Nutrition

what is energy balance?

calories eaten vs calories burned; intake = burned = steady weight

what accounts for weight homeostasis?

seems to have setpoint; heredity and environment

what accounts for appetite control?

psychological factors, sight and smell of food, empty or full stomach, hormones

what structure regulates hunger sensation and behavior?

hypothalamus

where are the hunger and satiety centers located?

arcuate nucleus of hypothalamus

what is the target of hormones regarding hunger and satiety?

hypothalamus

what are the short term regulators of appetite?

ghrelin, PYY, CCK

what are the long term regulators of appetite?

insulin and leptin

what hormones have an inhibiting effect on appetite?

PYY, CCK, insulin

what hormones have a stimulating effect on appetite?

ghrelin and leptin

where is ghrelin produced?

parietal cells in fundus of empty stomach

where is PYY produced?

large intestine; ileum and colon

where is CCK produced?

small intestine

where is insulin produced?

pancreas

where is leptin produced?

adipose tissue

what is the stimulus for CCK?

food molecules in duodenum

what are the effects of CCK?

gallbladder squeeze and others, short term satiety

do levels of PYY increase or decrease before food reaches ileum?

increase

what is the relationship between fat cells and hunger?

more fat → more leptin, more leptin → less hunger

what insensitivity could be linked to obesity?

leptin insensitivity

is the effect of insulin stronger or weaker compared to leptin?

weaker

what is the purpose of nutrition?

fuel, growth, maintenance, and repair of body

what is an RDA and what is it called before that?

recommended daily allowance; called adequate intake with less research

what is a calorie?

measure of energy; 1 cal = amount of heat to raise 1 g of water by 1 degree celsius

what are nutrients?

required substances that are ingested

what are inorganic nutrients?

minerals and electrolytes

what are organic nutrients?

carbs, fats, proteins, vitamins, phytochemicals

what are macronutrients?

energy and building blocks, eaten in relatively large quantities; carbs, fats, proteins, and water

what are micronutrients?

needed for proper function; electrolytes, trace minerals, vitamins

what are the characteristics of phytochemicals?

antioxidants and anti inflammatory

what are examples of phytochemicals?

polyphenols, lycopene, xanthocyanins, reservatrol

what is interconversion and what cells can do it?

changing 1 type of nutrient into another; liver and most other cells

what are essential nutrients?

nutrients the body cannot synthesize; electrolytes, minerals, vitamins

how many essential amino acids are there?

8-10

how many essential fatty acids are there?

1-3

what is the purpose of carbohydrate intake and what is it the sole source for?

glucose is easy to burn for fuel; sole source for nerve cells and RBCs

what do carbohydrates make in the body?

glycoproteins and glycolipipds, polysaccharides in ECM, ATP for nucleotides

what are the characteristics of insoluble fiber and what are 3 examples?

indigestible, from plants, aids mobility in GI tract, prevents constipation; cellulose, hemicellulose, lignin

what is soluble fiber digested by and what is it turned into?

gut bacteria; SCFAs and sometimes gas

what lipids are used for aerobic respiration?

fatty acids and glycerol

what are sources of saturated fats?

meat, dairy, tropical oils, hydrogenated oils

what are sources of unsaturated fats?

seeds, nuts, olive oil, most vegetable oils

what are the two fatty acids the liver cannot convert other fatty acids into?

essential fatty acids; linoleic acid (omega 6) and linolenic acid (omega 3)

where are omega 6 and 3 found?

most vegetable oils

what are sources of cholesterol?

egg yolk, meat and fish, dairy

how much of cholesterol does the liver make despite intake?

