All biophysics PMU questions

270. Sodium equilibrium potential (ENa+) for typical neurons is about: a) +45 mV; b) - 90 mV; c) +95 mV.

a) +45 mV;

243. The resting potential in nerve cells is about: a) -70 mV; b) -70 kV; c) -70 μV.

a) -70 mV;

434. The approximate value of the resting potential of cardiac muscle cells is: a) -90 mV b) -90 V c) -40 mV

a) -90 mV

46. During smooth muscle contraction, the concentration Ca2+ in the cytosol increases to: a) 10^-5 mol/l; b) 10^-7 mol/l; c) 10^7 mol/l.

a) 10^-5 mol/l;

467. The operational mode of the thyroid Na+/I- symporter is as follows: a) 2 Na+ ions move in, for each I- ion moving in; b) 2 Na+ ions move out, for each I- ion moving in; c) 3 Na+ ions move in, for 2 I- ions moving out.

a) 2 Na+ ions move in, for each I- ion moving in;

302. What is the approximate thickness of the cellular membrane? a) 6 - 10 nm; b) 6 - 10 μm; c) 60 - 100 nm.

a) 6 - 10 nm;

501. Membrane receptors connected to G - proteins, are large proteins that cross the membrane lipid bilayer: a) 7 times; b) once; c) different number times, depending on the receptor.

a) 7 times;

143. Choose the correct order of events, related to the increase of Ca2+ concentrations in the sarcoplasm to 10^-5 M: a) Ca2+ bonds to troponin C → change in the conformation of the troponin-tropomyosin complex → myosin heads are allowed to bond to actin → formation of cross-bridges; b) myosin heads spontaneously bond to actin filaments and form cross-bridges → activation of the myosin light chain kinase → inhibition is removed; c) formation of Ca2+- calmodulincomplex → myosin heads bond to actin and form cross - bridges→ change in the conformation of the Ca2+- calmodulin complex and its inhibiting effect.

a) Ca2+ bonds to troponin C → change in the conformation of the troponin-tropomyosin complex → myosin heads are allowed to bond to actin → formation of cross-bridges;

47. Spike potentials in smooth muscles provide: a) Ca2+ influx from the extracellular space into the cytosol; b) Ca2+ efflux from the cytosol into the extracellular space; c) bidirectional transfer of Ca2+ across the membrane, leading to equilibrium.

a) Ca2+ influx from the extracellular space into the cytosol;

432. The plateau phase of the action potential of cardiac myocytes is due to: a) Ca2+ influx through slow voltage-gated channels; b) K+ efflux; c) N+ influx.

a) Ca2+ influx through slow voltage-gated channels;

533. Which of the following factors have immediate relevance to the released of from the vesicles neurotransmitters? a) Ca2+; b) H+; c) the surface charge of the vesicles.

a) Ca2+;

198. The following equation describes: (dm/S*dt) = -D (dc/dx) a) Fick's law of diffusion; b) Van't Hoff law of osmosis; c) Nernst equation.

a) Fick's law of diffusion;

166. Choose the formula that describes the correction of Ohm's law for direct current passing through living tissue: a) IT = V-P(t) / RT b) IT = V-R(t) / PT c) IT = V-P(t) T should be as subscript

a) IT = V-P(t)/RT

428. Which of the following ions are responsible for the final repolarization phase of the myocardial cells? a) K+ efflux; b) Cl- influx; c) Ca2+ influx.

a) K+ efflux;

226. What is the sequence and the types of membrane ion currents during period of the action potential in neurons? a) Na+ influx and K+ efflux; b) Na+ influx, Ca2+ influx, and K+ efflux; c) K+ influx and Na+ efflux.

a) Na+ influx and K+ efflux;

509. When acetylcholine bonds to a nicotinic cholinergic receptor, the following membrane channel is opened: a) Na+ ion channel; b) G-protein coupled channel; c) Ca2+ ion channel.

a) Na+ ion channel;

257. During the depolarization phase of the axonal membrane, there is increase for its permeability for: a) Na+ ions; b) K+ ions; c) Cl- ions.

a) Na+ ions;

271. The depolarization phase in typical neurons is due to: a) Na+ ions; b) Na+ and Ca2+ ions; c) Ca2+ ions.

a) Na+ ions;

242. The ions that participate in Goldman equation are: a) Na+, K+, Cl- ; b) Na+, K+, Ca2+; c) Na+, Cl-, Ca2+;

a) Na+, K+, Cl- ;

567. Which of the following defines the ohmic (active) resistance of an object: a) R = ρ∙l/S (where: ρ is resistivity, l is distance between electrodes, and S is the surface area); b) R = ε∙l/S (where:ε is permeability , l is distance between electrodes, and S is the surface area); c) R = ω∙l/S (where: ω is frequency, l is distance between electrodes, and S is the surface area).

a) R = ρ∙l/S (where: ρ is resistivity, l is distance between electrodes, and S is the surface area);

373. Which formula is used to calculate the electric impedance Z? a) Z = V /I; b) Z = V∙I; c) Z = I /V.

a) Z = V /I;

515. The transport antibiotic (ionophore) valinomycin is: a) a carrier type ionophore; b) a channel forming ionophore; c) not dependent on on temperature.

a) a carrier type ionophore;

178. Electro-muscular contraction of denervated muscles is: a) a muscle contraction resulting from depolarization; b) a muscle contraction triggered by a high voltage; c) a muscle relaxation following the polarization of muscle cells.

a) a muscle contraction resulting from depolarization;

172. The electrical conductance of biological tissue is: a) a passive property; b) an active property; c) biological tissue has only resistance.

a) a passive property;

309. What type of membrane allows for the generation of diffusion potential? a) a permeable membrane: all ions can pass; b) non-permeable membrane: no ions can pass; c) semipermeable membrane: only certain type of ions can pass.

a) a permeable membrane: all ions can pass;

310. What kind of state is established between the extra and the intra-cellular spaces during constant membrane potential? a) a stationary state; b) a thermodynamic equilibrium; c) a non-equilibrium .

a) a stationary state;

2. Spike potentials in smooth muscles are defined as: a) action potentials; b) slow waves; c) Ca2+ equilibrium potentials.

a) action potentials

268. Choose the correct statement: a) action potentials propagate without attenuation (decrease) of amplitude and with relatives constant speed; b) action potentials propagate with significant decrease of amplitude over the length of the membrane; c) action potentials propagate with increase of the amplitude over the length of the membrane.

a) action potentials propagate without attenuation (decrease) of amplitude and with relatives constant speed;

312. Choose the correct statement: a) after reaching a maximum, the diffusion potential decreases to zero; b) after reaching a maximum, the membrane potential decreases to zero; c) the membrane potential never reaches a stationary point.

a) after reaching a maximum, the diffusion potential decreases to zero;

405. What type of current is used in rheography? a) alternating current with frequency range: 30,000 Hz -100,000 Hz; b) direct current with magnitude: 3 μA- 5 μA; c) low frequency current with low power.

a) alternating current with frequency range: 30,000 Hz -100,000 Hz;

121. Electro-mechanical (excitation-contraction) coupling in the so called "triad" in striated muscle cells occurs when: a) an action potential activates the voltage-gateddihydropyridine receptors; b) an action potential activates the voltage-gated Ca2+ channels at the membrane; c) post-synaptic electrotonic currents activate voltage-gated sodium channels along the sarcolemma.

a) an action potential activates the voltage-gateddihydropyridine receptors;

412. The rising part of the rheographic curve is called: a) anacrota; b) catacrota; c) incisura

a) anacrota;

528. In what stage of the radiation exposure does oxygen level have a greater effect? a) at the formation stage of free radicals and peroxides (10-6 s after exposure); b) at the stage of membrane lipid oxidation by peroxides; c) at the stage of synthesis of non-typical proteins (radiotoxins).

a) at the formation stage of free radicals and peroxides (10-6 s after exposure);

104. Troponin molecules from the thin myofilaments of striated muscles are: a) attached to tropomyosin molecules on specific locations; b) spirally wrapped around the double spiral of F - actin; c) spirally wrapped around the double spiral of tropomyosin.

a) attached to tropomyosin molecules on specific locations;

351. Why zeta potential decreases when the ionic strength of the medium is increased? a) because the diffusion layer around the particle decreases; b) because there is a compression of the absorption layer around the particle, but the double electric layer remains the same; c) because there is an increase of the ionic atmosphere around the particle.

a) because the diffusion layer around the particle decreases;

401. Which type of tissue is characterised by the least value of specific impedance? a) blood; b) bones; c) adipose tissue.

a) blood

179. The specific electrical conductance is the greatest for this type of tissue: a) blood; b) muscle tissue; c) fat tissue.

a) blood;

391. Which of the following human tissues has the least specific resistance? a) blood; b) bones; c) skin.

a) blood;

514. The transport antibiotic (ionophore) valinomycin: a) bonds preferentially to K+; b) bonds preferentially to Na+; c) is nonselective to Na+ and K+.

a) bonds preferentially to K+;

109. What is the role of troponin C in the contraction process in skeletal muscles? a) bonds to 4 Ca2+ ions, changes the conformation of the troponin-tropomyosin complex, and allows the formation of actin-myosin cross bridge; b) provides the mechanical contact between troponin and tropomyosin; c) bonds to 2 Ca2+ ions and 2 ATP molecules, activates the Ca2+- pump, and increases the concentration of calcium in the cytosol.

a) bonds to 4 Ca2+ ions, changes the conformation of the troponin-tropomyosin complex, and allows the formation of actin-myosin cross bridge;

32. What is the role of Ca2+ in the smooth muscle contraction? a) bonds to regulatory protein calmodulin; b) bonds to the myosin molecule; c) Ca2+ does not affect smooth muscle contraction.

a) bonds to regulatory protein calmodulin;

392. Where in the human body is the specific impedance the greatest? a) bones (ρ = 104÷106 Ω.m) and dry skin(ρ = 105÷106 Ω.m); b) soft tissue; c) blood.

a) bones (ρ = 104÷106 Ω.m) and dry skin(ρ = 105÷106 Ω.m);

76. Nifedipine and Verapamil are channel blockers for this type of ions: a) calcium membrane channels; b) sodium channels located on cellular organelles; c) potassium membrane channels.

