Question

Myoglobin is present in red muscle fibres to
A. Store oxygen to be utilized during muscle contraction
B. Remove oxygen to help in anaerobic respiration
C. Compensate for lack of haemoglobin during anemia
D. Remove pyruvic acid formed during respiration

Answer 1

Hint: Muscles are specialized tissue of mesodermal origin and made up of contractile fibres which in turn are formed of myofibrils. In human adults, muscles constitute nearly 40 - 50 per cent of the total body weight.

Complete Answer:
- Muscle tissue is about 75% water, 20% protein and 5% non protein organics and minerals, important non-protein organics include ATP, phosphocreatine, creatine, urea and glycogen. Potassium is the main abundant mineral element in muscle. The iron-protein pigment of muscle which carries oxygen is called myoglobin.
- Myoglobin is an important haem-containing dark globular protein; it is an oxygen storing protein in red muscle fibres of vertebrate muscles.
- Myoglobin is especially abundant in the muscles of diving mammals such as whales, porpoises, dolphins and seals and in diving birds like penguins.
- Myoglobin stores oxygen as oxymyoglobin, which releases oxygen for utilization during muscle contraction. It enhances the capacity of the muscle fibres to perform aerobic respiration.
- Myoglobin has only one haem group, so each myoglobin molecule can carry only one $O_2$ molecule. The curved form of oxygen dissociation of myoglobin is a simple hyperbola' (sigmoid for oxyhaemoglobin).

The correct answer is (A) i.e. Store oxygen to be utilized during muscle contraction.

Note: Red muscle fibres are thinner, darker in colour, slower in contraction rate, rich in mitochondria and rich in red haem protein myoglobin. These Depend mainly on aerobic metabolism Perform slow and sustained contractions for w long periods without fatigue. And Carry out aerobic contraction without accumulating much lactic acid.
Example: Extensor muscles used on the back of the body, avian flight muscles used for prolonged slow flying kites.