Exam 3 NSCI 4123
What type of amino acids are absorbed the fastest?
*BCAAs & essential AA are absorbed fastest
How is nitrogen balance/status calculated?
*[protein intake (g) x0.16]-[UN+2g] *[protein intake (g) x 0.16]-[UUN+4g]
During protein digestion, after the proteins have left the stomach, what takes place in small intestines?
*acidic chyme stimulates the release of secretin & cholecytokinin *secretin stimulates the release of pancreatic juice *cholecystokinin stimulates the secretion of pancreatic enzymes *enterocytes produces several peptidases that aid in protein digestion
What is albumin?
*an indicator of visceral protein status *levels decline with protein malnutrition *half life is 14-18days (not a reliable indicator of short-term protein intake)
What is BUN?
*blood urea nitrogen *used to clinically assess nitrogen balance
What can inborn errors of metabolism lead to?
*can lead to an accumulation of compounds with harmful effects *can also lead to deficiencies of substances that are essential for normal growth and development
What are complete proteins?
*contain all essential AAs in the approximate amounts needed by humans *most ANIMAL products are complete protein sources *soy, chia, quiona, are complete protein
What is the half life for albumin?
14-18 days
If an average adults has ~5 liters of blood and a circulating cholesterol level of 150 mg/dL, how much total cholesterol do they have circulating in their blood?
150mg/dLx50dL=7500mg
How much supplementation of glutamine has been shown to improve patient outcomes after infection or trauma?
20-25 g/day can improve patient outcome
If that same adult then consumes a meal containing ~300 mg cholesterol, what would their circulating cholesterol concentration be assuming all of it was absorbed?
7800/50=156 mg/dl
True/False: An essential amino acid cannot be synthesized by the body, and must be acquired through diet
TRUE
True/False: If BUN levels are LOW- ammonia is not being converted- ammonia levels would be high
TRUE
True/False: In healthy individuals nitrogen excretion should be equal to nitrogen intake
TRUE
True/False: Peptide absorption requires transport system PEPT1
TRUE
True/False: Peptide transport is more rapid than AA transport
TRUE
True/False: Protein degradation can occur through lysosomal degradation (autophagy) or proteosomal degradation
TRUE
True/False: Protein synthesis & protein degradation account for ~10-25% of resting energy expenditure
TRUE
True/False: Removal of AA helps maintain pH of blood- if they are not removed then the pH levels would rise
TRUE
True/False: Skeletal muscle prefers branched-chain amino acids
TRUE
True/False: The LARGER the side chain the HIGHER the affinity for absorption
TRUE
True/False: The brain has high capacity for active transport of AAs
TRUE
True/False: With renal failure individuals ability to get rid of urea is compromised
TRUE
True/False: Zygomens are inactive but activate with break down of peptide bonds?
TRUE
True/False: animal-based proteins are associated with greater gains in lean body mass in individuals participating in resistance training
TRUE
True/False: creatinine clearance can be used as an estimator of kidney function
TRUE
True/False: excess ammonium ions can be used to make non-essential AA
TRUE
True/False: plant-based proteins are typically limiting in one or more essential AA
TRUE
True/False: the liver derives ~50% of its energy from AA oxidation
TRUE
True/False: when energy needs are insufficient the catabolism of skeletal is increased in response to an elevation in plasma glucagon levels
TRUE
If a patient has elevated alanine aminotransferase, what would that indicate to medical staff?
elevated ALT levels suggest liver damage
If a patient presents elevated aspartate aminotransferase levels, what would that indicate to medical staff?
elevated AST levels would indicate heart damage
What cellular process can AA carbon skeleton be used for?
energy production (not ideal), glucose production, ketone body production, cholesterol production, fatty acid synthesis
Intestinal cells use AA for _______________ _________, ____________ ___ ____________, & ____________ ___________ _________________
energy production, synthesis of proteins, and nitrogen containing compounds
What are transamination reactions catalyzed by?
enzymes called aminotransferase
What is creatinine an important component of?
