Lesson 5 Flashcards
Describe the balance of proteins in muscle mass accretion.
protein anabolism»_space; protein catabolism
What are sources of free amino acids and its uses?
Sources: protein breakdown, blood, and de novo synthesis
Uses: muscle protein synthesis, released into blood, and participate in metabolic reactions –> oxidation
What is the myonuclear domain theory?
-increase the capacity of skeletal muscles to produce proteins by proportionally increasing number of myonuclei w/ hypertrophy, since each myonuclei responsible for its area’s protein synthesis
Where do myonuclei originate?
satellite cells are precursor cells proliferate into myoblasts and can help with muscle damage too by forming myotube or fusing with existing
–which is different from myonuclei b/c has basal lamina
What is the function of myogenic regulatory factors?
part of the environment that influences satellite cells –> myoblast
What is hepatocyte growth factor’s role in satellite cell –> myoblast?
HGF must bind to c-met receptor to activate satellite cell
Muscle disruption increases…
strength, IGF-1 expression, MHC
Where do we see most muscle disruption (in which muscle fiber type and contraction)?
3x’s more in Type IIb vs Type I (b/c Z-disc and M line are 1/2 thickness of Type I fibers)
more w/ eccentric contractions
At what point does sarcomere tear apart?
at titin??
Why are myonuclei important?
- mediate transcription and/or translation after muscle disruption
- source of additional protein
What is the time course of elevation in muscle protein synthesis after an isolated bout of RT?
-6-12 hours post-exercise
What is myostatin and its function?
negative regulator of muscle mass, so if decrease myostatin - increase muscle mass
–bound to follistatin naturally and can’t negatively regulate its activin receptor until released from follistatin
What are the two ways to increase muscle mass with follistatin and myostatin?
increase follistatin
decrease myostatin
How does myostatin levels change with exercise and with age?
exercise: myostatin decreases
age: increases
What is the hypertrophic pathway or insulin-signaling cascade also called? What is it?
PI3K-AKT-mTOR
up-regulation of protein synthesis and activated by exercise, insulin, androgens, and amino acids
Describe the relationship b/w myostatin, satellite cells, and PI3K-AKT-mTOR.
myostatin inhibits IGF-A activation of satellite cells and inhibits the pathway
the pathway helps activate and proliferate satellite cells
Define LBM
fat free mass and essential body fat
What is the difference between overweight and overfat?
can have inc. muscle and dec. % fat and still be “overweight” in BMI standards or obese (>30)
What is the difference in males and females in essential fat?
males: 2%
females: 7% for childbirth
What is anthropometry and its adv/disadvantages?
girth measurements to determine relative fatness
- adv: determining patterns of fat distribution; cheap
- disadv: measurement error
What do skin folds measure and its adv/disadvantages?
measures subcutaneous fat to predict body density through the equation
- adv: gives regional fat distribution
- disadv: 4-6% error
What is bioelectrical impedance analysis? Adv/disadv?
- estimates body water based on time it takes for electrical current to pass from electrodes (with faster conduction in water - in blood and muscle)
- from body water, body fat can be calculate
- -adv: easy
- -disadv: 3-5%
What is the hydrostatic weighing measuring and adv/disadv?
- compute body volume as difference b/w body mass in air and during water submission using Archimedes principle, so fat = less dense and will float
- a greater difference in mass in air and mass in water = increased % body fat and decreased body density
- adv: old gold standard
What is the gold standard for body comp?
DEXA
What are reasons for classifying overweight and obesity?
- provides meaningful comparisons of body weight status w/I and b/w populations
- IDs individuals/groups at inc. risk for morbidity
- IDs priorities for intervention
- establishes firm basis for evaluating intervention strategies
Why does dramatic caloric restriction ultimately lead to weight gain?
you decrease metabolic rate w/ decrease caloric restriction
What is leptin? Absence of it means?
hormone in body weight responsible for how much on eats and E expended to regulate body weight
-absence: produces continual hunger and marked obesity
What is diff b/w adipocyte hypertrophy and hyperplasia?
hypertrophy: existing adipocytes enlarge/fill with fat
hyperplasia: totally adipocyte number increases
