Carbohydrates Flashcards
what are monosaccharides?
one sugar carbohydrates
what are the 3 monosaccharides?
- glucose
- fructose
- galactose
what are disaccharides?
two sugar carbohydrates
what are the disaccharides?
- maltose = glucose + glucose
- sucrose = glucose + fructose
- lactose = glucose + galactose
what are olgiosaccharides?
short chains of monosaccharides that of 3-10 sugar units
dissacharides mainly make up which structure?
makes up part of plant cell walls
what are polysaccharides?
long chains and branches of monosaccharides
what are the 3 polysaccharides?
- starch
- fiber
- glycogen
what is starch?
the storage form of glucose in plants
what are the two different forms of starch?
- amylose = straight chains of starch
- amylopectin = branched chains of starch
what is fiber?
a non digestible food component - comes in the form of cellulose
what is glycogen?
the storage form of glucose in animals
what are the functions of carbohydrates?
- provides energy for the body
- regulates blood glucose
- protein sparing since glucose is the preferred fuel source
what is insulin?
a hormone that decreases blood glucose level by transporting glucose into the cell
what is glucagon?
a hormone that releases glucose into the bloodstream
what are steps in the action of insulin?
- insulin secretion
- cellular uptake of glucose by increasing the number of GLUT transporters
- glucose storage as glycogen
what are the steps in glucagon action?
- glucagon secretion from prancreas
- glycogenolysis - breakdown of stored glucagon into glucose
- gluconeogensis - forming glucose from other substances
what is glycogenolysis?
the process in which glucagon stimulates breakdown of glucagon into glucose in the liver, which is then released into the blood stream and transported to the cells for energy
what is gluconeogenesis?
the process in which glucagon stimulatates the conversion of glucogenic amino acids in the liver to glucose
insulin inhibits ____ which causes the body to store fat instead of breaking it down
lipolysis
what is lipolysis?
the breakdown of fat in the body
what happens when there is excess glucose in the body that cant be converted into gluccagon?
glucose are converted to fatty acids
what is lipogenesis?
formation of fatty acids
what is the role of epinephrine in maintaining BGL?
increases BG levels by stimulating glycogenolysis and gluconeogenesis in the liver
what is the role of norepinephrine in maintain BGLs?
increases BGLs by stimulating glycogenolysis and gluconeogenesis in the liver
what is the role of cortisol in maintaining BGLs?
stimulates gluconeogenesis which reduced glucose uptake which in turns increases BGLs
what is the role of growth hormones in maintaining BGLs?
converses glucose by stimulating fat breakdown (lipolysis) for energy
what is hyperglycemia?
elevated BGLs
what is hypoglycemia?
decreased BGLs
what is reactive hypoglycemia?
when BGLs decreases after a meal
what is fasting hypoglycemia?
BGL decrease due to not having anything to eat
what are the DRIs (RDA and AMDR) for carbohydrates?
- RDA: 130g CHO/day
- AMDR: 45-65% of total kcals
what are the intake recommendations for grains?
6 servings/day; half of grains should be whole grains
what are the intake recommendations for veggies?
3 servings/day
what are the intake recommendations for dairy?
3 servings/day
what are the intake recommendations for fruit?
2 servings/day
what is a whole grain?
grains abundant in complex carbohydrates, including starch and fiber
what is a phyochemical?
a component of a food that may have unknown health benefits
in terms of carbohydrate digestion what happens in the mouth?
- mechanical digestion of food using teeth
- salivary amylase is secreted
what is salivary amylase?
an enzyme that breaks down amylose and amylopectin
in terms of carbohydrate digestion, what occurs in the stomach?
chemical digestion occurs with the mixing of HCl
what are parietal cells?
cells that secrete HCl
what are goblet cells?
cells that secrete mucus to protect the stomach lining from HCl
in terms of carbohydrate digestion, what occurs in the small intestine?
- brush border enzymes are released
- pancrease releases pancreatic amylase
what is pancreatic amylase?
an enzyme that breaks down amylose and amylopectin
what is sucrase?
an enzyme that breaks down sucrose
what is lactase?
an enzyme that breaks down lactose
what is maltase?
an enzyme that breaks down maltose
________ bonds are easier to digest compared to ____ bonds which are harder to digest
alpha-glycosidic; beta-glycosidic
where are alpha-glycosidic bonds found?
sucrose and maltose
where are beta-glycosidic bonds found?
lactose and cellulose
what is a resistant starch?
a starch that is harder to digest; higher in amylose
- ____ and ____ are absorbed through active transport
- ____ is absorbed through facilitated diffusion
- glucose; galactose
- fructose
where does absorption occur in the small intestine?
enterocytes
describe the carbohydrate transport after absorption
- carbohydrate is transported to the liver via the portal vein
- galactose and fructose are used for energy or converted into glucose and released into the bloodstream
- glucose is then stored as glycogen via glycogenesis
- excess glucose is stored as fatty acids and glycerol in adipocytes
- metabolic needs direct the fate of monosaccharides
what are glycemic load and glycemic index?
the measure of effect of carbohydrate containing foods or meals on blood glucose levels
what is the difference between glycemic load and glycemic index?
