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Locomotion and Support (Test 2)

Locomotion and Support (Test 2) - Locomotion and Support 4...

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Locomotion and Support 4 fundamental locomotor patterns in protests and metazoan Ameboid movement Ciliary and flageller movement Hydrostatic propulsion Locomotor limb movement 3 basic support systems Structural endoskeletons Structural exoskeletons Hydrostatic skeletons Reynold’s Number Ratio of inertial force to viscous force At higher RN, the inertial force predominates and determines the behavior of water flow around an object At lowe RN, viscous force predominates and determines the behavior of the water flow υ plU R e = Large animals, by virtue of size and/or velocity, move in a world of high RN With increased body size, fluid viscosity becomes less and less significant as far as the animal’s energy output during locomotion is concerned Inertia becomes more and more important A large animal must expend more energy than a small animal does to put its body into motion Inertia works in favor of the moving large animal by carrying it forward when the animal stops swimming Small organisms generally move in a world of low RN Inertia and turbulence are virtually non existent, but viscosity becomes important, increasingly so as body size and velocity decrease Small organism swimming through water have been likened to a human swimming through liquid tar or thick molasses Start and stop suddenly Neither pay the price or receive the benefits of the effects of inertia Must extend a lot of energy Ameboid locomotion Ameboid cells possess a gel-like ectoplasm, which surrounds a more fluid endoplasm Movement is facilitated by changes in the states of these regions of the cell At 1 or several points on the cell surface, pseudopodia develop; and as endoplasm flows into a growing pseudopodium, the cell creeps in that direction 2 principle theories Actin molecules floating freely in the endoplasm, polymerizing into the filamentous form at the point of active pseudopodium growth, where they interact with myosin molecules
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Resultant contraction literally pulls the streaming endoplasm forward, while at the same time converting it to the ectoplasm that rings the forward-streaming pseudopodium Actin-myosin interaction takes place at the rear of the cell, where it produces a contraction of the ectoplasm The contraction squeezes the cell like a tube of tooth past, causing the endoplasm to stream forward and create a pseudopodium directly opposite the point of ectoplasmic contraction Cilia and flagella Cilia are shorter and tend to occur in relatively larger numbers Flagella are long and generally occur singly or in pairs Each one arises from an organelle called the basal body, to which it remains anchored The movement of cilia and flagella creates a propulsive force that either moves the organism through a liquid medium, or is the animal is anchored, creates a movement of fluid over it Structure
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