I N: Metabolism of PRO & FAT Flashcards
what are the branched chain amino acids?
valine, leucine, isoleucine
___ is needed for the transport of amino acids
pyridoxine
during exercise, oxidation of what AAs increase?
alanine and leucine
_______ can be synthesized from phenylalanine; ________ from methionine
phenylalanine –> tyrosine
methionine –> cysteine
what does nitrogen balance measure?
body equilibrium - compares intake to output
N balance: 0 balance
maintenance, nitrogen equilibrium
N balance: + balance
NET GAIN of protein = infant, teenager, pregnancy, healing
N balance: negative balance
erosion of body protein; inadequate intake
Nitrogen balance formula***
(protein intake in grams / 6.25) - (urinary urea nitrogen + 4)
methods to determine protein quality
1) biological value (BV)
2) net protein utilization (NPU)
3) PDCAAS (protein digestibility corrected amino acid score)
what is biological value?
uses N BALANCE to determine FRACTION OF ABSORBED NITROGEN
eggs have a BV of?
100% = all the nitrogen absorbed is retained
what is net protein utilization?
measures the amount of protein ACTUALLY USED
what is PDCAAS?
(protein digestibility corrected amino acid score)
estimates % of protein in each food category that is ACTUALLY DIGESTED
plant vs. animal proteins
protein from animal products is generally better used and digested than that from plants
anabolism of DNA
DNA forms RNA on ribosomes, which forms the template which carries the plan to the cytoplasm
catabolism of proteins: what AA is involved?**
pyridoxine
first step of catabolism in proteins?***
deamination- splitting off of NH2 by hydrolysis in liver
after deamination of proteins, what happens?**
1) NH2 –> NH3/ammonia, toxic
2) keto acid –> oxidized for energy
what happens to the NH3/ammonia?**
1) UREA –> EXCRETED BY KIDNEYS = WASTE
2) purine –> uric acid
3) transamination to make NEW AA (non-essential ones)
what is deamination?
splitting off of NH2 by hydrolysis in liver
what is transamination?
transfer of amino group to a keto acid to form a new AA
hormones involved in protein anabolism
pituitary growth hormone, thyroid, insulin, testosterone
hormones involved in protein catabolism
adrenal steroids (glucocorticoids = protein –> glucose) stimulate gluconeogenesis (creation of glucose from non-CHO sources)
end products of fat digestion are?
monoglycerides, diglycerides, glycerol, fatty acids
what fat products from digestion are directly absorbed into the portal blood?
1) glycerol
2) SCFA (<12 Cs)
3) some phospholipids
monoglycerides, diglycerides, LCFA combine with bile salts to form what?
micelles
micelles bind to protein to form ________?
LIPOPROTEINS (chylomicron), which penetrate intestinal mucosa, travel through lymph, into the thoracic duct into the blood
how is cholesterol absorbed?
some w/ bile salts; MOST with CHOLESTEROL ESTERASE
how is cholesterol excreted?***
by LIVER as BILE
what is lipogenesis? 2 forms?
synthesis or deposition of fat; can be via adipose tissue or the liver
adipose tissue lipogenesis- what occurs?
most ACTIVE site: FA + glycerol –> TGs (needs NADPH)
liver lipogenesis- what occurs?
liver synthesizes fat, but should NOT store it
how can fat accumulation be prevented in the liver?
lipotropic factors (choline) produce lipoproteins which transfer FA out of the liver
what is lipolysis?
oxidation of fats –> forms acetyl coA which enters Krebs cycle to be broken further into ENERGY
hormones for lipogenesis
insulin (anabolic)
hormones for lipolysis: insulin antagonists
growth hormone, glucagon
glucocorticoids, thyroxine, epinephrine, and ACTH are all hormones that do what?
increase rate of fat mobilization
normal fat metabolism requires what for complete fat oxidation?***
CARBOHYDRATES
what occurs in abnormal fat metabolism?***
INADEQUATE CHO = incomplete fat oxidation & BUILDUP OF KETONES –> buildup of acetyl coA as there is NO OAA to combine with it
active transport is used to transport what nutrients?**
MOST NUTRIENTS (glucose, AA, Na, K, Mg, Ca, FE)
what is an example of active transport?***
sodium pump
what does a sodium pump do?***
form of active transport: uphill pumping from LOWER TO HIGH concentration across a membrane AGAINST AN ENERGY GRADIENT (need ATP)
what is simple diffusion? what is transported via it?
higher to lower concentration, intestine to blood to lymph; some water and electrolytes
what is carrier-facilitated passive diffusion? what is transported via it?***
HIGHER TO LOWER CONCENTRATION; WATER-SOLUBLE NUTRIENTS
factors that aid in vitamin A, D, E/K absorption
- A = bile salts, pancreatic lipase, fat
- D = bile salts, acidity of chyme, accompanies Ca and P absorption
- E, K = bile salts, fat
factors that aid in thiamin absorption
acid
factors that aid in riboflavin absorption
phosphorous
factors that aid in B12 absorption
ileum, stomach secretions (HCl, IF)
factors that aid in calcium absorption
acid, vitamin D, lactose
factors that aid in iron absorption**
HCl, calcium (binds oxalates)
central regulation of food intake is via what gland?***
hypothalamus gland
what are glucoreceptors?***
thought to regulate desire to eat
other functions of hypothalamus gland
- satiety and feeding center
- regulates body temperature
