Module 4 - Carbohydrates Flashcards
What chemicals make up carbohydrates?
Carbon, hydrogen and oxygen, arranged as a monosaccharide
Name at 3 least sources of carbohydrates (when in natural unrefined state)
whole grain breads, fruit, beans, lentils, vegetables
What are the 3 ways to classify Carbohydrates?
- degree of processing
- chemical composition
- physiological effect on blood glucose
What is Refining?
the processing of carbohydrates that alters nutrient density (separates carbohydrates from vitamins, minerals and fibre)
What is Whole Grain made up of?
Germ (innermost), Endosperm (middle), Bran (outside)
What parts of the grain is taken out during refining process?
Germ and Bran, this prolongs shelf life
What part of the grain makes up most refined grains?
Endosperm
Simple carbohydrates, or sugars (milk, table sugar, fruits), refer to…
monosaccharides and disaccharides
Complex carbohydrates (starches, glycogen, dietary fibre) refer to…
oligosaccharides and polysaccharides
How many monosaccharides in an oligosaccharide?
3-10
How many monosaccharides in a polysaccharide?
more than 10
Name the 3 monosaccharides
Glucose,
Fructose, Galactose
What is the chemical structure of a monosaccharide?
Hexose, 6 carbon sugar
The different structure of each monosaccharide accounts for difference in ___
sweetness
Arrange the monosaccharides in terms of sweetness: Glucose, Fructose, Galactose
Fructose > glucose > galactose
What is the most and least common of the 3 monosaccharides?
Most: Glucose
Least: Galactose
What is the primary form of carbohydrates in the body and main component of all polysaccharides?
Glucose
Blood glucose level is regulated by the hormonal secretion of __ and __ from the __
insulin and glucagon from the pancreas
Monosaccharides are absorbed by the microvilli in the small intestine and actively transported to the capillary which carries it to __
the liver
The liver converts galactose and fructose to ___
glucose
How is glucose transported to all body cells?
via blood
What is the primary source for nervous tissue (brain, spine)?
glucose
The brain uses __% of glucose required by the body
> 70%
What is a disaccharide?
two monosaccharides linked through condensation
Explain condensation
OH group from one monosaccharide and H atom from another monosaccharide combine to form H20, which leaves the compound, then the two monosaccharides bond together with a single O atom to form a disaccharide
Explain hydrolysis
H20 is added to a compound, H goes to one part, OH goes to another and this splits the compound
Glucose + Glucose =
Maltose
Glucose + Fructose =
Sucrose
Glucose + Galactose =
Lactose
Maltose is formed upon the breakdown of ___
Starch
When does lactose intolerance happen?
Not enough of enzyme lactase is present in the small intestine to break down lactose
Naturally occurring sugar is…
sugar found naturally in whole foods
Free sugar or added sugar…
sugar no longer in its naturally occurring state
Total Sugar =
naturally occurring sugar + free sugar
What are Nutritive Sugars?
sugars that contribute energy to foods (4 kcal/gram)
What is the DRI in % for added sugars?
≤ 25% total energy from added sugars
How are dental caries(cavities) formed?
when bacteria that live in the mouth form colonies on teeth, the bacteria metabolizes carbohydrates and creates acid which dissolves teeth enamel (cavities)
What is the relation between sugar and dental caries (cavities)?
The longer sugar stays in your mouth, the higher the chance of cavity
What are “Non-Nutritive Sugars” (NNS)?
Sweeteners without nutrient value (0 or almost 0 calories)
Are “Non-Nutritive Sugars” sweeter than sugar?
Yes, can be over 10,000x stronger
Complex Carbohydrates (oligosaccharides and polysaccharides) are sugars: true or false?
False, but they are made of sugars combined through condensation
Are oligosaccharides digested by human enzymes?
No
Give 3 examples of oligosaccharides
Beans, onions, bananas, garlic, artichokes
Indigestible carbohydrates include…
some oligosaccharides, fibre, resistant starch
What is an insoluble fibre (non-viscous)?
does not dissolve in water, from plant cell walls (broccoli)
What is a soluble fibre (viscous)?
dissolves in water to form gel, small amounts are digested by bacteria in large intestine
Most foods of plant origin are a mix of insoluble and soluble fibre: true or false?
TRUE
What is the key difference in structure which differentiates insoluble and soluble fibre?
Insoluble fibre are formed by (β 1-4) links, which humans can not break down, while soluble fibre (starch) are formed through (α 1-4) links
Name one example of an insoluble fibre
cellulose, lignin
Does insoluble fibre increase or decrease transit time through intestine?
Decrease, the matter moves quicker through the intestine, reduces constipation
Soluble fibre serves as a food for ___ in colon
Microflora
Does soluble fibre increase or decrease transit time through intestine?
Increase, matter moves slower through intestine, because it makes gel with water, delays gastric emptying
Which increases the absorption of nutrients and why: soluble fibre or insoluble fibre?
