels decline.

Glucagon

Pancreas

Fat cell

Liver

Muscle

High blood glucose stimulatesthe pancreas to release insulin.

Pancreas

Insulin

ImbalanceImbalance

diabetesdiabetes– after food intake, blood glucose rises and after food intake, blood glucose rises and

is not regulated because insulin is is not regulated because insulin is inadequateinadequate

hypoglycemiahypoglycemia– blood glucose drops dramaticallyblood glucose drops dramatically

too much insulin, activity, inadequate too much insulin, activity, inadequate food intake, illnessfood intake, illness

diet adjustment includes fiber-rich carbs diet adjustment includes fiber-rich carbs and proteinand protein