Carbohydrate Nutrition Flashcards
what are the three macronutrients
carbohydrates
lipids
proteins
what is the nature of carbohydrates
composed of carbon, hydrogen, oxygen
what is the CHO formula
(H2O)n
glucose = C6H12O6
what are the three classifications of cho
monosaccharides
oligosaccharides
polysaccharides
what are monosaccharides
basic unit of carbohydrates
glucose
fructose (converted to glucose in liver)
galactose (converted to glucose in liver)
what are oligosaccharides
2-10 monosaccharides bonded chemically (disaccharides)
maltose=glucose+glucose
lactose= glucose+galactose
sucrose = glucose+fructose
what are polysaccharides
3-thousands of sugar molecule linkages
starch
fiber=cellulose
glycogen
what is starch
storage form in plants
amylose-long and straight
amylopectin-branched
what are the two different types of fiber
soluble and insoluble
what is glycogen
storage form of polysaccharides in mammalian muscle (branched)
what are soluble fiber
attracts water and turns to gel during digestion. this slows digestion
where is soluble fiber found
oat bran barley nuts seeds beans lentils peas and some fruits and vegetables (help lower risk of heart disease)
what is insoluble fiber
it adds bulk to the stool and spears to help food pass more quickly through the stomach and intestines
where is insoluble fiber found
wheat bran vegetables and whole grains
what is the daily recommended intake of fiber under 50 years of age
over 50 years
38g for men
25g for women
30g for men
21g for women
what is the ratio for water insoluble to soluble fiber
3:1 (water soluble =3)
where are carbs stored
liver glycogen (100g) plasma glycogen (3g) muscle glycogen (400g)
where are fats stored
adipose tissue (12,000g) intrmuscular tricylglycerols (300g) plasma FFA (0.4g) plasma triacylglycerols (4g)
what is glycogen
storage carbohydrate in muscle and liver
how much glycogen does the body store
how much of that does muscle store
how much of that does liver store
2000kcal
400g
90-100g
what is glucogenesis
glycogen synthesis
what are the steps of glucogenesis
1) start with glucose. ATP is needed to convert glucose into G-6-P
2) G-6P is enzymatically converted into G-1-P
3) G-1-P is enzymatically converted into (UDP)-glucose
4) (UDP)glucose attaches to one end of an existing glycogen polymer chain. UDP is then released
what is
glucogenesis
gluconeogenesis
glycogenolysis
glucogenesis = glycogen synthesis from glucose
(glucose to glycogen)
gluconeogenesis (glucose synthesis largely from structural components of noncarbohydrate nutrients
(protein to glucose)
glycogenolysis = glucose formation from glycogen
(glycogen to glucose)
what are the four roles of carbohydrates in the body
energy source (during high intensity exercise)
protein sparer
glycogen depletion triggers glucose synthesis from amino acids
metabolic primer
CHO catabolism serves as a primer substrate for fat oxidation
fuel for the CNS
nerve cells and red blood cells use glucose for fuel
excretion of urea in sweat is a measure of
protein breakdown because the bosy is converting proteins into CHO substrates
when is most urea seen
in carbohydrate depleted state
what are the 5 sources of carbohydrate metabolism
muscle glycogen glucose liver glycogen lactate CHO ingestion
what affects the use of carbohydrate substrates during exercise
exercise intensity
exercise duration
fed state
trained state
how does exercise intensity affect the use of carbohydrate substrates during exercise
muscle glycogen in the major substrate used at exercise intensities greater then 50-60% vo2max followed by blood glucose derived from liver glycogen
how does exercise duration affect the use of carbohydrate substrates during exercise
as duration increases, glycogen stored deplete and reduced blood glucose. reduced blood glucose and glycogen stores are associated with fatigue
how does fed state affect the use of carbohydrate substrates during exercise
increased carbohydrate intake increases the contribution of glucose to substrate oxidation but this result is due to lower fat oxidation
does starvation appear to impact carbohydrate substrate use during moderate intensity exercise
does not appear
does there appear to be an impact on muscle glycogen use in fasted for carbohydrate fed state
no impact
how does the trained state affect the use of carbohydrate substrates during exercise
endurance exercise training typically enhances carbohydrate oxidation due in large part to enhanced citric acid cycle and ETC activity
what are the three hormonal regulation of glycogen
insulin
glucagon
epinephrine
describe insulin
secreted by beta cells of pancreas
facilitates uptake of glucose into cells
feedback to inhibit further insulin secretion
describe glucagon
secreted by alpha cell of pancreases
facilitates glycogenolysis and gluconeogenesis
acts to normalize low blood sugar
describe epinephrine and the hormonal regulation of glycogen
similar to glucagon, stimulates glycogenolysis in the liver, resulting in the raising of the level of blood glucose
glucose transporter and regulate the movement of glucose into muscle
1 and 4
exercise induced muscle contraction stimulates glut4 translocation and increases glucose transport via an
insulin independent pathway in both normal and insulin resistant condition
depletion of intracellular glycogen stores increases
insulin sensitivity upto 48hrs post exercise
plasma glucose use during cycling ____ over time as glycogen is depleted
increases
as exercise intensity increases the rate of ____
glycogenolysis increases
the regulation of glycogenolysis is extremely sensitive to what
the rate of ATP use of skeletal muscle during exercise
carbohydrate loading depletion influences the regulation of
blood glucose and plasma free fatty acids
what are the daily recommendation of carbohydrates
sedentary 70kg person
- 300g or 40-50% of total calories
physically active person
- 400-600g or 60% of total calories
athlete
- 70% of total calories (8-10g per kg of body mass)
muscle glycogen loading delays what
the onset of fatigue
what are sex differences in CHO loading
total glycogen concentration was higher for the men on the CHO and CHO + E trials compared with Hab, whereas women increased only on the CHO + E trial compared with Hab
