Chapter 3: Carbohydrates Flashcards
organic compounds composed of carbon, hydrogen, oxygen, and hydrogen
carbohydrates
synthesis
sugars and starches are produced in plants by the process of
photosynthesis
synthesis
storage form of carbohydrates in plants
starch
synthesis
storage form of carbohydrates in animal
glycogen
synthesis
process by which disaccharides are formed
hydroxyl group from one monosaccharide links with oxygen of the other monosaccharide to form h2o
condensation
synthesis
splitting of disaccharides
hydrogen is added to one and _____ is added to the other
occurs during digestion
hydrogen
hydroxyl group
classification
contain either one or two molecules
simple carbohydrates
classification
contain hundreds to thousands of molecules
complex carbohydrates
simple carbohydrate (2)
monosaccharides and disaccharides
complex carbohydrates (1) and its component
polysaccharides:
starch, glycogen, fibers
are single sugar units
the important to nutrition are glucose, fructose, and galactose
monosaccharides
each monosaccharides (g, f, g) contains
but differ in the arrangements of the atoms, which explains the differing sweetness of the monosaccarides
6 carbon atoms
12 hydrogens
6 oxygen
body’s major fuel to provide energy
not generally occur by itself in foods, attached to other sugars to form disaccharides and complex carbohydrates
ex: grapes, dextrose, corn syrup
glucose
levulose or fruit sugar
fructose
blood sugar
glucose
sweetest natural sugar
digestive end product of sucrose
arrangement of atoms stimulates the taste buds on the tongue to produce the sweet sensation
ex: honey, ripe fruits, high-fructose corn syrup
fructose
milk sugar
galactose
digestive end product of lactose
does not occur alone in foods and joins with glucose to create lactose
galactose
molecules of 2 sugar units
disaccharides
malt sugar
maltose
consists of 2 glucose units
produced from starch digestion
occurs during the fermentation
minor constituent of few foods
ex: barley
maltose
saccharose
table or cane sugar
sucrose
consists of 1 glucose and fructose molecule
ex: sugar beets and sugar cane
sucrose
consists of 1 glucose and galactose molecule
ex: milk
lactose
carbohydrates that contain 3-10 monosaccharides
oligosaccharides
2 most common oligosaccharides found in the diet
raffinose
stachyose
oligo means
few
composed of galactose, glucose, and fructose
ex: beans, cabbage, brussel sprouts, broccoli, whole grains
raffinose
composed of 2 galactose molecules (1 glucose and fructose molecule)
ex: beans and other legumes
stachyose
aka complex carbohydrates
made-up of 10 or more monosaccharides
polysaccharides
polysaccharides
storage form of carbohydrates in animals
glycogen
polysaccharides
storage of glycogen in animals
liver and muscle tissues
starch occurs in 2 forms
amylose
amylopectin
polysaccharides
ling, branched or unbranched chains of hundreds or thousands of glucose linked together
ex: plants (grains)
starch
resist hydrolysis because of their physical structure
occurs in raw starch granules (raw bananas, potatoes) or during prolonged cooling of some cooked foods
escapes digestion in small intestine but may degraded by bacterial enzymes in the large intestines
resistant starch
intermediate products in the hydrolysis of starch
ex: toasted flour
dextrin
fiber
the non-digestible parts of plants that form the support structures of leaves, stems, and seeds
dietary fiber
fiber
consists of non-digestible forms of carbohydrates that are extracted from plants or manufactures in a laboratory and have known health benefits
added to foods and is the form found in fiber supplements
functional fiber
fiber
the sum of dietary fiber and functional fiber
total fiber
pectin and gums
soluble fiber
cellulose, lignin, and many hemicellulose
insoluble fiber
have little effect on fecal bulk
tend to increase the rate of the passage of material through the upper gi tract and delays the absorption of nutrients
ex: fruits, oats, barley, and legumes
soluble fiber
may decrease the rate of absorption of glucose by the small intestine and plasma cholesterol levels
soluble fiber
result in greater fecal bulk and increase in the rate of passage of material through the large intestine
type of fiber used to treat constipation
ex: vegetables, wheat, grains
beans, barley, carrots, apple, avocado, pears, cauliflower, brown rice
insoluble fiber
cho functions
cheap and main energy source
yields _____ kcal/g
4 kcal/g
cho functions
spares protein so it can be used for building and repairing body tissues
protein sparer
cho functions
prevent incomplete oxidation of fat
regulator of fat metabolism
cho digestion and absorption
breaks the food into small particles and mixes it with saliva
mastication
cho digestion and absorption
acts on starch and begins its breakdown into dextrins and maltose