important component of the energy compounds phosphocreatine
True/False: AA absorption requires carriers
true
What are the end products of protein digestion?
typically di & tripeptides & free AA
Which amino acid becomes conditionally essential in patients with PKU?
tyrosine
Which of the following is a conditionally essential amino acid?
tyrosine
What are examples of fairly common conditionally essential AA?
tyrosine, cysteine, proline, arginine, and glutamine
What occurs after urea is formed?
urea travels through the blood to the kidneys for excretion in urine
What are nitrogen losses measure in?
urine, feces, and skin
What are inborn errors of metabolism?
when some component of BCKAD is mutated an leads to a build up of a-keto acids which leads to acidemia which will lower blood pH and can lead to neuro toxicities *a diet recommendation would be very LOW or NO branched AA
What are pancreatic enzymes secreted as?
zymogens
How much of total body protein is turned over each day?
~1-2%
What percentage of protein is nitrogen?
~16%
How much nitrogen is lost in feces, skin, nails, or hair?
~2g
How much of all essential AA are absorbed from the diet by the intestines?
~30-40%
How much protein do endogenous sources produce?
~70g
What percentage of dietary glutamate do the intestines use?
~90%
True/False: Albumin play an important role in the maintenance of osmotic pressure.
TRUE
What would you expect for BUN levels during renal failure?
BUN levels would be HIGH
What are BCAAs most commonly taken up and used by?
muscle
What is maple syrup urine disease?
*defect in one of the proteins in the branched-chain ketoacid decarboxylase complex *inability to catabolize isoleucine, *leucine*, valine *clinical manifestations include seizures, acidosis, coma, and death
What are endogenous proteins?
*desquamated mucosal cells & digestive enzymes
What is the function of phosphocreatine?
*functions as a storehouse for high energy phosphate *phosphocreatine replenishes ATP in muscle that is contracting *this can help preserve muscle glycogen stores
Amino Acid carbon skeletons can be used for?
*glucose production *fatty acid synthesis *energy production *ketone bodies
What are the storage forms for glucose and for lipid?
*glucose storage form: glycogen *lipid storage form: triaglycerol
What would be recommended for an individual with early stage vs advanced renal failure?
*in early stages a low protein would likely be recommended *advanced renal failure dialysis would be necessary to remove urea nitrogen
What is the glucose-alanine pathway?
*in fasted/catabolic state glutamate will transfer its amino group to pyruvate to form a-ketoglutarate *alanine is released into blood & travels to liver *once alanine is in the liver it undergoes transanimation back to pyruvate- which is used to make glucose *glucose is released into the blood where it can be taken up and used by muscles *muscles cells can use the glucose through glycolysis and generate pyruvate *pyruvate can be used by transamination to reform alanine
What can lead to hepatic encephalopathy and how is it treated?
*increased nitrogen levels *treated by targeting GI tract to promote ammonia diffusion and by promoting the colonic bacteria to DECREASE ammonia production
What occurs during deamination of AA?
*involves the removal of an amino group with NO transfer to another compound *amino group is released as AMMONIA and is converted to AMMONIUM and is taken to the liver to be cleared
What is transthyretin?
*pre-albumin & retinol binding protein *indicators of visceral protein status *half life of 2 days and 12 hours
What is histamine?
*synthesized from histidine *mediates attention and alertness
What is serotonin?
*synthesized from tryptophan * an excitatory neurotransmitter & potent vasocontrictors *affects sleep, mood, appetite, & cognitive functions
What is catecholamines?
*synthesized from tyrosine *dopamine helps coordinate movement (disregulation causes tremors in parkinsons) *norepinephrine is important for alertness and sleep *epinephrine functions as hormone with effects on nutrient metabolism
What are incomplete proteins?
*tend to have too little of one or more essential AAs (limiting AA) *most plant-based proteins are incomplete protins
What would you expect for BUN levels during liver disease?
