<span>The discovery of thornless plants was made around the turn of the 20th century. To name one such thornless plant, particularly, the Blackberry plant, the deviation from the thorned blackberry canes were discovered in the United States. Since then, several different thornless blackberry varieties have been cultivated for fruit gardens.</span>
Muscle contraction that results in a change in joint angle is called <span>concentric contraction.
This contraction occurs when enough force that can overcome the resistance applied is developed by the muscle where this force developed is larger than the force of the resistance applied.</span>
<span>No.The involuntary muscles of the muscular system are not striated or furrowed.
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<span><span>These muscles that are
not striated are very smooth to the sight which is why they are also
called Smooth muscles.</span> Involuntary muscles
are not striated. Even among the striated muscles that are voluntary,
the heart which is also a muscle, is involuntary.
On the other hand the striated muscles, which
are voluntary are highly fibrous and their primary function is to move
the body voluntarily, and producing heat as a result of this muscle
action.
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