Carbohydrates Flashcards
Calories
energy
-unit of food energy
-Kcal/100g
Functions of CHO
- Energy 4kcals/g
-fuels work for body cells (preferred for nervous and RBC
-excess is stored as GLYCOGEN in liver and muscles - Sparing Body Protein
-if carb intake <50-100, body protein will be used to make glucose
Monosaccharides
-consist of 3, 5, or 6 C atoms
glucose-source of energy
fructose- simple sugar found in fruits, sweetest
galactose- a component of milk sugar
Disaccharides
2 mono joined by a glycosidic bond
-sucrose (table sugar): glucose and fructose
-lactose (milk): glucose and galactose
-maltose (grain): glucose and glucose
3 types of Polysaccharides
glycogen, starch, fiber (cellulose)
trioses
n=3
-glyceraldehyde
pentoses
n=5
-ribose and deoxyribose
hexoses
n=6
fructose, glucose, and galactose
Dehydration synthesis
remove water to add two molecules
oligosaccharides
short chains of 3-10 monos
-legumes and human milk
-raffinose and stachyose (can’t be broken down by human enzymes, though can be digested by colonic bacteria)
glycogen
animal storage for carbs
-100g in liver and 400g in muscle
-negligible source of carbs in diet (meat)
Alpha Glucose
-starch
-OH group faces down
Beta Glucose
-cellulose (every other glucose is upside down)
-OH group faces up
starch
-plant storage
-branched or unbranched
-amylose-straight 40%
-amylopectin-branched 60% (easier to digest)
Fiber
non-digestible carbs that have beneficial physiological effects in humans
-in plants
-refining removes fiber from whole grains and other foods
insoluble fiber
cellulose (cell wall)
-speed transit through digestive tract
-absorb water to soften stool
-promotes healthy GI and bowels
-cereal grains, legumes, veggies, nuts
Soluble Fiber
gums and pectins
-easily fermented by gut bacteria
-delay gastric emptying
-slow transit
-delay glucose absorption
-bind to bile, help decrease cholesterol
-oats, legumes, citrus
CHO digestion in Mouth
-chewing
-salivary amylase (starch to shorter poly)
DandA in stomach
fibers remain in the stomach longer, delays gastric emptying
DandA in Small Intestine
pancrease secretes enzyme to break down poly to di (amylase)
-enzymes located on the cell membrane of intestines complete digestion
-only monosaccharides can be absorbed by microvilli
-galactose and glucose= active transport
-Fructose= facilitated diffusion
DandA in Large In,
resistant starch and fibers may be digested by bacteria
-makes short fatty acids (can be absrobed by intestine 2kcal/g)
-vitamin K
after absorption
all monos travel to liver via the portal vein
-turns fructose and galactose into glucose
-can be used for energy, storage as glycogen, or released to blood
blood glucose
fates: glycogen (liver muscle), kidney for excretion, adipose tissue, other tissues
Functions:
-energy
-building blocks
-spares protein
-prevents ketosis
-cell surface markers
regulation of BG
normal= 70-100mh/dL
-Hyperglycemia=126
-hypoglycemia=50
-endocrine system is primarily responsible for regulating blood glucose (insulin and glucagon)
insulin vs glucagon
-insulin stimulates liver to store glucose as glycogen
-glucagon stimulates liver to make glucose
AMDR (adults)
45-65% of total average energy intake
RDA for carbs
130G
-recommended dietary allowance
daily value
300G
AI for fibers
38 men
25 women
sugar
intrinsic-fruits and veggies
added-saccharides added to foods and bevs by manu, cook, or consumer
