Personal Fitness Unit 2 Lesson 4: Types of Muscles

When a muscle fiber contracts as much as it can it is called the ___.

all or nothing principle

Select the answer below that best fits the following description. (involuntary, only found in the heart)

cardiac muscles

Slow-twitch muscles are needed for

endurance activities

Every human has an uncountable number of this basic unit of a muscle known as

muscle fibers.

Select the answer below that best fits the following description (voluntary, come in pairs, attach through the bones through tendons, made up of long, cylindrical fibers)

skeletal muscles

Select the answer below that best fits the following description. (involuntary, found in internal organs, can stretch or maintain tension for long periods of time)

smooth muscles

A group of muscle fibers responsible for a specific movement is called

a motor unit.