Exam 2: Carbohydrates Flashcards
What are carbohydrates
organic compounds that contain carbon,
hydrogen, and oxygen in various combinations
CHO nomenclature typically ends in “ose”?
not always true
What are the 3 major categories of CHO?
- simple
- complex
- dietary fiber
Types of simple sugars
Monosaccharides
Disaccharides
What are monosaccharide
Glucose
Fructose
Galactose
What are the 3 disaccharides
Maltose=
Lactose
Sucrose
What are refined sugars
Monosaccharides and disaccharides, such as glucose and
sucrose, may be isolated from foods in purified forms
corn syrup
Trisaccharides and higher saccharides also exist
and may be found in commonly used sweeteners such as corn
syrup. For example, high-fructose corn syrup, a common food
additive, is a manufactured carbohydrate derived from the conver-
sion of glucose in corn starch to fructose. Other food additives
that are primarily sugar include honey, brown sugar, maple syrup,
molasses, and fruit juice concentrate.
What are complex CHO made up of?
three or more glucose molecules combine
Types of complex carbohydrates
- Polysaccharides
- Oligosaccharides
complex carbohydrates are commonly known as _______
starches
What are polysaccharides composed of?
more than
ten glucose molecules are combined
Types of polysaccharide
- Dextrins
- Starch
- Glycogen
- Dietary Fiber
Forms of Starches, starch is the storage of what?
- amylose
- amylopectin
- resistant starch
Plants
Glycogen is storage form of
storage form in humans
3 types of Fiber
- Dietary Fiber
- Functional Fiber
- Total Fiber
What are glucose polymers?
polysaccharides prepared commercially by con-
trolled hydrolysis of starch
Which is common glucose
polymers used in sports drinks
maltodextrins
Dietary Fiber is
nondigestible
carbohydrates and lignin that are intrinsic and intact in plants;
this would include resistant starch
Functional Fiber is
Functional fiber consists of iso-
lated, nondigestible carbohydrates that have beneficial physiologi-
cal effects in humans
Total Fiber is
Total fiber is the sum of dietary fiber and
functional fiber. These nondigestible substances, which means
that they are not digested and absorbed in the human small intes-
tine, are usually a mixture of polysaccharides found in the plant
wall or intracellular structures.
Primary sources of digestible CHO
- Grains
- Fruits
- Vegetables
Other sources of digestible CHO
- Dairy group: ice cream, chocolate milk
- Protein group: beans, lentils, nuts,
- Sweets:
- Sports drinks/food
What is soluble fiber
found to dissolve or swell in water and may be metabo-
lized by bacteria in the large intestine
3 types of Soluble Fiber
- pectins
- gums
- algal polysaccharides
Key sources of Soluble fiber
- fruits
- most grains
- beans
What is Insoluble Fiber
do not dissolve or metabolized by bacteria
3 types of insoluble fiber
- cellulose
- hemicellulose
- lignin
key sources of insoluble fiber
- wheat
Which part of a triglyceride can be used for glucose production?
Glycerol
What is the glycemic load formula?
GL = gly ind x gram of nonfiber carb in 1 service/ 100
True or False
It is now generally thought that the component of fatigue correlated with lactate results from the lactate itself rather than the effects of an increased free hydro ion and the associated acidity
True
What is Amylose
What is Amylopectic
what is resistant starch
What is the typical dietary fiber recommendations for athletes (% calories
45-65% of calories
What is the typical dietary fiber recommendations for athletes (DRV)q
300 g for every 2000Cal diet
What is the typical dietary fiber recommendations for athletes (male and women)
- 25g women
- 38g men
Osmosis is
the passive diffu-
sion of water.
facilitated diffusion
, a receptor in the cell mem-
brane is needed to transport the substance from the intestine into
the villi.
no energy
active transport
energy supplied by the villi cells in order to be absorbed
Carbohydrates usually are ingested in the forms of
polysaccharides (starches), disaccharides (sucrose, maltose, and lactose), and
monosaccharides (glucose and fructose).
