BIOS 252 Midterm Review

BIOS 252 Midterm Review Definitions: 1. Origin: the attachment of a muscle’s tendon to the stationary bone. 2. Insertion: the attachment of the muscle’s other tendon to the moveable bone 3. Sarcomere: the basic functional units of myofibril. It extends from one Z disc to the next Z disc. 4. Sarcolemma: the plasma membrane of a muscle cell. Where transverse tubules (t-tubule) are attached to it and go to the sarcoplasmic reticulum. 5. A band: darker middle part of the sarcomere. 6. I band: a lighter, less dense area that contains the rest of the thin filaments but not thick filaments, and a Z disc passes through the center of each I band 7. T-Tubules: open to the outside of the fiber, they are filled with interstitial fluid. 8. Elasticity: the ability of muscular tissue to return to its original length and shape after contraction or extension. 9. Extensibility: the ability of muscular tissue to stretch, within limits, without being damaged. 10. Contractility: the ability of muscular tissue to contract forcefully when stimulated by an action potential. 11. Electrical Excitability: ability to respond to certain stimuli by producing electrical signals called action potentials. 12. Sarcoplasmic Reticulum: a fluid-filled system of membranous sacs encircles each myofibril. 13. Graded potential: used for short-distance communication only 14. Spatial summation: summation of postsynaptic potentials in response to stimuli that occur at different locations in the membrane of a postsynaptic cell at the same time. 15. Temporal summation: summation of postsynaptic potentials in response to stimuli that occur at the same location in the membrane of the postsynaptic cell but at different times. 16. Agonist: an agent that binds to receptors and enhances or mimics the effect of a natural neurotransmitter. 17. Antagonist: an agent that binds to and blocks neurotransmitter receptors 18. Synergist: contract and stabilize the intermediate joints, to prevent unwanted movements at intermediate joints or to otherwise aid the movement of the prime mover.