Chapter 4: The Carbohydrates: Sugars, Starches, and Fibers (Test Review)

INCLUDES ALL SECTIONS: 4.1 - The Chemist’s View of Carbohydrates 4.2 - Digestion and Absorption of Carbohydrates 4.3 - Glucose in the Body 4.4 - Health Effects and Recommended Intakes of Sugars 4.5 - Health Effects and Recommended Intakes of Starch and Fibers

monosaccharides

Single sugar molecules

disaccharides

pairs of monosaccharides chemically bonded together

polysaccharides

large macromolecules formed from monosaccharides (chains of monosaccharides)

1 bond

how many atoms of hydrogen can form a chemical bond?

2 bonds

how many atoms of oxygen can form a chemical bond?

3 bonds

how many atoms of nitrogen can form a chemical bond?

4 bonds

how many atoms of carbon can form a chemical bond?

simple sugars, simple carbohydrates

what are some alternative names for monosaccharides?

glucose, fructose, galactose

what are the three most nutritionally important monosaccharides?

the structure of the monosaccharide

what accounts for differing tastes?

fructose?

which monosaccharide is the sweetest?

galactose?

which monosaccharide is the most bland?

glucose

commonly known as blood sugar; serves as an essential energy source for all bodily functions

fructose

a natural form of sugar responsible for the sweetness of fruits

galactose

monosaccharide that occurs naturally in foods as a single sugar only in very small amounts

maltose, sucrose, lactose

what are the three most nutritionally important disaccharides?

condensation

chemical reaction that links two monosaccharides together, via dehydration synthesis

hydrolysis

chemical reaction that breaks a disaccharide in two; also occurs in digestion

maltose

a disaccharide composed of two glucose units; product of starch digestion and alcohol fermentation; notably high in barley

sucrose

a disaccharide composed of glucose and fructose; accounts for natural sweetness of fruits, vegetables, and grains

lactose

a disaccharide composed of glucose and galactose; also known as "milk sugar"; principal carbohydrate of milk

glycogen, starches, and fibers

what are the three most nutritionally important polysaccharides?

glycogen

an extensively branched glucose storage polysaccharide found in the liver and muscle of animals; the animal equivalent of starch.

starch

long, branched or unbranched chained glucose storage polysaccharide found in plants; the plant equivalent of glycogen

amylose

a linear or straight-line polymer of glucose; form of starch

amylopectin

a branched chain of glucose; form of starch

fibers

found in plant foods, the nonstarch polysaccharides that are not digested by human digestive enzymes, although some are digested by GI tract bacteria

solubility, viscosity, fermentability

dietary fibers are classified by?

soluble fibers

nonstarch polysaccharides that dissolve in water to form a gel; benefit heart disease, diabetes, cancers, and weight management

insoluble fibers

nonstarch polysaccharides that do not dissolve in water; benefit GI health

viscous fibers

fibers that have gel-forming properties in the GI tract

fermentable fibers

fibers that can be digested by bacteria in the GI tract

soluble fibers, insoluble fibers

order fibers by most viscous and fermentable

dietary fibers

fibers naturally occurring and eaten in foods

functional fibers

manufactured or extracted fibers that are added to foods or supplements for beneficial health effects

total fiber

the sum of dietary and functional fibers

polysaccharides

in digestion, which class of carbohydrate requires extensive breakdown?

disaccharides

in digestion, which class of carbohydrates only need to be broken once?

monosaccharides

in digestion, which class of carbohydrates do not need to be broken down at all?

to break them into small molecules—mostly glucose—that the body can absorb and use (breakdown carbohydrates in food into monosaccharides)

what is the ultimate goal of digestion and absorption of sugars and starches?

long chains to shorter chains, short chains to disaccharides, and disaccharides to monosaccharides

describe the order of which enzymes hydrolyze starch

starch to shorter polysaccharides, polysaccharides to shorter chains and maltoses

describe the order of which salivary amylase hydrolyzes starch

the stomach's acid and protein-digesting enzymes

what inactivates salivary amylase?

in the stomach

where does carbohydrate digestion cease?

the small intestine

where does most digestion of carbohydrates take place?

pancreatice amylase

what breaks down the polysaccharides to shorter glucose chains and maltose?

maltase

a digestive enzyme that breaks disaccharide maltose into glucose

sucrase

a digestive enzyme that breaks disaccharide sucrose into glucose and fructose

lactase

a digestive enzyme that breaks disaccharide lactose into glucose and galactose

fibers

what isn't digested in the small intestine, but slows absorption to prevent surges in blood glucose levels?

nondigestible carbohydrates

what carbs remain in the large intestine (colon) as digestive activities slow to a halt?