a) calcium membrane channels;

77. The repolarization phase of spike potentials is due to the opening of this type of channels: a) calcium-activated potassium channels; b) voltage-gated calcium channels; c) sodium channels.

a) calcium-activated potassium channels;

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.

a) calmodulin

381. Which type of electric impedance (resistance) is prevalent in cellular membranes during the application of an external electric current? a) capacitive reactance; b) active (ohmic) resistance; c) inductive reactance.

a) capacitive reactance;

414. Which of the following factors has an effect on the steepness of the anacrotic part of the rheogram? a) cardiac stroke volume; b) total blood volume; c) the heart rate

a) cardiac stroke volume;

456. The Na+/K+ pump is found in: a) cellular membranes; b) cellular membrane and the membrane of the endoplasm reticulum; c) nuclear and cellular membranes.

a) cellular membranes;

366. Zeta potential is used as a diagnostic marker for: a) changes in the cellular membrane; b) changes in the cytoplasm; c) changes in the blood pressure.

a) changes in the cellular membrane;

265. The excitation of a neuron is related to: a) changes in the electrical conductivity of the cellular membrane; b) exchange of signal molecules between receptors of the cellular and nuclear membranes; c) activation of the process of cellular division.

a) changes in the electrical conductivity of the cellular membrane;

476. The known inter-cellular information systems are: a) chemical and electrical; b) mechanical, chemical, and electrical; c) biochemical.

a) chemical and electrical;

489. The principle of recognition between ligands and receptors is called: a) complementarity; b) bifocal; c) positive-negative match;

a) complementarity

229. The propagation of the action potential along the membrane is carried out as: a) consecutive depolarization of the membrane, triggered by local longitudinal currents, caused by the depolarization of the adjacent point of the membrane; b) consecutive depolarization of the membrane, triggered by local longitudinal currents, emanating from the initial point of stimulation; c) as an electric current flowing longitudinally along the membrane.

a) consecutive depolarization of the membrane, triggered by local longitudinal currents, caused by the depolarization of the adjacent point of the membrane;

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.

a) contraction in smooth muscle cells

337. The adsorption layer is: a) counter ions attracted to the surface of the bio-object; b) ions with the same charge as the ions of the potential-generating ions; c) none of the above.

a) counter ions attracted to the surface of the bio-object;

521. The work of Ca2+ pumps: a) decrease the level of cytosolic calcium; b) increase the level of cytosolic calcium; c) keep cytosolic calcium level constant.

a) decrease the level of cytosolic calcium;

542. The amplitude of the electrotonic potential: a) decreases exponentially away from the source; b) increases exponentially away from the source; c) remains with a constant amplitude.

a) decreases exponentially away from the source;

372. How does skin impedance (resistance) vary with increase of the frequency of the applied electric field? a) decreases, because the capacitive reactance of skin decreases; b) increases, because skin resistance is proportional to the frequency; c) decreases, because the (active) resistance of skin decreases.

a) decreases, because the capacitive reactance of skin decreases;

383. How does the capacitive reactance of biological tissue change when the frequency of the applied electric current increases? a) decreases, inversely proportional to the frequency; b) increases, proportional to the frequency; c) increases, proportional to the square root of the frequency.

a) decreases, inversely proportional to the frequency;

249. Which of the following bioelectrical processes initiates the action potential? a) depolarization of the membrane; b) repolarization of the membrane; c) hyperpolarization of the membrane.

a) depolarization of the membrane;

64. Which of the following membrane conditions activate the voltage-gated (potential-dependent) ion channels? a) depolarization of the plasma membrane; b) hyper-polarization of the plasma membrane; c) keeping the membrane potential unchanged for period of 50 ms.

a) depolarization of the plasma membrane;

356. Micro-electrophoresis is used for: a) determination the electrophoretic mobility and zeta potential of suspensions of cells (particles); b) determination of the chemical composition of mixtures; c) inception of pharmaceutical drugs in the body through the skin.

a) determination the electrophoretic mobility and zeta potential of suspensions of cells (particles);

269. Which of the following factors affects the speed of propagation of axonal action potentials? a) diameter and myelination; b) only the diameter of the axon; c) the length of the axon.

a) diameter and myelination;

386. What is the path of the electric current in suspension of cells in electrolyte solution, if the frequency of the current is high? a) electric current flows through the cells and in the spaces between the cells; b) electric current flows mostly in the spaces between the cells; c) electric current flows only when there is charge accumulation on the membranes of the cells.

a) electric current flows through the cells and in the spaces between the cells;

406. Rheography is non-invasive method for investigation of the dynamics of pulsed blood-filling of tissues through the graphical recording of: a) electrical resistance; b) electrical bio-potentials; c) cardiac sounds.

a) electrical resistance;

72. What forces drive ions through the ion channels? a) electrochemical gradients; b) hydrostatic pressure; c) osmotic pressure.

a) electrochemical gradients;

146. Which of the following tissue-polarization types has the longest time constant? a) electrode polarization; b) dipole polarization; c) macrostructural polarization.

a) electrode polarization;

454. What are the operation modes of the Na+/K+ pump? a) electrogenic and non-electrogenic; b) transmembrane and intracellular; c) passive and active.

a) electrogenic and non-electrogenic;

147. Which of the following types of polarization takes place 10-16 s after the application of external current through the tissue? a) electronic; b) ionic; c) superficial.

a) electronic;

334. Which of the following is not an electrokinetic phenomenon? a) electrotonic potential; b) sedimentation potential; c) streaming potential.

a) electrotonic potential;

558. Choose the correct ordering of the chemical type communications according to the distance between emitting and target cells: a) endocrine > paracrine > autocrine; b) autocrine > paracrine > endocrine; c) paracrine >endocrine > autocrine.

a) endocrine > paracrine > autocrine;

200. What cause the end of net ion diffusion across the membrane? a) equalisation of ion concentrations on both sides of the membrane; b) heating up of the less concentrated solution; c) engaging of membrane co-transport.

a) equalisation of ion concentrations on both sides of the membrane;

547. Which of the following defines best an "closed thermodynamic system"? a) exchange of energy with the surrounding environment; b) exchange of energy and matter with the surrounding environment; c) exchange of matter with the surrounding environment.

a) exchange of energy with the surrounding environment;

252. The term "resting potential" applies to: a) excitable cells; b) muscle cells only; c) nerve cells only.

a) excitable cells;

33. Which intracellular factors lead to a smooth muscle relaxation? a) factors that activate the enzyme myosin light chain phosphatase; b) factors that inhibit the enzyme myosin light chain phosphatase; c) factors that activate the enzyme myosin light chain kinase.

a) factors that activate the enzyme myosin light chain phosphatase;

359. Which of the following processes causes a streaming potential? a) filtration; b) osmosis; c) diffusion.

a) filtration;

510. Signaling molecules that bond to receptors are called: a) first messenger or ligand; b) second messenger; c) cellular effector.

a) first messenger or ligand;

322. Equilibrium potential across the membrane is achieved when: a) forces due to concentration gradient = forces due to electric gradient; b) osmotic pressure = hydrostatic pressure; c) membrane potential = diffusion potential.

a) forces due to concentration gradient = forces due to electric gradient;

390. The impedance of biological tissue is: a) frequency dependent, because the capacitive component is frequency dependent; b) frequency independent, because the resistive component is frequency independent; c) frequency dependent, because the ohmic resistance is frequency dependent.

a) frequency dependent, because the capacitive component is frequency dependent;

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+).

a) from intracellular Ca2+ depots

344. How far does the diffuse layer spread around a bio-object? a) from the adsorption layer to the point where the potential decreases e-times (where e = 2.71); b) from the charged surface of the bio-object to the point where the potential decreases 10 times; c) from the charged surface of the bio-object to the point where the potential decreases to zero.

a) from the adsorption layer to the point where the potential decreases e-times (where e = 2.71);

83. During the resting state of the cell, the Na+ electrochemical gradient points: a) from the extracellular into the intracellular space; b) from the intracellular into the extracellular space; c) in both directions.

a) from the extracellular into the intracellular space;

4. "Slow waves" are present in: a) gastrointestinal smooth muscle tissue; b) bronchial smooth muscle tissue; c) arterial smooth muscle tissue.

a) gastrointestnal smooth muscle tissue

150. What causes the decrease of the DC current passing through living tissue? a) generation of polarization potential, opposing the external voltage; b) increase of the internal resistance of the tissue; c) the leakage of charge out of the tissue.

a) generation of polarization potential, opposing the external voltage;

297. Membrane proteins: a) have transport functions; b) build the glycocalyx of the cell; c) contribute to the formation of membrane kinks.

a) have transport functions;

496. Receptors are characterised with: a) high-affinity, high-specificity, and reversible bonding to signaling molecules; b) high-affinity, low-specificity, and reversible bonding to signaling molecules; c) high-affinity, high-specificity, and irreversible bonding to signaling molecules.

a) high-affinity, high-specificity, and reversible bonding to signaling molecules;

292. Phospholipid molecules are generally build of: a) hydrophilic head and two hydrophobic tails; b) hydrophilic head and one hydrophobic tail; c) hydrophobic head and two hydrophilic heads.

a) hydrophilic head and two hydrophobic tails;

382. The total opposition of a material (or tissue) to the propagation of an alternating electric current is called: a) impedance; b) reactance; c) admittance.

a) impedance;

451. The Na+/K+ pump is found: a) in all types of cells; b) in the excitable cells only; c) in the human excitable cells.

a) in all types of cells;

187. Which of the following is a necessary condition for stopping osmosis? a) when the pressure of the solute molecules on the semipermeable membrane is equal to the pressure exerted by the water molecules on the other side of the membrane; b) when the pressure from the protein molecules on the semipermeable membrane is equal to the pressure exerted by the water molecules on the other side of the membrane; c) when the pressure on the membrane from the small solute molecules in the intracellular space is equal to the pressure from the protein molecules.

a) when the pressure of the solute molecules on the semipermeable membrane is equal to the pressure exerted by the water molecules on the other side of the membrane;

