Myofibrils are composed of repeating contractile elements called __________.

Which of the following muscle types is/are both voluntary and striated?

Which of the following is present in muscle cells but absent in most other cell types?

The __________ are inward invaginations of the sarcolemma that run deep into the cell and ensure that every myofibril in the muscle fiber contracts at virtually the same time.

Which of the following muscles is voluntary?

The thin myofilaments of skeletal muscle are composed chiefly of __________.

Use the key to classify each of the following described tissue types into one of the four major tissue categories.Key:connective tissueepitheliummusclenervous tissue_________(1) Tissue type composed largely of nonliving extracellular matrix; important in protection and support_________(2) The tissue immediately responsible for body movement_________(3) The tissue that enables us to be aware of the external environment and to react to it_________(4) The tissue that lines body cavities and covers surfaces

Differentiate between the roles of neurons and the supporting cells of nervous tissue.