Chapter 3- Carbohydrates Flashcards
What is a simple carb?
Small compounds comprised of either one or two sugar molecules
What is a complex carbohydrate?
larger compounds that contain more than three sugar molecules joined together
How many sugar molecules are in oligosaccharides?
3-10 monosaccharides
How many sugar molecules are in polysaccharides?
More than 10 monosaccharides
What are monosaccharides?
The simplest unit of a carbohydrate
What are the 3 most common monosaccharides in the diet?
glucose, fructose, and galactose
What is glucose?
the form of fuel brain function depends on
Galactose
Not usually found alone in foods; typically binds to lactose to form a disaccharide
Do the 3 monosaccharides have the same general structure?
Yes, but structure is slightly different which changes sweetness
What are the 3 types of disaccharides?
sucrose, lactose, and maltose
Sucrose
compound of one glucose and one fructose
Lactose
Compound of one glucose and one galactose
Maltose
compound of two glucose molecules, a by-product of the breakdown of larger carb compounds like starch
Examples of oligosaccharides
beans, legumes, cruciferous vegetables, whole grains, sports drinks
Examples of polysaccharides
starch, fiber, glycogen
what are high-quality complex carbs?
minimally or not at all processed; made of whole grains; contains all nutrients and fiber that nature intended (whole grain rice, seed bread)
What are low-quality complex carbs?
extensively processed; some components of the whole grain removed or added back; much less fiber and fewer naturally occurring vitamins and minerals than high-quality carbohydrates (white rice, wonder white bread)
Starch
primary polysaccharide; simple chains of glucose molecules, bound by alpha bonds
Can you break down alpha bonds with digestive enzymes?
Yes
What is amylose?
common form of starch; straight chain of glucose and amylopectin, salivary amylase in saliva starts breaking it down by breaking the alpha bonds
Fiber
polysaccharide that contains beta bonds that cannot be broken by human enzymes, not digested, absorbed, or metabolized in the body; soluble or insoluble
What are soluble fibers?
dissolvable in water; gel-like consistency when wet; digested by gut bacteria; fermentable; found in and around plant tissue cells
Common sources of soluble fibers
citrus fruits, berries, oats, beans
What are insoluble fibers?
the structural component of plant cell walls; not dissolvable in water; usually not fermentable
Common insoluble fibers
outside portion of the corn, outer husks of whole grains, fruits, vegetables, legumes
What is glycogen?
polysaccharide, storage form of glucose, similar to starch, but much more highly branched and has a greater surface area for enzymatic action
What are the 2 places we store glycogen in the body?
3/4 is stored in the muscles, 1/4 is stored in the liver
Where does digestion occur for carbohydrates?
digestion begins in the mouth, but majority happens in small intestine, all chemical digestion stops when it gets to the stomach because acid deactivates enzymes but mechanical digestion still occurs
What are the steps of breakdown of carbs?
breakdown carbs into individual monosaccharides in small intestine, which move into bloodstream via capillaries, transported to the liver, in the liver, fructose and galactose get converted into glucose
What are the options for metabolic needs of glucose?
- Turned into ATP if needed for energy
- Converted to glycogen to store it
- If glycogen storage is full, it will be converted to fatty acids and stored in adipose tissue
- if we don’t need it, excrete it
When is glycogen storage favored?
After an energy-depleting workout and when glucose and insulin are present after the consumption or ingestion of carbs
What is the regular blood glucose range?
70-100 mg/dl while fasting
What helps glucose get into the cell by binding to a receptor and allowing glucose in?
Insulin
What is the problem in Type 1 Diabetes?
the cells in the pancreas that make insulin don’t work, individuals completely lack or have very little insulin but everything else works fine
What is the problem with Type 2 Diabetes?
They have plenty of insulin but the cells are insensitive to insulin, but exercise increases insulin sensitivity
What do people have to go through before a diabetic diagnosis?
Oral glucose Tolerance Test, patient consumes 75 grams of glucose, blood samples are drawn every 30-60 min for 3 hours
What is hypoglycemia?
low blood sugar, triggers pancreas to release glucagon to break down stored glycogen into glucose
What is hyperglycemia?
high blood sugar
What is the glycemic index?
qualitative method of ranking foods based on relative blood glucose response observed after ingesting them; how quickly blood glucose rises (tool not rule)
What is glycemic load?
Indicator of blood glucose response resulting from total carb ingestion, amount of carbs consumed in a serving
Is it possible for a food to have a high glycemic index, but low glycemic load?
Yes
Carbs as fuel during exercise
Source of glucose is generally the stored muscle glycogen and amount is dependent on intensity of exercise
Fatigue during exercise typically results from 3 circumstances?
- Muscle cannot produce enough force to meet the demands of the activity
- High ATP demand prevents the complete oxidation of glucose, causing lactate accumulation
- energy reserves in muscle become depleted
What is the general carbohydrate recommendations?
130 grams per day, minimum requirement needed for brain function
what are the health benefits of fiber?
reduces the risk of developing colon cancer, increases stool bulk, may play a role in prevention of cardiovascular disease
What is lactose intolerance?
a condition in which the small intestine doesn’t produce enough of the enzyme lactase, therefore the disaccharide lactose cannot be digested
Why is a milk allergy different than lactose intolerance?
Milk allergy is an allergy to the protein in milk
What are the differences between intolerances and allergies?
intolerances involve symptoms of the GI tract, while allergies involve an immune response
What is celiac disease?
An autoimmune disorder that renders the person sensitive to the protein gluten, which contains a specific sequence of amino acids in wheat, barley, and rye
What is high intake of sugar associated with?
Increased levels of LDL (bad) cholesterol and a reduced level of HDL (good) cholesterol, the pattern increases the risk of cardiovascular disease
What are sugar alcohols?
carbs present naturally in some fruits and vegetables and can also be made in a lab, less calorically dense and less sweet than sugar, moderate doses are tolerated but greater than 30 g per day can result in undesirable GI effects
What are non nutritive sweeteners?
Contain very little or no energy; valued for taste, and do not cause a rise in blood glucose
What is high-fructose corn syrup?
a synthesized product from corn starch, inexpensive and results in stable, concentrated, sweet product with long shelf life, and not a lot of evidence to support that it is less healthy than nutritive sweeteners.
Relationship between HFCS and obesity
Consumption of HFCS has been declining, but obesity continues to rise
