Question

Distinguish between red muscle fibres and white muscle fibres.

Answer 1

Hint:Skeletal muscles consist of bundles of muscle fibres or cells called fascicles that are enclosed in the fibrous connective tissue that finally emerge as tendons at both ends by which they attach with bones. Each muscle fibre is long, cylindrical, and coenocytic or multinucleated.

Complete answer:

Red muscle fibre	White muscle fibre
These are thinner and smaller in size.	These are thicker and linger in size.
These are innervated by smaller nerve fibres.	These are innervated by longer nerve fibres.
These are highly vascularized.	These are less vascularized.
They have less number of sarcoplasmic reticulum.	They have more number of sarcoplasmic reticulum
It has more numbers of mitochondria as it depends upon the energy provided by the aerobic cell respiration.	It is less in number as it depends upon the energy provided by the glycolytic pathway.
These are dark red colored as they have myoglobin that stores oxygen.	These are light colored as they do not have myoglobin so no oxygen is stored.
These muscles do not undergo fatigue.	These muscles easily undergo fatigue.
These show slow but sustained contraction.	These show rapid contraction for a short period.
Examples of red muscle fibres are- extensor muscles of back and flight muscles of pigeons, etc.	Examples of white muscle fibres are- eyeball muscles and flight muscles of a sparrow.

Note:So muscles contain a red pigment called myoglobin. Myoglobin content is high in some muscles which gives them red appearance while those with very less myoglobin content appear pale or whitish in color.