Q1/ Skeletal muscle fibres are considered to be “plastic” as they can respond to
ID: 88095 • Letter: Q
Question
Q1/ Skeletal muscle fibres are considered to be “plastic” as they can respond to various stimuli. Describe in detail the properties of the three basic types of skeletal muscle fibres and describe the major pathways that cause hypertrophy.
Q2/You are conducting typical force-voltage, force-frequency and length-tension experiments on the toad sciatic nerve/gastrocnemius muscle preparation. Draw and explain the twitch characteristics, recruitment and length-tension results obtained during these experiments. How might the results differ if SR density was increased?
Explanation / Answer
Q.1 Based on the qualities the muscle fibres are divided into 3 types;
- Type (I)
- Type (II) A
- Type (II) B
Now let us understand all the three in detail.
Type (I)
They are red in color and are considered as slow twitch fibres. The large volume of myoglobin and oxygen is responsible for the red color of the fibre. These fibres are resistant to fatigue. Through aerobic metabolic cycle they produce large number of ATP molecules. They are also called as postural muscle because they help maintain the posture of the neck and spine.
Type(II) A
Another term for these fibres is fast oxidative fibres. Because of presence of large number of myoglobin and mitochondria they are red in color. The ATP produced is used in both aerobic and anaerobic metabolism. Due to this the muscle movement (contraction) is very rapid.
Type(II) B
Also known as fast glycolytic fibres. These fibres are usually white in color due to low myoglobin content. The ATP is produced through anaerobic respiration at a slower rate and breaks down very quickly. This causes rapid fatigue. They are found in the arm muscles.
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