Every human body has an uncountable number of this basic unit of a muscle known as the: (1 point)

Amuscle fibers
Bligaments
Ctendons
Dmuscle tissues

Slow-twitch muscles are needed for: (1 point)

AQuick, short bursts of energy for high intensity
BEndurance activities
CSpeed or power activities
DLow endurance and short duration exercises

A group of muscle fibers responsible for a specific movement is called: (1 point)

Aa motor unit
Ba striated group
Ca fast-twitch unit
Da slow-twitch unit

When a muscle fiber contracts as much as it can it is called the _________________. (1 point)

AMaximum potential principal
BContraction principal
CMuscular capacity principal
DAll or none principal

Select the answer below that best fits the following description.

Voluntary

Come in pairs

Attach to the bones through tendons

Made up of long, cylindrical fibers (1 point)

AStriated muscles
BCardiac muscles
CSmooth muscles
DContracted 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

(1 point)

AStriated muscles
BCardiac muscles
CSmooth muscles
DSkeletal muscles

Select the answer below that best fits the following description.

Involuntary

Only found in the heart

(1 point)

AStriated muscles
BCardiac muscles
CSmooth muscles
DSkeletal muscles

Option A, muscle fibers. Skeletal muscle is made up of bundles of individual muscle fibers.
Option B, endurance activities. There are two types of muscle fibers; fast-twitch and slow-twitch. Slow-twitch muscle fibers are necessary for aerobic exercises which involve low levels of exertion but with high level of endurance.
Option A, a motor unit. A motor unit consists of one neuron and all of the muscle fibers that it innervates.
Option D, all or none principle. The all or none principle states that the strength by which a muscle fiber responds to a stimulus is independent of the strength of the stimulus. If that stimulus exceeds the threshold potential, the nerve or muscle fiber will give a complete response; otherwise, there is no response.
Option A, striated muscles. It is a muscle tissue in which the contractile fibrils in the cells are aligned in parallel bundles and come in pairs, so that their different regions form stripes visible in a microscope. Muscles of this type are attached to the skeleton by tendons and are under voluntary control.
Option C, smooth muscles. It is a muscle tissue in which the contractile fibrils are not highly ordered, occurring in the gut and other internal organs and not under voluntary control.
Option B, cardiac muscle. Cardiac muscle (also called heart muscle or myocardium) is one of three types of vertebrate muscles, with the other two being skeletal and smooth muscles. It is an involuntary, striated muscle that constitutes the main tissue of the walls of the heart.