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What is "Recommended Dietary Allowances (RDA)"?
RDA provides the amount of various nutrients that will provide satisfactory nutrients for 97.5% of the population in designated age and sex groups (two standard deviations above the average requirements).
What is "Dietary Reference Intake (DRI)"?
Revised RDA values intended to also prevent chronic disease. Includes EAR, UL, and AI
What is "Adequate Intake (AI)"?
The amount that appears to sustain good health in a group of people
What is "Estimated Average Requirement (EAR)"?
The nutrient update that will meet the needs of 50% of the population in a specific age and sex group.
What is "Tolerable Upper Intake Level (UL)"?
The highest level of a nutrient that is likely to pose no risk of adverse health effects in 98% of a population
What is the relationship between EAR, RDA, and UL?
What is Primary malnutrition?
Malnutrition due to a poor diet or lack of food
malnutrition due to reasons other than poor diet (ie, absorption problems)
Dangers of overnutrition:
Overnutrition can lead to toxicity and result in suboptimal function
What is a calorie?
- The energy needed to raise 1 gram of water 1 degree Celsius.
- 1Kcal = 1 Cal = 1000 cal = 4.18 kj (kilojoules)
define respiratory quotient
- RQ = Volume CO2 produced / volume of O2 consumed
- Carbs: 1
- Protein: 0.8
- Fats: 0.7
How to determine the energy from each food source using the respiratory quotients
- 1) Determine the amount of nitrogen excreted.
- 16% of protein is nitrogen, so we can use the nitrogen values to determine how much protein was used. N x 6.25 = amount of protein.
- 2) Determine the amount of CO2 and O2 from protein.
- We know that we get 4 Kcal/g of protein, consume 1 liter of O2 per 4.5 Kcal, and produce 1 liter CO2 per 5.6 kcal. Subtract the O2 and CO2 to determine the amount of non-protein CO2 and O2 (non-protein RQ or NPRQ).
- 3)Use carb RQ = 1 and fat RQ = 0.7 to determine the amount of each.
- 1 x + 0.7 y = NPRQ (x + y) -> determine the ratio of fat to carbs
How does direct calorimetry work?
- Direct calorimetry involves combusting food in a calorimeter and determining how much heat was released. This measures the inherent energy released through
- This yields the following
- Carbohydrates: 4 kcal/g,
- protein: 4 kcal/g,
- fat: 9 kcal/g,
- alcohol: 7 kcal/g
How does indirect calorimetry work?
- Indirect calorimetry is performed by measuring the oxygen consumed, CO2 produced, and the nitrogen eliminated.
- carb: 5.0 kcal/liter O2
- protein: 4.5 kcal/liter O2
- fat: 4.7 kcal/liter O2
What are the 3 Major energy expenditures of the human body?
- 1) Basal metabolism (50%-70% of Total Energy Expenditure, TEE) - measured just after waking up (it is 10% lower if asleep). On average, BMR = 1.0 kcal/hour/kg (males) or 0.9 (females)
- Resting basal metabolism (RBM) can also be used for calculations. It is 10% higher than BMB.
- 2) Physical activity (15%-30% of TEE)
- 3) Thermic effect of food (10% of TEE - the energy required to process food)
How to calculate daily energy needs
- 1) Determine BMR for 24 hours, including a 10% decrease for sleep
- 2) Determine the energy requirements for activities, and add that to the BMR
- 3) Correct for thermogenesis (10% - times by 1.1)
Describe classical conditioning
An unconditioned or neutral stimulus (bell ringing) can be connected to a conditioned or natural stimulus (meat), causing a neutral stimulus to produce a conditioned response (dog salivates).
Describe systematic desensitization
- A behavioral therapy that consists of
- 1) Teaching the patient an incompatible response to a fear (ie, deep relaxation),
- 2) create an anxiety hierarchy (what causes a little anxiety, what causes a lot?),
- 3) slowly expose the patient to items higher and higher on the hierarchy while using an incompatible behavior.
Challenges of desensitization
- Controlling exposure: In the event that the stimulus isn’t able to be presented slowly (ie, flight phobia, traumatic experience), a simulation or re imagining the event can be used instead.
- Identifying the focus of fear: For panic attacks, the trigger may be something besides location or crowds. It could be the patient noticing a faster heartbeat and expecting a panic attack.
- Timing the exposure: Too brief of an exposure won’t help
- Making the exposure sufficiently challenging: ie, simulate a dance AND have the date break up with the patient halfway through.
