Lesson 5

Question 1

Describe the balance of proteins in muscle mass accretion.

Answer 1

protein anabolism&raquo_space; protein catabolism

Question 2

What are sources of free amino acids and its uses?

Answer 2

Sources: protein breakdown, blood, and de novo synthesis
Uses: muscle protein synthesis, released into blood, and participate in metabolic reactions –> oxidation

Question 3

What is the myonuclear domain theory?

Answer 3

-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

Question 4

Where do myonuclei originate?

Answer 4

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

Question 5

What is the function of myogenic regulatory factors?

Answer 5

part of the environment that influences satellite cells –> myoblast

Question 6

What is hepatocyte growth factor’s role in satellite cell –> myoblast?

Answer 6

HGF must bind to c-met receptor to activate satellite cell

Question 7

Muscle disruption increases…

Answer 7

strength, IGF-1 expression, MHC

Question 8

Where do we see most muscle disruption (in which muscle fiber type and contraction)?

Answer 8

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

Question 9

At what point does sarcomere tear apart?

Answer 9

at titin??

Question 10

Why are myonuclei important?

Answer 10

• mediate transcription and/or translation after muscle disruption
• source of additional protein

Question 11

What is the time course of elevation in muscle protein synthesis after an isolated bout of RT?

Answer 11

-6-12 hours post-exercise

Question 12

What is myostatin and its function?

Answer 12

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

Question 13

What are the two ways to increase muscle mass with follistatin and myostatin?

Answer 13

increase follistatin

decrease myostatin

Question 14

How does myostatin levels change with exercise and with age?

Answer 14

exercise: myostatin decreases
age: increases

Question 15

What is the hypertrophic pathway or insulin-signaling cascade also called? What is it?

Answer 15

PI3K-AKT-mTOR

up-regulation of protein synthesis and activated by exercise, insulin, androgens, and amino acids

Question 16

Describe the relationship b/w myostatin, satellite cells, and PI3K-AKT-mTOR.

Answer 16

myostatin inhibits IGF-A activation of satellite cells and inhibits the pathway
the pathway helps activate and proliferate satellite cells

Question 17

Define LBM

Answer 17

fat free mass and essential body fat

Question 18

What is the difference between overweight and overfat?

Answer 18

can have inc. muscle and dec. % fat and still be “overweight” in BMI standards or obese (>30)

Question 19

What is the difference in males and females in essential fat?

Answer 19

males: 2%
females: 7% for childbirth

Question 20

What is anthropometry and its adv/disadvantages?

Answer 20

girth measurements to determine relative fatness

• adv: determining patterns of fat distribution; cheap
• disadv: measurement error

Question 21

What do skin folds measure and its adv/disadvantages?

Answer 21

measures subcutaneous fat to predict body density through the equation

• adv: gives regional fat distribution
• disadv: 4-6% error

Question 22

What is bioelectrical impedance analysis? Adv/disadv?

Answer 22

• 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%

Question 23

What is the hydrostatic weighing measuring and adv/disadv?

Answer 23

• 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

Question 24

What is the gold standard for body comp?

Answer 24

DEXA

Question 25

What are reasons for classifying overweight and obesity?

Answer 25

• 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

Question 26

Why does dramatic caloric restriction ultimately lead to weight gain?

Answer 26

you decrease metabolic rate w/ decrease caloric restriction

Question 27

What is leptin? Absence of it means?

Answer 27

hormone in body weight responsible for how much on eats and E expended to regulate body weight
-absence: produces continual hunger and marked obesity

Question 28

What is diff b/w adipocyte hypertrophy and hyperplasia?

Answer 28

hypertrophy: existing adipocytes enlarge/fill with fat
hyperplasia: totally adipocyte number increases