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what is nutrition?
study of nutrients in the body
what are nutrients?
Chemicals from the environment that organisms need for survival
Used to supply energy to fuel metabolic processes, and for building blocks for producing the molecules the body needs
what are the two major nutrient classes?
macronutrients
micronutrients
what is macronutrients?
Required in large quantities, such as carbohydrates, lipids, proteins; provide energy
what is micronutrients?
required in small amounts, such as vitamins and minerals; help extract energy from macronutrients
what are essential nutrients?
Nutrients that the body cannot synthesize or cannot synthesize in sufficient quantity
Must be obtained from the diet
what are calories?
Units of heat used to express amount of energy in foods
what are carbohydrates?
Organic compounds, such as sugars and starches
Energy held in their chemical bonds is used to power cellular processes
what are the three carbohydrate sources?
polysaccharides, disaccharides, monosaccharides
what are polysaccharides?
Complex carbohydrates, such as starch from plant foods and glycogen from meats
what are disaccharides?
(double sugars): milk sugar, cane sugar, beet sugar, molasses
what are monosaccharides?
(single sugars) from honey and fruits
Digestion breaks complex __ into monosaccharides that are small enough to be absorbed
carbohydrates
Cellulose is a __ carbohydrate abundant in our food; not digested, but provides fiber
complex
Different __ are absorbed from digestive tract: fructose, galactose, and glucose
monosaccharides
Since __ is the most common cellular fuel oxidized in glycolysis, the other monosaccharides are converted into glucose by enzymes in the liver
glucose
Glucose is broken down into CO2, H2O, and __ when needed
energy
Excess glucose is converted into __ by glycogenesis, and stored in liver and muscle cells
glycogen
After storing a certain amount of glycogen, excess glucose is converted into __ by lipogenesis, and stored in the adipose tissue
fats
Many cells can __ down fatty acids for energy, but some require glucose
break
what is gluconeogenesis?
Conversion of noncarbohydrates (amino acids, glycerol) to glucose, for cells that require glucose as energy source
what is the primary source of fuel for cellular processes?
carbohydrates
does the need for carbohydrates vary with individual energy requirements?
yes
Minimal requirements for carbohydrates in the human diet is unknown, but an intake of at least 125 to 175 __/day is likely necessary
grams
Average diet in the United States includes 200 to 300 grams/__.
day
what are lipids?
Organic compounds that include fats, oils, phospholipids, and cholesterol
Supply energy for cellular processes
Serve as building blocks for structures such as cell membranes
what are triglycerides?
Composed of glycerol and 3 fatty acids
Most common dietary lipids
Also called “fats”
what kind of foods are triglycerides found in?
plant-based and animal-based foods
what are saturated fats?
Mainly in foods of animal origin, such as meat, eggs, milk, and lard
Also in palm and coconut oils
No double bonds between carbon atoms in fatty acids
Associated with increased risk of cardiovascular disease
what are unsaturated fats?
Found in seeds, nuts, and plant oils
Contain one or more double bonds between carbon atoms
Monounsaturated fats are the healthiest
what is cholesterol?
Abundant in liver and egg yolk
Some in whole milk, butter, cheese, and meats
Not found in foods of plant origin
Lipids in foods include phospholipids, __, and most commonly, fats/triglycerides
cholesterol
what are the functions of lipids?
Mainly supply energy
Contain more than twice as much chemical energy per gram as carbohydrates or proteins
Triglycerides are broken down to glycerol and fatty acids, in order to release energy
Glycerol and fatty acids can be used to synthesize storage fats in adipose tissue
Excess glucose or __ acids can also be converted into fat molecules
amino
can the liver convert fatty acids from one form to another?
yes
Liver cannot synthesize certain fatty acids, called essential __ acids; these must be obtained from the diet.
fatty
Lipids can combine with proteins to form __.
lipoproteins
what are lipoproteins?
Classified on the basis of density; as proportion of lipids decreases, density increases
Used in lipid transport to specific target cells
what are VLDLs?
(very low density lipoproteins): high triglyceride content
what are LDLs?
(low density lipoproteins): high cholesterol content
what are HDLs?
(high density lipoproteins): high protein content
how does the liver control cholesterol?
Produced by the liver, and released into the blood
Can be used to make bile salts
Excreted in bile
how is adipose tissue used?
stores and releases triglycerides as needed
Note 
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