Question

Myoglobin is found in
(a)White fibers
(b)Red fibers
(c)Can be traced in both
(d)Cardiac muscles only

Answer 1

Hint: Fibers that appear red and have relatively high oxygen content and are constantly in use. A special protein or pigment is present in these fibers that facilitate the transport of oxygen.

Complete answer:
The myoglobin pigment is found in red muscle fibers and is responsible for the red-colored appearance of the muscle fibers. It is an iron-containing pigment or protein that binds to the oxygen in the skeletal muscles of the vertebrates and most of the mammals and facilitates the transport of oxygen. Red muscle fibers are also called slow-twitch muscle fibers and remain in a state of constant use. Due to this, these fibers require an adequate amount of oxygen supply that is accomplished with the help of myoglobin.

Additional Information: -There are two types of muscle fiber in birds and mammals, which are red and white muscle fiber. White muscle fibers are longer and thicker in size. These are less vascularized and are light-colored, so lack myoglobin and do not store oxygen. Sarcoplasmic reticulum is less developed in red muscle fibers but is more developed in white muscle fiber. Example - red muscle fibers are found in the extensor muscle of the back and flight muscle of kite while white muscle fibers are found in the eyeball muscles and flight muscles of the sparrow.
-Cardiac muscles are found in the myocardium of the heart. These muscle fibers represent both, smooth as well as striated muscle fibers.
-Endomysium is a connective tissue sheath around muscle fiber.
-Epimysium is a connective tissue around the whole muscle.
-The duration for which a muscle can contract depends upon the supply of ATP to the muscle fiber.
So, the correct answer is, ‘Red fibers.’

Note: Red muscle fibers have more mitochondria than white muscle fibers hence provide more energy and do not fatigue for a long time. The Red muscle fibers show slow and sustained contraction while the white muscle fibers show rapid and short contractions.