Question

breif notes on types of muscle fibers ?

Answer 1

Hey friend!!! ☺
There Are Three Primary Muscle Fiber Types In Humans:
*.Type I
*.Type IIA
*.Type IIB

Type I are referred to as "slow twitch oxidative",
Type IIA are "fast twitch oxidative" and
Type IIB are "fast twitch glycolytic".
As their names suggest, each type has very different functional characteristics.

Type one fibers are characterized by low force/power/speed production and high endurance.

Type IIB by high force/power/speed production and low endurance, while,

Type IIA fall in between.These characteristics are a result, primarily, of the fiber's Myosin Heavy Chain (MHC) composition, with Mysosinheavy chain isoforms I, IIa and IIx corresponding with muscle fiber types I,IIA, and IIB.
Individual muscles are made up of individual muscle fibers and these fibers are further organized into motor units grouped within each muscle.
When you want to move the brain nearly instantaneously sends a signal or impulse through the spinal cord that reaches the motor unit.
The impulse then tells that particular motor unit to contract it's fibers.
When amotor unit fires all the muscle cells in that particular motor unit then contract with 100% intensity.

So, a muscle cell either contracts 100% or not at all. A motor unit is either recruited 100% or not at all.

Therefore, there is no such thing as a partially firing motor unit or a partially contracted muscle fiber.

Hope it helps!!! ☺