8/23/17 Flashcards
(37 cards)
Classical conditioning
Neutral stimulus (CS) paired with unconditioned stimulus (UCS)
UCS elicits a natural response (UCR)
Eventually CS will elicit a conditioned response (CR), which is often similar to the UCR
Operant Conditioning
Learning due to environmental contingencies of reward and punishment
Positive reinforcement: applying rewards makes behavior more likely to occur
Negative reinforcement: withdrawing aversive consequences makes behavior more likely to occur
Punishment: applying aversive consequences makes behavior less likely to occur
Extinction: withdrawing positive consequences makes behavior less likely to occur
Challenges of Operant Conditioning
Shaping: progress, not perfection
Frequency of consequences (at least for positive reinforcement): continuous reinforcement to acquire, intermittent reinforcement to maintain (fading reinforcement)
Timing of consequences: close temporal link between behavior and consequence
Clarity of consequences
Clinical Application of Operant Conditioning
Feeding disorder of infancy or early childhood
Counts of Disease Frequency
Can’t be compared since can be from pop. of different sizes
Good if single count is useful for public health (Ebola) or for allocating resources
Ratio for Disease Frequency
Shows the relative size of two values/groups
Proportion of Disease Frequency
Ratio in which the numerator is a subset of the denominator
Rate of Disease Frequency
Like proportion but during some period of time
Contain counts of disease frequency, size of pop. at risk, and a time period
Incidence
Cumulative incidence
Incidence rate (density)
Frequency of new cases over time period, measures the appearance of diseases
Cumulative: risk of getting a disease, usually used in fixed pop. but most dynamic so bad measure # new cases / # originally at risk (over certain time)
Rate: # of new cases / sum of disease free person-time over a certain time period
Point prevalence vs. Period prevalence
Point: # of existing cases / total pop. At a specific point in time
Period: (# of existing cases + # of cases that occur during the interval) / pop. at midpoint of interval or the average pop. size
Both are proportions
Relationship between prevalence and incidence
Prevalence is similar to incidence * disease duration (P=ID)
I~P if short disease duration
Prevalence higher than incidence if chronic disease
Measure incidence if care about etiology
Protein turnover
Total flux through protein synthesis and degradation
Conversion of AA pool into protein and breakdown of protein into the free AA pool
AA precursors for N-containing compounds
Cys to taurine to bile salts
Tyr to thyroid hormones, melanin, catecholamines (NE, epi, dopamine)
Gly to heme, purines, creatine, bile salts
Nitrogen balance
Nitrogen ingested - nitrogen excreted
At eq.: you intake 100 mg/kg/day of nitrogen or 600 protein
Positive: anabolic state to build mass, plateaus, normal growth, athletes, increased protein translation from free AA pool
Cachexia
Negative nitrogen balance that accompanies chronic diseases like cancer, renal diseases, severe burns, and septicemia
Rapid weight loss of 5-20%, high catabolic state that leads to muscle loss
Need nutritional supplementation since normal nitrogen diet is still negative nitrogen balance, also use stimulation of anabolism through steroids
Protein turnover accelerated from inflammatory process
Reductive amination
Glutamate-dehydrogenase with any aminotransferase can form any non-essential AA except Tyr/Cys given the proper alpha-keto acid and ammonia source
Phenylketonuria
Phe is converted to Tyr by phenylalanine hydroxylase
PKU has mutated Phe hydroxylase or enzymes in tetrahydrobiopterin (it’s cofactor)
Avoid Phe in diet and supplement with Tyr, avoid aspartame
Homocystinuria
Recessive, deficiency in gene for cystathionine beta-synthase
Accumulate homocysteine and Met
Free sulfhydrl of of homocysteine disrupts collagen cross linking and leads to premature atherosclerosis, strokes, heart stacks, vascular disease, ectopia lentis, and mental retardation
Avoid Met in diet and supplement with Cys
Cys becomes conditionally essential
Cystathioninuria
Recessive, Cys becomes essential AA
Cystathionine accumulates, is more benign since Met and homocysteine levels are more normal
Asparagine synthetase
Requires ATP
Adds NH2 to Asp to make Asn, also Gln becomes Glu by losing an NH2
Acute lymphonic leukemia
Accumulate immature lymphocytes in blood, they lack aspargine synthetase and Asn becomes an essential AA
L-asparaginase hydrolyzed Asn to Asp in the plasma conc. and deprive lymphoblasts only source of Asn, lymphoblasts do apoptosis
Most abundant AA in plasm
Gln which is made by glutamine synthetase from Glu
AA absorption
Active transport that requires Na+ in the small intestines
Transporters:
- Small neutral
- Large neutral
- Basic
- Acidic
- Proline
AA imbalance even if get min cuz competition at transporters
Go to liver via hepatic portal vein and then transported in the blood
Essential AA
PVT TIM HALL
Arg and His are not as essential
Can’t be made in human body and need from diet
Conditional essential AA if have like PKU
