Across
- 2. _____ make up a myofibril
- 3. The myosin head pivots and bends as it pulls on the actin filament, sliding it towards the M _____
- 7. As ATP is ______ into ADP and Pi, the myosin head is energized (cocked into high energy conformation)
- 9. Skeletal muscle has an optimal _____ length where is can generate maximum force
- 12. The cross bride detaches when a new _____ (abbreviation) binds to the myosin head
- 14. In recruitment of motor units as force requirements increase, ____-twitch, fatigue-resistant fibers are recruited first
- 15. An action potential travels along a motor nerve to its endings on muscle fibers, where _____ is secreted
- 17. At rest,_____ blocks the active site on actin, preventing the myosin from binding
- 18. Type IIb muscle fibers are _____ glycolytic, very fatiguable
- 19. A muscle cell is also known as a muscle ____
- 22. High-frequency and prolonged stimulation of a muscle can lead to _____
- 24. Each sarcomere is made up of actin and ____ filaments, the molecular components of the muscle
- 25. When ACh channels open, there is a Na influx that causes local depolarization, triggering opening of voltage-gated Na channels, causing an action potential at the ______ (this part of the cell)
Down
- 1. ____ (size) motor units control gross movements
- 4. This type of receptor is stimulated by acetylcholine (ACh)
- 5. The action potential travels down the T-tubule until it reaches this voltage-sensitive receptor (use the abbreviation), causing a conformational change
- 6. In skeletal muscle, the source of Ca2+ is 100% endogenous; it comes from stored Ca2+ in the _____ reticulum
- 8. Inorganic phosphate generated in the previous contraction cycle is released, which initiates the power _____
- 10. _____(size) motor units control fine motor skills
- 11. Type IIa muscle fibers are fast-oxidative-_______
- 13. A muscle cell contains many of these (plural)
- 14. The ____ (abbreviation) pumps hydrolyze ATP to make ADP and uptake Ca from the intracellular compartment back to the SR (muscle relaxes)
- 16. Ca2+ ions will move down their concentration gradient into the intracellular compartment, where they will bind to _____ and initiate the cross bridge cycle, generating force
- 18. Type I muscle fibers are slow-oxidative and ______ resistant
- 20. Calcium binds to troponin C, causing a conformational change in the troponin-tropomyosin complex that opens the active site on ____ so myosin can bind, forming a cross bridge
- 21. This type of receptor is coupled to DHPR, and releases calcium when DHPR undergoes a coformational change
- 23. At rest, myosin heads are bound to ____ (abbreviation) and are said to be in a "cocked" position; there is no Ca bound to the troponin-tropomyosin complex