BIOL 1002 Chapter : Chapter 40 The Muscles And Skeleton
Document Summary
A muscle can only contract or not contract it cannot use energy to make itself longer. Lengthening occurs when muscles relax and are stretched by other forces. Movement is produced by alternating contractions of muscles with opposing actions, called antagonistic muscles. Animal skeletons come in three different forms: the animal kingdom has three types of coordinated systems of skeletons and muscles. Endoskeletons (invertebrates-chordates, starfish, sea urchins: antagonistic muscles act on each type of skeleton to provide movement (all of these) The bodies of arthropods, such as spiders, crustaceans, and insects, are encased by rigid exoskeletons ( outside skeletons ). To grow, arthropods must molt their exoskeletons periodically because exoskeletons cannot expand. Nearly all skeletal muscle is under voluntary control: skeletal muscles produce contractions ranging from quick twitches to powerful, sustained tension. Skeletal muscles consist of a series of nested, repeating parts. Skeletal muscles are encased in connective tissue sheaths and attached to the skeleton by tough, fibrous tendons.