What is operant conditioning?
A type of learning in which an individual's behavior is modified by its consequences.
What are the motivating forces in operant conditioning?
- Positive reinforcement: Increase behavior by applying rewards
- Negative reinforcement: Increase behavior by withdrawing negative consequences (ie, nagging)
- Punishment: Decrease behavior by applying aversive consequences
- Extinction: Decrease behavior by withdrawing positive consequences (ie, withdrawing attention, as in ferberizing)
Challenges of operant conditioning
- Shaping: You must reward progress, not perfection.
- Frequence of consequences (at least for positive reinforcement): praise less and less until no praising is needed.
- Timing of consequences: A close temporal link between the behavior and consequence is needed.
- Clarity of consequences: Are you clear about what you are praising?
What causes atrophy?
- Decreased functional demand
- decreased oxygen
- decreased trophic stimulation (ie, cut nerve, missing hormones)
- persistent cell injury
What are the results and causes of hypertrophy
- Increased cell or organ size, increased functionality.
- Causes: mechanical stress, growth hormones, and agonists to induce signal transduction
What are the essential amino acids?
- PVT TIM HALL
What are Complete, partially complete, and incomplete proteins?
- Protein sources can contain everything needed to maintain life and growth, or only a subset.
- Complete: Life and growth.
- Partially complete: Life, not growth.
- Incomplete: Neither
What is a chemical score?
The chemical score of a food source is the lowest score from all the amino acids (the limiting amino acid) where the score for each amino acid is calculated as...
(mg of essential amino acid per gram of test protein / mg of essential amino acid per gram of egg protein) x 100%
What is the protein digestibility corrected amino acid score (PDCAAS)?
Similar to chemical score, but is instead based on the needs of someone in the 2-5 year age group.
- = lowest value of…
- mg of essential amino acid in 1 g of test protein / mg of EAA in 1 g of protein requirement pattern.
1.0 is the highest allowed value, so anything above 1 is considered 1
What are the cause and effect of Kwashiorkor?
Kwashiorkor occurs when sufficient calories, but insufficient protein (especially essential proteins), are consumed.
It causes edema and extended abdomen, mental apathy, changes in skin and hair pigmentation, retarded growth, muscle wasting, and high mortality. It often progresses quickly, killing within weeks.
What are the cause and effect of marasmus?
Marasmus (“wasting”) is a protein-calorie malnutrition that results in wasting away of fat and muscle. Mental alertness and appetite remain. Mortality is usually low. The disease may not become severe for years.
What is the sparing effect?
- High amounts of some nutrients spare other nutrients that are used to make the other.
- Ie, if A->B, and we have high amounts of B, A is not needed and is spared. So, ingesting non-essential amino acids can help spare essential amino acids since less will be converted.
- Cystine or Cysteine spares methionine, Tyrosine spares phenylalanine, carbohydrates spare protein.
What are complementary proteins?
Two protein sources that are deficient in different areas can be taken together to mimic a better protein source that has no deficiencies. ie, beans and wheat.
What is the biological value?
- The percentage of absorbed amino acids retained for protein synthesis during growth. This provides a measure of what happens to protein in the body.
- BV = protein retained / protein retained or urinated.
- This requires taking a baseline for nitrogen excretion when no protein is digested.
What is Net protein utilization (NPU)?
NPU =Protein retained / protein ingested
What is the Protein efficiency ratio (PER)?
Weight gain / weight of protein ingested
What is Digestibility?
Digestibility: = (N ingested - (fecal N -fecal N0)) / N ingested
What hereditary enzyme defects respond favorably to treatment with vitamin mega doses?
The defects, which result in an increased Km for the substrates
Vitamin B12 is required as a coenzyme for the synthesis for which amino acid?
What amino acid is the precursor for heme synthesis?
Large amounts of the artificial sweetner aspartame should be avoided in children who have which metabolic disorder?
Serotonin is synthesized from which of the following amino acids?
Asp and Asn are synthesized from what CAC intermediaries?
What enzyme is deficient in cystathioninuria?
What change suggests the presence of a defective enzyme?
Accumulation of the substrate(s) and the toxic metabolic intermediaries, which are derived from the substrate(s) of the defective enzyme
What two ketogenic amino acids cannot be used for glucose synthesis?
Leucine and lysine
What metabolite is accumulated in homocysteinuria?
