Chapter 4 Carbs Flashcards
What is the monomer of carbohydrates? What are the 3 6C sugars? What are the 2 5C sugars? What structure do they have and what chemical formula? What form must they be in to be absorbed?
- monosacharides
- 4 simple sugars: glucose, fructose, galactose (hexose sugars, 6C), pentose (deoxyribose & ribose, 5C)
- they are all isomers of each other: same structure but rearranged (all have chemical formula C6H12O2)
- C:H:O 1:2:1 ratio
- to absorb sugar, must be in monosach form
“ose”
sugar
What are the 3 kinds of disaccharides? What kind of bond are they held together by? What kind of reaction takes place?
- 2 monosach joined together by covalent bond (glycosidic bonds)
- dehydration synthesis, anabolic
- table sugar = sucrose (G+F)
- milk = lactose (G+Gal)
- malt sugar = maltose (G+G)
Polysaccharides are ___ of monosaccharides. Is it a complex or simple sugar? They release quickly or slowly? In order to be absorbed, they must be ____. What is the most abundant polysach? What is its functions? (2)
- polymers of monosaccharides
- slow-releasing or complex sugar
- needs to be broken down to absorb
- glycogen the most abundant polysach (bunch of glucose)
- gives energy
- some for structural components, not for energy
important polysaccharides in humans (3)
- starches: plant version of glycogen (ex. potatoes, wheat, corn)
- fibers
- glycogen: animal storage of sugars
Soluble (6)
Insoluble Fibers (7)
Excess fiber results in ___ (3). It is a ___ that binds to metal so that it ___.
Soluble
- viscous fiber
- thick/paste consistency
- goes through bacterial fermentation (different word for digestion)
- helps slow down digestion & absorption of glucose (-> no spike in blood glucose levels)
- satiety (feeling of fullness) increased -> helps with losing weight
ex. oats, apples, strawberries
Insoluble
-pushes/paves way to get rid of it. picks up things along the way
-alleviates constipation
-lowers risk of hemorrhoids, appendicitis (feces move into appendix)
-cellulose (plant fiber): humans cannot digest cellulose but is important for cleaning the digestive tract
-nonviscous
-does not mix well with water so maintains shape
Ex. corn, whole grain, vegetables
Excess fiber
- diarrhea, dehydration, malnutrition
- a chelating agent: anything that binds to metal. too much fiber attaches to nutrient metals and cannot be absorbed
Adequate intake levels for total fiber
21g/day for women 50+
25g for women <50
30g for men 50+
38g for men <50
What are the byproducts of gut bacteria/microflora that we do and don’t want? _____ protects the large intestine.
- gas
- byproduct dont want - short-chain fatty acid: provide nutrients/energy to bacteria in large intestine
- anti-inflammatory protects large intestine
- byproduct we want
What is bile? What does it do? How is fiber associated with it? Where is it produced? Where is it stored? How does it move into the SI? What health effect does it have?
- fat that helps breakdown fat in small intestine
- soluble fiber helps bind to bile and eliminate out of GI tract
- produced by liver, stored in gallbladder
- movement by bile duct into SI
- elimination of excess fat (bile) out of body prevents heart disease
Table: Viscous/soluble fiber examples (5) Actions (5) health benefits (3)
Ex. beta glucans, gums, inulin, pectin, psyllium
Actions:
- bind bile to cholesterol
- slows glucose absorptions
- delays nutrient absorption
- nourish bacteria in colon (energy)
- increases satiety
Health Benefits
- alleviate constipation
- lowers risk of heart disease, diabetes, colorectal cancer
- weight management
Non-viscous/insoluble fiber Examples (4) Actions (3) Health benefits (3)
-cellulose, lignins, resistant starch, hemicellulose
Actions:
- increases fecal weight
- speeds up fecal passage
- increases satiety
Health benefits:
- alleviate constipation
- lowers risk of appendicitis and hemorrhoids
- lowers risk of colorectal cancer
Process of digestion and absorption of carbs (5). What is special about fiber digestion?
