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BiologyModule4 - Module 4 Pgs 1066-1098 Locomotion the...

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Module 4 Pgs. 1066-1098 29/10/2007 23:26:00 Locomotion - the movement of an entire animal Exoskeletons- hard hollow structures that envelop the body Locomotion in animals with exoskeletons and hydrostatic skeletons is also based on antagonistic muscle groups o Animals with exoskeletons have paired flexor/ extensor muscles inside their hollow leg joints Hydrostatic Skeletons- use the pressure of eternal body fluid to support the body Animals with hydrostatic skeletons have both circumferential muscles and longitudinal muscles, and these muscles work in concert to shorten and lengthen body segments Endoskeletons- hard structures inside the body, composed of connective tissue called cartilage and bone. Cartilage- made up of cells scattered in a gelatinous matrix of polysaccharides and protein fibers. Provides padding between bones Bone- is made up of cells in a hard extra cellular matrix of calcium phosphate with small amounts of calcium carbonate and protein fibers. They articulate in ways that allow limbs to move, swivel, and pivot. Joints- where the bones meet and interact. Tendons - are bands of tough fibrous connective tissue, connects bones and skeletal muscles. Antagonistic Muscle group- the pairing of muscles when one muscle moves in one direction, and the other muscle pulls it in the opposite direction (in a limb) Flexor- the muscle that swings to long bones in an arc toward each other Extensor- the muscle that straightens them out Motor Neurons- in all vertebrate animals the movements of paired muscles are coordinated by motor neurons that originate in the brain and spinal cord. These motor neurons project from processing centers that receive input from sensory systems. Motor neuron activity changes in response to information about balance, smells, sights, and sounds. Animals movements are directly tied to the functioning of it’s sensory systems Coordinated Behaviors- result from the interplay of sensory input and motor output we call running, eating, swimming, and flying Muscle fiber- a long, thin muscle cell
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Myofibrils- small strands found within muscle cells Smooth Muscle- lacks myofibrils Intercalated disc- - contains branched cells whose ends are connected via specialized regions Vertebrates- have three distinct types of muscle tissue Skeletal muscle - consists of unbranched multinucleate cells- they contain multiple nuclei. This muscle is also known as striated muscle, because it appears to be striated, or striped Smooth muscle - is unbranched, lacks myofibrils, and is often organized into thin sheets. Cardiac muscle - In an intercalated disc, protein- lined openings called gap junctions provide a direct cytoplasmic connection between adjacent muscle cells. Intercalated discs are critical to the flow of electrical signals from cell to cell and to the coordination of the heartbeat.
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