40. Is there a relationship (and if there is then what type) between spike potentials and the Ca2+ concentration in the cytosol? a) yes there is. Spike potentials are caused in part by Ca2+ influx and that leads to increase in the intracellular calcium; b) no; c) yes, there is. Spike potentials cause Ca2+ efflux which leads to decrease of the calcium concentration in the cytosol.

a) yes there is. Spike potentials are caused in part by Ca2+ influx and that leads to increase in the intracellular calcium;

525. Does the effect of ionising radiation depend on the types of exposed tissues? a) yes, different tissues have different radiosensitivity; b) no significant difference; c) it only depends on the frequency of the waves.

a) yes, different tissues have different radiosensitivity;

527. Does partial oxygen pressure in tissue have an influence on the damage induced from exposure to ionising radiation? a) yes, higher partial oxygen pressure leads to higher radiation damage; b) yes, lower partial oxygen pressure leads to higher radiation damage; c) no, partial oxygen pressure does not have an effect on the radiation damage.

a) yes, higher partial oxygen pressure leads to higher radiation damage;

453. Does the Na+/K+ pump require an energy source? a) yes, it hydrolyses adenosine triphosphate; b) no, ions are driven by concentration gradients; c) yes, it uses redox reactions in the annular lipid molecules.

a) yes, it hydrolyses adenosine triphosphate;

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.

a) yes, slow waves can trigger spike potentials

424. Is there a difference in the rate (frequency) of sinoatrial and atrioventricular potentials? a) yes, the sinoatrial node generates potentials with a faster rate; b) no difference; c) yes, the atrioventricular node generates potentials with a faster rate.

a) yes, the sinoatrial node generates potentials with a faster rate;

566. Electrophoretic mobility is defined as follows: a) μ = v/E (where: v-veolcity, E-external electric field); b) μ = v/η (where: v-veolcity, η-viscosity of fluid); c) μ = v/ε (where: v-veolcity, ε-electric permeability).

a) μ = v/E (where: v-veolcity, E-external electric field);

554. Which of the following is the theorem of Prigogine? a) ∆S/∆t = ∆Si/∆t + ∆Se/∆t b) S = k∙ln(W) c) ∆S = ∆Si + ∆Se Where: S - total entropy of system, W - thermodynamic probability (number of microstates), Si - change of internal entropy, Se - change of entropy due to exchange with the environment.

a) ∆S/∆t = ∆Si/∆t + ∆Se/∆t

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.

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);

217. Which of the following processes signifies the end of the depolarization phase of the action potential? a) inactivation of voltage-gated Na+ channels; b) activation of outgoing Cl- ion current, which compensates for the incoming Na+ current; c) activation of the membrane Ca2+ pumps.

a) inactivation of voltage-gated Na+ channels;

52. In the living body all muscles maintain certain level of tension called tonus. During contraction this tonus will: a) increase; b) decrease; c) stay the same.

a) increase

409. Decreased blood volume in vessels during the diastole leads to: a) increase of the electrical resistance in that area; b) decrease of the electrical resistance in the area; c) exponential change of the resistance in that area.

a) increase of the electrical resistance in that area;

564. Accommodation is the process of change of the following functional properties of the menrane: a) increase of the threshold potential; b) increase of the membrane potential; c) decrease of the threshold potential.

a) increase of the threshold potential;

50. The two known Ca2+ depots in the sarcoplasmic reticulum (IP3-regulated and Ryanodineregulated) are: a) independent of each other; b) one depot with two different channels; c) dependent on the membrane potential.

a) independent of each other;

189. Vasogenic cerebral edema is characterized by: a) inflation of the extracellular spaces; b) inflation of the intracellular spaces; c) vasodilation of cerebral vessels.

a) inflation of the extracellular spaces;

84. The bonding of a specific channel blocker with a target ion channel will result in: a) inhibition of the passive transport of the particular ion species; b) inhibition of the active transport of the particular ion species; c) inhibition of the passive ion transport in the entire body.

a) inhibition of the passive transport of the particular ion species;

494. The second messenger molecule that opens calcium channels on the membrane of the endoplasmic reticulum is: a) inositol triphosphate (IP3); b) diacylglycerol (DAG); c) cyclic adenosine monophosphate (cAMP).

a) inositol triphosphate (IP3);

221. What is the correlation between the magnitude of the minimal threshold stimulus and the excitability of the membrane? a) inverse; b) positive; c) no correlation.

a) inverse;

266. Which of the following currents is responsible for the depolarization phase of the axonal action potential? a) inward sodium ion current; b) inward potassium ion current; c) outward calcium ion current.

a) inward sodium ion current;

163. Dipole polarization: a) is related mostly to water molecules; b) involves the formation of a double electric layer; c) decreases the intercellular communication.

a) is related mostly to water molecules;

115. Muscle contractions could be classified in the following three types: a) isometric, isotonic, and auxotonic; b) isometric, isosmotic, and axonal; c) isometric, isospheric, and auxotonic.

a) isometric, isotonic, and auxotonic;

116. Which of the following types of muscle contraction does not produce classical work even though there still is an ATP consumption? a) isometric; b) isotonic; c) auxotonic.

a) isometric;

192. For a given temperature, solutions with equal concentrations will have equal osmotic pressure. These solutions are called: a) isotonic; b) hypertonic; c) hypotonic.

a) isotonic;

400. What causes the cyclic (pulsed) character of the rheographic recordings? a) it follows from the periodic variation of the measured resistance (the periodic change of the amount of blood) during cardiac cycles; b) it follows the periodic variation of the measured resistance caused by the propagation of pulse waves; c) it is caused by the blood retention during the systolic cardiac cycle, which increases the capacitive properties of the organ, and the respective decrease during the diastole.

a) it follows from the periodic variation of the measured resistance (the periodic change of the amount of blood) during cardiac cycles;

37. What is the function of protein calmodulin for the smooth muscle contraction? a) it forms a complex with four calcium ions, which activates the enzyme myosin light chain kinase (MLCK); b) does not affect smooth muscle contraction; c) it transports Ca2+ from the cellular membrane to the protein troponin C.

a) it forms a complex with four calcium ions, which activates the enzyme myosin light chain kinase (MLCK);

275. What makes the membrane resting potential so close to the potassium equilibrium potential? a) leak potassium channels and low membrane permeability for other ions; b) the much higher potassium concentration inside the cell compared to other ions; c) the work of the sodium-potassium pump which balances the outward leak of potassium.

a) leak potassium channels and low membrane permeability for other ions;

181. Electro-muscular stimulation for physical therapy uses: a) low frequency pulsed current; b) high frequency pulsed current; c) sine-wave current.

a) low frequency pulsed current;

462. The secondary active transport is carried through: a) membrane protein carriers; b) transmembrane ion channels; c) spontaneously formed (and vanishing) membrane pores.

a) membrane protein carriers;

71. Choose the best fitting description for ion channels from the following: a) membrane protein structures that span across the membrane, and under certain conditions provide selective ion transport between extra and intra cellular spaces; b) membrane lipid structures that span across the membrane, and under certain conditions allow a water-filled passage between extra and intra cellular spaces; c) membrane protein structures that provide uninterrupted ion transport between intra and extra cellular spaces.

a) membrane protein structures that span across the membrane, and under certain conditions provide selective ion transport between extra and intra cellular spaces;

487. Which of the following structures is an integral part of the chemical information system? a) membrane receptors; b) DNA molecules; c) actin molecules.

a) membrane receptors;

298. Phospholipid molecules placed in the air-water interface will form: a) monolayer; b) bilayer; c) micelles.

a) monolayer;

55. In the human body, smooth muscles are found in: a) most of the internal organs; b) the skeletal muscles; c) the pacemaking tissue of the heart muscle.

a) most of the internal organs;

449. The electrical conduction system of the heart is composed of: a) muscle cells; b) neurons; c) lymphocytes.

a) muscle cells;

26. The basis of the thick myofilaments in smooth muscles is the protein: a) myosin; b) actin; c) tropomyosin.

a) myosin

98. The major protein component of the thick myofilaments in striated muscle cells is: a) myosin; b) actin; c) troponin.

a) myosin

123. The lighter-shaded H-zone in skeletal muscle fibres is made of: a) myosin; b) actin; c) none of the above.

a) myosin;

138. Thick myofilaments are composed of the protein: a) myosin; b) tropomyosin; c) actin.

a) myosin;

562. The second law of thermodynamics states that: a) natural processes have a preferred direction; b) energy is never created or destroyed; c) that entropy in biological systems decreases.

a) natural processes have a preferred direction;

490. The neurotransmitter acetylcholine activates: a) nicotinic and muscarinic receptors; b) nicotinic receptors; c) muscarinic receptors.

a) nicotinic and muscarinic receptors;

68. Are ion channels completely impermeable for all but the ion species that give the channel's name? a) no, other similar ions can pass with low probability; b) yes, they permit only the ion species that give the channel's name; c) no, large organic molecule can also pass through the channels.

a) no, other similar ions can pass with low probability;

555. Which of the following energies is not part of classical thermodynamics? a) nuclear energy; b) heat; c) internal energy.

a) nuclear energy;

549. What type of thermodynamic system are living organisms? a) open; b) isolated; c) closed.

a) open;

380. What is the direction of the polarization electric field in a conductive environment? a) opposite on the applied external electric field; b) the same as the direction of the external electric field; c) the direction depends on the sign of the electric charges.

a) opposite on the applied external electric field;

523. How does ionising radiation damage lipid molecules? a) oxidation by peroxides; b) denaturation; c) chromosome aberrations.

a) oxidation by peroxides;

442. What type of cells make up the electrical conduction system of the heart? a) pacemaker type; b) phasic type; c) tonic type.

a) pacemaker type;

559. What kind of signaling is synaptic signaling? a) paracrine; b) endocrine; c) juxtacrine.

a) paracrine;

421. The plateau phase of the myocardial action potential is caused by the following ion transport: a) passive Ca2+ transport; b) passive Cl- and active Ca2+ transports; c) active Na+ and passive Ca2+ transports.

a) passive Ca2+ transport;

248. The term "influx" is usually associated with: a) passive transport through ion channels from extracellular into intracellular space; b) active transport through ion channels from extracellular into intracellular space; c) passive transport through ion channels from intra cellular into extracellular space.

a) passive transport through ion channels from extracellular into intracellular space;

