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A&P Exam 4
| Question | Answer |
|---|---|
| Which of the following creates the largest amount of ATP? | Aerobic (oxidative) respiration |
| The latchbridge mechanism of myosin heads is a property of ________ muscle. | smooth |
| Fibers from one motor unit | are dispersed throughout muscle. |
| In skeletal muscle, the term that describes the alternating light and dark bands is ___________. | striations |
| The triads of a skeletal muscle fiber consist of __________. | two terminal cisterns and one T tubule |
| Muscle fibers are arranged in bundles called ___________. | fascicles |
| A myofilament that runs through the core of a thick filament and anchors it to a Z disc is called a(n) __________. | elastic filament |
| The property of muscle tissue that allows an impulse to travel down the entire length of the cell membrane is | Conductivity |
| Which of the following is not a feature of skeletal muscle cells? | Branched cells |
| Which muscle type depends only on the sarcoplasmic reticulum as its calcium source? | Skeletal muscle |
| True or False: A contraction in which the muscle does not shorten, but its tension increases is called an isometric contraction. | True |
| True or False: Mitochondria are required for proper function of the phosphagen system. | False |
| Which of the following is not a characteristic of a muscle cell? | Regeneratibility |
| Smooth muscle tissue in which cells are individually sent signals to contract (rather than contracting in unison) is referred to as | multiunit. |
| The myosin filaments are located in the ______. | A band |
| Which of the following describes a stimulus that cannot elicit a stronger muscle contraction, because all motor units are already firing in the muscle? | Maximal stimulus |
| Each muscle cell (fiber) is surrounded by this tissue: | Endomysium |
| Which function of fascia helps prevent infections from spreading between body compartments? | Compartmentalization |
| Why does one continue to breathe heavily after rigorous physical activity has stopped? | The body requires more oxygen to restore levels of ATP and creatine phosphate. |
| Repolarization of the muscle sarcolemma is primarily caused by: | Efflux of potassium |
| Which of the following is true of the cross bridge cycle? | ATP is required for the detachment of the myosin head from actin |
| Which organelle is primarily responsible for aerobic ATP production in muscle fibers? | Mitochondrion |
| In a direct (fleshy) attachment of muscle to bone | The muscle appears to attach directly to bone with very little connective tissue visible |
| In controlled movements, the antagonist muscle often acts to | Prevent overextension or injury |
| 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 |
| The correct sequence of events at the NMJ after an action potential arrives at the axon terminal is | Ca²⁺ influx → ACh release → ACh binds receptors → Muscle depolarization |
| During short, intense bursts of activity creatine phosphate | is broken down to release energy for ATP generation |
| Supplementing with creatine | increases the stores of creatine phosphate to enhance short-term muscle performance |
| During a concentric muscle contraction, the H -zone | Decreases in size |
| Which of the following occurs just before the latent phase begins? | The action potential reaches the neuromuscular junction |
| What is the main function of the protein dystrophin in muscle cells? | To link actin cytoskeleton to the sarcolemma and stabalize the muscle fiber during contraction |
| The functional unit of skeletal muscle is | the sarcomere |
| If a somatic motor neuron axon is damaged, what will happen to the muscle it innervates? | The muscle will become paralyzed and eventually atrophy |
| Type I , slow twitch muscle fibers have | high endurance and are fatigue resistant |
| Compared to anaerobic respiration, aerobic respiration | Produces more ATP per glucose molecule but at a slower rate |
| When a muscle acts to help the prime mover (agonist) perform its action, it is called a: | Synergist |
| When you lift a heavy dumbbell to flex your elbow, your biceps brachii muscle is doing what type of work? | Concentric (shortening) |
| 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 |
| Type IIb, fast glycolytic fibers are best suited for | rapid, high intensity activities like sprinting and heavy lifting |
| What is the primary purpose of normal muscle tone (resting tension)? | To stabilize joints and maintain posture |
| Which of the following is true concerning eccentric contraction? | The muscle lengthens but tension remains constant. |
| These statements about myosin myofilaments are all true except: | Attached to the Z disc |
| Which term describes a broad, flat sheet of connective tissue that connects muscle to bone or to another muscle? | Aponeurosis |
| The process of engaging more motor units to increase the strength of a muscle contraction is called | Recruitment |
| What exposes myosin-binding sites on actin? | Calcium (Ca²⁺) binding to troponin |
| Which energy system is used in a 100m sprint? | Immediate energy (creatine phosphate system) |
| What causes the power stroke? | Release of ADP + phosphate |
| What happens if ACh receptors don’t work? | The muscle will NOT depolarize properly |
| Which of the following is used to convert ADP to ATP by transfer of a high-energy phosphate group? | Creatine phosphate |
| To stimulate skeletal muscle contraction, acetylcholine is released from the ___________ into the synaptic cleft. | synaptic vesicles |
| Immediately following the arrival of the stimulus at a skeletal muscle cell there is a short period during the twitch called the ________ period during which the neurotransmitter is released by exocytosis, | Latent |
| Which of the following marks the boundaries of a sarcomere? | Z discs |
| Which of the following is the final chemical messenger for skeletal muscle contraction, which binds to troponin? | Calcium ions |
| A dark band formed by parallel thick filaments that partly overlap the thin filaments is known as an H band. True or False? | False |
| The branch of the nervous system that helps govern smooth muscle contraction is the _______ nervous system. | autonomic |
| True or False: Once a motor neuron fires, all of the muscle fibers in a motor unit will contract. | True |
| Which region of the sarcomere consists of the thin actin and elastic filaments? | I band |
| True or False: Some smooth muscle is autorhythmic. | True |
| True or False: Energy requirements for smooth muscle contractions are generally higher than those for skeletal muscle contractions. | False |
| What molecule(s) must bind to the myosin head to initiate the contraction stage of the skeletal muscle contraction-relaxation cycle? | ATP |
| True or False: Extensibility refers to the ability of a muscle to stretch. | True |
| Which type of muscle fiber depends on oxygen delivery and aerobic mechanisms for its ATP supply? | Slow oxidative fibers |
| The transfer of phosphate from creatine phosphate to ADP is catalyzed by __________. | creatine kinase |
| Myoglobin is a molecule within muscle cells that can bind | Oxygen |
| True or False: A motor neuron and all of the muscle cells that it stimulates are referred to as a motor end plate. | False |
| Which of the following is not a function of the muscular system? | Secretion |
| Which connective tissue sheath separates neighboring muscles from one another? | Fascia |
| In skeletal muscle, an action potential moves across | The sarcolemma |
| The thinner filaments are the ______ filaments. | Actin |
| When acetylcholinesterase outlasts the release of acetylcholine from the synaptic vesicles, the skeletal muscle __________. | relaxes |
| true or false: Muscle contraction will always promote movement of body parts. | False |
| A local change in voltage at the motor end plate, resulting from the opening of ligand-gated ion channels is called | End-plate potential |
| The thinner filaments are the ______ filaments. | Actin |
| How many somatic motor neurons stimulate one muscle fiber? | 1 |
| Which connective tissue wraps around multiple muscle fibers to create fascicles? | Perimysium |
| What is the functional role of the T tubules in skeletal muscles? | To transmit an action potential toward the interior of the cell. |
| The sliding filament model of contraction involves which of the following changes? | Actin and myosin sliding past each other and partially overlapping. |
| Muscles that are used for precisely controlled movements generally contain large motor units. | False |
| Which region of the sarcomere consists of overlapping thin actin and thick myosin filaments? | A band |
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