CARBOHYDRATES Flashcards
are organic compounds composed of carbon, hydrogen and oxygen
Carbohydrates
Carbohydrates Usually occurs in ratio _______________
2:1 (H2O)
Provides the major source of energy for the body
Carbohydrates
Plays a significant role in providing cells with energy and supporting the normal functioning of the body.
Carbohydrates
Functions of Carbohydrates
- Major source of energy for the body: Every gram of glucose yields 4 kcal
- Protein sparing action
- Influences metabolism of fat
- Insoluble, indigestible CHO aids in normal elimination
- Supplies significant quantities of proteins, minerals and B vitamins
- Influences specific functions in bodily systems and processes
Simplest form of carbohydrates
Monosaccharides
Require no digestion and absorbed directly into the bloodstream from the small intestine
Monosaccharides
glucose is also known as
dextrose
principal form of CHO most easily used by the body
glucose
Blood sugar
glucose
Circulates in the blood, main source of energy of CNS and brain
glucose
Normal blood glucose range:
70—120 mg/dl
Needs insulin to be taken into cells where energy is released
glucose
Sweetest simple sugars
fructose
Provides the characteristic taste of honey and fruits
fructose
fructose absorbs in the ___________________________
small intestine
Some infants are born with an inability to metabolize galactose, a condition called
galactosemia
Rarely found in nature or free in foods
galactose
Produced from lactose (milk sugar)
galactose
galactose absorbs in the ___________________________
small intestine
Consists of two single carbohydrate (monosaccharide) bound together
Disaccharides
Glucose + fructose
sucrose
sucrose
Glucose + fructose
also known as “table sugar” - granulated, powdered or brown sugar
sucrose
sources of sucrose
sugar cane and beets, fruits, vegetables, sweet food production
Galactose + glucose
lactose
lactose
Galactose + glucose
also known as “milk sugar” - found in milk and milk products
lactose
less soluble and less sweet than sucrose
lactose
remains in the intestine longer than other sugars and encourages growth of useful bacteria
lactose
favors calcium and phosphorous assimilation
lactose
Glucose + glucose
maltose
maltose
Glucose + glucose
Composed of many molecules of simple sugars
Polysaccharides
Commonly known as complex sugars
Polysaccharides
Storage form of plant carbohydrate
starch
starch is broken down by ______________ to provide _______________
GI tract; glucose
Most significant polysaccharide in human nutrition
starch
Supplies energy over a longer period of time
starch
Formed as intermediate products in the breakdown of starch
dextrins
Also known as Fiber
cellulose
Human digestive enzymes _________ breakdown fiber
cannot
Provides bulk that thickens chyme and eases work of GI tract
cellulose
cellulose is classified as:
Soluble (fruits, legumes, oats, barley) and Insoluble (wheat brans, corn brans, whole grain breads)
Colloidal polysaccharides having a gel quality
pectins
- Sources include fruits and is used as a gelling agent
pectins
Used as a stabilizer and adhesive
pectins
glycogens are also known as
animal starch
are formed from glucose and stored in liver and muscle tissues
glycogens
glycogens food sources include _____________________________
meats and seafoods
helps the liver convert glycogen to glucose as needed by the body
glucagon
Secreted by parotid glands
amylase
DIGESTION OF CARBOHYDATES
- Mouth - Mechanical digestion
Ptyalin - Amylase; Chemical digestion
- Secreted by parotid glands
- breaks down starch to dextrin and maltose - Stomach - Stomach acid and enzymes halt amylase action
- action by ptyalin may continue to a minor degree - Small Intestine - Intestinal enzymes and pancreatic amylase continue breakdown of simple CHO
- Brush border cells secrete specific enzymes for disaccharide hydrolysis
Maltase (Maltose –> glucose + glucose)
Sucrase (Sucrose—> glucose + fructose)
Lactase (Lactose—> Galactose + glucose)
- The above monosaccharides are then absorbed - Large Intestine - Fiber continues through the GI tract and are either digested by bacteria or passed out of the body
Potential negative effects of fiber include
reduced absorption of vitamins, minerals, protein, and calories.