204. Transport across the cellular membrane without direct use of metabolic energy is called: a) passive transport; b) active transport; c) secondary active transport.

a) passive transport;

73. What type of transport takes place through ion channels when they are activated: a) passive; b) active; c) passive when moving in, and active when moving out of the cell.

a) passive;

17. Phasic contraction in smooth muscle cells are responsible for: a) peristaltic movement; b) the heartbeat; c) release of neurotransmitter molecules.

a) peristaltic movement

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.

a) phasic smooth muscle cells

214. What is the correlation between the level of membrane depolarization and the number of activated voltage-gated Na+- ion channels during the early phase of the action potential? a) positive correlation; b) inverse correlation; c) no correlation.

a) positive correlation;

244. The equilibrium potential for Na+ is: a) positive; b) negative; c) zero.

a) positive;

264. The resting potential in excitable tissues has a magnitude close to: a) potassium equilibrium potential; b) sodium equilibrium potential; c) calcium equilibrium potential.

a) potassium equilibrium potential;

256. The resting membrane potential is due (among other factors) to the high permeability of the membrane to: a) potassium ions; b) sodium ions; c) chloride ions.

a) potassium ions;

458. According the type of energy supply, the active membrane transport is divided into: a) primary and secondary; b) simport and antiport; c) active and passive.

a) primary and secondary;

169. For efficient electro-muscular stimulation this type of current is used: a) pulsed current above the threshold; b) direct current with high voltage; c) direct current with variable voltage.

a) pulsed current above the threshold;

30. What is the spacial orientation of the smooth muscle contractile apparatus? a) random orientation; b) aligned in one direction, along the length of the fiber; c) aligned in two perpendicular directions.

a) random orientation;

426. Which of the following bioelectrical process take place during the diastolic phase of the heart? a) recovery of the ionic concentrations of intra- and extracellular fluids myocardial cells; b) flow of ionic currents between the Golgi apparatus and the endoplasmic reticulum; c) generation of reverse action potentials, propagating from myocardial cells to the sinoatrial node.

a) recovery of the ionic concentrations of intra- and extracellular fluids myocardial cells;

315. Which of the following conditions are necessary for the generation of membrane potential? a) regulation of ion traffic, and the maintenance of ionic concentration gradients; b) maximisation of the entropy for the combined system of intra and extra-cellular spaces; c) activation of the Na+/K+ pump in non-electrogenic mode.

a) regulation of ion traffic, and the maintenance of ionic concentration gradients;

101. The sarcoplasmic reticulum (SR) in striated muscles is: a) related to the muscle contraction through the release of Ca2+ ions; b) related to the muscle contraction through conduction of action potentials; c) not related to the muscle contraction.

a) related to the muscle contraction through the release of Ca2+ ions;

539. What is the function of phospholipase C for the release of neurotransmitters? a) removes the polar heads of membrane lipid molecules, this removing the electric repulsion between the membrane and the vesicles, and allowing for their docking; b) mediates the flow of Ca2+ into the vesicles and the formation of hyper osmotic environment; c) dissembles the vesicles and allows for the release and passive transport of the neurotransmitters.

a) removes the polar heads of membrane lipid molecules, this removing the electric repulsion between the membrane and the vesicles, and allowing for their docking;

154. What type of impedance to the propagation of electric current is found in living tissues? a) resistive and capacitive; b) resistive and inductive; c) capacitive and inductive.

a) resistive and capacitive;

155. What is the predominant type of electrical impedance in cellular fluids? a) resistive, because cellular fluids are rich in electrolytes; b) capacitive, because cellular fluids have sub-structures; c) inductive, because there are inductive currents in the fluids.

a) resistive, because cellular fluids are rich in electrolytes;

403. What is rheoencephalography? a) rheography of the brain; b) rheography of the heart; c) geography of the extremities.

a) rheography of the brain;

58. What is characteristic about the membrane potential of the stomach? a) rhythmic fluctuations with low frequency and below threshold; b) constant potential at rest; c) depolarization reaching threshold once every second.

a) rhythmic fluctuations with low frequency and below threshold;

207. What type of membrane depolarization is associated with the action potential? a) secondary; b) primary; c) the action potential is not associated with depolarization.

a) secondary;

480. Which of the following functions is not characteristic for receptors? a) secretion of signaling molecules; b) activation of second messenger systems; c) transmembrane signal transduction.

a) secretion of signaling molecules;

347. The zeta potential of a cell do not depend on: a) shape of the cell; b) temperature; c) ion concentration of the medium.

a) shape of the cell;

85. The phospholipid bilayer of the plasma membrane allows passive diffusion of: a) small hydrophobic molecules: oxygen, nitrogen, and carbon dioxide; b) small inorganic ions: sodium, potassium, and magnesium; c) large organic molecules: amino acids, peptides, and glucose.

a) small hydrophobic molecules: oxygen, nitrogen, and carbon dioxide;

278. The equation gNa = 1/RNa describes: a) sodium membrane conductance; b) sodium membrane current; c) sodium membrane voltage.

a) sodium membrane conductance;

532. Synapse is: a) specialised functional contact between cells of excitable tissues, used to communicate excitation of inhibition signals; b) specialised functional intracellular unit, used for Ca2+ storage and release during excitation; c) element of the electrical communication system of the organism, where cells use signaling molecules.

a) specialised functional contact between cells of excitable tissues, used to communicate excitation of inhibition signals;

437. Which of the following phases is characteristic for the action potential of pacemaker cells of the sinoatrial node? a) spontaneous diastolic depolarization; b) stable resting phase; c) the "plateau" phase.

a) spontaneous diastolic depolarization;

438. Which of the following phases is not fond in the action potential of cardiac mysocytes? a) spontaneous diastolic depolarization; b) resting phase; c) fast depolarization.

a) spontaneous diastolic depolarization;

134. Transverse tubules (T-tubules) are features in the membrane of: a) striated muscles; b) intestinal smooth muscles; c) arterial smooth muscles.

a) striated muscles;

152. What type of polarization occurs in the double electric layers surrounding cells, suspended in ionic solution, when constant electric field is applied? a) surface polarization; b) macrostructural polarization; c) orientational polarization.

a) surface polarization;

335. Potential-generating layer is: a) the accumulated, non-compensated charge on the surface of the dispersed phase (particle); b) dissociated layer of counter-ions surrounding the dispersed phase; c) the diffuse layer of particles surrounding the biological object.

a) the accumulated, non-compensated charge on the surface of the dispersed phase (particle);

209. Choose the correct statement: a) the action potential propagates along the membrane with constant speed; b) the action potential propagates across the membrane with constant speed; c) the action potential propagates in the form of longitudinal electric current.

a) the action potential propagates along the membrane with constant speed;

288. What drives phospholipid molecules, contained water environment, to self-assemble into bilayer structures? a) the amphiphilic properties of the phospholipid molecules; b) the electrostatic attraction between the polar heads of the lipid molecules; c) the repulsive forces between the lipid heads and the water molecules.

a) the amphiphilic properties of the phospholipid molecules;

108. Which of the following processes occurs immediately before the formation of actin-myosin crossbridges in skeletal muscles? a) the bonding of Ca2+ with the molecules of troponin C; b) the increase of Ca2+ concentration in the cytosol; c) the excitation of an action potential in the membrane.

a) the bonding of Ca2+ with the molecules of troponin C;

477. Of the following inter-cellular communication systems, which one is distributed throughout the entire organism? a) the chemical; b) the mechanical; c) the electrical.

a) the chemical;

397. What quantity is directly measured by the rheographic equipment? a) the cyclic variation of electric resistance, which is inversely proportional to the blood volume in a given area of the body; b) the variation of electric resistance for given organ for one cardiac cycle, which is proportional to the frequency of the applied electric field; c) the variation of the electric resistance of given organ, which depends on the area covered by the applied electrodes.

a) the cyclic variation of electric resistance, which is inversely proportional to the blood volume in a given area of the body;

263. Depolarization is: a) the decrease of the absolute value of the membrane potential; b) the increase of the absolute value of the membrane potential; c) decrease of the value of the membrane potential relative to the resting potential.

a) the decrease of the absolute value of the membrane potential;

353. Electrophoresis is: a) the directed motion of charged particles in a dispersion medium under influence of an external electric field; b) the directed motion of liquid under external electric field, towards the oppositely charged electrodes; c) the generation of a vertical electric potential between layers of the dispersion during the sedimentation of the solid phase.

a) the directed motion of charged particles in a dispersion medium under influence of an external electric field;

313. Choose the best definition for diffusion: a) the directed motion of the molecules of the solute from area with high solute concentration toward area of low solute concentration; b) the directed motion of the molecules of the solvent from area of low solute concentration toward area of high solute concentration; c) the directed motion of the molecules of the solute, leading to decrease of the total entropy of the system.

a) the directed motion of the molecules of the solute from area with high solute

354. Sedimentation potential is: a) the electric potential difference between upper and lower layers of a solution, when part of the phase (with zeta potential) settles down due to gravity; b) the electric potential difference across a membrane, after increase of the hydrostatic pressure on one of its sides; c) the potential difference acquired due to decrease of the surface charge of cells and increase of their speed of sedimentation.

a) the electric potential difference between upper and lower layers of a solution, when part of the phase (with zeta potential) settles down due to gravity;

441. Self-excitation is a property of: a) the electrical conduction system of the heart; b) all cardiac cells; c) the cardiac myocytes.

a) the electrical conduction system of the heart;

552. Which is the most likely state of a thermodynamic system? a) the entropy (disorder) is maximised; b) the entropy is minimised; c) the energy is maximised.

a) the entropy (disorder) is maximised;

276. What is represented on the graph on the right? (Graph missing, MCQ book p.28) a) the evolution of total membrane current during the course of the action potential; b) the inward Na+ current during the course of the action potential; c) the outward K+ current during the course of the action potential.

a) the evolution of total membrane current during the course of the action potential;

241. During the resting state of the cell, the concentration of Na+ ions is higher in: a) the extracellular space; b) the intracellular space; c) concentration is the same on both sides.

a) the extracellular space;