- glycemic load takes carbohydrate quanity and preparation methods into account
- glycemic index is bases off of white bread
what is lactose intolerance?
the absense of lactase in the body which prevents lactose from being broken down
what happens as a result of lactose intolerance?
- undigested lactose pulls water through the GI tract - causes diarrhea
- lactose is digested by bacteria in large intestine which is then fermented - causes gas production
what is lignin?
a fiber/glue that holds cellulose together
what are the two classifications for fiber?
- insoluable fiber = fiber that doesn’t dissolve in water
- soluable fiber = fiber that does dissolve in water
what is functional fiber?
fiber that is manufactured by the food industry and included in products for health benefits
what are the dietary fiber recommendations (AI)?
- adult females <50 years: 25g/day
- adult males <50 years: 38g/day
- > 50 years: 21-30g/day
- ages 1-3: 19g/day
what is adquate fiber intake associated with?
- regular bowel movements
- increased satiety
- decreased risk of heart disease
- improved diabetes
- lower risk of cancer
what is constipation?
infrequent or difficult bowel movement; less than 3x/week
what is diverticulosis?
increased pressure in the colon causes weak spots along the wall forming pouches called diverticula
what is diverticulitis?
infection of diverticula.
how does soluable fiber reduce blood cholestrol levels?
- soluable fiber is a bile acid sequestrant
- bile acids contain cholesterol
- Soluable fiber prevents bile acids from being reabsorbed and instead causes it to be secreted through feces
how does soluable fiber help reduce BGLs?
viscous gel helps slow digestion and absorption of glucose
how does soluable fiber help decrease cancer risk?
viscous gel decreases the time in which cancer-promoting substances spend in contact with the GI tract
what are GI flora?
bacteria of the GI tract
what are the major strain of GI flora?
- firmicutes
- bacteroidetes
what is dysbiosis?
the imbalance of the body’s microbial composition
what are probiotics?
bacteria that are associated with health benefits
what are prebiotics?
non-digestible resistance starches that support the growth of gut bacteria populations
what is insulin resistance?
when the body doesn’t respond to insulin which results in higher levels of glucose in the blood
true or false: reduced diversity of gut microbiota is associated with an increase in metabolic disorders
true
this can be in the form of changes in weight, insulin resistance, etc.
what are the two most common added sugars?
sucrose and fructose
what is the connection between sugar and dental caries?
- sugar is a food source for the bacteria in the mouth
- acid is produce as a result of digestion of sugar from mouth bacteria
- this acid is associated with erosion of tooth enamel
what are the different sugar substitutes?
- polyols/sugar alcohols
- stevia
- aspartame
what are the charecteristics of polyols/sugar alcohols?
- fewer kcals than sucrose
- decreased impact on BG and risk of dental carries
what are some examples of polyols/sugar alcohols?
- xylitol
- mannitol
- sorbitol
what are the charecteristics of stevia?
- higher concentration of sweet flavor (250x sweeter than sugar)
- no kcals
- does not raise BG
what are the charecteristics of aspartame?
- made of amino acids phenylalanine and modified aspartic acid
- provides 4 kcals/g
- 200x sweeter than sugar
- not appropriate for phenylketonuria (PKU)
what is phenylketonuria (PKU)?
a genetic disorder in which the body is not able to break down the amino acid phenylalanine
what is gastroesophageal reflux disease (GERD)?
inadquate/improper closing of the the lower esophageal sphincter causing stomach acid to flow back into the esophagus
what is belching/burping?
expelling air from the stomach
what is aerophagia?
swallowing air
what is gastroenteritis?
infection and inflammation of the stomach due to bacteria/virus
what are some symptoms of gastroenteritis?
- nausea
- vomiting
- diarrhea
- cramping
what are ulcers
formation of sores/erosion of the stomach lining or duodenum
what causes ulcers?
a bacteria called heliobacter pylori (H.pylori)
what is gallbladder disease?
a group of conditions that can affect the gallbladder
what is celiac disease?
an autoimmune disease that results in flattened villi and malabsorption
what is diarrhea?
condition involving loose watery stools more than 3x a day
what is the pathophysiology behind diarrhea?
the enterocytes become inflammed and instead of absorbing fluid they secrete fluid
what is inflammatory bowel disease?
inflammation of the GI tract; includes ulcerative colitis (large intestine) and crohns disease (entire GI tract)
what is diabetes mellitus?
inadequate regulation of blood glucose
describe the different types of diabetes?
- type 1 diabetes = the pancrease stops producing insulin
- type 2 diabetes = insulin resistance
- gestational diabetes = insulin resistance in pregnancy
what is the normal range for fasting BG?
<100 mg/dL
what is the prediabetic range for fasting BG?
100-125 mg/dL
what is the diabetic range for fasting BG?
> 126 mg/dL
what is the normal range for BG?
70-110 mg/dL