\~85%

what are phospholipids used for in the body?

myelin and all cell membranes

what is cholesterol used for in the body?

cell membranes, precursor of bile salts, vitamin d, and steroid hormones

what is adipose tissue used for in the body?

protection and cushioning, insulation, fuel storage

what are the sizes of serum lipoproteins from largest to smallest?

chylomicron, very low density lipoprotein (VLDL), low density lipoprotein (LDL), high density lipoprotein (HDL)

what is lipoprotein lipase and what does it do?

endothelial surface enzyme in capillaries; turns triglycerides into 2 fatty acids and a monoglyceride

where do the VLDLs from the liver stored in?

triglycerides removed and stored in adipocytes

where do cholesterol filled HDL shells go to?

the liver

what does ROS stand for?

reactive oxygen species

what are free radicals and what is an example?

unpaired electron; superoxide (O2-)

what is an example of a peroxide?

H2O2

what do oxidants damage and what can it lead to?

lipids, proteins, dna; aging or cancer

what are oxidants products of?

normal metabolism (aerobic respiration), inflammation (neutrophils), pollutants, tobacco smoke, radiation (90Sr)

what are antioxidant enzyme systems and what is an example?

built in defenses; superoxide dismutase (SOD)

how many superoxide dismutase (SOD) genes are there in humans?

at least 3

what are 4 cofactors of superoxide dismutase (SOD)?

Fe, Cu, Zn, Mn

what is catalase and what does it do?

antioxidant enzyme; breaks hydrogen peroxide into water and oxygen

where is catalase found?

peroxisomes, mitochondria, liver, blood

what do non enzymatic antioxidants do?

scavenge free radicals

how do non enzymatic antioxidants do no damage?

stable with unpaired electron

what are 5 examples of non enzymatic antioxidants?

vitamins A, C, and E, beta carotene, many phytochemicals

what are sources of proteins?

eggs, dairy, fish and meats, legumes, seeds, nuts, nutritional yeast

what is the purpose of protein intake?

to get amino acids for building blocks and raw materials

what is the all or none rule regarding protein synthesis?

if even 1 AA is missing you cannot make the protein

what are excess amino acids turned into?

ATP, glucose, or fat

how many essential amino acids are there and how many in adults?

10; 8 in adults

what are the intake requirements for essential amino acids?

\~10-15% of total protein

what are conditionally essential amino acids?

essential during disease and wound healing

what are the 6 conditionally essential amino acids?

arginine, cystine, glycine, glutamine, proline, tyrosine

what does complete dietary protein mean and what are 3 examples?

contain all essential amino acids; animal proteins, soybeans, quinoa

what are 3 sources of incomplete protein?

most legumes, nuts, and grains

what 2 incomplete sources of protein can be combined to be a complete protein source?

legumes and grains

how are proteins constantly produced?

translation

what is amino acid metabolism?

constant recycling of proteins

what is nitrogen balance?

nitrogen intake vs excretion

when is there a positive nitrogen balance?

in growing children, AAs used for building

when is there a negative nitrogen balance?

starvation, AAs used for fuel causing muscle atrophy

what is the purpose of electrolytes?

osmotic balance, transport, membrane potentials

what minerals are enzyme cofactors?

Zn, Mg, Fe, Se, etc

why is Zn an important enzyme cofactor?

in carbonic anhydrase, some DNA binding proteins

what minerals provide structure?

calcium, phosphate, fluoride

what is the formula for hydroxyapatite and where is it found?

Ca10(PO4)6(OH)2; bone

what is the formula for fluorapatite and and what does it do?

Ca10(PO4)6F2; resists acid in tooth enamel

what are vitamins?

small organic molecules that mostly cannot be synthesized by humans, “vital amines”

what are provitamins?

can be converted to a vitamin

what can beta carotene be converted to?

vitamin A

what can panthenol be converted to?

vitamin B5 (panthothenic acid)

what are 2 examples of water soluble vitamins?

vitamin B and C

what causes urine to be yellow?

riboflavin (B2)

what are the fat soluble vitamins?

vitamin A, D, E, and K

what can cause toxic hypervitaminosis?

overdose from supplements, 10-1000x the RDA

what are the symptoms of B6 overdose?

numbness in mouth and hands, difficulty walking

what are the effects B3, A, and K overdose?

liver damage

what do coenzymes do?

bind with enzyme to make functional enzyme

what is an example of a non enzyme cofactor?

vitamin A → opsins