The enzyme that digests complex carbo-
hydrates is ____________, which is secreted by the _____________ and ____________________
amylase, salivary glands, pancrease
Saliva amylase initiates digestion of the polysaccharides
to disaccharides, but most digestion is done in the ___________________ by _______________________
small intestine by
pancreatic amylase
sports drinks may be designed to take advantage of the different_____________________ receptors in the villi.
monosaccharide
although there is very little digestion of carbohydrate in the stomach, the_____________
with which carbohydrate leaves the stomach, and its impact upon
the _______________ of water, may be important considerations for ath-
letes involved in prolonged exercise under _____________ environmental
conditions.
rapidity, absorption, warm
High concentrations of simple sugars, particularly______________, may
exert a reverse _____________ effect in the intestines, drawing water from
the circulatory system into the intestinal lumen. The resulting
symptoms are referred to as the dumping syndrome and include
_________________________.
fructose, osmotic, weakness, sweating, and diarrhea
Most dietary carbohydrates are broken down
to _______________ for absorption into the blood, while the majority of the
absorbed ______________- and _______________ are converted to glucose by the
liver. Glucose is the blood sugar.
glucose, fructose and galactose,
The ________________ represents a ranking system relative to
the effect that consumption of 50 grams of a particular carbohy-
drate food has upon the blood glucose response over the course of
2 hours. The normal baseline measure is 50 grams of glucose, and
the resultant blood glucose response is scored as _______.
glycemic index (GI), 100,
glycemic index (GI) 70 or more
high GI foods
●
glycemic index (GI) 69–55
medium GI foods
●
glycemic index (GI) 55 or less
low GI foods
●
Many factors other than a food’s carbohydrate content, such
as the ________________ (coarse or fine) and __________________`(raw or
cooked), may influence the glycemic index of any given food
physical form, serving mode
The ______________ also repre-
sents a ranking system relative to the
effect that eating a carbohydrate food
has on the blood glucose level, but GL
also includes the portion size. While the
glycemic index is based on 50 grams of
a particular food, a typical serving size for that food may be 6–8
ounces (180–240 grams).
glycemic load (GL),
GL =
(glycemic index) × (grams of nonfiber carbohydrate in 1 serving) / 100
glycemic load 20 or omre
high GL foods
glycemic load 19-11
medium GL foods
glycemic load 10 or less
low GL foods
normal blood glucose level
80 - 100 mg/mL
the human body possesses
a variety of mechanisms, primar-
ily ________________, to help keep blood
glucose levels under precise con-
trol
hormones
explain Insulin role in detail
The rise in blood glucose, also
known as serum glucose, stimulates
the pancreas to secrete insulin into
the blood. Insulin is a hormone that
facilitates the uptake and utilization
of glucose (facilitated diffusion) by
various tissues in the body, most
notably the muscles and adipose
(fat) tissue.
The primary receptors in
muscle and fat cell membranes are known as _______ receptors,
which are directly activated by insulin
GLUT-4
what two factors activate GLUT-4 receptors?
Insulin and exercise
The major fates of blood glucose
- Blood glucose may be used for energy, particularly by the brain
and other parts of the nervous system that rely primarily on
glucose for their metabolism. - Blood glucose may be converted to either liver or muscle gly-
cogen - Blood glucose may be converted to and stored as fat in the
adipose tissue. - blood glucose also may be excreted in the urine if an
excessive amount occurs in simple sugars
Hypoglycemia can impair the
normal function of the ____________
brain
liver glycogen may later be
reconverted to _____________ but not in the ______________. Why?
blood glucose, muscle glycogen
lack of a specific enzyme needed to change its form so that it
can cross the cell membrane back into the bloodstream
why is blood glucose converted and stored as fat?
dietary carbo-
hydrate, in combination with caloric intake of other nutrients,
exceeds the energy demands of the body and the storage capac-
ity of the liver and muscles for glycogen
The chemical formula for glucose is
C6H12O6,
so it contains 6 parts of carbon and oxygen and 12 parts of hydrogen
he body has three major energy sources
of carbohydrate:
blood glucose, liver glycogen, and muscle gly-
cogen
The ________- has the greatest concentration of glycogen in the body
liver
the liver normally contains
only about 75–100 g of glycogen, or 300–400 kcal.
