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what are carbohydrates?
major source of energy/ supplies glycogen stores for liver and muscles
monosaccharide
one
disaccharide
two
saccharide
sugar
what are some monosaccharides?
glucose, fructose, galactose
glucose
primary energy source for cells, measured as blood sugars
fructose
sweetest, fruit sugar
galactose
part of milk sugar (lactose)
what are some disaccharides?
sucrose, lactose, maltose
sucrose
table sugar, made from sugar cane or sugar beets
nutritive sweeteners
contribute energy to foods, provide 4 kcal/g
added sugars
nutritive sweeteners added during processing or preparation
what are alternative sweeteners?
substances added to a food to sweeten it but provide no or few calories
what are sugar alcohols?
alternative sweeteners (candies, gums)
nonnutritive sweeteners
intensely-sweet synthetic compounds that sweeten foods without providing kcal
saccharin
most scientific evidence supports its safety
cyclamates
banned in the US since 1970, despite being determined as safe by panel of experts from FDA and NAS
aspartame
brand names include nutrasweet and equal phenylalanine and aspartic acid
stevia
from leaves of south american shrub
polysaccharides
carbohydrates that are made up of more than two monosaccharides
starch
storage form of carbohydrate in plants, mainly in seeds, roots, and tubers
glycogen
storage form of glucose (carbs) in humans, stored/ made primarily in liver and muscles
what’s a whole grain?
the intact, ground, cracked, or flaked seeds of cereal grains, fiber-rich bran, starchy endosperm, oily germ
mouth (carbs)
salivary amylase begins starch digestion
stomach (carbs)
acid inactivates salivary amylase
small intestine (carbs)
main site for carbohydrate digestion/ absorption-site
liver (carbs)
absorbed monosaccharides (glucose, galactose, and fructose) travel to liver
large intestine (carbs)
some soluble fiber fermented/ causes feeling of satiety
rectum (carbs)
little dietary carbohydrate excreted
what happens after eating carbohydrates?
insulin released from pancreas (first organ to respond when blood glucose falls)
glycogenolysis
glycogen breakdown— releasing glucose (not fatty acids) into the blood for fuel- thus raises blood glucose into a normal fasting range
lipolysis
breakdown of triglycerides (fat) for fuel (not for glucose)
ketone bodies
form as a result of incomplete fat breakdown
ketosis
conditions that occurs with very high blood ketone bodies
hypoglycemia
abnormally low blood glucose levels
lipids include (3 classes)
triglycerides, phospholipids, cholesterol
lipids are
insoluble in water, less dense than water
functions of fats
providing and storing energy as fat (adipose), maintaining cell membranes, producing certain hormones
fatty acids contain?
a hydrocarbon chain (carbon and hydrogen atoms) with a methyl group (CH3) at one end and an acid group (COOH)
saturated
each carbon atom in the chain holds 2 hydrogen atoms (no double bonds)
unsaturated
1 or more carbon atoms within the chain lack 2 hydrogen atoms so the molecule has 1 or more double bonds
the 2 essential fatty acids are?
alpha-linolenic acid, linoleic acid
effects of prostaglandins
stimulate uterine contractions, regulate blood pressure, promote immune system response
what are trans fats?
unsaturated fats with at least 1 trans double bond rather than the more common cis double bond
hydrogenation
process that adds hydrogen atoms to liquid vegetable oils
partial hydrogenation
not all double bonds are hydrogenated, natural cis double bonds convert to the unhealthy trans form.
triglycerides
composed of 3 fatty acids attached to a glycerol backbone
phospholipids
a lipid consisting of a glycerol bound to two fatty acids and a phosphate group
lecithin
main phospholipid in foods, such as egg yolks, liver, wheat germ, peanut butter, and soy
hydrophobic region
attracts lipids and avoids water
hydrophilic region
attracts water and avoids lipids
cholesterol
the body uses cholesterol to make various substances, including :bile, vitamin D, steroid hormones
bile
made in liver, stored in gallbladder
stomach (lipids)
minor fat digestion occurs
liver (lipids)
produces bile that helps emulsify fat
pancreas (lipids)
secretes pancreatic lipase enzyme into small intestine
small intestine (lipids)
main site for lipid digestion and absorption
atherosclerosis
disease in which lipid-containing plaques build up inside arteries (main cause CVD)
plaque
forms in an artery when something irritates the lining of the artery wall
arteriosclerosis
hardening of the arteries
hypertension
abnormally high blood pressure levels
lipoproteins
protein molecules which transport lipids in the blood
high- density lipoproteins (HDL)
transports cholesterol away from tissues and to the liver where it can be eliminated
low density lipoprotein (LDL)
conveys cholesterol to tissues, may contribute to atherosclerotic plaque
c-reactive protein
produced primarily by liver in response to inflammation
Omega-3
lowers inflammation/ blood clotting/ blood pressure, fatty fish, canola oil, walnuts, and flaxseed
omega- 6
increases inflammation and blood clotting, animal fats and vegetable oils
what are proteins?
main function is for growth and repair of body cells and tissues
structural proteins
in cartilage, ligaments, bones, hair, skin, and nails
contractile proteins
that enable muscles to move
pigment proteins
such as melanin determine color of eyes, hair, and skin
clotting proteins
that are needed for blood clotting
transport proteins
oxygen and many nutrients are transported in blood by special proteins, lipoproteins, retinol binding protein
antibodies
protecting body against disease
fluid balance
the proper distribution of fluids within bloodstream and body tissues
acid-base balance
maintaining the proper pH of body fluids
amino acids
proteins are made of smaller units
amino group
has nitrogen bonded to 2 hydrogen atoms
R-group (side chain)
varies in each amino acid
acid group
acid portion
essential amino acids
cannot be made by the body, must be supplied by the diet, 9/20 amino acids
nonessential amino acids
can be made by the body, 11/20 amino acids
legumes
plants that produce pods with a single row of seeds, soybeans, peas, peanuts, lentils, and beans
high quality protein (complete protein)
contains all 9 essential amino acids in amounts that support growth, most animal products
low-quality protein (incomplete protein)
lacks or has inadequate amounts of 1 or more essential amino acid. most plant foods and gelatin
whey protein
high quality protein derived from the production of cheese
sickle cell anemia
is an inherited condition that affects red blood cells
stomach (protein)
undergo denaturation by stomach acid and partial digestion by pepsin
small intestine (protein)
further digestion occurs as the pancreas secretes protein-splitting enzymes
liver (protein)
after being absorbed amino acids enter the portal vein and travel to the liver
transamination
transfer of nitrogen-containing group from an unneeded amino acid to a carbon skeleton, forming a non-essential amino acid and a keto acid
deamination
removal of nitrogen-containing group from an unneeded amino acid
nitrogen equilibrium
occurs when healthy adults meet protein & energy needs
gliadin
Protein found in gluten of wheat, buckwheat, barley, and rye
phenylketonuria (PKU)
genetic disorder, caused by lack of enzyme that converts the amino acid phenylalanine to another compound
lactovegetarian
consumes milk and milk products
ovo vegetarian
consumes eggs
lactoovovegetarian
consumes eggs, milk, and milk products