salivary amylase
cho digestion and absorption
contains pancreatic amylase
contains sucrase, lactase and maltase that break down dextrins and maltose into monosaccharides, mainly glucose with some fructose and galactose
pancreatic secretions
cho digestion and absorption
are either absorbed by diffusion or by a sodium dependent active transport
glucose and galactose
cho digestion and absorption
absorbed by facilitated diffusion
fructose
cho digestion and absorption
converted into glucose in the liver (2)
galactose and fructose
cho digestion and absorption
hormone that facilitates the entry of glucose into the cells, except for brain and liver
insulin
cho metabolism
after ingesting carbohydrate contain meal, blood glucose level increases to _____
this stimulates the pancreas to release insulin
120-130 mg/dL
hours after a meal, during fasting or sleep, blood glucose decreases to _____
decrease in blood glucose levels signals the pancreas
70 mg/dL
decrease in blood glucose levels signals the pancreas to release _____ into the bloodstream
glucagon
stimulates the liver cells to breakdown glycogen and release glucose in the blood, causing corresponding increase in the blood glucose level
glucagon
main hormones involved in cho metabolism
insulin and glucagon
hormones involved in blood glucose control
secreted by the adrenal cortex; favors gluconeogenesis
cortisol
hormones involved in blood glucose control
secreted by the adrenal medulla
increases glycogen breakdown
epinephrine
hormones involved in blood glucose control
secreted by the pituitary gland
acts as an insulin antagonist
growth hormone
hormones involved in blood glucose control
secreted by the thyroid glans
influences the rate of insulin destruction and epinephrine
thyroxine
hormones involved in blood glucose control
secreted by adrenal cortex
act by increasing protein gluconeogenesis
steroid hormone
pathways of cho metabolism
formation of glycogen from glucose
occurs in the liver and muscle cells
glycogenesis
pathways of cho metabolism
breakdown of glycogen to glucose for use by the body
glycogenolysis
glycogenolysis
a debranching enzyme breaks down glycogen
liver
glycogenolysis
cori cycle may take place if there is an immediate need for glucose to fuel an activity
muscles
pathways of cho metabolism
synthesis of glucose from non-cho sources such as protein and fat
gluconeogenesis
pathways of cho metabolism
breakdown of glucose to pyruvic acid
glycolysis or embden-meyerhoff pathway
pathways of cho metabolism
requires oxygen and occurs in the mitochondria
includes decarboxylation of pyruvic acid to acetic acid
condensation of acetic acid with coa
other reactions that produce hydrogen ions and electrons, hydrogen ions produced from breakdown of acetyl coa are transferred by niacin and riboflavin to etc
kreb’s cycle or tricarboxylic acid cycle or citric acid cycle
water soluble vitamins involved in kreb’s cycle (2)
niacin and riboflavin
pathways of cho metabolism
free energy released from kreb’s cycle is captured here using electron- or hydrogen- transferring ions to form atp
water as an end-product of a series of reactions
electron transport chain (etc) or respiratory chain
kreb’s cycle and electron transport chain occurs in the
mitochondria
cho health effects
concentrated sweets are carcinogenic and cause bacterial overgrowth and tooth decay
dental caries
cho health effects
for cho-sensitive people, increased cho intake provides glyceril 3 po4, a precursor for fat synthesis
obesity
cho health effects
for cho-sensitive pt, cho may cause excessive fat synthesis
high-blood triglyceride levels
cho health effects
indigestible cho or lactose intolerance promoted fas formation and colic
flatus
frequent, prolonged and intense crying or fussiness in a healthy infant
colic
cho health effects
form of severe undernutrition (wasting) referred to alternatively as non-edematous malnutrition or has the appearance of “skin and bones”
maramsus
cho health effects
high fiber diet delays glucose absorption
diabetes
issues
compounds used to substitute cho in the diet
ex: saccharin, aspartame, acesulfame potassium, and sucralose are the only approved sweeteners
artificial sweeteners
not associated with any adverse effects except for being a source of phenylalanine, a hazard for phenylketonurics
aspartame
have been associated with cancer, but studies have shown that they are safe for use
saccharin and acesulfame potassium
describes the effect of food on blood glucose
-how quickly glucose is absorbed after a person eats
-how high blood glucose rises
-how quickly it returns to normal
glycemic index
gives an estimate of glucose load by multiplying the gi by the amount of cho of all foods in a meal
glycemic load
glycemic load formula
GL = qty x quality (remove %) / 100
high gi
> 70%
medium gi
56-69%
low gi
<54%
