Exercise

Question 1

Fatigue =

Answer 1

decline in muscle tension due to previous contractile activity&raquo_space; impaired ability to maintain muscle tension (prevents onset of rigger)

Question 2

How can recovery be inadequate?

Answer 2

1. Conduction failure - build up of eternal K+ within tubes so AP failure
2. Lactic acid build up : associated with anaerobic glycolysis -> rate of lactate production exceeds rate of its disappearance -> acidification leads to conformational changes in muscle proteins
3. Inhibition of X-bridge cycling due to build of ADP and Pi

Question 3

How does slow -oxidative skeletal muscle respond to strenuous activity?

Answer 3

Slow -oxidative skeletal muscle responds well to repetitive tetanic stimuli without becoming fatigued; muscles of body posture are examples. Fatigue resistant

Question 4

How does fast-oxidative -glycolytic skeletal muscle respond to strenuous activity?

Answer 4

Fast-oxidative -glycolytic skeletal muscle responds quickly to repetitive stimulation, becoming fatigued slowly; muscles used in walking are examples. Intermediate capacity to resist fatigue. Slow recovery.

Question 5

How does fast- glycolytic skeletal muscle respond to strenuous activity?

Answer 5

Fast-glycolytic skeletal muscle is used for quick bursts of strong activation: muscles used to jump or to run a short sprint. Fatigue rapidly, Fast recovery .

Question 6

What type of control do smaller motor units allow?

Answer 6

Finer control of muscle tension

Question 7

Describe the order of recruitment of motor units

Answer 7

The small motor units are most excitable and are recruited first. They develop low forces that can be maintained for long periods. The large motor units are recruited later, after ~ 40% of the maximal tension in a whole muscle had been reached.

Question 8

What does threshold for activation of a motor unit depend on?

Answer 8

the magnitude of its synaptic inputs and on their processing by that neurone.

Question 9

How does nerve fibre activity differ in white muscle and red muscle?

Answer 9

High frequency phasic in white muscles and continuous with low frequency and tonic with red muscles

Question 10

Endurance training leads to

Answer 10

augmentation of oxidative mechanisms increase in capillary density, more mitochondria -> Fibre diameter does not increase

Question 11

Strength training leads to

Answer 11

Fibre diameter increase leads to larger pale Fast Gl. muscle fibres Higher levels of glycolytic enzymes

Question 12

The muscle’s plasticity potential may involve

Answer 12

1. a change in the amount of protein (quantitative changes)
2. the type of protein isoform it expresses (qualitative changes)
3. a combination of the two.

Question 13

How does the firing pattern of a motor neurone affect the expression of myosin isoforms in skeletal muscle ?

Answer 13

Muscles can be altered by the motor neurones pattern of activity, disuse and /or denervation&raquo_space;> lead to atrophy (e.g. after spinal cord injury) Frequency motor neurone of firing. This is due to Ca2+ regulation.