Muscles

Question 1

What is the structure of Skeletal muscle?

Answer 1

Skeletal muscle is voluntary. It is striated, and multinucleated.

Question 2

What is the structure of Cardiac muscle?

Answer 2

Cardiac muscle is involuntary. It is striated, and has a single nucleus.

Question 3

What is the structure of Smooth muscle?

Answer 3

Smooth muscle is involuntary. It is non-striated and has a single nucleus.

Question 4

What is the muscle cell called? What is it made up of?

Answer 4

One Muscle fibre is one muscle cell. It is made up on many myofibrils.

Question 5

Where are the Epimysium, Perimysium, and Endomysium?

Answer 5

1) Epimysium is around the muscle belly. 2) Perimysium is around one Fasicle (many muscle cells 3) Endomysium around one Muscle cell.

Question 6

How are myofibrils arranged?

Answer 6

Myofibrils are made up of many sarcomeres, which are the main units of muscle contraction.

Question 7

What are Isometric, Concentric and Eccentric muscle contraction?

Answer 7

I - No change in muscle length. C - Muscle shortens. E - muscle lengthens.

Question 8

What three muscle fibre types are there?

Answer 8

Type I - Slow Oxidative. Type IIa - Fast Oxidative Glycolytic. Type IIb - Fast Glycolytic.

Question 9

What are Slow Oxidative Muscle fibres? What are they used for?

Answer 9

Fatigue resistant, smaller diameter. Low myosin ATPase activity, but high oxidative capacity. Used for postural stability.

Question 10

What are Fast Oxidative Glycolytic (IIa) Muscle fibres? What are they used for?

Answer 10

High myosin ATPase activity. Both high oxidative and high glycollytic capacity.

Question 11

What are Fast Oxidative (IIb) Muscle fibres? What are they used for?

Answer 11

Fatigue easily, larger diameter. High myosin ATPase activity, high glycolytic capacity. Used in power e.g. jumping.

Question 12

Where might muscle fibre types differ in muscle?

Answer 12

In different muscles, within muscles themselves, between different species.

Question 13

Give an example of muscles that may have high slow and fast muscle fibres.

Answer 13

1) Fast fibres e.g. flying, running etc.

2) Slow fibres e.g. standing.

Question 14

Which muscle type would contain more mitochondria? How can this be stained?

Answer 14

Slow muscle. You can stain for Succinate Dehydrogenase (stored in mitochondria)

Question 15

Where within a muscle would you expect there to be more slow muscle fibres?

Answer 15

Deep (closer to the bone) postural muscle would most likely have more slow fibres than more superficial muscles.

Question 16

Give 4 circumstances in which muscle adapts.

Answer 16

Growth, Nutrition, Excercise, Ageing.

Question 17

How does muscle adapt in growth?

Answer 17

Hypertrophy of muscle fibres, but there is NO change in number of fibres. Possible change in arcitecture (pennate vs. parallel)

Question 18

Which muscle fibres hypertrophy most in strength training?

Answer 18

In specific ‘strength’ training, Fast fibres hypertrophy twice as fast as slow fibres.

Question 19

When a muscle changes in length (excercise), what happens to the number of sarcomeres?

Answer 19

Chronic stretch = New sarcomeres

Shortened position = Decreased number.

Question 20

When a muscle changes in length (exercise) where are sarcomeres added? What type of sarcomeres are they?

Answer 20

Fibres are added at the myotendinous junction. Regardless of parent type, they are ALWAYS slow sarcomeres.

Question 21

Why is it important to consider type of training, as well as amount?

Answer 21

It is difficult to train for increased anaerobic capacity, as increased use makes more ‘slow’ fibres, and causes hypertrophy.

Question 22

What is the best way to increase Fast twitch muscle fibres?

Answer 22

Resistance training e.g. strength training.

Question 23

What happens in detraining? What happens to the fibre types?

Answer 23

Happens 2x as quickly as training. Fibre types return to Type II. Anti-gravity muscles are most at risk.

Question 24

What are satellite cells?

Answer 24

Stem cell like cells in muscle, between BM and CM. Important in hypertrophy and muscle memory.

Question 25

How does ageing affect muscles?

Answer 25

Decreased satellite cells, so reduced proliferation. Decreased muscle size and performance, increased fibrous CT.

Question 26

What muscle is important for lifting the wing in a bird?

Answer 26

Supracoracoideus runs through the Triosseal canal and pulls the wing upwards.

Question 27

Which muscle is important for pulling the wing down in birds?

Answer 27

Pectoralis Muscle