402 . Anacrotic part of the rheographic curve, caused by: a) the inflow of blood into the examined area, during the systole; b) the speed matching of blood and the pulse wave in the examined area; c) the closing of the aortic valve.

a) the inflow of blood into the examined area, during the systole;

177. A complete (smooth) tetanus is achieved when: a) the interval between action potentials is shorter than the duration of the muscle contraction; b) the interval between action potentials is longer than the duration of the muscle contraction; c) when the duration of the action potential is longer then the duration of the muscle contraction.

a) the interval between action potentials is shorter than the duration of the muscle contraction;

299. "Phase transition" of the lipid membrane is when: a) the lipid bilayer transforms between liquid and crystal-like (gel) states; b) the membrane proteins change conformational states; c) the membrane ion permeability changes due to rapid depolarization.

a) the lipid bilayer transforms between liquid and crystal-like (gel) states;

253. Goldman equation is used to calculate: a) the membrane potential at rest and during the action potential; b) the contribution of the Na+/K+ pump for the resting membrane potential; c) the duration of the action potential in neurons.

a) the membrane potential at rest and during the action potential;

224. Which of the following factors has an effect on the excitability of the neuron? a) the membrane potential at the moment of stimulation; b) the activity of the sodium-potassium pumps; c) the activity of the Ca2+ pumps.

a) the membrane potential at the moment of stimulation;

357. Electroosmosis is: a) the movement of the dispersion medium due to an external electric field; b) the movement of the dispersed phase due to an external electric field; c) none of the above.

a) the movement of the dispersion medium due to an external electric field;

233. The absolute refractory period is: a) the period where a depolarised portion of the membrane cannot be re-excited and generate a new action potential; b) the period where a hyper-polarised portion of the membrane can be re-excited with stronger-thanusual stimulus; c) the period where a sub-threshold stimulus causes membrane depolarization insufficient to trigger an action potential.

a) the period where a depolarised portion of the membrane cannot be re-excited and generate a new action potential;

369. Which of the following properties of biological tissues contribute to their electrical (active) resistance? a) the presence of electrolytes in the tissue; b) the surface charges of cellular membranes; c) the sub-cellular structures.

a) the presence of electrolytes in the tissue;

182. Which of the following definitions refers to osmotic pressure? a) the pressure exerted by the solute particles on a semipermeable membrane, due to their thermal motion; b) the pressure exerted on a semipermeable membrane from the solvent particles, due to their thermal motion; c) the pressure that proteins of blood plasma apply onto the walls of capillaries.

a) the pressure exerted by the solute particles on a semipermeable membrane, due to their thermal motion;

261. Action potential in neurons is: a) the rapid depolarisation followed by repolarization that propagates along the cellular membrane; b) the specific magnitude of the membrane potential when concentration and electrical gradients are equal and opposite in direction; c) the change in the amphiphilic properties of the membrane lipids allowing for electric charge redistribution between intra cellular and extracellular fluids.

a) the rapid depolarisation followed by repolarization that propagates along the cellular membrane;

350. What is the ratio of positive/negative potential-generating charges at the isoelectric point of the cell? How does it affect the interaction between cells? a) the ratio of positive/negative charge is unity (one) and there is agglutination of the cells; b) there are more positive than negative charges and the cell is charged positively; c) there are more negative charges which leads to the accommodation of the cell.

a) the ratio of positive/negative charge is unity (one) and there is agglutination of the cells;

162. Which of the following is related to dipole polarization? a) the reorientation of mostly water molecules due an external field; b) the conversion of the double electric layer into directional dipoles; c) the formation of dipole moment due to the external field.

a) the reorientation of mostly water molecules due an external field;

545. Given that the intracellular longitudinal Na+ currents, that spread the action potential, can take any direction, what is the reason that they move from excited into un-excited regions of the membrane? a) the resting membrane regions have more voltage-gated Na+ channels that are activation ready; b) the longitudinal currents always take the path of least resistance; c) longitudinal currents move only in the direction of the axonal synapse.

a) the resting membrane regions have more voltage-gated Na+ channels that are activation ready;

231. Is there a correlation between the propagation speed of the action potential along the axon, and the number of voltage-gated Na+ channels on the membrane? a) the speed increases with the number of voltage-gated Na+ channels; b) the speed decreases with the number of voltage-gated Na+ channels; c) no correlation.

a) the speed increases with the number of voltage-gated Na+ channels;

340. The electrokinetic potential is measured/calculated by: a) the speed of the dispersed phase in external electric filed; b) directly, using a unpolarisable electrodes and and a voltmeter; c) indirectly, using polarisable electrodes.

a) the speed of the dispersed phase in external electric filed;

246. Bioelectrical measure of the strength of a sub-threshold stimulus is: a) the strength of the graded potential; b) the frequency of action potentials; c) the adaptation to the stimulus.

a) the strength of the graded potential;

294. The so called "flip - flop" motion of the phospholipids in the membrane is: a) the transverse migration of phospholipid molecules form one layer into the other; b) the lateral migration of the phospholipid molecules within the same layer; c) the rotational motion of the hydrocarbon tails, without change of position or layers.

a) the transverse migration of phospholipid molecules form one layer into the other;

286. A common property of "excitable" cells are: a) the voltage-gated ion channels of the cellular membrane; b) the Na+/K+ pumps of the cellular membrane; c) the membrane specialisation for communication via neurotransmitters and hormones.

a) the voltage-gated ion channels of the cellular membrane;

338. The double electric layer is defined as: a) the volume surrounding the bio-object, where the potential-generating charges and the counter-ions have an asymmetrical distribution, which is electro-neutral as a whole; b) the collection of counter-ions from the diffuse layer around the bio-object, and those from the dispersion medium; c) the ions of the extracellular and intracellular fluids.

a) the volume surrounding the bio-object, where the potential-generating charges and the counter-ions have an asymmetrical distribution, which is electro-neutral as a whole;

560. Does the chemical activity of molecules exposed to ionizing radiation change? a) they become more chemically reactive; b) they become less chemically reactive; c) no change in the chemical reactivity.

a) they become more chemically reactive;

485. What are the functions of second messengers? a) they carry the information from receptors to cellular effectors or to cyclic cascades that amplify the signal; b) they interact with first messengers (signaling molecules) in the extracellular fluid, and carry the information to receptors; c) they interact with membrane receptors from the intracellular side and cause secondary activation of receptor proteins.

a) they carry the information from receptors to cellular effectors or to cyclic cascades that amplify the signal;

142. Acetylcholine (ACh) is a neurotransmitter that takes a major part in the contraction of striated muscles. How can ACh be inhibited without blocking the ACh - receptorsat the membrane? a) through the hydrolysis of ACh by acetylcholinesterase; b) through the excitation of an action potential; c) through the blocking of the Na+/K+ pump.

a) through the hydrolysis of ACh by acetylcholinesterase;

429. What is the function of the artificial cardiac pacemaker? a) to send electrical pulses to the heart; b) to control the resting potential of pacemaker cells; c) to take over the pumping function of the heart.

a) to send electrical pulses to the heart;

19. Blood vessels are predominately build of: a) tonic smooth muscle tissue; b) phasic smooth muscle tissue; c) satiated muscle tissue.

a) tonic smooth muscle tissue

358. Medical iontophoresis is: a) transcutaneous administration of drugs with the use of direct electric current; b) the use of micro-electrophoresis to apply drugs to patients; c) the use of electroosmosis to apply medical drugs to the body.

a) transcutaneous administration of drugs with the use of direct electric current;

495. What is the function of the membrane receptors? a) transduce information from extra- into intra-cellular space; b) transfer protein molecules from extra- into intra-cellular space; c) induce phase transitions in membrane lipid molecules.

a) transduce information from extra- into intra-cellular space;

508. According to their interaction with the membrane, receptors are: a) transmembrane (integral) proteins; b) surface membrane (integral) proteins; c) proteins diffusing through the membrane.

a) transmembrane (integral) proteins;

124. The troponin molecule bonds to: a) tropomyosin; b) actin; c) myosin.

a) tropomyosin;

128. During the process of electro-mechanical coupling in striated muscle cells, Ca++ ions are released into the sarcoplasm and bond to this protein: a) troponin; b) tropomyosin; c) myosin.

a) troponin;

317. Diffusion potential arises in a model system that satisfies the following conditions: a) two electrolyte solutions of different initial concentrations (c1 ≠ c2) and different anion and cation mobility (u1 ≠ u2) are separated by a porous membrane; b) two electrolyte solutions of the same initial concentrations (c1 = c2) and different anion and cation mobility (u1 ≠ u2) are separated by a porous membrane; c) two electrolyte solutions of different initial concentrations (c1 ≠ c2) and the same anion and cation mobility (u1 = u2) are separated by a porous membrane.

a) two electrolyte solutions of different initial concentrations (c1 ≠ c2) and different anion and cation mobility (u1 ≠ u2) are separated by a porous membrane;

78. TTX is a blocker of this type of channels: a) voltage-gated membrane sodium channels found in neurons; b) potassium membrane channels found in smooth muscle tissue with spontaneous bioelectric activity; c) non-activating sodium channels found in the cardiac sinoatrial node.

a) voltage-gated membrane sodium channels found in neurons;

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.

a) voltage-gated sodium channels

120. Which set of characteristics describes best the contraction of striated muscles? a) voluntary, fast, large energy intake; b) involuntary, fast, low energy intake; c) voluntary, slow, low energy intake.

a) voluntary, fast, large energy intake;

205. Higher (than normal) intracellular concentration of Na+ will lead to: a) water moving into the cell; b) water moving out of the cell; c) potassium moving into the cell.

a) water moving into the cell;

367. Drug administration with electrophoresis (iontophoresis) is done with: a) water solutions where the drug is in ionic form; b) colloid solutions and suspensions of cells; c) alternating electric current with low frequency.

a) water solutions where the drug is in ionic form;

303. Lipids are not soluble in: a) water; b) ethyl alcohol; c) benzene.

a) water;

407 . Choose the correct statement: a) when blood volume, in the investigated area, increases the specific resistance decreases; b) when blood volume, in the investigated area, increases the specific resistance also increases; c) when blood volume, in the investigated area, increases the specific resistance remains the same.

a) when blood volume, in the investigated area, increases the specific resistance decreases;

