Muscle Physio II

Question 1

When do Muscle Fibers adapt?

Answer 1

Considerably in response to demands placed on them

Question 2

What are the Types of Muscle Fiber Adaptations?

Answer 2

1. Muscle Hypertrophy

2. Muscle Atrophy

Question 3

Describe Muscle Hypertrophy.

Answer 3

Anaerobic Hi intensity resistance training; Increase Myosin and Actin filaments; Influenced by Testosterone; Interconversion between Fast muscle types

Question 4

Describe Muscle Atrophy.

Answer 4

Disuse, denervation, aging; Limited repair of muscle (limited stem cells: satellite cells)

Question 5

What are Whole Muscles?

Answer 5

Groups of Muscle Fibers bundled together and their tendons attached to bones

Question 6

When and where is Muscle tension produced?

Answer 6

As the contractile component tightens the series-elastic component; produced internally within sarcomeres

Question 7

What system do the interactive units of skeletal muscles, bones and joints form?

Answer 7

Lever system (Bones: Levers, Joints: Fulcrum, Skeletal Muscle: Force)

Question 8

What are the Primary Types of Contraction?

Answer 8

1. Isotonic: Constant load, muscle change
2. Isokinetic: Constant velocity, muscle fibers shorten
3. Isometric: Constant muscle length, tension increases
4. Concentric: Muscle shortens
5. Eccentric: Muscle lengthens

Question 9

What skeletal muscle does not attach to bones at both ends but still produce movement?

Answer 9

Tongue muscle

Question 10

What is the Load-Velocity relationship?

Answer 10

Velocity of shortening related to loud

Question 11

What is most of the energy converted to when muscles contract?

Answer 11

Heat

Question 12

What are the 2 primary factors that can be adjusted to produce graded contractions?

Answer 12

1. No. of muscle fibers contracting

2. Tension developed by each contracting fiber

Question 13

What are the factors affecting the Contraction?

Answer 13

1. Extent of Motor Unit Recruitment (No. of fibers contracting within muscle)
2. Frequency of Stimulation, fiber length and thickness, extent of fatigue (Tension developed by each muscle fiber)

Question 14

What is Twitch Summation?

Answer 14

Increase in tension accompanying repetitive stimulation of a muscle fiber

Question 15

What is Tetanus?

Answer 15

Smooth, sustained contraction of max strength

Question 16

What does Twitch Summation result primarily from?

Answer 16

Sustained elevation in cytosolic Ca2+ (muscle fiber restimulated before complete relaxation)

Question 17

When does Tetanus occur?

Answer 17

Muscle fiber stimulated so rapidly that it cannot relax at all between stimuli

Question 18

What happens after Tetanus?

Answer 18

Stimulation stops or fatigue sets in

Question 19

How do Muscles respond to Stimulus Strength?

Answer 19

Strength of contractions increase with strength of stimulus until max contraction

Question 20

When can Max Tension be developed?

Answer 20

At optimal Muscle Length

Question 21

What happens when muscle length is less than Optimal Muscle length?

Answer 21

Too much overlap in sarcomere

Question 22

What happens when muscle length is more than Optimal Muscle length?

Answer 22

Too little overlap in sarcomere

Question 23

Describe the Withdraw Reflex.

Answer 23

1. Thermal pain receptor in finger activated
2. AP generated in Afferent pathway; impulses propagated to spinal cord
3. Spinal cord = Integrating center:
   - Excitatory interneurons (biceps)
   - Inhibitory interneurons (triceps)
   - Interneurons ascending to brain
4. 2 efferent pathways to antagonistic muscles
5. Resultant flexion of elbow joint pulls hand away from stimulus
6. Events beyond reflex arc

Question 24

What do Muscle Receptors provide?

Answer 24

Afferent Info needed to control Skeletal Muscle activity

Question 25

Why does the CNS need continual info regarding ongoing changes in muscle length and tension?

Answer 25

For effective control of motor output

Question 26

What do Muscle Spindles monitor?

Answer 26

Muscle Length

Question 27

What do Golgi tendon organs detect?

Answer 27

Changes in tension

Question 28

What is the Stretch reflex?

Answer 28

Local -ve feedback mechanism to sense and resist changes in muscle length when an additional load is applied

Question 29

How is the Muscle Spindle structured?

Answer 29

Consists of collections of specialised muscle fibers (intrafusal fibers)

Question 30

What fiber is the secondary sensory endings?

Answer 30

Type II fiber

Question 31

What fiber is the primary sensory endings?

Answer 31

Type Ia fiber

Question 32

What does Alpha gamma coactivation contract?

Answer 32

Both intra and extrafusal muscle fibers

Question 33

Describe the process of an Unstretched Muscle.

Answer 33

AP generated at constant rate

Question 34

Describe the process of a Stretched Muscle.

Answer 34

Increased rate of APs due to activation of muscle spindle

Question 35

Describe the process of a Slack Muscle.

Answer 35

No APs are fired because only Alpha motor neurons are activated, contracting only Extrafusal muscle fibers; Unable to signal further length changes

Question 36

Describe the process of a Muscle maintained by muscle spindle tension.

Answer 36

Alpha-gamma coactivation: Both muscle fibers contract; Still can signal changes in length

Question 37

What type of tone is a single unit smooth muscle?

Answer 37

Myogenic (pacemaker and slow-wave potentials)

Question 38

How are Smooth Muscle contractions different from Skeletal Muscle?

Answer 38

- Modification of activity by ANS - Arrangement of Thick and Thin Filaments - Ca2+ dependent phosphorylation of myosin

Question 39

How is the Arrangement of Thick and Thin Filaments in Smooth Muscles?

Answer 39

No troponin; Tropomyosin does not cover actin

Question 40

What is the function of phosphorylated myosin?

Answer 40

Permits binding with actin

Question 41

Describe the characteristic of Smooth Muscle.

Answer 41

Can still develop tension yet inherently relaxed when stretched (Stress relaxation response); Slow and Economical (Latch phenomenon)

Question 42

Describe the features of the Cardiac muscle.

Answer 42

Clear length-tension r/s; Interconnected by gap junctions in intercalated discs; Innervated by ANS

Question 43

Where does Control of motor contraction by NS?

Answer 43

1. Motor cortex (Premotor and Primary) 2. Brain stem 3. Spinal cord 4. Cerebellum 5. Somatic and ANS (Somatosensory)

Question 44

What alterations occur during skeletal muscle hypertrophy and atrophy?

Answer 44

Myonuclear number (in conjunction with changes in myofibrillar protein content and CSA, resulting in a constant ratio of cytoplasmic area to nuclear number

Question 45

What is Sarcopenia?

Answer 45

Gradual muscle loss after the 4th decade of life

Question 46

Who does Sarcopenia mostly impact?

Answer 46

Males after the age of 50

Question 47

How much is the % of loss per year through inactivity?

Answer 47

1%

Question 48

Which type of fiber is more severely affected?

Answer 48

Type II

Question 49

What will loss of muscle protein affect?

Answer 49

Permanent; Affect activities of daily living and bone mass later in life; Affect Immune system, insulin absorption, blood sugar levels; Increase risk of type II diabetes

Question 50

What can the maintenance of muscle mass throughout life do?

Answer 50

Metabolic syndrome may be ameliorated

Question 51

What are the Causes of Sarcopenia?

Answer 51

- Motor neuron death - Changes in testosterone status - Changes in activity - Changes in protein metabolism rate - Mitochondria dysfunction