1. What is the necessary condition for generation of spike potentials in smooth muscle cells?
a) sufficient intra-cellular calcium deposits;
b) reaching membrane depolarization threshold;
c) sufficient density of voltage-gated Na+ channels. correct answers b
2. Spike potentials in smooth mu...
BIOPHYSICS MCQS – ALL || with Complete Solutions.
1. What is the necessary condition for generation of spike potentials in smooth muscle cells?
a) sufficient intra-cellular calcium deposits;
b) reaching membrane depolarization threshold;
c) sufficient density of voltage-gated Na+ channels. correct answers b
2. Spike potentials in smooth muscles are defined as:
a) action potentials;
b) slow waves;
c) Ca2+ equilibrium potentials. correct answers a
3. Smooth muscle tissue is build of this type of cells:
a) cylindrical cells;
b) spindle-shaped cells;
c) relatively small hexagonally-shaped cells. correct answers b
4. "Slow waves" are present in:
a) gastrointestinal smooth muscle tissue;
b) bronchial smooth muscle tissue;
c) arterial smooth muscle tissue correct answers a
5. Slow waves are changes in the membrane potential in certain smooth muscles:
a) due to input from the nervous system;
b) not due to stimuli from the nervous system or endogenous substances;
c) due to endogenous substances. correct answers b
6. Is there a functional relationship between slow waves and spike potentials in smooth muscle
cells?
a) yes, slow waves can trigger spike potentials;
b) there is no known functional dependence;
c) yes, spike potentials can trigger slow waves. correct answers a
7. The dynamics of ion flow during spike potentials is:
a) Na+ influx → depolarization, K+efflux → repolarization;
b) Ca2+influx → depolarization, K+efflux → repolarization;
c) Ca2+efflux → depolarization, Na+influx →repolarization. correct answers b
,8. In the cytosol Ca2+ ions bond to, and activate a protein which plays a critical role in the
contraction of the smooth muscle. This protein is:
a) calmodulin;
b) tropomyosin;
c) troponin C. correct answers a
9. Which of the following muscles do not have an ordered sarcomere structures?
a) skeletal muscles;
b) cardiac muscle;
c) smooth muscles. correct answers c
10. Which ion channels permit the Ca2+ion influx, necessary for the spontaneous phasic
contractions of smooth muscles?
a) receptor-regulated channels (triggered by ligands);
b) voltage-gated (membrane potential dependent);
c) stretch-regulated (mechanical forces on the membrane). correct answers b
11. What type of contraction results in smooth and striated muscles when the intervals between
consecutive action potentials are shorter than the duration of muscle fiber contractions?
a) single contraction;
b) phasic contractions;
c) complete or incomplete tetanus. correct answers c
12. Which is the best description of the membrane potential of striated muscles when there are
no muscle contractions?
a) rhythmic low frequency fluctuations below threshold excitation- formation for slow waves;
b) steady resting potential;
c) slow depolarization initiated from pacemaker cells. correct answers b
13. What is the source of Ca2+ needed for the contraction of striated skeletal muscles?
a) from intracellular Ca2+ depots;
b) influx of Ca2+ from the extracellular fluid into the sarcoplasm, which leads to additional
Ca2+ release form intracellular depots;
c) through suppression of the activity of the calcium pumps (which remove intracellular Ca2+).
correct answers a
14. What type of membrane channels are activated during action potential propagation along the
sarcolemma of striated muscle cells?
,a) voltage-gated sodium channels;
b) calcium channels, regulated by ryanodine receptors;
c) voltage-dependent calmodulin receptors. correct answers a
15. The sarcoplasmic reticulum of smooth muscle cells can be characterized as:
a) very elaborate;
b) moderately developed;
c) not elaborate. correct answers c
16. Are there motor endplates in smooth muscle tissues?
a) yes;
b) no;
c) sometimes. correct answers b
17. Phasic contraction in smooth muscle cells are responsible for:
a) peristaltic movement;
b) the heartbeat;
c) release of neurotransmitter molecules. correct answers a
18. The existence of "slow waves" in the membrane potential is characteristic for:
a) phasic smooth muscle cells;
b) tonic smooth muscle cells;
c) neurons. correct answers a
19. Blood vessels are predominately build of:
a) tonic smooth muscle tissue;
b) phasic smooth muscle tissue;
c) satiated muscle tissue. correct answers a
20. Activation of the enzyme myosin light chain kinase (MLCK) leads to:
a) contraction in smooth muscle cells;
b) relaxation in smooth muscle cells;
c) initiation of slow waves. correct answers a
21. The basic contraction unit in muscle tissues is:
a) the smooth muscle cell;
b) the smooth muscle fiber (myofibril);
c) the fiber bundle, wrapped in connective tissue (fascicle). correct answers b
, 22. Choose the correct statement:
a) in visceral smooth muscle tissue, found in hollow organs, fiber bundles are innervated together
(as a
single unit), and individual cells communicate via nexuses (gap junctions);
b) in visceral smooth muscles, found in hollow organs, each muscle cell is innervated
individually (as a
multi-unit), and individual cells communicate via gap junctions;
c) in visceral smooth muscles, found in hollow organs, each muscle cell is innervated
individually, and
individual cells do not communicate. correct answers a
23. Choose the set of characteristics that describes best smooth muscle contractions:
a) voluntary, slow, large energy expenditure;
b) involuntary, fast, low energy expenditure;
c) involuntary, slow, low energy expenditure. correct answers c
24. The thin myofilaments in smooth muscle cells are build of:
a) 4 types of contractile proteins;
b) 2 types of contractile proteins;
c) 3 types of contractile proteins. correct answers b
25. The basis of the thin myofilaments in smooth muscle tissue is the protein:
a) myosin;
b) actin;
c) troponin. correct answers b
26. The basis of the thick myofilaments in smooth muscles is the protein:
a) myosin;
b) actin;
c) tropomyosin correct answers a
27. Choose the correct statement regarding discrete (multi-unit) smooth muscles:
a) in discrete smooth muscle tissue, found in hollow organs, each cell is innervated separately,
and
individual cells communicate via nexuses (gap junctions);
b) in discrete smooth muscles each cell is innervated individually, thus cells do not communicate
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