333. In which of the following cases there is an electrokinetic potential? a) when cells are placed in electrolyte solution; b) when the liquid surrounding the cells moves; c) when cells do not move in an external electric field.

a) when cells are placed in electrolyte solution;

238. How is the equilibrium potential for given ion species established across the membrane? a) when forces due the concentration gradient are balanced with forces due to the electrical gradient acting on the ion species; b) when the concentrations of the ions species is on both sides of the membrane are equal; c) when the total amount of electric charge due to ion distribution becomes equal on both sides of the membrane.

a) when forces due the concentration gradient are balanced with forces due to the electrical gradient acting on the ion species;

90. In which of the following cases will a voltage-gated (potential-dependent) ion channel be activated? a) when the membrane potential is higher than the activation threshold for the ion channel b) when the membrane potential is at resting level c) when the membrane potential is lower than the activation threshold for the ion channel

a) when the membrane potential is higher than the activation threshold for the ion channel

35. What is the role of the enzyme myosin light chain kinase (MLCK) in the smooth muscle contraction? a) it shortens the thin myofilaments and, after phosphorylation, it bends actin into a spiral; b) it phosphorylates the 20-kDa myosin light chain (MLC 20) of the myosin molecule, allowing for cross-bridge formation between thin and thick myofilaments; c) it interacts with ATP and the thin myofilaments, delivering energy for the contraction.

b) it phosphorylates the 20-kDa myosin light chain (MLC 20) of the myosin molecule, allowing for cross-bridge formation between thin and thick myofilaments;

61. What is the role of the electrostatic filter in ion channels? a) it changes the ion channel state: open or closed; b) it selects the ion species that can pass through the channel; c) it interacts with the electrically charged heads of the phospholipid molecules in order to change conformation.

b) it selects the ion species that can pass through the channel;

93. An ion channel that could be activated by a hormone, neurotransmitter, mediator, or other biologically active substance is called: a) potential-dependent channels; b) ligand-gated channels; c) Ca2+ dependent channels.

b) ligand-gated channels;

291. The following phase state is attributed to the lipid bilayers of biological membranes: a) dimeric - crystalstate; b) liquid - gel (crystal) state; c) liquid - gasstate.

b) liquid - gel (crystal) state;

148. Choose the correct relationship between the frequency of alternating current (AC) and the number of different types of polarizations that take place in the tissue: a) higher frequency → higher number of polarizations; b) lower frequency → higher number of polarizations; c) lower frequency → lower number of polarizations.

b) lower frequency → higher number of polarizations;

153. Which of the following types of polarization occur within the cell volume, due to the application of a constant electric field? a) superficial polarization; b) macrostructural polarization; c) electrode polarization.

b) macrostructural polarization;

505. Which of the following types of complementarity is not present between membrane receptors and ligand molecules? a) spatial; b) magnetic; c) electric.

b) magnetic;

450. The Na+/K+ pump is: a) cytosolic enzyme; b) membrane protein with enzyme activity; c) membrane lipid.

b) membrane protein with enzyme activity;

60. Ion channels are: a) temporary openings (pores) in the cellular membrane; b) membrane proteins that span across the lipid bilayer and come in contact with the extra- and intracellular environments; c) mobile membrane proteins that move across the lipid bilayer from the extracellular into the intracellular space.

b) membrane proteins that span across the lipid bilayer and come in contact with the extra- and intracellular environments;

293. When placed water, phospholipids form: a) ion channels; b) micelles; c) two dimensional solid crystal lattice.

b) micelles;

399. What is the frequency of the electric current used in rheography? a) high-frequency current, because it flows in equal amounts through cells and extracellular fluids; b) mid-frequency current, because it flows preferentially through the large blood vessels; c) low-frequency current, because it flows mostly through the extracellular fluids.

b) mid-frequency current, because it flows preferentially through the large blood vessels;

455. Describe the directions of ion transport through the Na+/K+ pump: a) moves Na+ and K+ ions out of the cell; b) moves Na+ out, and K+ in; c) moves Na+ in, and K+ out.

b) moves Na+ out, and K+ in;

460. In the electrogenic regime the sodium - potassiumpump: a) moves one negative charge out of the cell; b) moves one positive charge out of the cell; c) moves three positive charges in, for two positive charges out.

b) moves one positive charge out of the cell;

491. Atropin is: a) muscarinic agonist; b) muscarinic antagonist; c) nicotinic agonist.

b) muscarinic antagonist;

48. In smooth muscle cells, the complex 4Ca∙Calmodulin activates: a) the light chain of myosin phosphatase; b) myosin light chain kinase (MLCK); c) the Ca2+ regulated K+ channels.

b) myosin light chain kinase (MLCK);

81. Conduction of inorganic ions through the plasma membrane is carried by: a) endocytosis; b) narrow water-filled channels with diameter of 0.3 - 0.65nm; c) phagocytosis.

b) narrow water-filled channels with diameter of 0.3 - 0.65nm;

237. What is the value of the membrane potential on the inside of the cell relative to the outside, during the resting state of the cell? a) positive; b) negative; c) zero.

b) negative;

331. What is the sign of the electrokinetic potential (zeta) for living cells under normal physiological conditions? a) positive; b) negative; c) zero.

b) negative;

536. Which of the following statement about neurotransmitters is incorrect? a) neurotransmitters are released from neurons; b) neurotransmitters travel long distances to reach their target cells; c) neurotransmitters bond to membrane receptors of the target cell.

b) neurotransmitters travel long distances to reach their target cells;

16. Are there motor endplates in smooth muscle tissues? a) yes; b) no; c) sometimes.

b) no

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.

b) not due to stimuli from the nervous system or endogenous substances

86. Which of the following names of ion channel structures is not part of the accepted terminology? a) narrow tunnel; b) opening; c) gating mechanism.

b) opening;

551. A natural process is one where: a) the free energy increases spontaneously; b) part of the energy of the system is transformed into heat; c) the order of the system increases.

b) part of the energy of the system is transformed into heat;

218. What type of membrane transport processes have predominant role during the action potential? a) active membrane transport; b) passive membrane transport; c) active transport during depolarization and passive during repolarization.

b) passive membrane transport;

88. The type of transport through the ion channels is called: a) active; b) passive, driven by existing gradients; c) passive for some ions, and active for others.

b) passive, driven by existing gradients;

188. What type of membrane transport is the osmosis: a) active; b) passive; c) facilitated.

b) passive;

158. In which of the following practices uses electro-muscular stimulation? a) echography; b) physical therapy; c) electrophoresis.

b) physical therapy;

180. When constant magnitude voltage is applied to biological tissue the resulting current does not follow Ohm's law. This is due to: a) depolarization; b) polarization; c) induction.

b) polarization;

74. Which ion types can pass through the calcium-activated potassium channels? a) calcium ions; b) potassium ions; c) sodium ions.

b) potassium ions

503. Receptors of the cellular membrane are: a) lipids or glycolipids; b) proteins or glycoproteins; c) polymeric carbohydrate.

b) proteins or glycoproteins;

541. What is the function of the interstitial cells of Cajal (ICC) in the gastrointestinal tract? a) increase the elasticity of the intestines; b) provide pacemaker activity; c) provide mechanical bonding between phasic layers of smooth muscle tissue.

b) provide pacemaker activity;

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.

b) reaching membrane depolarization threshold

518. The electrical impedance of biological tissue has the following two components: a) resistance (R) and inductive reactance (ωL); b) resistance (R) and capacitive reactance (1/ωC); c) resistance (R) and conductance (G).

b) resistance (R) and capacitive reactance (1/ωC);

141. The source of calcium for the contraction of striated muscles is: a) extracellular fluid; b) sarcoplasmic reticulum; c) sarcomeres.

b) sarcoplasmic reticulum;

493. Cyclic adenosine monophosphate (cAMP) function as: a) G-protein; b) second messenger (intracellular); c) first messenger (inter-cellular).

b) second messenger (intracellular);

473. What type of membrane transport involves the accumulation of iodine in the follicular cells of the thyroid gland? a) primary-active; b) secondary-active; c) facilitated passive.

b) secondary-active;

176. Choose the best definition for tetanic muscle contraction: a) series of fast sequential muscle contractions; b) series of muscle contractions, where new contractions begin before the ending of previous contractions; c) group of sequential muscle contractions, triggered by singlesub-threshold stimulation.

b) series of muscle contractions, where new contractions begin before the ending of previous contractions;

478. The information carriers of the chemical inter-cellular communication are: a) receptors; b) signaling molecules; c) synaptic cleft.

b) signaling molecules;

174. Single muscle twitch is cause by: a) sub-threshold stimulation; b) single action potential; c) a series of fast local responses.

b) single action potential;

448. What is the original source of the bioelectrical pulses leading to the contraction of the heart? a) central nervous system; b) sinoatrial node; c) cardiomyocytes.

b) sinoatrial node;

410. Rheography uses the following electric current: a) sawtooth alternating current with frequency: 300 kHz to 10 MHz; b) sinusoidal alternating current with frequency: 30 kHz to 100 kHz; c) pulsed electric current with varying frequency according to the organ or tissue under investigation.

b) sinusoidal alternating current with frequency: 30 kHz to 100 kHz;

419. What causes the self-excitation (spontaneous generation of action potentials) of the cells of the sinoatrial (SA) node? a) the condition of sinus block; b) slow Na+ influx through non-inactivating sodium channels; c) systemic neuronal inputs to the cells of the SA node.

b) slow Na+ influx through non-inactivating sodium channels;

482. Are signaling molecules specific to given receptors? a) not specific; b) specific, but not uniquely specific; c) they are uniquely specific.

b) specific, but not uniquely specific;

3. Smooth muscle tissue is build of this type of cells: a) cylindrical cells; b) spindle-shaped cells; c) relatively small hexagonally-shaped cells.

b) spindle-shaped cells

439. Which of the following phases is not found in the action potential of pacemaker cells of the sinoatrial node? a) spontaneous diastolic depolarization; b) stable resting phase; c) fast depolarization.

b) stable resting phase;

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.

b) steady resting potential

561. The first law of thermodynamics states: a) that entropy is the measure of order in a system; b) that energy is always conserved; c) that entropy in biological systems decreases.