BUN has decreased levels & ammonia levels are high
True/False: nonessential AA are absorbed faster than essential AA
FALSE- essential are absorbed faster than nonessential
True/False: the urea cycle is an energy producing process
FALSE- it is an energy CONSUMING process
True/False: Transamination reactions are important for essential AA synthesis.
FALSE- transamination is important for NON ESSENTIAL synthesis
True/False:Advanced liver disease results in increased urea synthesis
FALSE0 advanced liver disease results in DECREASED urea synthesis
True/False: AA catabolism generates a significant amount of ammonia
TRUE
What are the 9 essential amino acids?
PVT TIM HLL 1. Phenylalanine 2. Valine 3. Threonine 4. Tryptophan 5. Isoleucine 6. Methionine 7. Histidine 8. leucine 9.lysine
True/False: 24 hour urinary creatine secretion is compared against a standard based on height * a value of 60-80% of standard suggest moderate skeletal muscle depletion *40-59% suggest moderate skeletal muscle depletion *<40% is considered a SEVERE loss of skeletal muscle
TRUE
What is BCKAD?
a large mutlienzyme complex that requires cofactors: thiamin, niacin, magnesium, and panthoenic acid
What does deamination produce?
a-keto acid
What is a conditionally essential amino acid?
aa can become conditionally essential if an essential AA is limiting (not getting in diet) or if the metabolism of an essential AA is impaired
How are the majority of AA absorbed?
absorbed as peptides
What is kwashiorkor?
adequate consumption but insufficient protein intake
What is sarcopenia?
age-related loss of muscle mass and function
What are the major categories for sources of amino acids?
animal products, plant products, endogenous proteins
What percentage of animal proteins are digestible? What about plants?
animal proteins ~90-99% plant proteins ~70-90%
What does muscle preferentially catabolize?
aspartate, asparagine, glutamate, leucine, isoleucine, & valine
Where does AA interdependence of organs begin?
beings with intestinal cells because they are the first cells in the body to receive dietary AAs
How would hypoglycemia be the primary concern with both carbohydrate disorders and fatty acid disorders of metabolism?
blood glucose levels drop because glycogen isn't being broken down anymore
Why is both too much and too little protein a major concern with urea cycle disorders?
both would result in increased nitrogen accumulation
What occurs during the catabolism of branched-chain a-keto acids?
branched-chain a-keto acids are catalyzed by branched-chain a-keto acid dehydrogenase (BCKAD)
What is glutamate dehydrogenase?
can use ammonium ion & a-ketoglutarate to make amino acid glutamate
What is glutamine sythetase?
can use an ammonium ion and glutamate to make the amino acid glutamine
In a _________ state, glucagon levels increase, and there is a net breakdown of protein.
catabolic
What occurs during amino acid catabolism?
catabolism of skeletal muscle contributes gluconeogenic substrates made available to the liver to synthesis & export glucose to maintain plasma glucose levels during periods of fasting
What is marasmus?
chronic reduced access to food
Within the first 3 hours after consuming a cholesterol containing meal, which lipoprotein will be transporting the majority of the dietary cholesterol?
chylomicrons
What are neurotransmitters?
compounds generated in the body that transmit signals from a neuron to a target cell across a synapse
What is the most likely fate of alanine during a fasted or catabolic state?
converted to pyruvate for glucose production
What are the functional roles of protein?
enzymes, hormones, structural elements (actin & myosin in skeletal muscle and fibrous proteins (collagen in skin, bones, and teeth)), buffers, fluid balancers, immunoprotectors, transporters
What scenario would creatinine levels not be contraindicated for use as an indicator of muscle mass?
extremely fit individuals
What are the preferred energy substrate at rest?
fatty acids
Where is glutamine formed and where does it go after formation?
formed in the muscle and released into the blood for transport & is used by other muscles
What is body comp influenced by?
gender, age, race, and genetics
Infection or trauma significantly increases the use of which amino acid?
gluatmine
What hormones promote muscle protein catabolism?
glucagon, epinephrine, and cortisol
Histidine is transanimated to a-ketoglutarate and is thus described as a _________?
