HLTH 230 Midterm Flashcards
role of carbohydrates
-provide energy for the brain & NS
-help keep digestive system healthy
-within limits, keep body lean
Indigestible carbohydrates
yield little or no energy
carbohydrate rich foods
-whole grains
-plants
-legumes
-vegetables and fruits
-milk products are the only animal-derived foods that contain significant carbs (milk, yogurt, sour cream)
-concentrated sugars
categories of carbohydrates
simple and complex
simple carbohydrates
Monosaccharides - single sugar
Disaccharides -pairs of monosaccharides (one is usually glucose)
3 monosaccharides
glucose, fructose and galactose
*all have the same number & kind of atoms arranged in different ways
Glucose
-blood sugar
-monosaccharide
-mildly sweet
-essential energy source for body activities
-one of 2 sugars of every disaccharide
-polysaccharides are made almost exclusively of glucose
Complex carbohydrates
polysaccharides - chain of monosachharides
galactose
-component of milk sugar
-not sweet at all
-one of the two sugars in milk products
-found occasionally as a single sugar (fermented milk products)
Fructose
-very sweet
-naturally in fruit and honey
-often used in soft drinks, cereals and desserts
-
high fructose corn syrup
syrup made from cornstarch that has been treated with an enzyme tha converts some of the glucose to the sweeter fructose
3 disaccharides
lactose (glucose + galactose)
Maltose (glucose + glucose)
Sucrose (glucose + fructose)
**joined by cindensation rxns, split by hydrolysis rxns that release a water
Lactose
-milk sugar
-glucose and galactose
-principle carbohydrate in milk
-provides about 1/2 kcal in skim milk
maltose
-2 glucose
-prodcued duing starch breakdown
-occurs during process of alcohol fermentation
-only occurs in a few foods ex. barley
Sucrose
-glucose and fructose
-sweetest disaccharide
-naturally in fruit, vegetables and grains
-table sugar is sucrose refined from beets or sugarcane
Eating sugar
-monosaccharides are absorbed diretly into the blood
-disaccharides are digested before absorption (slit into monosaccharides)
-glucose is most used nutrient in the body
sugar on nutrition label
-cannot tell from % DV what sugar is natural or artificial
most energy in fruit and vegetables comes from
sugar
why are fruits different than purified sugars?
fruit contains fibre, phytochemicals, vitamins and minerals
polysaccharides
-starch
-glycogen
-fibre
**made up of many strands of glucose units
Starch
-storage form of glucose in plants
-long chains of glucose molecules linked together (branched-amylopectin and unbranched-amylose)
-starch is nutritive: we digest starch to glucose
rich food sources of starch
-grains
-tubers (yams and potatoes)
-legumes (peas and beans)
Glycogen
-storage form of carbs in animals
-highly branched glucose chains (this allows for rapid hydrolysis and surge of glucose)
-stored in muscle(2/3) and the liver (1/3)
**meat does not contain glycogen because it breaks down when animal is slaughtered
how long could you sustain energy on stored glycogen
about 1 hr