Explain the characteristics of smooth muscle tissue.

(N/A) $\Rightarrow$ Location: The walls of internal organs such as blood vessels,stomach,and intestine contain this type of muscle tissue.
$\Rightarrow$ Structure: Each cell is spindle-shaped and has a nucleus in its central broader part.
$\Rightarrow$ Sarcolemma: The sarcolemma is indistinct. Dark and light bands (striations) are not observed.
$\Rightarrow$ Myofibrils: There is no regular arrangement of myofibrils.
$\Rightarrow$ Sarcoplasm: Granular sarcoplasm surrounds the nucleus,while the remaining cytoplasm contains a large number of minute myofibrils.
$\Rightarrow$ Organization: They are bundled together in a connective tissue sheath.
$\Rightarrow$ Function: The contraction and relaxation of smooth muscle tissue are not rapid. They are involuntary in action; hence,they are called involuntary muscles.
$\Rightarrow$ Fatigue: Their contraction and relaxation occur at a very slow speed and persist for a longer period,so they do not get fatigued easily.