Movements of the Body Are Usually Smooth and Occur at Differing

question 40

Multiple Choice

Movements of the body are usually smooth and occur at differing rates because

• A) they are a mixture of isotonic and isometric contractions.
• B) motor units contract out of phase at their own particular rates.
• C) most muscle contractions closely resemble individual muscle twitches.
• D) muscles of different sizes contract at different rates.
• E) of the all-or-none principle.

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Definitions:

Endoderm

Innermost primary tissue layer of an animal embryo that gives rise to the linings of the digestive tract and associated structures.

Germ Layer

Primary tissue layer of a vertebrate embryo—namely, ectoderm, mesoderm, or endoderm.

Ectoderm

Outermost primary tissue layer of an animal embryo; gives rise to the nervous system and the outer layer of the integument.

Differentiate

To recognize or ascertain what makes something or someone different, or in biology, the process by which cells or tissues change from relatively generalized to specialized kinds, during development.