b) that energy is always conserved;

468. An example for secondary active transport is: a) the Ca2+ pump; b) the Na+/I- symporter; c) the K+ leak channel.

b) the Na+/I- symporter;

51. What are the elastic properties of muscles? a) the ability to stretch; b) the ability to return to initial size after a stretch; c) the ability to contract.

b) the ability to return to initial size after a stretch;

394. When constant voltage applied to biological tissue, the value of the resulting current decreases with time until it becomes thousand smaller than its initial value. This could be explained by: a) the increase of the static capacitance; b) the appearance of polarization voltage, opposing the external voltage; c) the generation of inductive reactance, opposing the propagating current.

b) the appearance of polarization voltage, opposing the external voltage;

355. Filtration (streaming) potential is: a) the electric potential between upper and lower layers of the dispersion during the sedimentation of the solid phase; b) the electric potential difference across a porous membrane, when electrolyte medium is driven by hydrostatic pressure; c) the electric potential difference acquired due to an increase of the surface charge of cells and the decrease of their agglutination.

b) the electric potential difference across a porous membrane, when electrolyte medium is driven by hydrostatic pressure;

465. What is the direct driving force for the transmembrane transport of iodide? a) energy from the hydrolysis of ATP; b) the electrochemical gradient of Na+ ions; c) the concentration gradient of Na+ ions.

b) the electrochemical gradient of Na+ ions;

415. What is the physiological meaning of the part of the rheogram called incisura (dicrotic notch)? a) the beginning of the cardiac contraction cycle; b) the end of the systolic period; c) the moment where the outflow overcomes the inflow of blood, in a given tissue.

b) the end of the systolic period;

110. The direct energy donor for the contraction of skeletal muscles is: a) an exothermic reaction in the cytosol; b) the hydrolysis of adenosine triphosphate; c) the electric energy released from action potentials.

b) the hydrolysis of adenosine triphosphate;

290. Which surface of the phospholipid molecule interacts with the water molecules? a) the hydrophobic surface; b) the hydrophilic surface; c) in the multilayer complex both surfaces interact with water.

b) the hydrophilic surface;

44. Tonic smooth muscle contractions are characterized by: a) generation of autonomous action potential; b) the lack autonomous action potential; c) positive membrane potential.

b) the lack autonomous action potential;

371. What causes the large value of skin impedance (resistance) when low-frequency electric current is applied? a) the large value of (ohmic) resistance; b) the large value of capacitive reactance; c) low-frequency current flows slower through the layers of skin.

b) the large value of capacitive reactance;

126. During the contraction of striated muscles, the following section of the sarcomere remains without change: a) the length of I - band (isotropic); b) the length of A - band (anisotropic); c) the length of H - zone (from German "heller" = brighter).

b) the length of A - band (anisotropic);

157. The neuromuscular junction (myoneural synapse) is: a) a type of action potential; b) the location where a neuronal excitation is transferred to a muscle; c) the structure that opens voltage-gated Ca2+ channels.

b) the location where a neuronal excitation is transferred to a muscle;

513. According to Boltzmann equation, the entropy of a thermodynamic system is proportional to: a) the equilibrium temperature of the system; b) the logarithm of the thermodynamic probability (W = number of microstates); c) the thermodynamic probability (W = number of microstates).

b) the logarithm of the thermodynamic probability (W = number of microstates);

262. Equilibrium potential for given ion species is: a) the membrane potential during the resting state of the cell, when the membrane is not permeable to the ion species; b) the membrane potential when the ion species are free to move across, and concentration and electrical gradients are balanced; c) the state when the membrane is equally permeable to K+ and Na+ ion species.

b) the membrane potential when the ion species are free to move across, and concentration and electrical gradients are balanced;

210. The neuron "threshold potential" is: a) the Na+ equilibrium potential; b) the membrane potential which activates voltage-gated Na+ channels; c) the Nernst potential for potassium ions.

b) the membrane potential which activates voltage-gated Na+ channels;

222. What is the meaning of "threshold stimulus"? a) the maximal stimulus that reaches the membrane threshold potential; b) the minimal stimulus that reaches the membrane over-threshold depolarization; c) a stimulus that changes the membrane potential below threshold.

b) the minimal stimulus that reaches the membrane over-threshold depolarization;

395. The high electrical conductivity of blood is due to: a) the mobility of free electrons; b) the mobility of ions; c) the mobility of electron holes.

b) the mobility of ions;

365. Choose the most precise definition of electroosmosis: a) the movement of particles (dispersed phase) through capillaries or porous material due to an applied external electric field; b) the movement of liquid (dispersion medium) through capillaries or porous material due to an applied external electric field; c) a phenomenon where the relative motion between dispersed phase and the medium leads to the generation of electric potential difference.

b) the movement of liquid (dispersion medium) through capillaries or porous material due to an applied external electric field;

281. The repolarization phase of the axonal action potential is contributed to: a) the outward K+ current due to potassium leak channels; b) the outward K+ current due to the activation of voltage-gated potassium channels; c) the outward K+ current due to the electrogenic work of the sodium-potassium pump.

b) the outward K+ current due to the activation of voltage-gated potassium channels;

349. How does the pH of the medium affect the surface charge of the cell? a) the pH of the medium affects the electric charge of the "heads" of the phospholipid molecules; b) the pH affects the dissociation activity of basic and acidic surface groups; c) the pH affects the adsorption of basic and acidic groups.

b) the pH affects the dissociation activity of basic and acidic surface groups;

234. The relative refractory period is: a) the period where a depolarised portion of the membrane cannot be re-excited and generate a new action potential; b) the period where a hyper-polarised portion of the membrane can be re-excited with stronger-thanusual stimulus; c) the period where a sub-threshold stimulus causes membrane depolarization insufficient to trigger an action potential.

b) the period where a hyper-polarised portion of the membrane can be re-excited with stronger-thanusual stimulus;

530. What is expressed with the following equation? Phi(e)-Phi(i) = (RT/zF)ln(K(i)/K(e)) a) the membrane potential; b) the potassium equilibrium potential; c) the repolarization phase of the action potential.

b) the potassium equilibrium potential;

342. Electrokinetic (zeta) potential is: a) the potential difference between the dispersed phase and the dispersion medium; b) the potential difference between the adsorption layer and the medium beyond the diffuse layer; c) the potential difference between top and bottom layers in heterogeneous system, after sedimentation. of the particles of the dispersed phase

b) the potential difference between the adsorption layer and the medium beyond the diffuse layer;

308. How does the diffusion potential evolve with time? a) the potential increases until the system reaches a thermodynamic equilibrium, then it assumes a constant value; b) the potential increases until reaching a maximum value (stationary point) then it decreases back to zero; c) the magnitude of the diffusion potential increases continuously with time.

b) the potential increases until reaching a maximum value (stationary point) then it decreases back to zero;

517. Prigojin's equation calculates: a) the entropy of isothermal biological system; b) the rate of change of entropy in isothermal biological system; c) the maximal change of entropy in isothermal biological system.

b) the rate of change of entropy in isothermal biological system;

314. Choose the correct statement regarding the process of diffusion. a) the rate of diffusion is independent of the temperature of the system; b) the rate of diffusion depends on the concentration gradient; c) the rate of diffusion depends on the forth digit of pi.

b) the rate of diffusion depends on the concentration gradient;

38. The electro-mechanical coupling of smooth muscles is: a) muscle contraction stimulated with electric current; b) the relation between action potential and subsequent increase of intracellular Ca2+ leading to contraction; c) the directed movement of Ca2+ (electric current) in the cytosol towards the contractile apparatus (mechanical).

b) the relation between action potential and subsequent increase of intracellular Ca2+ leading to contraction;

111. Which of the following processes take place in the sarcomere during contraction? a) electrical attraction between the oppositely charged Z - discs; b) the sliding between thin and thick myofilaments; c) shortening of the think myofilaments.

b) the sliding between thin and thick myofilaments;

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).

b) the smooth muscle fiber (myofibril)

319. Choose the most precise definition of diffusion: a) the process of migration of substance from area of higher concentration into area of lower concentration; b) the spontaneous migration of substance from volume of high concentration into volume of low concentration due to the random thermal motion of the constituent particles; c) the process of mass transfer down the concentration gradient.

b) the spontaneous migration of substance from volume of high concentration into volume of low concentration due to the random thermal motion of the constituent particles;

279. Membrane conductance for Na+ and K+ ions is not constant. It depends on: a) the strength of the sub-threshold stimulus; b) the state of the voltage-gated ion channels; c) the state of the leak ion channels.

b) the state of the voltage-gated ion channels;

227. What is the explanation for the constant (non-damping) amplitude of the propagating action potential along the membrane? a) the indirect influence of Cl- on the Na+ influx and K+ efflux; b) the steady electrochemical gradients for Na+ and K+ along the length of the membrane; c) the isotonic conditions between intra- and extracellular environments.

b) the steady electrochemical gradients for Na+ and K+ along the length of the membrane;

194. Which of the following factors do not have an effect on osmotic pressure? a) the concentration of solutes; b) the type of solutes; c) the temperature of solutes.

b) the type of solutes;

259. What is meaning of "R" in the Nernst equation? Ek= (RT/zF)ln ([K+]out/[K+]in) a) the radius of the K+ ion; b) the universal gas constant; c) the Faraday's constant.

b) the universal gas constant;

161. When very high frequency alternating current (AC) is applied through biological tissue: a) there is a polarization of the ion channels; b) there is a heating effect; c) there is a decrease of the current due to accommodation.

b) there is a heating effect;

516. During isometric contraction of skeletal muscle: a) there is (classical) work done; b) there is emission of heat; c) there is a balance between emitted heat and work done.

b) there is emission of heat;

544. What is the direction of propagation of the intracellular longitudinal Na+ currents, which carry the action potential along the membrane, from the point of excitation of an action potential? a) they always flow from excited into unexcited regions; b) they flow in all directions of the cytosol; c) hey flow from one excited region into other excited regions.

b) they flow in all directions of the cytosol;

553. From thermodynamic point of view, how can biological organisms sustain low level of entropy (high level of order) for prolonged periods of time? a) they can regulate their metabolic processes; b) they generate large amount of entropy in the surrounding environment; c) their ability to mitigate unfavourable environmental factors.

