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FNN Carbohydrates
WEEK 3
| Question | Answer |
|---|---|
| What are the 3 potential fates of glucose in carbohydrate metabolism? | 1. Used to produce fuel for body cells 2. Single molecules of glucose stored as glycogen (liver and muscle) 3. Excess glucose stored as fat |
| What is the role of the Krebs cycle in carbohydrate metabolism? | The Krebs' cycle oxidizes the carbon atoms of the acetyl group of acetyl coenzyme A resulting from the breakdown of carbohydrates from glucose to pyruvate and acetyl coenzyme A |
| What are the EAR and RDA values for carbohydrates (in adult men and women) | EAR for adults 19+ (men/women) – 100 g/day RDA for adults 19+ (men/women) – 130 g/day |
| What is the Acceptable Macronutrient Distribution (AMDR) for carboydrates | 45-65% of total daily energy intake |
| What are the two monosaccharides that make up sucrose? | Glucose and Fructose |
| True or false: fructose is a hexose sugar | False |
| State the difference between Hexose sugars and Pentose sugars | Pentose is a five-carbon monosaccharide, whereas hexose contains six carbon atoms |
| True or False: Glycogen can be relied on for long term energy needs | False Glygen stored in the liver is converted to glucose and released into the blood for short term energy. Long term energy needs rely on fat in adipocytes (adipose tissue) |
| Describe the differences between soluble and insoluble fibre | Soluble fibre dissolves in water in the GI tract and forms a gel that increases the transit time (slows the passage of food) Insoluble fibre does not dissolve in water in the GI and decreases the transit time of food |
| Fill in the blank. Very high source of fibre __g fibre per serving High source of fibre __g fibre per serving Source of fibre __g fibre per serving | Very high source of fibre ≥ 6 g fibre per serving High source of fibre ≥ 4 g fibre per serving Source of fibre ≥ 2 g fibre per serving |
| What are the two places in the human body where starch is broken down into simple reducing sugars? | In the mouth and small intestine where salivary amylase and pancreatic amylase break down amylose into dextrins, maltotriose & maltose |
| What are the 3 pathways in which glucose oxidation from carbohydrates occurs? | Pathway 1 -Glycolysis Pathway 2 -Krebs Cycle Pathway 3 -Oxidative phosphorylation in the ETC |
| Explain the reason we experience muscle pain during physical exertion | When exertion exceeds cardiac capacity to deliver O2 and remove C02 from muscles pyruvate is converted to lactate (lactic acid) with the enzyme lactate dehydrogenase and that build up of lactic acid. Muscle pain is due to a change in pH. |
| Excess glucose in the liver is converted to glycogen with what enzyme? | Glycogen synthase |
| What happens when there is not enough (insufficient) glucose in the body? | The body undergoes Gluconeogenesis (the making of glucose from a non-carbohydrate source like pyruvate and amino acids) |
| Why is it dangerous for body protein to be broken down for glucose when glycogen stores are depleted? | Because body protein (e.g., muscle cells) is broken down and cannot perform functions like growth and maintenance of body cells; transport of nutrients, hormones, etc.; production of enzymes and hormones; immune system regulation |
| What does glycemic response refer to? | How quickly and how high blood glucose rises after carbohydrates are consumed |
| Describe how the hormones insulin and glucagon regulate blood glucose levels | Insulin: a hormone secreted by the pancreas in response to a rise in blood glucose levels Glucagon: a hormone secreted by the pancreas in response to a decline in blood glucose levels (stimulates glycogen breakdown in the liver) |
| What are the dangers of extremely high fibre intake | It lowers nutrient availability by: Inhibiting digestive enzymes Creating a physical barrier Containing phytic acid which binds Ca (calcium), Fe (iron), Mg (magnesium), Zn (zinc) and decreases their absorption |
| What is fiber? | Fiber is a long chain of glucose molecules joined by beta (1-4) links, which is from plant sources only and not considered a nutrient. |
| What is the difference between dietary fibre and functional fibre? | Dietary fibre is edible, non-digestible, and comes from plants, while functional fibre is isolated, extracted, and added to food or pills for health benefits. |
| What is the General Dietary Reference Intakes (DRI) for fibre in adults | 25- 38 g/day |
| What is the difference between soluble and insoluble fibre? | Soluble fibre dissolves in water and forms a gel in the GI tract, while insoluble fibre does not dissolve in water and adds bulk to stool. |
| What is the role of carbohydrases in carbohydrate digestion? | Carbohydrases (e.g., pancreatic amylase) hydrolyses starch into dextrins, maltotriose & maltose in the small intestine. |
| What happens to pyruvate in muscle cells when oxygen is lacking? | When O2 is lacking (anaerobic conditions, i.e., when exertion exceeds cardiac capacity to deliver O2 and remove CO2 from muscles), pyruvate is converted to lactate (lactic acid), released to blood, resulting in "oxygen debt." |
| Explain the configuration of the two forms of starch | Amylose: continuous single chains of glucose molecules joined in alpha (1-4) links Amylopectin: branched chains of glucose molecules joined in alpha (1-4) links with branches joined by alpha (1-6) links |
| What is dextrin? | Dextrin is a straight chain polysaccharide produced by the digestion of starch with acid or heat to form shorter chains. |
| What are the enzymes that produce dextrin? | Salivary and pancreatic enzymes produce dextrin. |
| What is the difference between dextrin and starch? | Dextrin tastes sweeter than starch, its precursor. |
| What are the 3 ways soluable fibre may lower blood cholesterol levels | 1. Increases intestinal excretion of bile 2. Slows lipid absorption 3. Fermentation of soluble fibre by colon bacteria into short chain fatty acids (SCFA) (absorbed by the body and metabolized) |
| What is the definition of carbohydrate digestion? | Carbohydrate digestion is the process by which food is broken down into component parts (absorbable units). |
| How are monosaccharides absorbed in the body? | Monosaccharides (glucose, galactose, fructose) are absorbed via intestinal microvilli into the capillaries where they travel via the portal vein to the liver. |
| What percentage of glucose required by the body is used by the brain? | >70%. |
| Define Hypoglycemia | a low blood-glucose level, usually below 2.2 to 2.8 mmol/L of blood plasma |
| What is the role of the liver in glycolysis? | Lactic acid in blood is converted to glucose in the liver (liver coordinates glycolysis, gluconeogenesis, and lipogenesis). |
Created by:
Fatimma
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