Locomotor- Muscles, Tendons Flashcards Preview

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Flashcards in Locomotor- Muscles, Tendons Deck (8)
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1
Q

Would you see more or less SDH - succinate dehydrogenase– in slow-twitch muscles in an SDH stain of muscle fibres?

A

You would see more SDH in slow-twitch. SDH is used in the citric acid cycle as a substrate, so in slow oxidative Type I muscle fibres, you would see a lot of mitchondria.

2
Q

When muscle fibres are stained for myosin-ATPase, muscle fibres with lots of myosin-ATPase are stained light and those with less are very dark. How would fast-twitch, Type II or Type IIb look? How would slow-twitch type I look?

A

Type II & IIb would be light because they are fast-twitch muscles that have a lot of myosin-ATPase for rapid contraction.

Type I slow-twitch muscles have less and are thus dark (remember this is reverse staining).

3
Q

Are fast-twitch muscles located superficially or deep, in general?

A

Superficial, like thigh muscles and cutaneous muscles.

4
Q

Mr Smith, a greyhound trainer has decided to switch his dog to 800m races from 400 m. What type of muscle adaptations will you see?

A

You will see hypertrophy of muscle fibres due to exercise. You would also see an increase in the proportion of slow-twitch muscle fibres with more SDH/mitochondria.

5
Q

Cinnamon McCain’s racehorse Blue Brandy has been underperforming and so Cinnamon has increased the incline for his hill work during training. What muscle-fibre adaptations will you see?

A

Hypertrophy of muscle fibres, and transition to fast-twitch, Type IIB fast-glycolytic fibres.

6
Q

Mrs Arnold has been prescribed a physiotherapy regime of gentle stretching and light walks for her spaniel Darcy after her leg was in a cast for 6 weeks. What muscle adaptions will you see?

A

Decreased number of sarcomeres due to being casted. Light walking & stretching will add muscle fibres; maybe some selective hypertrophy. Slow fibre types will be re- established. Example of de-training.

7
Q

What role does satellite cells play in muscle plasticity/adaptation?

A

Satellite cells play a role in adaptation as they have stem-cell-like properties & are stimulated by IGF and other growth factors to migrate & form myotubules, or bind to myofibres at times of injury to help repair muscle. They are important in hypertrophy.

8
Q

In terms of muscle innervation, what is the difference between spatial summation & temporal summation?

A

Spatial summation - increasing levels of force brought about by increasing number of motor units; interesting way animals can change what their muscles are doing to suit different locomotor needs. Motor-unit “recruitment”.

Temporal summation - within a single motor unit; increasing the force of contraction within the muscle that neuron innervates *by increasing frequency of firing *

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