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A&P exam 4
| Question | Answer |
|---|---|
| Which of the following best describes the cross-bridge cycle? | The sequence in which myosin cocks, binds to actin, undergoes a power stroke, and detaches. |
| The process of engaging more motor units to increase the strength of a muscle contraction is called | recruitment |
| Which term describes a broad, flat sheet of connective tissue that connects muscle to bone or to another muscle? | Aponeurosis |
| These statements about myosin myofilaments are all true except: | attached to the Z disc |
| Which of the following is true concerning eccentric contraction? | The muscle lengthens but tension remains constant. |
| What is the primary purpose of normal muscle tone (resting tension)? | To stabilize joints and maintain posture |
| Type IIb, sat glycolytic fibers are best suited for | rapid, high intensity activities like sprinting and heavy lifting |
| In muscles that lack functional acetylcholine receptors (AChRs), what happens when acetylcholine is released from the motor neuron? | The muscle fiber does not depolarize properly |
| When you lift a heavy dumbbell to flex your elbow, your biceps brachii muscle is doing what type of work? | Concentric (shortening) |
| When a muscle acts to help the prime mover (agonist) perform its action, it is called a: | Synergist |
| Compared to anaerobic respiration, aerobic respiration | Produces more ATP per glucose molecule but at a slower rate |
| Type I , slow twitch muscle fibers have | high endurance and are fatigue resistant |
| If a somatic motor neuron axon is damaged, what will happen to the muscle it innervates? | The muscle will become paralyzed and eventually atrophy |
| Place the steps of skeletal muscle relaxation in the correct order. | 1) nerve signal ceases 2) acetylcholine release into the synaptic cleft stops 3) acetylcholinesterase breaks down the acetylcholine in the synaptic cleft 4) calcium is actively transported into the sarcoplasmic reticulum; Ca diffuses away from the trop |
| The functional unit of skeletal muscle is | the sarcomere |
| What is the main function of the protein dystrophin in muscle cells? | To link the actin cytoskeleton to the sarcolemma and stabilize the muscle fiber during contraction |
| Which of the following occurs just before the latent phase begins? | The action potential reaches the neuromuscular junction |
| During a concentric muscle contraction, the H -zone | decreases in size |
| Excitation-Contraction Coupling Pleace the events in Excitation-Contraction Coupling inthe correct order. | ACh causes an action potential to propagate along the sarcolemma (muscle cell membrane). The action potential travels down the T-tubules into the interior of the muscle fiber. The electrical impulse triggers calcium (Ca²⁺) to be released from the sarcop |
| Supplementing with creatine | increases the stores of creatine phosphate to enhance short-term muscle performance |
| During short, intense bursts of activity creatine phosphate | is broken down to release energy for ATP generation |
| The correct sequence of events at the NMJ after an action potential arrives at the axon terminal is | release of acetylcholine from vesicles into the synaptic cleft. binding of acetylcholine to cholinergic receptors in muscle cells. opening of sodium channels causing an influx of sodium ions. |
| What is the name of the mechanical contraction that occurs when a muscle develops tension but does not shorten (e.g., holding a plank)? | Isometric contraction |
| In controlled movements, the antagonist muscle often acts to | |
| In a direct (fleshy) attachment of muscle to bone | The muscle appears to attach directly to bone with very little connective tissue visible |
| Cross-Bridge Cycle Place the event of the Cross-Bridge Cycle in the correct order starting with the calcium and ATP present. | Calcium binds to troponin causing tropomyosin to move and expose myosin-binding sites on actin. The myosin head pivots and pulls the actin filament toward the center of the sarcomere (M line). A new ATP molecule binds to the myosin head. The energy rel |
| Which organelle is primarily responsible for aerobic ATP production in muscle fibers? | Mitochondrion |
| Which of the following is true of the cross bridge cycle? | ATP is required for the detachment of the myosin head from actin. |
| Repolarization of the muscle sarcolemma is primarily caused by: | Efflux of potassium |
| Why does one continue to breath heavy after rigorous physical activity has stopped? | The body requires more oxygen to restore levels of ATP and creatine phosphate. |
| Which function of fascia helps prevent infections from spreading between body compartments? | Compartmentalization |
Created by:
InshaC