Soluble fibre, it increases transit time and makes food stay in small intestine for longer, increases volume of intestinal contents by absorbing water, increasing absorption
What is the effect of soluble fibre on the stomach? remember it increases volume intestinal contents
causes stomach distension (balooning) and slows emptying
Slow absorption of glucose, (increases or decreases?) glucose fluctuation after a meal
decreases
What is the effect of increased soluble fibre on cholesterol?
Cholesterol is excreted as it is binded to soluble fibre, so cholesterol levels in body is lower
Fiber can cause intestinal gas: true or false
True, specifically insoluble fibre is more likely to
What is Starch?
a primary source of food energy composed of many glucose molecules (*less branched)
What are the two types of starches?
Amylose: continuous single chain of glucose
Amylopectin: branched chains of glucose molecules
Give at least one example of a starch
potato, sweet potato, beets
What is a resistant starch?
starches that do not break down into glucose when digested
Give at least one example of a resistant starch
rice or potatoes that have been cooked and then cooled, unripe bananas
What is Glycogen?
storage form of carbohydrates composed of many glucose molecules (*highly branched)
is glycogen subject to fast or slow hydrolysis?
fast, due to highly branched shape, release quick supply of energy
What are some places where glycogen are stored?
Muscle (provides glucose for energy), Liver (releases glucose into bloodstream for delivery to body cells)
The body stores a lot of glycogen: true or false?
FALSE, only (200-500g)
Glycogen holds ___ which causes bulk
Limited amount of water
Since glycogen is for short term energy, where does long term energy come from?
Fat in adipose tissue, not bulky
When liver glycogen is depleted, what happens?
Body produces glucose via gluconeogenesis and blood glucose falls stimulating appetite
Where does most of carbohydrate, starch, digestion occur?
small intestine, can not occur in stomach as salivary amylase is inactivated by acid
What accesory organ aids in the digestion of carbohydrates in the small intestine?
Pancreas, through the release of pancreatic amylase which breaks down starch
How are the digestion of carbohydrates completed?
by the brush border enzymes on the villi, break down disaccharides and oligosaccharides into monosaccharides
In the large intestine, what happens to remaining insoluble carbohydrates (insoluble fibre, resistant starch, some oligosaccharides)
they are broken down by bacteria to form short chain fatty acids and gas, some fibre is excreted
What is the key for a healthy microflora, and helps maintenance of beneficial species of bacteria in colon?
prebiotics, soluble fibres, resistant starch are present and reach the colon
Define Glycemic Response
how quickly and how high blood glucose rises after carbohydrates are consumed
Define Glycemic Index (GI)
ranking of how a food affects the glycemic response (1-100) relative to white bread/pure glucose
What is considered a high Glycemic Index (GI)?
> 70 GI
What is considered a low Glycemic Index (GI)
<55 GI
In low Glycemic Index foods, aborption of glucose is __
Slower
Glycemic Load =
(Glycemic Index) * (amount of available CHO)
What is considered a high Glycemic Load?
> 20
What is considered a low Glycemic Load?
<11
What cells release insulin?
beta-cells
What cells release glucagon?
alpha-cells
What is the function of Insulin?
stimulates glucose uptake into most cells in the body and stops glucose release from the liver
What is the function of Glucagon?
promotes breakdown of glycogen that releases glucose into circulation
When there is increased blood glucose, what hormone is released by the pancreas to regulate blood glucose?
insulin, it transfers glucose from blood to body cells
When blood glucose is decreased, what hormone is released by pancreas to control blood glucose?
glucagon, it breaks down glycogen in liver into glucose which is released into blood
Where do monosaccharides get transported after being absorbed?
Liver, to be stored as glycogen and transported through body
What is the name of the cluster of cells in the pancreas which produce glucagon and insulin?
Islets of Langerhans (contain alpha cells and beta cells)
What is Gluconeogenesis?
When glucagon is sent to stimulate kidney and liver cells to produce glucose from certain amino acids
When glycogen stores reach max capacity, liver can convert excess glucose into…?
Fat
What is Diabetes Mellitus
Group of metabolic disorders caused by improper function of insulin
What % of the population have Diabetes Mellitus
10%, 25% over the age of 65
In Diabetes, is blood sugar high or low?
High (the insulin is unable/has diffuclty in taking glucose into cells)
In which type of diabetes does the body provide normal amounts of insulin, but the glucose transporters in the cell don’t move to the membrane?
Type 2 (insulin resistance)
What are 3 risk factors for insulin resistance?
Obesity, lack of exercise, hypertension
What are the four main symptoms of diabetes and/or hyperglycemia?
Polyphagia (a lot of eating)
Glycosuria (glucose in urine)
Polyuria (a lot of urine)
Polydipsia (a lot of thirst)
In what type of diabetes does the pancreas stop making insulin?
Type 1
What is Gestational Diabetes?
diabetes that occurs due to pregnancy
What is Drug-Induced Diabetes?
diabetes that occurs due to side effects of medication
What is treatment for Type 1 Diabetes?
Insulin
What is treatment for Type 2 Diabetes?
weight loss, exercise, healthy diet, Antidiabetic Medications
What is an example of antidiabetic medication for type 2 diabetes?
Metformin
