Module 4: Carbohydrates Flashcards
what are the functions of carbohydrates
supply energy or calories
how many kcal/gram do carbohydrates provide
4 kcal/gram
what is the AMDR for carbohydrates
45-65% of total daily calories
how are carbohydrates produced
photosynthesis in plants
what are the 3 elements in carbohydrates
- carbon
- hydrogen
- oxygen
define simple carbohydrates
less than 10 monosaccharide units
define complex carbohydrates
more than 10 monosaccharide units
define monosaccharides
single sugar molecules used to assemble all carbohydrates
what are the 3 monosaccharides
- glucose
- fructose
- galactose
what is the chemical composition for glucose, fructose, and galactose
all C6H12O6
what makes glucose, fructose, and galactose different
different spatial arrangements of C6H12O6
what is the most common form of monosaccharide
glucose
what two foods can you find fructose in abundant amounts
- fruits
- honey
how would you distinguish between the structure of glucose, fructose, and galactose
- glucose: 1C outside ring, H over OH on left side
- fructose: 2C outside ring
- galactose: 1C outside ring, OH over H on left side
components of the disaccharide sucrose
- glucose
- fructose
components of the disaccharide maltose
- glucose
- glucose
components of the disaccharide lactose
- glucose
- galactose
what are the two categories of sweetners
- nonnutritive: provide no calories
- nutritive: provide calories
examples of non-nutritive sweeteners
- aspartame
- acesulfame-K
- saccharin
- sucralose
examples of nutritive sweeteners
- sucrose
- fructose
- honey
- molasses
- high fructose corn syrup
what is the composition of high fructose corn syrup
- 55% fructose
- 45% glucose
what is honey composed of
- fructose
- glucose
why is honey not recommended for infants
it may contain clostridium botulinum
examples of polysaccharides
- starch
- glycogen
define starch
- storage form of carbohydrates found in plants
- generally either long and straight chains or branched chains
define glycogen
- storage form of carbohydrates found in the liver and muscles of animals
- more branches than starch
define dietary fiber
- composed of repeating units of glucose and other monosaccharides
- cannot be digested by human enzymes
what is the RDA for carbohydrates
130 g/day
sources of complex carbohydrates
- whole grains
- vegetables
- fruit
- legumes
- nuts and seeds
what are whole grains
- contain all components of the grain kernel
- endosperm, bran, and germ
what are the components of the endosperm, bran, and germ in wheat kernels
- endosperm: carbohydrates
- bran: fiber, B vitamins
- germ: minerals, fat soluble vitamins
define refined grains
- germ and bran removed
- only contains endosperm (carbohydrate part)
describe the energy gained from simple carbohydrates
- easily digested and absorbed creating a quick energy source
- quick spurt of high energy followed quickly by drop in energy
describe the energy gained from complex carbohydrates
- slowly digested and absorbed creating a sustained level of energy
- slow climb to energy point that plateaus for a period of time before slowly drifting off
why do you need to consume a sufficient amount of carbohydrates
so proteins and amino acids can be spared for growth and repair
what happens if you don’t consume enough carbohydrates
body begins to use protein as a source of energy
what are 2 amino acids that are used for energy
- aspartate
- alanine
defien gluconeogenesis
synthesis of new glucose from non-carbohydrate sources
where does gluconeogenesis occur
liver
what cells make insulin
beta cells in pancreas
what cells make glucagon
alpha cells in pancreas
what hormone drives glycolysis
insulin
what hormone drives gluconeogenesis
glucagon
does insulin increase or decrease glucose levels
decrease
does glucagon increase or decrease glucose levels
increase
what are fats, carbs, and proteins converted to which eventually gets broken down for energy
acetyl CoA
describe acetyl CoA
- universal energy substrate
- 2 carbon molecule
define oxaloacetate
- chemical derived from carbohydrates and certain amino acids
- needed to fully break down fats
how are ketones created
created by breakdown of fats when glucose levels are low
can the body convert fat to glucose
- no
- converts to ketones
what does the brain use for energy
- glucose
- ketones
define ketosis
- elevated ketones in the blood
- doesn’t require medical intervention
define ketoacidosis
- extremely elevated ketones in the blood
- requires medical intervention
what are normal blood glucose levels
70-100 mg/dL
why is insulin injected into the body
- insulin is protein hormone (made of proteins)
- will be denatured in the stomach if swallowed
what happens if we have extra glucose in the body
- stored as glycogen in the liver and muscles
- stored as fat
what happens when glucagon is released
- glycogen is broken down for glucose
- triggers gluconeogenesis
describe how insulin helps cells intake glucose
- insulin is secreted from pancreas into bloodstream
- binds to receptors on cells
- causes reactions inside of the cell
- golgi apparatus sends glucose transport protein to the surface of the cell
what tissues respond to insulin
- skeletal muscle
- adipose tissue (fat)
define glycemic index
- measure of how fast blood glucose levels rise after ingestion
