Types of Skeletal Muscle Fibers

How do muscles fibers differ?

in how they obtain ATP to fuel their contractions

Fast/White fibers

contract quickly following stimulation; produce powerful contractions; use a lot of ATP; fatigue quickly; do not contain many mitochondria

How do white fibers get energy for contraction?

anaerobic metabolism/glycolysis

Slow/Red Fibers

take a long time to contract after stimulation; specialized to continue contracting for extended periods of time; fatigue slowly; contain a large number of mitochondria

Why do red fibers fatigue slowly?

because their mitochondria continue producing ATP throughout the contraction process

Why are slow fibers red?

they contain myoglobin

Through what process do red fibers gain ATP?

aerobic metabolism

Where do red fibers get their oxygen content from?

from their large network of capillaries that provide greater blood flow for oxygen transport, and through their myoglobin content that has the ability to bind oxygen

What properties do intermediate fibers share with white fibers?

have a low myoglobin content, have high glycolytic enzyme concentration, contract using anaerobic metabolism

What properties do intermediate fibers share with red fibers?

have a lot of mitochondria, have a great capillary supply, are able to resist fatigue

True or false: Muscle motor units are composed of different types of muscle fibers.

False