A 60 year old male complains of headaches and loss of muscular coordination. His blood values for hemoglobin are 12.1 g/dL (normal, 13.5-17.6 g/dL); urinary ALA is 18.9 mg/24hr (normal, 1-7 mg/24hr). What metal ion has he been poisoned by?
What enzyme is deficient in homocysteinuria?
Homocysteinuria cases improve upon treatment with mega doses of what vitamin?
What enzyme has normal catalytic activity in BH4 deficiency?
The production of what nitrogen-containing compounds is reduced in phenylketonuria?
What compound is produced by NOS from arginine?
Liver biopsy analysis from a child with a severe form of PKU showed a modest decrease in phenylalanine hydroxylase and dihydrobiopterin synthetase activities but no detectable dihydropteridine reductase activity. What might be the cause of this severe disease?
BH4, which is required by Phe, Tyr and Trp hydroxylases, is not available.
The production of which metabolite is reduced in cystathioninuria?
Pyruvate is a keto acid and the precursor for the synthesis of which amino acid?
What enzyme is induced by phenobarbital, requires PLP for its activity, and is the rate-limiting enzyme in heme synthesis?
How is heme formed, and what disease can be caused by a deficient pathway?
Explain how 9 of 11 non-essential amino acids can be synthesized from a single cycle.
Describe 3 transamination reactions
How does asparagine synthesis work?
How is glutamine synthesized?
How is proline synthesized?
How are serine, glycine, and cysteine synthesized?
How is arginine synthesized?
How is tyrosine synthesized?
How is phenylalanine removed from the body?
How can methionine and cysteine be formed from homocysteine?
How is creatine phosphate made?
Describe the synthesis and effects of histamine
Describe the synthesis and effects of serotonin
How are dopamine, norepinephrine, and epinephrine made?
How is nitric oxide (NO) formed?
List some of the cellular functions of mitochondria
- Protein synthesis (mitochondria produce 13 enzymes for oxidative phosphorylation, 2 rRNAs, and 22 tRNAs)
- Translocase of the outer membranes (TOM complexes)
- Transolcase of the inner membranes (TIM complexes)
- Oxidative phosphorylation
Compare the features and functions of the outer membrane, inner membrane, intermembrane space, and the matrix of mitochondria
- Outer membrane: (6-7 nm thick) is in contact with the cytosol and contains voltage-dependent anion channels (aka mitochondrial porins, 3nm wide) that are permeable to uncharged molecules as big as 5,000 daltons.
- Inner membrane: contains the matrix and is arranged into cristae (folds). rich in the phospholipid cardiolipin, which makes the membrane impermeable to ions. The inner membrane is lined with elementary particles (tennis racquet shaped enzymes that are involved in oxidative phosphorylation).
- Intermembrane space: contains creatine kinase, adenylate kinase, and cytochrome c
- The matrix: contains the soluble enzymes of the citric acid cycle (kreb’s cycle), the enzymes for fatty acid ß-oxidation, mitochondrial DNA, ribosomes, and tRNAs. The products of the matrix are C02 and reduced NADH. The matrix also contains matrix granules which hold divalent and trivalent cations (ie, Ca2+)
What protein in the intermembrane space is associated with cell death?
Cytochrome c causes cell death (apoptosis) when released from the intermembrane space into the cell cytoplasm. This is regulated by the Bcl-2 protein family
How does ATP get from the matrix into the cytoplasm?
An ATP/ADP exchange protein in the inner membrane (voltage-dependent anion channel?)
Where in the generation of ATP by mitochondria is oxygen (O2) involved?
Oxygen is reduced to H2O as the final oxidizer
What molecules maintain the electrochemical proton gradient?
- Complex I (NADH dehydrogenase) [-4H] ->
- Coenzyme Q ->
- Complex III (cytochrome b-c1) [-4H] ->
- Complex IV (Cytochrome oxidase) [-2H].
- ATP synthase [+H, -ADP, +ATP]
What is the relationship between the electron transport system and ATP synthase?
The electron transport system creates a large proton motive force. As H atoms move through the ATP synthase enzyme, chemiosmotic coupling occurs and the energy is used to phosphorylate ADP into ATP.
How much nitrogen is lost in fecal matter and urine?
For an intake of 80 g of protein (average daily American intake), 10 grams are excreted in fecal matter, and 70 grams are excreted in urine.
What is the path of dietary proteins? Include the location, proteins, and enzymes
Dietary protein -> (Stomach: Pepsin) -> polypeptides and amino acids -> (Pancreas: trypsin, chymotrypsin, elastase, carboxypeptidases) -> oligopeptides and amino acids -> (small intestine: aminopeptidases) -> amino acids, di- & tripeptides
What is transcytosis?
