Nutrition Chapter 5 Flashcards by Ashley McCarthy

What are the 3 types of carbohydrate?

sugar, starch, fiber

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What are the 4 forms of carbohydrate?

monosaccharide
disaccharide
oligosaccharide
polysaccharide

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What are monosaccharides?

simple carbohydrate - one sugar, C6H12O6
galactose, glucose and fructose, sugar alcohols and pentoses (ribose, deoxyribose)
Foods - honey, fruits

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What are the sugar alcohols?

xylitol, sorbitol, manitol

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What are disaccharides?

simple carbohydrate, two sugars C12H24O12
maltose (2 glucose), sucrose (glucose and fructose), lactose (galactose and glucose)
Foods - table sugar, milk products

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What are oligosaccharides?

complex carbohydrates, 3-10 sugar units
raffinose and stachyose
Foods - onions, beans, broccoli

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What are polysaccharides?

complex carbohydrate, hundreds of sugars

starch and fiber

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How is the digestibility of carbohydrates determined?

Whether they are linked by an alpha or beta bond. Alpha are easier to digest

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What are starch and glycogen?

digestible polysaccharides
starch - storage form of glucose in plants
glycogen - storage form of glucose in animals

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What are the 2 types of starch?

amylose and amylopectin
amylose - linear structure
amylopectin - high-branched structure
Foods - potatoes, beans, breads, pasta, rice

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What is fiber?

indigestible polysaccharide
composed of cellulose, hemicelluose, pectins, gums and mucilages
can be soluble or insoluble
provides no appreciable energy
metabolized by colonic bacteria

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What are sources of soluble fiber?

fruits, oats, barley, beans

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What are sources of insoluble fiber?

whole grains, vegetables

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How is fiber classified?

by its physical and chemical properties

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What occurs during CHO digestion in the mouth?

salivary amylase breaks down starch

digestion is not appreciable

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What occurs during CHO digestion in the stomach?

no digestion occurs in the stomach

HCl neutralizes the enzymes

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What occurs during CHO digestion in the SI?

enzymes breakdown starch and disaccharides into monosaccharides

intestinal cells release disaccharidases
pancreatic amylase

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What role does the pancreas play in CHO digestion?

releases sodium bicarbonate to neutralize acid and allow digestion to occur
releases enzymes

How are the monosaccharides absorbed?

via facilitated or active absorption

What occurs when monosaccharides are absorbed?

They are transported to the liver and converted to glucose for energy or stored as glycogen.

How is fiber digested?

mouth - mechanical actions break it down
stomach - no digestion, but it delays gastric emptying
SI - no digestion, delays absorption of nutrients
LI - bacteria enzymes digest fiber, covert to fatty acids or gas

What functions does fiber have in the LI?

holds water, regulates bowel activity, binds to bile, cholesterol and some minerals and carries them out of the body, enhances health of large intestinal cells

How does fiber effect cholesterol?

enterohepatic circulation

What is the recommended dietary fiber intake?

AI for women 25g
AI for men 38g
DV = 25g

How much fiber does the average American intake?

13-17g

What are problems of excessive fiber intake (chronic)?

need extra fluid binds to some minerals develop phytobezoars fill the stomach of a young child quickly

Carbohydrate Metabolism

energy - ATP from TCA cycle, ETC, glycolysis | stored - fat or glycogen

What are problems with lack of dietary carbohydrate?

glycogenolysis (glucose released from glycogen stores) gluconeogenesis (protein used as source of glucose) ketosis (incomplete metabolism of fats leads to ketone production)

What are the functions of carbohydrates?

provide energy spare protein prevent ketosis

How is glucose regulated (homeostasis)?

major organs: pancreas and liver major hormones: insulin and glucagon other hormones: epinephrine/norepinephrine, cortisol, growth hormone

What happens if glucose homeostasis isn't achieved?

hyperglycemia (diabetes) | hypoglycemia

What is insulin? What are its functions?

hormone released by the pancreas in response to high blood glucose increases glucose uptake by the cells, promotes glycogen synthesis, reduces gluconeogenesis net effect: lower blood glucose

What is glucagon? What are its functions?

hormone released by the pancreas in response to low blood glucose breaks down glycogen, enhances gluconeogenesis net effect: raises blood glucose

What is the function of epinephrine and norepinephrine?

raises blood glucose fight or flight response breaks down glycogen

What is the function of cortisol and growth hormone?

raises blood glucose | increases gluconeogenesis

What is the glycemic response?

refers to how quickly and how high blood glucose levels rise after eating and how quickly the return to normal

What is the glycemic index?

blood glucose response of a given food compared to a reference food

What is the glycemic load?

amount of CHO in a food x the GI

What is the effect of a high glycemic load?

increases insulin output, insulin increases triglycerides, small LDL and fat synthesis reduces satiety, muscles may become insulin resistant

What is the recommended CHO intake?

45-65% of calories RDA is 130g need 50-100g to prevent ketosis current intake is about 50% of kcal

What is the recommend intake of added sugars?

``` DGA = less than 6% of kcal WHO = less than 10% of kcal ```

What are the effects of a high sugar diet?

dental caries high glycemic index indirectly related to dev. of diabetes nutrient deficiencies (low nutrient density, empty and excess kcal, soda replacing milk)

What are the effects of starch and fiber?

reduces the risk of certain diseases | CVD, diabetes, obesity, some cancers, diverticular disease