- starch digestion begins in the mouth: salivory amylase splits into shorter units
- moves down the esophagus (no digestion), enter stomach (no digestion here)
- chyme enters SI where digestion resumes: pancreatic amylase
- absorption into the bloodstream through primary active transport
- enters hepatic portal system and taken to the liver
fiber goes through SI untouched and goes to the colon
Why is active transportation needed for the transportation of monosaccharides? What is its process (5)
- because not fat
- primary active transport on basal surface, secondary on apical surface
- Na pumped out from cell into blood. K pumped into cell
- secondary transport recognizes drop in Na and allows Na to move through cell membrane (hi to low concentration)
- brings friends (glucose)
- once glucose goes into cell, released into the blood
Glucose regulation: what cells of which organ release insulin and glucagon? Are they catabolic or anabolic hormones? What is the value of homeostasis?
- beta cells of pancreas releases insulin (anabolic hormone to synthesize glycogen)
- alpha cells release glucagon (catabolic hormone to break down glycogen)
-homeostasis around 80-100mg/dl (below 80 release glucagon, above 80 release insulin)
What is the first thing made when having excess glucose? Which two organs make, break, and store glycogen (while using some as energy)? Which organ system uses all the glycogen?
- glucose used to make fat but the first thing made is glycogen
- liver and skeletal muscle makes, break down, and store glycogen (uses some energy)
- skeletal muscle uses all the glycogen
Glucose is a source of what cellular process?It is converted into what? How much energy do we need?
- cellular respiration
- convert glucose into ATP
- need energy 24/7, even when asleep
well fed state (finished eating) process (6)
- Blood glucose (and everything else from food) levels go up
- beta cells recognize increase in blood sugar and secrets insulin
- insulin levels goes up as released from pancreas
- insulin turns on phosphatase (dephosphorylation - takes phosphate off other structures)
- phosphatase turns on glycogen synthase by removing a phosphatase
- phosphatase turns off glycogen phosphorylase by removing phosphate
fasting state (6)
- blood glucose levels & insulin levels drop
- alpha cells in pancreas senses drop in glucose and release glucagon
- glucagon levels increase
- glucagon turns on kinase (phosphorylates - attached phosphate)
- kinase phosphorylates glycogen phosphorylase and turns it on
- kinase phosphorylates glycogen synthase and turns it off
What is glycemic index? What is it also called? What has high glycemic indexes? This is an example of ____. What is it called with regards to people with diabetes?
- measures degree of elevation of blood glucose and insulin (how fast blood glucose levels rise)
- “food score”
- high in simple sugars (mono, disach) that are rapidly metabolized
- metabolism affects body’s insulin response
- important for diabetics: glycemic load (lower GL less glucose build up and less insulin needed) - same thing as glycemic index
5 functions of carbs
- energy production - glycolysis breakdown of glucose to provide ATP. glucose the preferred form of energy
- energy storage - first, glycogen & second, fat
- building macromolecules - DNA, RNA, fat
- production of proteins
- assist in lipid metabolism - sparing fat
What is the first step after consuming glucose? What happens to fat in the blood? What is liver’s role? Is glycogen stored in fat tissue?
- most used as energy (esp in skeletal muscle)
- fat circulates blood and stored as fat
- liver uses some glucose, make glycogen and triglycerides
- v little glycogen stored in fat tissue
Do added sugars cause obesity? When is glucose made into fat? What is the trend in America for obesity? What are top calorie sources? (2)
- added sugar causes obesity (also type 2 diabetes)
- uses up glycogen storage then converted into fat
- americans have grown fatter in past decades
- top calorie sources: sugary desserts & beverages (liquid calories - soda & coffee)
What is high fructose corn syrup made of? How are they made? How does it alter our biochemical processes? (2) What disease is asoociated with HFCS?
- is made of fructose
- affects appetite differently: makes it taste sweet
- corn starch converted into glucose & fructose and then glucose converted into more fructose
- handled differently in body: fructose sent straight to make fat, not energy like glucose. Blood lipids stimulates body fat-making pathway. then liver can only make so many triglycerides at a time. so starts storing fat in the liver
- nonalcoholic fatty liver disease (NAFLD) - AFLD also formation of fat. liver does not know where protein needed, etc body doesn’t function
What are the dietary guidelines for Americans on whole-grain consumption? (2)
Dietary Guidelines for Americans recommendation:
- at least half daily grains should be whole
- DRI min of digestible carbs: 130g/day
