What is the function of calcium in muscle contractions? to bind to troponin and change its interaction with tropomyosin to alter membrane potential causing a depolarization to bind to myosin and allow it to attach to tropomyosin to release ADP from myosin

Muscle spindle structures consist of:     Extrafusal muscle fibers and gamma motor neurons     Extrafusal muscle fibers and alpha motor neurons     Golgi tendon organs and gamma motor neurons     Intrafusal muscle fibers and gamma motor neurons

Describe the contraction of a muscle fiber, starting with what events take place at the neuromuscular junction, explaining how depolarization along the length of the sarcolemma occurs, the role of calcium (where it is released, what it binds to, etc.), and the events that occur after calcium binds to troponin.  Draw a few simple, labelled diagrams of a neuromuscular junction and sarcomere and outline the steps of excitation-contraction coupling, including power stroke, recovery stroke, formation of cross bridges, role of ATP, etc.

Why does continuouns calcium release within a muscle fiber cause greater tension? Acticates more calcium pump  Activates myofibrils continuously  Increase action potential frequency  Lengthens sarcomere

In the absence of O Ca2+; Tropomyosin and Tropomodulin the myosin binding sites in the actin microfilament are masked by O ATP: Tropomyosin and Troponin ATP: Cofilin and Profilin OCa2+; Tropomyosin and Troponin Previous

What prevents the filaments from sliding back to their original position each time a myosin cross bridge detaches from actin?

Why is myosin II the only myosin capable of producing contractile force?

What step DIRECTLY causes a sarcomere to shorten? cross- bridge formation  calcium transport into SR calcium release  power stroke myosin heads in high energy state

hen an action potential arrives at the nerve terminal of a neuromuscular junction, which of the following statements best describes the events that occur?     Depolarisation of the nerve terminal causes the release of ACh which activates nicotinic receptors on the skeletal muscle membrane to cause Ca2+ entry and muscle contraction.     Depolarisation of the nerve terminal opens voltage-gated Ca2+ channels, Ca2+ entry brings vesicles containing ACh to the membrane which form fusion pores causing the release of ACh which activates voltage-gated Na+ channels at the end-plate.     Depolarisation of the nerve terminal opens voltage-gated Ca2+ channels, Ca2+ entry brings vesicles containing ACh to the membrane which form fusion pores causing the release of ACh which binds to muscarinic receptors at the end plate.     Depolarisation of the nerve terminal opens voltage-gated Ca2+ channels, Ca2+ entry brings vesicles containing ACh to the membrane which form fusion pores…

How is the list below to be properly put in order to describe a muscular contraction? 1. Calcium causes exocytotic release of Acetylcholine into the synaptic gap; all this happens at an area called the neuromuscular junction2. ATP is consumed which allows myosin to "pivot" the myosin head, which pulls actin toward it.3. This process is repeated multiple times and is called the "sliding filament theory".4. Myosin filaments perform "crossbridging".5. Calcium is released and circulated throughout the muscle cell6. The brain predicts the action necessary and decides which muscles and how many "motor units" are needed to perform that action.7. Tropomyosin moves to reveal the active site of the F-Actin strand8. Upon reception of a calcium ion, the Troponin complex becomes activated9. Proteins embedded in the Sarcolemma receive enough of the ACH neurotransmitter to generate an electrical impulse.10. The electrical impulse is perpetuated throughout the muscle fiber.11. A nervouse impulse is…