One hour of
aerobic exercise uses more than half of the liver glycogen supply
the liver glycogen content may be
decreased by starvation or increased by a carbohydrate-rich diet
The greatest amount of carbohydrate stored in the body is in
the form of muscle glycogen
because the muscles com-
pose such a large proportion of the body mass as contrasted
to the liver
gluconeogenesis
formation of glucose from protein, fats,
what componenets of protein and fat are converted to glucose?
amino acids (alanine) and glycerol
What are the major functions of
carbohydrate in human nutrition?
- supply energy
other - produce trioses and pentoses (glycolipids, glycoproteins) Ribose for RNA
Carbohydrates can be used to produce energy either
aerobically or anaerobically
oxidation of glucose produces
water, CO2, energy
Explain lactic acid system produce ATP
ATP is produced rapidly via anaerobic gly-
colysis, but for this system to continue functioning, the end prod-
uct of glycolysis, pyruvic acid or pyruvate, must be converted into
lactic acid
anaerobic metabolism yields
3 ATP when starting with glycogen and only 2 ATP when start-
ing with glucose
Explain oxygen system produce ATP
aerobic glycolysis predominates
and pyruvic acid is converted into acetyl CoA, which enters into
the Krebs cycle and electron transfer system for complete oxida-
tion and the production of relatively large amounts of ATP
aerobic metabolism yields about 32 ATP
In what types of activities does the body rely
heavily on carbohydrate as an energy source?
person is working at 65–85 percent of capacity
for high-intensity anaerobic
events lasting for less than 1 minute and high-intensity aerobic
events lasting more than an hour or two.
Why is carbohydrate an important
energy source for exercise?
can be used
for anaerobic energy production in the lactic acid sys-
tem, it is also the most efficient fuel for the oxygen sys-
tem
2. metabolic pathways for carbohydrate are also more efficient than
those for fat. more ATP than fat
The primary carbohydrate source of energy for physical perfor-
mance is muscle glycogen, specifically the glycogen in the muscles
that are active
As the muscle glycogen is being used
during exercise, blood glucose enters the muscles and the energy
pathways. In turn, the liver will release some of its glucose to help
maintain or elevate blood glucose levels and prevent hypoglyce-
mia.
Because carbohydrate is a primary fuel for exercise, as you initiate an
endurance exercise program, a major proportion of your energy will
be derived from your muscle glycogen stores. A single bout of exercise
can activate the genes that produce GLUT-4 receptors, which can exert
an insulin-type effect by facilitating the transport of blood glucose into
the muscle both during and immediately following the exercise bout.
What effect does endurance training
have on carbohydrate metabolism?
- increase GLUT-4 receptor production
Which CHO need to be digested?
all except for monosaccharides
Where does CHO absorption occur
Small intestine
How does CHO absorption occur
- Depends on type of monosaccharides
- Almost all get absorbed as monosaccharides
Glucose and galactose are absorbed via which transport?
How?
- by active transport (SGLT1/GLUT2)
- Require energy
- Pump mole against conc gradient
- SGLT1 carrier to take into epithelial cells
- GLUT2 carrier takes into circulatory system
Fructose is absorbed via which transport?
How?
- by facilitated diffusion (GLUT5/GLUT2)
- High to low concentration
- Abs a lot of fructose carriers get saturated so can get in bc carriers are full, fructose go to large intestine. Fruc sit in LI. needs water, cause diarrhea, fructose is food for bacteria, release gas
- Consume fructose with other carbs makes symptoms better
What 3 Factors may impact performance
- Rate of stomach emptying
- Rate of absorption
- Effect on water absorption
What affects rate of stomach emtyping
Fiber rich meal and fat content in meal
What affects rate of absorption
pure or high fructose feeding
