Carbohydrates Flashcards

Question

How long do glycogen stores last?

Answer 1

* holds 3 grams of water for each gram of glycogen, bulky energy storage system, therefore limited supply of energy stored as glycogen (hours)

Answer 2

* body energy needs are met, glycogen stores are full and still excess CHO kcal entering body * liver catabolizes GLU to smaller fragments and uses them to synthesize fat, called LIPOGENESIS * fat travels to adipose cells for storage § virtually unlimited fat storage

Answer 3

* generally, excess quantities of CHO kcal are not consumed over long term when choosing higher quality dietary CHO (unrefined, fibre-containing): increased bulk, feeling of fullness sooner, greater satiety, lower fat/kcal intake * excess quantities of CHO kcal may be consumed when choosing lower quality dietary CHO (refined, concentrated sugars, often containing fat)

Answer 4

a. PROTEIN (Gluconeogenesis) * proteins in muscles & other organs – only C-skeleton portion of amino acid used * proteins needed for own functions, over time can lead to reduced functioning of organs (e.g., heart, muscles, liver, kidneys) * adequate dietary CHO intake “spares” body protein b. FAT * only glycerol portion of TG available for GLU synthesis * when adequate CHO present, fat is completely oxidized to CO2 and H2O * “FAT burns in a fire of CHO” c. Lactate * lactate that is produced from the anerobic glycolysis in RBC and active muscle (low O2) travels to liver where it is converted to GLU * Gluconeogenesis of GLU from lactate costs metabolic energy (ATP) and cannot be sustained indefinitely * GLU enters blood and returns to RBC or muscle for metabolic use

Answer 5

* if inadequate CHO present, fat is not completely oxidized leading to formation of KETONE BODIES * ketone bodies can be used as an energy source by the brain, heart, muscle and kidneys under conditions of low CHO intake (adaptive mechanism) * fruity smell on breath * ketones suppress appetite and cause dehydration * without this short-term adaptive process during periods of low/no CHO intake, body would be forced to greatly increase degradation of body proteins to supply GLU * ketosis may change blood pH, making it more acidic, which in the long term may damage organs * need to consume 50-100g CHO/day to spare body proteins and prevent ketone formation

Answer 6

* normal BGL ranges between 80-120 mg/dL (4-6 mmol/L) * BGL fluctuates in response to fed or fasted conditions * hyperglycemia: consistently \>120 mg/dL * hypoglycemia: consistently \<80 mg/dL * pancreatic hormones – main regulators of BGL: * insulin – lowers BGL * glucagon – raises BGL

Answer 7

Pancreatic hormones: * insulin – lowers BGL * glucagon – raises BGL

Answer 8

* at high BGL – circulating insulin contacts receptors on cell membranes which opens channels through which GLU enters cells * most cells move the amount of GLU that is needed as an immediate source of energy * as BGL drops, turn to liver stores to maintain BGL in normal range

Answer 9

* at low BGL – Glucagon released from pancreas, acts on liver to enhance GLYCOGENOLYSIS * GLU released from glycogen stores in liver, enters bloodstream to raise BGL * GLU travels to other body cells for use as fuel ## Footnote *Note: during stress or exercise, epinephrine (adrenalin) also acts similar to glucagon to cause release of GLU from glycogen stores for use as energy*

Answer 10

Dental cavities * bacteria in mouth ferment sugars in food to produce acids, acids erode the enamel to cause cavities * increased frequency of intake, especially of sticky sugary foods, increases exposure time of enamel to acid and increases risk of dental cavities Reduced nutrient density and relationship to risk of obesity * increased intakes of simple sugars, especially if combined with fat (lower quality dietary CHO) can displace more nutrient-dense foods in diet

Answer 11

A diet low in refined simple sugars and high in unrefined, complex CHO is often: * lower in fat * lower in energy * higher in fibre * higher in vitamins & minerals * this type of diet may assist in decreasing risk of obesity, diabetes, heart disease, cancer, dental caries, malnutrition * higher fibre intake increases diversity in gut microbiota – may help with weight control

Answer 12

**Weight Control** * slows eating, increases saliva production * delays gastric emptying – fullness, satiety * draws water into GI tract – fullness * sources: fruits, vegetables, legumes, whole grains – economical, nutritious, tasty **Improved Function/Health of GI Tract** * taken with plenty of water, prevents impaction * insoluble fibres attract water, increased stool size, easier elimination * prevents GI disorders including: * constipation * hemorrhoids * diverticulosis **Lowered Blood Cholesterol** * water-soluble fibres bind bile in small intestine making it unavailable for re-absorption in ileum – prevents ENTEROHEPATIC CIRCULATION of bile – bile exits in feces * decreased bile may lead to decreased fat and cholesterol absorption and lower cholesterol in the blood * with little bile being recycled to the liver, liver has to synthesize more bile * liver pulls cholesterol from blood to make bile **Slows Glucose Absorption** * soluble fibre slows release of chyme from stomach into small intestine * blunted insulin response to slower and smaller amounts of GLU entering bloodstream **Reducing Risk for Colon Cancer** * some populations with high intakes of fibre have shown reduced rates of colon cancer * dilution and/or binding of carcinogens, and/or rapid removal from colon * bacterial fermentation of resistant starches and fibres may reduce pH – protective effect?

Answer 13

**Bulk** * high fibre intakes can provide satiety without adequate energy/nutrient intake * elderly, children, malnourished at risk **Abdominal Discomfort** * rapid increase in fibre intake, gases produced, bacteria need time to adapt * gradually increase fibre from a variety of sources along with plenty of fluids **Impaction** * high fibre intake without adequate fluid intake can dehydrate feces and cause blockage of GI tract * may need surgery to remove blockage **Quicker Passage through GI Tract** * limited absorption of some nutrients * insoluble fibres bind minerals (e.g., Ca, Zn, Fe) * increased fibre intakes usually associated with increased mineral intake

Answer 14

Diverticula may develop anywhere along the GI tract, but are most common in the colon.

Answer 15

Enterohepatic circulation refers to the circulation of biliary acids, bilirubin, drugs or other substances from the liver to the bile, followed by entry into the small intestine, absorption by the enterocyte and transport back to the liver.

Answer 16

# * choose unrefined simple and complex CHO from a variety of sources whenever possible * aim for \<10% of total energy intake from “free sugars”; current Canadian intake ~11% * current Canadian intake of “total” sugars ~21% **DRI-RDA** * all adults: 130 g/day * based on energy needs of the brain **DRI-AMDR** * 45-65% of your total energy intake

Answer 17

* key = moderation (not too much or too little) * recommended 14 g mixed dietary fibre/1000kcal § DRI-AI * adult woman: 25 g/day * adult male: 38 g/day * children: age + 5 = total grams dietary fibre/day * select from a variety of sources – plant foods only – whole grains, legumes, vegetables, fruit * eating breakfast is a good way to add to your dietary fibre intake for the day * consume plenty of fluids with dietary fibre

Carbohydrates Flashcards

(44 cards)