- When an object is transported across the membrane by enveloping the object in a membrane bubble that is the reabsorbed when the object exits to the other side.
- This is demonstrated when immunoglobins are absorbed by infants to gain passive immunity.
What is Hartnup disease? How is it diagnosed and treated?
- Defect in the transport system of neutral and aromatic amino acids, causing pellagra-like symptoms (dermatitis, diarrhea, dementia).
- It is diagnosed by finding tryptophan degradation products (indoles, kynurenine, and serotonin) in the urine. Nicotinamide is also reduced.
- It is treated with a niacin supplement.
What is Cystinuria?
- A defect in the absorption of arginine, lysine, ornithine, and cystine from the gut and renal tubules, causing cystine stones and infections.
- It is treated with penicillamine and fluids.
Name the enzymes that cut C-N amino bonds, and specify what proteins they cut.
- Pepsin: hydrophobic amino acids (Phe, Tyr, Leu)
- Trypsin: basic amino acids (Arg, Lys)
- Chymotrypsin: Hydrophobic (Phe, Tyr, Trp, Leu, Met)
- Elastase: small amino acids (Ala, Gly, Ser)
- Carboxypeptidase A: hydrophobic
- Carboxypeptidase B: Basic
What is the difference between endo and exo peptidases?
Exopeptidases cleave terminal amino acids, endopeptidases cleave internal peptide bonds.
How are the digestive zymogens activated?
- Trypsin activates the pancreatic zymogens for chymotrypsinogen, trypsinogen, proelastase
- Trypsin is also activated by enterokinase
What is Glutathione (Gsh)?
A powerful antioxidant that counteracts the effects of free radicals
What is Glutathionuria?
A deficiency in gamma-GGT (diagnosed through excess glutathione in the urine and blood), causing hemolytic anemia, mental retardation, peripheral neuropathy, ataxia.
What is Oxoprolinuria?
- A defect in glutathione synthetase, glutamylcysteine synthetase, or 5-oxoprolinase.
- It causes acidosis, hemolytic anemia, electrolyte imbalance, jaundice, CNS symptoms.
- Diagnosed by mass-spec analysis of 5-oxoproline.
How is nitrogen removed from the body?
- Glutamate is converted to α-ketoglutarate, producing ammonium.
- Ammonium is then combine with glutamate (by glutamine synthetase) to form glutamine.
- The glutamine is transferred to the liver and lysed by glutaminase to form glutamate and ammonium which is converted to urea and excreted in the urine.
Net change in the urea cycle:
NH4 + Aspartate + CO2 + 3 ATP -> Urea + fumarate + 2 ADP + 2 Pi + AMP + PPi
What is Hyperammonemia?
Elevated blood ammonia due to a defect in liver function failing to detoxify ammonia, resulting in tremors, slurring of speech, blurring of vision, and in extreme cases coma or death.
What happens when you remove an amino group from an amino acid?
A keto acid is formed (ie, alanine -> pyruvate)
What is Argininemia?
Genetic hyperammonemia due to a defect in arginase
What is Argininosuccinicaciduria?
Genetic hyperammonemia due to a defect in Argininosuccinate lyase
What is Citrullinemia Type I?
A mutation in the argininosuccinate synthase gene leading to ammonia accumulation in the blood, causing lethargy, seizures, and ataxia
What is Citrullinemia Type II?
Defect in solute carrier family 25 gene causing dysfunction in citrin synthesis, ammonia, and other toxic material build up.
What does carnitine do?
Carnitine is involved in the transport of long chain fatty acids from the cytosol into mitochondria
What is oxaloacetate?
An intermediate of the citric acid cycle and gluconeogenesis. It reacts with Acetyl-CoA to form citrate.
What is the role of white adipose tissue?
- Metabolic energy storage, insulation, cushioning, hormone production, source of metabolic water.
- Differentiates in response to PPAR-gamma/RXR.
- Contains few mitochondria.
- Lipid formation is decreased during cold weather so lipolysis can occur
What is the role of brown adipose tissue?
- Heat production (thermogenesis) in response to UCP-1 (uncoupling protein, which uncouples beta-oxidation from ATP synthesis) and the sympathetic nervous system.
- Differentiates throughout life in response to PRDM16/PGC-1.
- Contains many mitochondria.
- Cell differentiation increases during cold weather.