HBIO 320 UNIT 3 EXAM QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS GRADED A++ LATEST UPDATE
What is muscle plasticity?
- Ability of muscle to alter its structural and functional properties in accordance to
environmental conditions imposed on it
What are principles of training adaptations?
- Progressive overload: System must be challenged for further adaptations
- Reversibility: Adaptations will be reversed when training is stopped
- Specificity: Effect of training is specific to the type of exercise performed
What is the basis for adaptation in muscle?
- Driven by changes in amounts of proteins
- Stress from exercise stimulates signaling pathways
- Activation of transcription factors
What environmental conditions can increase muscle protein synthesis?
- Increased protein ingestion
- Resistance exercise
- Combination of the two really increases protein synthesis
What environmental conditions can increase muscle protein degradation?
- Fasting/low insulin
- Not really influenced by protein intake
What environmental conditions can cause muscle lengthening?
,- Casting
- Chronic, high intensity and duration stretching
- Eccentric exercises (will affect fast twitch fibers first)
Where in the muscle does it tend to lengthen?
- Tends to lengthen near the tendon insertion point
Which fiber type is more responsive to lengthening?
- Slow twitch fibers
- Won't lengthen first but will have a greater response
Which fiber type is more responsive to shortening?
- Fast twitch fibers
- Gets taken back to stiffness baseline
Which muscles in the body are more responsive to lengthening?
- Postural leg muscles
When muscle is lengthened, which type of MHC class is added?
- Type 1 MHC
- Regardless of which type of fiber it is
What are the functional consequences of lengthening muscle?
- Decreased stiffness, increased flexibility
- Increased length of muscle at "optimal shortening length"
- Increased velocity of shortening, but not necessarily increase in power
How can muscle strength increase without increasing in muscle size?
- Increased neural drive
- recruitment of larger motor units
, - Increased AP frequency
- Increased motor unit synchronization
- Inhibition of GTO reflex
What stimuli are necessary to induce hypertrophy?
- Insulin or IGF-1
- Muscle tension/stretch detected by mechanoreceptors (drives second messenger
system)
mTOR
- Second messenger in hypertrophy pathway
- Anabolic kinase that increases protein synthesis and decreases protein degredation
- Stimulated by: RHEB, phosphatidic acid, BCAA (leucine)
What is the pathway of mTOR activation by Insulin/IGF-1?
1. Insulin/IGF-1 binds ti Insulin receptor on muscle
2. IR stimulates Insulin Receptor Substrate, phosphorylates P13K
3. P13K phosphorylates AKT
4. AKT phosphorylates TSC1&2, inhibits function
5. TSC stops its inhibition of RHEB
6. RHEB activates mTOR
What is the pathway of mTOR activation by Phosphatidic acid?
1. Stretch/tension is detected by mechanoreceptor Phospholipase D
2. PLD generates phosphatidic acid
3. PA activates mTOR
What is the pathway of mTOR activation by Leucine?
COMPLETE SOLUTIONS GRADED A++ LATEST UPDATE
What is muscle plasticity?
- Ability of muscle to alter its structural and functional properties in accordance to
environmental conditions imposed on it
What are principles of training adaptations?
- Progressive overload: System must be challenged for further adaptations
- Reversibility: Adaptations will be reversed when training is stopped
- Specificity: Effect of training is specific to the type of exercise performed
What is the basis for adaptation in muscle?
- Driven by changes in amounts of proteins
- Stress from exercise stimulates signaling pathways
- Activation of transcription factors
What environmental conditions can increase muscle protein synthesis?
- Increased protein ingestion
- Resistance exercise
- Combination of the two really increases protein synthesis
What environmental conditions can increase muscle protein degradation?
- Fasting/low insulin
- Not really influenced by protein intake
What environmental conditions can cause muscle lengthening?
,- Casting
- Chronic, high intensity and duration stretching
- Eccentric exercises (will affect fast twitch fibers first)
Where in the muscle does it tend to lengthen?
- Tends to lengthen near the tendon insertion point
Which fiber type is more responsive to lengthening?
- Slow twitch fibers
- Won't lengthen first but will have a greater response
Which fiber type is more responsive to shortening?
- Fast twitch fibers
- Gets taken back to stiffness baseline
Which muscles in the body are more responsive to lengthening?
- Postural leg muscles
When muscle is lengthened, which type of MHC class is added?
- Type 1 MHC
- Regardless of which type of fiber it is
What are the functional consequences of lengthening muscle?
- Decreased stiffness, increased flexibility
- Increased length of muscle at "optimal shortening length"
- Increased velocity of shortening, but not necessarily increase in power
How can muscle strength increase without increasing in muscle size?
- Increased neural drive
- recruitment of larger motor units
, - Increased AP frequency
- Increased motor unit synchronization
- Inhibition of GTO reflex
What stimuli are necessary to induce hypertrophy?
- Insulin or IGF-1
- Muscle tension/stretch detected by mechanoreceptors (drives second messenger
system)
mTOR
- Second messenger in hypertrophy pathway
- Anabolic kinase that increases protein synthesis and decreases protein degredation
- Stimulated by: RHEB, phosphatidic acid, BCAA (leucine)
What is the pathway of mTOR activation by Insulin/IGF-1?
1. Insulin/IGF-1 binds ti Insulin receptor on muscle
2. IR stimulates Insulin Receptor Substrate, phosphorylates P13K
3. P13K phosphorylates AKT
4. AKT phosphorylates TSC1&2, inhibits function
5. TSC stops its inhibition of RHEB
6. RHEB activates mTOR
What is the pathway of mTOR activation by Phosphatidic acid?
1. Stretch/tension is detected by mechanoreceptor Phospholipase D
2. PLD generates phosphatidic acid
3. PA activates mTOR
What is the pathway of mTOR activation by Leucine?
