BIOD 151 Module 5 Exam Answer key (portage learning)

BIOD 151 Module 5 Exam Answer key (portage learning) 1. what percentage of our body weight does skeletal tissue make up? - ANSWER 40% 2. antagonistic pairs - ANSWER how muscles work because they can only pull in one direction- the direction of their fiber orientation 3. how does an antagonistic pair operate? - ANSWER one muscle bends the joint & brings the limb toward the body, this muscle is known as the flexor, while the other muscle straights the joint and extends the limb (the extensor) 4. flexion - ANSWER closing/ bending of a joint 5. extension - ANSWER opening/straightening of a joint 6. abduction - ANSWER movement away from midline 7. adduction - ANSWER movement towards the midline 8. dorsiflexion - ANSWER flexion superiorly occurring at the subtalar (ankle joint), moves toes up 9. plantarflexion - ANSWER flexion inferiorly occuring at the subtalar (ankle joint), moves toes down 10. antagonistic pair example 1 - ANSWER dorsiflexor: tibalis anterior, plantarflexor: Gastrocnemius 11. radial deviation - ANSWER lateral movement of wrist towards radius 12. ulnar deviation - ANSWER medial movement of wrist towards ulna 13. pronation - ANSWER rotation of forearm so the palm faces posteriorly; rotation of ankle so the sole of the foot faces laterally 14. supination - ANSWER rotation of palm so it faces anteriorly; rotation of ankle so the sole faces medially 15. skeletal muscle is made of - ANSWER many muscle fibers in bundles 16. muscle fiber - ANSWER a cell containing thousands of myofibrils 17. myofibrils - ANSWER the contracted portions of the fibers; cylindrical and run the length of the muscle fiber 18. striations - ANSWER light and dark bands found in myofibrils that give skeletal muscle its look 19. how does a striation of myofibrils form? - ANSWER from protein myofilaments w/ in contractile units called sarcomeres 20. what two types of protein filaments does a sarcomere contain? - ANSWER thick filaments made from a protein called myosin and thin filaments made from a protein called actin 21. when a muscle fiber contracts - ANSWER the sarcomeres with in the myofibrils shorten 22. when a sarcomere shortens - ANSWER the actin filaments slide past the myosin filaments and approach one another 23. the movement of the actin filaments in relation to the myosin filaments causes - ANSWER the muscle to shorten 24. Z lines - ANSWER connect parallel bands of thin filaments 25. M line - ANSWER holds together thick filaments; center of the sarcomere 26. I band - ANSWER appears light when stained because only contains thin filaments 27. A bands - ANSWER contains thin & thick filaments; stains darker because it contains thick filaments 28. what happens to the z line when muscles contract? - ANSWER they move closer together towards the M line 29. Step 1 of muscle contraction - ANSWER nerve impulse is sent to the muscle where it reaches a place called the neuromuscular junction in the muscle fiber 30. Step 2 of muscle contraction - ANSWER acetylcholine is released from the motor nerve ending 31. Step 3 of muscle contraction - ANSWER the acetylcholine then bind to the receptors on the muscle cell, which triggers the opening of sodium channels and allows sodium to flow inside the sarcoplasm 32. sarcoplasm - ANSWER cytoplasm of a muscle cell 33. step 4 of muscle contraction - ANSWER the sodium ions trigger an action potential to occur in the sarcolemma (cell membrane of a muscle fiber) 34. step 5 of muscle contraction - ANSWER the action potential triggers calcium ions to be released from the sarcoplasmic reticulum 35. sarcoplasmic reticulum - ANSWER specialized type of smooth ER found in striated muscle tissue 36. Step 6 of muscle contraction - ANSWER in the presence of calcium ions, the myosin filaments called cross-bridges bend backwards and attach to actin filaments 37. step 7 of muscle contraction - ANSWER the cross-bridges bend forward & the actin filament is pulled along to the center of the sarcomere