Muscle Advanced PDF

Muscle Advanced 1. What function of skeletal muscle is least dependent on its connections to other tissues? a) Heat generation b) Movement c) Stability d) Protection of organs 2. Which muscle type does not contract spontaneously? a) Cardiac muscle b) Smooth muscle in digestive tract c) Skel...

Muscle Advanced 1. What function of skeletal muscle is least dependent on its connections to other tissues? a) Heat generation b) Movement c) Stability d) Protection of organs 2. Which muscle type does not contract spontaneously? a) Cardiac muscle b) Smooth muscle in digestive tract c) Skeletal muscle d) Smooth muscle in blood vessels 3. What is the role of Ca2+ in the muscle action potential? a) Depolarisation b) Hyperpolarisation c) None - Ca2+ only regulates contraction d) Repolarisation 4. What is the role of T-tubules in skeletal muscle function? a) Sequestration of Ca2+ b) Ensure the muscle is excited as quickly and evenly as possible c) Distribute acetylcholine (ACh) around the muscle d) Attachment to skeleton 5. A motor unit containing few muscle fibres produces: a) Fine movements b) Powerful movements c) Fast movements d) Weak movements 6. Curare completely blocks cholinergic transmission at the neuromuscular junction. It will therefore cause: a) Complete tetanus b) Complete paralysis & relaxation c) Uncontrolable twitching d) Complete muscle fatigue 7. When a whole motor nerve is stimulated electrically, increasing strength of stimulus causes the muscle to contract more strongly. Why is the all-or-none law apparently not obeyed? a) The all-or-none law does not hold in muscle. b) Motor neurons use graded potentials. c) A motor nerve contains many motor units. Greater stimulation causes additional motor units to become active. d) A motor nerve contains many motor units. Greater stimulation reduces activity in inhibitory interneurons. 8. Which organs are capable of generating heat? a) The gastrointestinal tract b) The nervous system and the lungs c) Skeletal muscle and the liver d) Skeletal muscle only 9. What component of a sarcomere does the I-band represent? a) The portion of thin filaments (on both side of the Z line) not overlapping with thick filaments b) The portion of thick filaments (on both side of the M line) not overlapping with thin filaments c) The area where thick and thin filaments overlap d) The total length of thin filaments 10. What component of a sarcomere does the A-band represent? a) The portion of thin filaments (on both side of the Z line) not overlapping with thick filaments b) The portion of thick filaments (on both side of the M line) not overlapping with thin filaments c) The area where thick and thin filaments overlap d) The total length of thick filaments 11. Which of the following correctly describes the sarcomere during contraction? a) A-band gets wider, zone of overlap increases, Z-lines move closer together. b) A-band is constant, I band gets smaller, Z-lines move closer together. c) A-band is constant, zone of overlap is constant, I-band gets wider. d) A-band gets smaller, I-band gets smaller, Z-lines move closer together 12. If a muscle is stretched until the zone of overlap disappears, a) its power increases b) it becomes fatigued more quickly c) it can no longer contract d) Ca2+ is released from the sarcoplasmic reticulum 13. At the molecular level, the energy source for contraction is a) ATP b) ADP c) glucose d) lactic acid 14. The energy-dependent rotation of the myosin head during muscle contraction is responsible for: a) Binding the action filament b) Releasing the actin filament c) Pusing the actin filament d) Releasing ADP 15. What is the first step in the contraction of a skeletal muscle fibre? a) An action potential is triggered at the neuromuscular junction b) Ca2+ binds troponin c) Myosin pushes on the actin filament d) Ca2+ is removed from the sarcoplasm 16. What is the role of the sarcoplasmic reticulum in skeletal muscle? a) Breakdown of acetylcholine (ACh) b) ATP synthesis and release when triggered by an action potential c) Protein synthesis d) Store Ca2+ and release it when triggered by an action potential 17. During excitation-contraction coupling, troponin binds Ca2+. How does this enable contraction to occur? a) Troponin causes tropomyosin to expose the actin binding site on the myosin head b) Troponin causes tropomyosin to expose the myosin binding site on the actin filament c) Troponin shifts to expose the myosin binding site on the actin filament d) Ca2+ allows troponin to bind the actin filament 18. While Ca2+ is present in the sarcoplasmic reticulum: a) The muscle will continue to contract b) Each myosin molecule will execute a single powerstroke c) Tropomyosin prevents binding of myosin to actin d) The muscle will produce action potentials 19. During peak activity muscles cannot generate enough energy (ATP) from oxygen-dependent metabolism. What happens in this situation? a) The muscle can no longer contract (fatigue) b) Energy is derived from CO2-dependent mechanisms c) ATP is supplied by other cells d) Energy is derived from oxygen-independent mechanisms 20. Accumulation of lactic acid in contracting skeletal muscle is also called the 'oxygen debt'. What does this mean? a) Lactic acid is a waste product of oxygen-independent glucose metabolism. It is converted back into glucose during recovery, consuming oxygen. b) Lactic acid is stored in muscle to release additional oxygen during heavy activity. c) Lactic acid is a waste product of oxygen-dependent glucose metabolism. It is converted back into glucose during recovery, producing oxygen. d) Production of lactic acid uses oxygen from surrounding tissues, which is replaced during recovery.