glucogenic amino acid
What is the primary source of energy for intestinal cells?
glutamine
What is glutamine used for in extrahepatic tissue (like skeletal muscle)?
glutamine is used for ammonia transport
What are the functional roles of nitrogen-containing nonprotein compounds?
glutathione, carnitine, carnosine, choline, purine & pyrimidine bases, creatinine
What AA act directly as neurotransmitters?
glycine, taurine, aspartate, glutamate
What are examples of plant product amino acid sources?
grains, legumes, nuts, & seeds
Which protein is an indicator of iron status in the blood?
hemoglobin
Which disease state is caused by increased blood nitrogen levels?
hepatic encephalopathy
An individual on an extremely high protein diet would likely have ________ BUN levels.
increased
What would be recommended for someone in negative nitrogen balance?
increased carbohydrate and protein intake
What increases protein synthesis?
ingestion of food and physical activity
What hormone typically increases protein synthesis?
insulin
To maximize AA uptake would administration of individual amino acids or intact proteins be more effective?
intact proteins
What is transamination of AA?
involves the transfer of an amino group from one AA to an a-keto acid (amino acid carbon skeleton)
What is an example of a clinical scenario in which the urea cycle might be impaired?
kidney failure, liver failure,
What organ is responsible for ridding the body of nitrogenous waste that would otherwise accumulate in plasma?
kidneys
What is renal failure?
kidneys failure in which kidneys lose the ability to remove waste and balance fluids
What occurs once creatinine is formed?
leaves the muscle and is excreted in the urine
Elevated levels of alanine aminotransferase (ALT) would indicate damage to which organ?
liver
What are common causes for decreased BUN levels?
liver failure, positive nitrogen balance, and in pregnant women
Urea is formed in the _______ and removed by the ________
liver; kidney
What dietary recommendations might you make to restore a patient's elevated creatinine levels back to normal?
low protein diet
What are examples of animal product amino acid sources?
meat, poultry, fish, eggs, & dairy
If an individual takes in 65 g protein, has a UUN output of 9.9 mg/ml, and a 24 hour urine volume of 1,000 ml would they be in positive or negative nitrogen balance?Remember, nitrogen status = Nitrogen intake - UUN + 4 g
negative
The primary function of the urea cycle is to remove __________ from the body?
nitrogen
What does a-keto acid help remove?
nitrogen
Where does AA absorption primarily occur?
occurs primarily in the duodenum and jejunum
In which form are the majority of amino acids absorbed?
peptides- more rapid as well
During pregnancy, nitrogen balance should be __________?
positive
during pregnancy nitrogen balance should be ________?
positive
What is the end product of protein digestion?
primarily large poly peptides along with some oligopeptides and free amino acids which are emptied into the small intestine
What formula do you use to convert grams nitrogen into grams protein?
protein (g)= nitrogen (g) x (100/16) OR protein (g)= nitrogen(g) x (6.25)
What are common causes for increased BUN levels?
renal disease, excessive protein catabolism
What is the primary therapeutic treatment for an individual with an amino acid disorder?
restrict intake of the problematic amino acid
What are urea cycle disorders?
results in impaired capacity of the body to excrete nitrogen in the form of urea
In which of the following scenarios would urinary creatinine secretion would be elevated?
sepsis
What AA act as biogenic amines?
serotonin, catecholamines, and histamine
Though most AAs are taken up and catabolized by the liver, branch chain AAs are taken up by ___________ ?
skeletal muscle
What does glutamine stimulate?
stimulates mucosal cell proliferation
Protein digestion begins in the _____ via the action of ________
stomach; HCl
What forms creatinine?
the cyclization of creatine and phosphocreatine forms creatinine
What is the main site for essential AA catabolism?
the liver
What is the primary site for most amino acid uptake?
the liver
Where does the urea cycle function?
the liver
Primary storage form of amino acids in the body?
there is not storage form of AA in the body
What occurs when peptides are taken into the intestinal cells?
they are broken down to free amino acids which are then released into the blood