- for a single food eaten alone
define glycemic load
- mathematical score that adjusts glycemic index for total carbohydrates in mixture
- for multiple foods eaten together
define diabetes mellitus
inability of the body to regulate blood glucose levels within normal limits
define hyperglycemia
elevated blood glucose
what are the 3 categories of diabetes
- type 1
- type 2
- gestational
define prediabetes
- struggling to bring glucose levels down
- can progress to diabetes if left untreated
describe type 1 diabetes
- often diagnosed in children or adolescents
- pancreas is unable to produce insulin
- autoimmune
describe type 2 diabetes
- over 90% of all cases of diabetes
- cells are insulin resistant (make insulin but it isn’t working properly)
- typically those over 40 and overweight/obese
is type 2 diabetes permanent
not always
who is having an increased number of type 2 diabetes diagnoses
young people
what are risk factors for type 2 diabetes
- overweight or obese
- older age
- family history
- previous gestational diabetes
- physical inactivity
- PCOS
- acanthosis nigricans
why is puberty beginning at younger ages
- obesity in younger children is increasing
- sex hormones are produced in fat cells
define acanthosis nigricans
dark patches around folds of skin
what are complications of diabetes
- water loss as kidneys try to eliminate excess glucose
- increase risk for coronary heart disease
- kidney disease
- high blood pressure
- damage to eyes and blood vessels
- damage to nervous system
define gestational diabetes
- occurs in some women during pregnancy
- resolved after pregnancy
what are the two hormones that contribute to gestational diabetes
- cortisol
- human placental lactogen hormone
complications of gestational diabetes for infants
- infant illness or death
- high birth weight
- low blood glucose post-delivery
- diagnosis of type 2 diabetes later in life
complications of gestational diabetes for mother
greater likelihood of developing diabetes within 5 to 10 years
what ethnicities have a higher susceptibility to gestational diabetes
- hispanics
- native americans
describe dietary fiber
- indigestible
- associated with prevention of several chronic diseases
- mostly comprised of polysaccharides
what are the 2 types of dietary fiber
- soluble
- insoluble
describe soluble fiber
- dissolves in water
- jellylike material that acts like a cement in plants
what are the health benefits of soluble fiber
- binds to bile in intestine lowering digestion and absorption of fats
- lowers blood cholesterol
- reduces risk of heart disease
dietary sources of soluble fiber
- fruit
- legumes
- oat bran
- potatoes
- peas
describe insoluble fiber
- cannot be dissolved in water
- composed of cellulose, hemicellulose, and lignin
what are the health benefits of insoluble fiber
- soften stool
- decrease transit time
dietary sources of insoluble fiber
- cereals
- whole grains
- wheat bran
- legumes
- brown rice
health benefits of dietary fiber
- reduces constipation, hemorrhoids, and diverticulosis
- reduces risk of colon cancer
- weight control
- reduces risk of heart disease
- improves blood glucose control
how does fiber reduce the risk of colon cancer
- enterocytes typically live for 3-5 days
- fiber can encourage them to be eliminated when they’re ready so they don’t stick around and become cancerous
what are the complications with overconsumption of fiber
- decreased absorption of calcium, zinc, copper, and iron
- increased number of bowel movements (diarrhea and dehydration)
what are the most widely consumed grain in the US
- wheat
- rye
- barley
what do grains provide
- fiber from the bran
- calories from the endosperm
- protein from throughout
- micronutrients from the germ and the brain
why do some people have an intolerance to the protein gluten
underproduction or lack of the protein that breaks down gluten
what two protein compose gluten
- gliadin
- glutenin
define celiac disease
intolerance to gluten that results in autoimmune response
what foods cause a response to gluten in people with celiac disease
- wheat
- barley
- rye
- oats
what are the complications of celiac disease
- flattens inside of intestinal wall
- reduces ability to absorb some nutrients
what is the treatment for celiac disease
eliminate sources of fluten form the diet
describe how sugar can lead to dental decay
- carbs can adhere to tooth enamel
- bacteria metabolize carbs in the mouth
- lactic acid produced by bacterial fermentation degrades tooth enamel
how do low carb diets promote weight loss
- forces fat to be metabolized for energy, producing ketones
- muscle glycogen also broken down to glucose and releases water
what are risks associated with low carb diets
- heart disease if the diet is high in saturated fats
- bas breath from ketones
- constipation due to low fiber intake
- dehydration from induced water loss
- difficult to maintain long-term
how many types of ketones do we produce
3
how many types of ketones are used by the body for fuel
2
which ketone is exhaled almost immediately after production
acetone
describe lactose intolerance
- unable to digest lactose from lack of lactase enzyme
- bacteria in colon metabolize lactose producing gas
how can you still get dairy with lactose intolerance
- smaller portions at one time
- lactose-free milk
- yogurt
- lactase pills