the lingering fiber

attracts water and creates bulk, which softens the stools for passage without straining in the colon

bacteria in the GI tract

ferments some fibers, which generates water, gas, and short-chain fatty acids

resistant starches

starches that escape digestion and absorption

FODMAPs

a group of carbohydrates that is not digestible by the GI tract: fermentable oligosaccharides, disaccharides, monosaccharides, and polyols; shown to have negative gut effects such as stomach pain, bloating, indigestion, diarrhea, and/or constipation.

enterocytes

lining cells of the small intestine where most nutrient absorption takes place

active transport

energy-requiring transport of materials against the concentration gradient/difference

facilitated transport

passive transport of materials down the concentration gradient/difference

glucose and galactose

monosaccharides absorbed via active transport (may also via facilitated transport after high-carb meals) in the small intestine

fructose

monosaccharide absorbed by facilitated transport in the small intestine

blood

what carries monosaccharides to the liver?

the liver

where are fructose and glucose mostly metabolized (converted into glucose by hepatocytes), and glucose is then sent out to the body's cells for energy?

lactose intolerance

an inability to completely digest lactose, due to an insufficient amount of lactase

about 35%

what percentage of people can retain lactase to digest and absorb lactose efficiently?

6g of lactose (1/2 cup of milk) daily

how much lactose can lactose intolerant individuals consume daily?

to provide energy

primary role of glucose in the body

• sugars attached to a protein change the protein's shape and function

• sugars bind to lipids in a cell's membrane to alter the ways cells recognize one another

what are some additional roles that glucose and other sugars perform?

glycogen

the stored form of glucose that's made up of many connected glucose molecules

as glycogen in the liver, skeletal muscles, and the brain

how and where can excess glucose in the blood be stored?

25%

how much excess glucose is stored in the liver?

storage: excess glucose (single molecules) are condensed into long-branching chains of glycogen release: when blood glucose falls, glycogen is broken down into single molecules of glucose into the bloodstream

how does the liver store and release glycogen?

75%

how much excess glucose is stored in skeletal muscles?

primarily used during high-intensity exercise, meaning its used within the muscles themselves

how is glycogen used in skeletal muscles?

the brain only maintains a small amount, and its thought to provide an emergency energy reserve during times of severe glucose deprivation

how much glycogen is stored in the brain, and what's it's purpose?

the body converts it to fat, which serves as long-term energy reserves

what happens when a lot of excess glucose is present?

via cellular respiration, glucose is broken into smaller compounds that yield energy, which byproducts carbon dioxide and water

how does glucose fuel the work of most of the body's cells?

50-100 g/day

what's an adequate dietary intake of carbohydrates?

body proteins are broken down to make glucose, via gluconeogenesis, to fuel the brain and other nerve cells

what occurs when an individual does not replenish glucose by eating carbs?

the liver and skeletal muscles

where are body proteins deprived primarily from during gluconeogenesis?

protein-sparing action

what is the role of adequate dietary carbohydrate to prevent the use of protein for energy?

ketone bodies

compounds produced during the incomplete breakdown of fat when glucose is not available in the cells

ketosis/ketoacidosis

what occurs when the production of ketone bodies exceeds their use and accumulate in the blood?

it acidifies the blood

what effect does ketosis have in the blood?

cells need a constant supply of glucose from good and glycogen breakdown

how does the body sustain glucose homeostasis?

pancreas

what organ produces glucose-regulating hormones?

insulin, glucagon, and epinephrine

what are some glucose-regulating hormones?

insulin

a hormone secreted by the pancreatic beta cells that lower blood sugar levels by facilitating the uptake of glucose into tissues

insulin

what moves glucose from the blood into cells, stimulates glycogen formation in the liver, and stimulates conversion of glucose to fat?

glucagon

a hormone secreted by the pancreatic alpha cells that raise blood sugar level/glucose concentration; also stimulates glycogen breakdown

epinephrine

a hormone produced by adrenal glands (above the kidneys) that stimulates the liver to release glucose in times of stress

adrenaline

an alternative name for epinephrine hormone, which stimulates energy in emergencies

diabetes

a condition in which the body fails to regulate persistent high blood glucose levels

Type 1

type of diabetes where genetic & viral autoimmune destruction of endocrine cells occurs, and is insulin dependent?

Type 2

common type of diabetes where cells fail to respond to insulin, as a strong correlation with overweight/obesity

weight loss, exercise, and diet before meds

how is type 2 diabetes managed?

hypoglycemia

abnormally low blood glucose (level of sugar in the blood)

diabetes, exercise, fasting, illness, pancreatic tumors, alcohol abuse

what are some causes of hypoglycemia?

bodily weakness, fast heartbeat, sweating, anxiety, hunger, bodily shaking

what are some symptoms of hypoglycemia?

milligrams per deciliter mg/dL

a unit of measure that describes the concentration of substance (glucose) in a specific amount of fluid (blood)

<70 mg/dL

FBG levels diagnostic of hypoglycemia