ANIMAL MOVEMENT AND MUSCULAR SYSTEMANIMAL MOVEMENTMovement is an important characteristic of animals. Animal movement occurs in many forms in animal tissues, ranging from barely discernible streaming of cytoplasm to extensive movements of powerful striated muscles.Most animal movement depends on a single fundamental mechanism: contractile proteins, which can change their form to elongate or contract.ANIMAL MOVEMENTThis contractile machinery is always composed of ultrafne fbrils fne flaments, striated fbrils, or tubular fbrils (microtubules)arranged to contract when powered by ATP. By far the most important protein contractile system is the actomyosin system, composed of two proteins, actin and myosin. This is an almost universal biomechanical system found from protozoa to vertebrates; it performs a long list of diverse functional roles. Cilia and fagella, however, are composed of diferent proteins, and thus are exceptions to the rule.AMOEBOID MOVEMENTAmeboid movement is a form of movement especially characteristic of amebas and other unicellular forms; it is also found in many wandering cells of metazoans, such as white blood cells, embryonic mesenchyme, and numerous other mobile cells that move through the tissue spaces. Ameboid cells change their shape by sending out and withdrawing pseudopodia (false feet) from any point on the cell surface. Beneath the plasmalemma lies a nongranular layer, the gel-like ectoplasm, which encloses the more liquid endoplasm.CILIARY MOVEMENTCilia are minute, hairlike, motile processes that extend from the surfaces of the cells of many animals.They are a particularly distinctive feature of ciliate protistans, but except for nematodes in which motile cilia are absent and arthropods in which they are rare, cilia are found in all major groups of animals.CILIARY MOVEMENTCilia perform many roles either in moving small organisms such as unicellular ciliates, fagellates, and ctenophores through their aquatic environment or in propelling fuids and materials across epithelial surfaces of larger animals.CILIARY MOVEMENTCilia are of remarkably uniform diameter (0.2 to 0.5 m) wherever they are found. The electron microscope has shown that each cilium contains a peripheral circle of nine double microtubules arranged around two single microtubules in the centerCILIARY MOVEMENTEach microtubule is composed of a spiral array of protein subunits called tubulin. The microtubule doublets around the periphery are connected to each other and to the central pair of microtubules by a complex system of connective elements.Also extending from each doublet is a pair of arms composed of the protein dynein. The dynein arms, which act as cross bridges between the doublets, operate to produce a sliding force between the microtubules.FLAGELLAR MOVEMENTA fagellum is a whiplike structure longer than a cilium and usually present singly or in small numbers at one end of a cell. They are found in members of fagellate protistans, in animal spermatozoa, and in sponges.FLAGELLAR MOVEMENTA fagellum beats symmetrically with snakelike undulations so that water is propelled parallel to the long axis of the fagellum.A cilium, in contrast, beats asymmetrically with a fast power stroke in one direction followed by a slow recovery during which the cilium bends as it returns to its original positionMUSCLE MOVEMENT:VERTEBRATE MUSCLE- TYPES OF MUSCLE TISSUESkeletal muscle tissue Associated with & attached to the skeleton Under our conscious (voluntary) control Microscopically the tissue appears striated Cells are long, cylindrical & multinucleateMUSCLE MOVEMENT:VERTEBRATE MUSCLE- TYPES OF MUSCLE TISSUESmooth (visceral) muscle tissue Makes up walls of organs & blood vessels Tissue is non-striated & involuntary Cells are short, spindle-shaped & have a single nucleus Tissue is extremely extensible, while still retaining ability to contractMUSCLE MOVEMENT:VERTEBRATE MUSCLE- TYPES OF MUSCLE TISSUECardiac muscle tissue Makes up myocardium of heart Unconsciously (involuntarily) controlled Microscopically appears striated Cells are short, branching & have a single nucleus Cells connect to each other at intercalated discsANATOMY OF SKELETAL MUSCLEMICROANATOMY OF MUSCLE FIBER (CELL)MICROANATOMY OF MUSCLE FIBER (CELL)MICROANATOMY OF MUSCLE FIBER (CELL)MUSCLE MOVEMENT:INVERTEBRATE MUSCLESmooth and striated muscles are also characteristic of invertebrate animals, but there are many variations of both types and even instances in which structural and functional features of vertebrate smooth and striated muscle are combined. Striated muscle appears in invertebrate groups as diverse as cnidarians and arthropods.The thickest muscle fbers known, approximately 3 mm in diameter and 6 cm long, are those of giant barnacles and of Alaska king crabs living alongthe Pacifc coast of North America.MUSCLE MOVEMENT:INVERTEBRATE MUSCLESmooth and striated muscles are also characteristic of invertebrate animals, but there are many variations of both types and even instances in which structural and functional features of vertebrate smooth and striated muscle are combined. Striated muscle appears in invertebrate groups as diverse as cnidarians and arthropods.The thickest muscle fbers known, approximately 3 mm in diameter and 6 cm long, are those of giant barnacles and of Alaska king crabs living alongthe Pacifc coast of North America.MUSCLE MOVEMENT:INVERTEBRATE MUSCLEBivalve molluscan muscles contain fbers of two types. One kind is striated muscle that can contract rapidly, enabling the bivalve to snap shut its valves when disturbed. Scallops use these fast muscle fbers to swim in their awkward The second muscle type is smooth muscle, capable of slow, long-lasting contractions. Using these fbers, a bivalve can keep its valves tightly shut for hours or even days.MUSCLE MOVEMENT:INVERTEBRATE MUSCLEInsect fight muscles are virtually the functional antithesis of the slow, holding muscles of bivalves. The wings of some small fies operate at frequencies greater than 1000 beats per second.The so-called fbrillar muscle, which contracts at these frequencies far greater than even the most active of vertebrate musclesshows unique characteristics. It has very limited extensibility; that is, the wing leverage system is arranged so that the muscles shorten only slightly during each downbeat of the wings.MUSCLE MOVEMENT:INVERTEBRATE MUSCLEFurthermore, muscles and wings operate as a rapidly oscillating system in an elastic thorax. Since the muscles rebound elastically and are activated by stretch during fight, they receive impulses only periodically rather than one impulse per contraction; one reinforcement impulse for every 20 or 30 contractions is enough to keep the system active.