Chapter 4 carbohydrates

12. Describe the effects of added sugars on dental health

Dental Caries Bacteria in the mouth ferment sugars>>>>>>Produces acid that erodes tooth enamel Development depends on:>>>>>Type of food((((Sticky foods stay on teeth, yield more acid)))) (((((((((((Juice vs. dried fruit))))))))))) Frequency>>>>>>Acid produced for 20-30 minutes after exposure to sugar>>>>Prolonging sugar intake will increase length of acid production(((((((((((Eating a piece of candy vs. sipping soda)))))))))))))) ....Non-sugary foods can help remove sugar from teeth ....Dairy foods can help minimize effects of acid and restore tooth enamel ....Practice good oral hygiene

5. Describe the digestion and absorption of carbohydrates

Digestion breaks down most carbohydrates into monosaccharides Mouth - Salivary amylase long polysaccharide chains >>>>> shorter polysaccharide chains + maltose Stomach Carbohydrate digestion does not occur in the stomach Hydrochloric acid (HCl) - destroys salivary amylase Role of fiber Small Intestine Pancreatic amylase >>>>>>polysaccharide chains >>>>>>>>shorter glucose chains + maltose Intestinal cells -Additional enzymes in the microvilli complete final digestion-(((((Sucrase,Maltase Lactase))))) End Products: mostly glucose but some fructose and galactose Absorbtion - Two absorption sites>>>>>Mouth: small amounts>>>>>Small intestine>>>Absorption mechanisms Active transport-glucose and galactose>>>>Facilitated diffusion -fructose >>>>>>>Milk vs. Juice tend to absorb faster due to ATP>>>>>Branched chain starches vs. unbranched chains Liver>>>>>>Converts fructose and galactose to glucose What happens to excess glucose?>>>>>Circulating blood glucose is our primary energy source Digestion Cont. Large intestine>>>>All sugars and starches digested 1-4 hours after a meal>>>>Most fiber remains undigested and is excreted in the feces>>>>Attracts water and soften stools>>>GI tract bacteria ferment some fibers>>>>Generates water, gas, and short-chain fatty acids (SCFA)

11. What are some of the health benefits of a high fiber diet?

Fiber>>>>>Helps prevent hemorrhoids, constipation, and other intestinal problems>>>>May reduce the risk of colon cancer>>>>>May reduce the risk of diverticulosis >>>>May reduce the risk of heart disease>>>>May enhance weight loss>>>>>May lower the risk of type 2 diabetes

8. What is the glycemic index?

Food's potential to raise blood glucose>>>>>Foods with a high glycemic index cause a sudden surge in blood glucose>>>>>Foods with a low glycemic index cause low to moderate fluctuations in blood glucose Used to determine the effect of a food on a person's glucose response >>>>>Grams of carbohydrates in a food are multiplied by the glycemic index>>>>>Glycemic index and glycemic load remain controversial >>>>Evidence of health benefits is weak

10. What is gluconeogenesis?

Gluconeogenesis Creation of new glucose units Increased rate with diets deficient in carbohydrates

1. Define the three monosaccharides.

Glucose- Most abundant carbohydrate, Produced by plants through photosynthesis, Hexagon form, soluble in water Commonly known as blood sugar and dextrose Essential energy source for entire body Primary energy source for certain organs, tissues and cells Fructose- Sweetest of the sugars Naturally occurring in fruits and honey High-fructose corn syrup: sweetens a variety of products Galactose- Rarely occurs naturally as a single sugar

7. What hormones are used to maintain glucose homeostasis? How do they function in the body?

Hormones control blood glucose levels: Insulin>>>>Glucagon>>>>Epinephrine, Norepinephrine - Neurotransmitters in the brain that pertain to the "fight or flight response>>>>>Cortisol>>>>>>>Growth hormone Insulin: The basics:>>>>Secreted by: >>>>>Amount secreted corresponds to rise in blood glucose levels>>>>>>Released: beta cells which release insulin Roles:>>>>Helps to lower blood sugar levels>>>>>Promotes storage of glycogen in liver and muscle>>>>Promotes conversion of excess glucose to fat Mechanism of action:>>>>>Stimulates glucose transporters (carrier proteins) to help take glucose from the blood across the cell membrane>>>>"Key" that unlocks cell Glucagon The basics:>>>>Secreted by: Pancreas>>>>>Released: the hormone glucagon is released from the alpha cells into the bloodstream. Roles: >>>>>Signals liver to convert glycogen to glucose>>>>>>Stimulates gluconeogenesis, the production of glucose from amino acids Result:

9. Define ketones and ketosis. What is ketoacidosis and why is it dangerous?

Ketones Formed from the incomplete breakdown of fat>>>>>Energy source during starvation Ketosis Ketosis: accumulation of ketone bodies in the blood>>>>Ketoacidosis: build-up of excess ketones in the blood causing an increase in blood acidity>>>>Ketosis prevention and reversal

4. What are the two major types of dietary fibers? What are their uses in the body?

Soluble Fiber- Share three characteristics (((Soluble ,Viscous, Fermentable))) Associated with risk reduction of certain chronic diseases Found in citrus fruits, berries, oats, beans **Examples: pectin, gum, mucilage Insoluble Fiber- Non-viscous & non-fermentable (((Benefits ,Promote regular bowel movements ,Alleviate constipation, May reduce risk for diverticulosis))) Good sources: whole grains, seeds, legumes, fruits, and vegetables Examples: lignins, cellulose, hemicelluloses

2. Define the three disaccharides. Know which monosaccharides combine to make them.

Sucrose Glucose + Fructose Sweet taste Naturally sweetens fruit, vegetables and grains Refined sugarcane and sugar beets are granulated to form various table sugars Brown, white and powdered sugar Lactose Glucose + Galactose Present in milk and milk products Maltose Glucose + Glucose Produced two different ways Small amounts only found in a few foods

3. What are the three polysaccharides?

The three most common types of polysaccharides are starch, glycogen, and cellulose. Starch is a glucose polymer and insoluble in water; they must be digested with amylases. Glycogen is the storage form of glucose in animals, where starch is the same in plants. Cellulose forms most structural components in plants, and is indigestible by humans.

6. What is glycogen? Where is it stored? What is glycogen's role in the body?

is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals and fungi.>>>>In humans, glycogen is made and stored primarily in the cells of the liver and the muscles, and functions as the secondary long-term energy storage (with the primary energy stores being fats held in adipose tissue).>>>>>>To provide long term energy in the body.