b) they generate large amount of entropy in the surrounding environment;

151. What is the path of the electric current through the body of patient who is subjected to galvanization? a) through the cytosol; b) through the interstitial spaces; c) through cellular membranes, via nexus junctions between cells.

b) through the interstitial spaces;

56. The structural muscle tissue found in arterial walls is of this type: a) phasic smooth muscle; b) tonic smooth muscle; c) striated muscle cells working in tandem with tonic smooth muscle cells.

b) tonic smooth muscle;

92. Ion channels are (choose the best): a) integral proteins; b) transmembrane proteins; c) peripheral proteins.

b) transmembrane proteins;

459. Which of the following statements does not hold for primary active transport? a) transmembrane transport of inorganic ions; b) transmembrane transport of organic molecules; c) uses energy from ATP.

b) transmembrane transport of organic molecules;

129. Which type of troponin bonds to calcium? a) troponin T; b) troponin C; c) troponin I.

b) troponin C;

102. The thin myofilaments in striated muscles are build of the following proteins: a) myosin, actin, titin, and troponin; b) troponin, actin, tropomyosin; c) myosin.

b) troponin, actin, tropomyosin;

63. How many gates do voltage-gated Na+ channels have? a) one; b) two; c) three.

b) two

471. When substances are transported across the membrane through specialised protein molecules, the process is described as: a) simple diffusion; b) uniport or cotransport; c) protein transport.

b) uniport or cotransport;

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).

b) voltage gated (membrane potential dependent)

75. Depolarization of the plasma membrane activates this type of ion channels: a) receptor-regulated (ligand-gated) channels; b) voltage-gated channels; c) none of the above.

b) voltage-gated channels;

94. Which of the following types of ion channels permit calcium, needed for the phasic contractions in smooth muscles, into the cell? a) ligand-gated channels; b) voltage-gated channels; c) stretch-gated channels (mechano-sensitive).

b) voltage-gated channels;

320. Diffusion potential is measured with: a) the "voltage clamp" method pioneered by Hodgkin and Huxley; b) voltmeter placed between the two compartments with different concentrations; c) scintillation counter placed at the membrane, that registers the ion traffic.

b) voltmeter placed between the two compartments with different concentrations;

323. Membrane potential is measured in units of: a) amperes b) volts c) coulombs

b) volts

352. What values of zeta potential indicate instability of the dispersion and a higher probability for aggregation of the particles (cells)? a) when the absolute value of zeta increases the propensity for aggregation increases; b) when the absolute value of zeta decreases the propensity for aggregation increases; c) the probability for aggregation is not dependent on zeta.

b) when the absolute value of zeta decreases the propensity for aggregation increases;

329. For which of the following cases the thickness of the double electric layer will increase? a) when the ion concentration in the vicinity of the cell is increased; b) when the ion concentration in the vicinity of the cell is decreased; c) when there is an increase in the hydrogen bonding in the water solution around the cell.

b) when the ion concentration in the vicinity of the cell is decreased;

388. When suspension of cells in electrolyte solution is subjected to constant electric potential, the resulting current: a) will increase fast with time until the current becomes hundred or thousand times that of the initial current; b) will decrease fast with time until the current becomes hundred or thousand times less than the initial current; c) does not change with time and settles at the constant value.

b) will decrease fast with time until the current becomes hundred or thousand times less than the initial current;

321. How do cells maintain a lower sodium concentration on the intracellular side of the membrane? a) by balancing the concentration and electrical gradients of Na+ across the membrane; b) with continuous use of energy of ATP; c) by balancing the diffusion and membrane potentials across the lipid bilayer.

b) with continuous use of energy of ATP;

425. Is there a difference between the form and the amplitude of the action potentials generated in different locations of the electrical conductive system of the heart? a) no difference; b) yes, every point of the electrical network of the heart generates a potential with specific form and amplitude; c) yes, the sinoatrial node has a specific potential which changes after passing through the atrioventricular node and remains constant until the target muscle cells.

b) yes, every point of the electrical network of the heart generates a potential with specific form and amplitude;

230. Is there a correlation between the propagation speed of the action potential along the axon, and the electrical resistance of the intracellular fluid? a) no; b) yes, increase of the resistance leads to decrease of the speed; c) yes, increase of the resistance leads to increase of the speed.

b) yes, increase of the resistance leads to decrease of the speed;

41. Is there a relationship (and what type) between spike potentials and the strength of contraction of smooth muscles? a) no; b) yes, it is proportional. The greater the number of spike potentials the stronger the contraction; c) Yes. An increased number of spike potentials will decrease the strength of muscle contraction.

b) yes, it is proportional. The greater the number of spike potentials the stronger the contraction;

57. Is there a relationship between slow wave membrane potentials and the contractions in smooth muscle cells? a) yes, slow waves are related with tonic contractions; b) yes, slow waves are related with phasic contractions; c) there is no relation between slow waves and contractions.

b) yes, slow waves are related with phasic contractions;

526. Does the radiosensitivity (radiation sensitivity) of a cell vary for different phases of the cellular cycle? a) no, the cellular phases do not have influence the radiosensitivity; b) yes, the cell is more sensitive near the mitosis; c) no, because the cell dispenses quickly all metabolic products caused from the ionizing radiation.

b) yes, the cell is more sensitive near the mitosis;

42. Is there a difference in the properties of phasic and tonic smooth muscle contractions? a) no, they are two names for the same basic process; b) yes. Phasic contractions occur with certain repetition of few times per minute, and tonic contractions rise slowly and can last many minutes; c) yes. Tonic contractions occur with regular frequency and amplitude, and phasic contractions are slow and can last many minutes.

b) yes. Phasic contractions occur with certain repetition of few times per minute, and tonic contractions rise slowly and can last many minutes;

422. In the electrical network of the heart, do structures other than the sinoatrial (SA) node have a pacemaker properties? a) no; b) yes; c) depends on their functional state.

b) yes;

345. What is relation between zeta potential and the pH of the dispersion medium? a) when the pH is increased, zeta potential increases; b) zeta potential dependence on the pH follows a sigmoid function; c) when the pH is increased, zeta potential decreases.

b) zeta potential dependence on the pH follows a sigmoid function;

348. If concentration of divalent and multivalent ions in a dispersion medium is increased: a) zeta potential will increase; b) zeta potential will decrease; c) zeta potential will remain the same.

b) zeta potential will decrease;

384. Which are the two components of the electrical impedance of living tissue? a) inductive and capacitive reactance; b) (active) resistance and inductive reactance; c) (active) resistance and capacitive reactance.

c) (active) resistance and capacitive reactance.

208. Given that the resting potential of a neuron is -70 mV, choose the threshold potential which makes it harder for the neuron to excite an action potential: a) -65 mV; b) -60 mV; c) - 53 mV.

c) - 53 mV.

258. If the electric potential of the extracellular space is 20 mV and the potential of the intracellular space is -80 mV (relative to a common reference point), what would be the membrane potential of the cell? a) 60 mV; b) -60 mV; c) -100 mV.

c) -100 mV.

140. The resting potential for skeletal muscle cells is about: a) -30 mV; b) -70 μV; c) -75 mV.

c) -75 mV.

96. Thin myofilaments in striated muscle cells are composed of: a) 4 type of proteins; b) 1 type of protein; c) 3 types of proteins.

c) 3 types of proteins.

522. What is the energy source for the mitochondrial Ca2+ pump? a) the concentration gradient; b) electrical forces; c) ATP.

c) ATP.

136. Muscle contraction in striated muscles is induced by: a) K+ influx into cytosol; b) Na+ efflux from the cytosol; c) Ca2+ influx into the cytosol.

c) Ca2+ influx into the cytosol.

287. What type of ion current does not pass through membrane treated with 10^-5 M of TEA (tetraethylammonium)? a) Na+ influx; b) Na+ efflux; c) K+ efflux.

c) K+ efflux.

272. The equilibrium potential of which of the following ions is the closest to the membrane resting potential? a) Na+; b) Ca2+; c) K+.

c) K+.

420. What type of ion transport is responsible for the fast depolarization phase of the action potential in myocardial muscle cells? a) Mg2+ influx; b) Cl- efflux; c) Na+ influx.

c) Na+ influx.

363. The following equation refers to: Fr=6*π*η*r*v a) Reynolds number; b) Newton's law for external friction between the molecules of fluids; c) Stokes' law for internal friction of spherical body moving in fluid. where: η- coefficient of internal friction, r-radius of particle, v-velocity of particle.

c) Stokes' law for internal friction of spherical body moving in fluid.

375. When the frequency of the applied current is very high, the impedance of the skin will approach the following: a) Z = 0, skin impedance approaches zero; b) Z = Xc, skin impedance approaches the value of capacitive reactance; c) Z = R, skin impedance approaches the value of ohmic resistance.

c) Z = R, skin impedance approaches the value of ohmic resistance.

133. The thin myofilaments of the striated muscle cells contain: a) myosin, actin, and tropomyosin; b) actin, actomyosin, troponin; c) actin, tropomyosin, troponin.

c) actin, tropomyosin, troponin.

452. The Na+/K+ pump is a type of: a) passive ion transporter; b) facilitated ion channel; c) active ion transporter.

c) active ion transporter.

325. The magnitude of the diffusion potential in an isolated system which starts with off-equilibrium: a) remains constant in time; b) changes in time, depending on the diffusion coefficient; c) after reaching a maximum it decreases to zero.

c) after reaching a maximum it decreases to zero.

260. Which cells maintain non zero membrane potential? a) nerve cells; b) all excitable cells; c) all living cells.

c) all living cells.

99. In skeletal muscles the ratio between actin and myosin filaments is: a) undetermined; b) it varies from 6:1 to 15:1; c) always 6:1.

c) always 6:1.

324. In a thermodynamic system under constant external conditions, the magnitude of the diffusion potential: a) remains constant in time; b) approaches the resting potential; c) approaches zero.

c) approaches zero.

31. What is the source of Ca2+ needed for the contraction of the smooth muscles? a) from the extracellular medium, where calcium concentration is much greater than in the intracellular space; b) from in the intracellular depots, found in the sarcoplasmic reticulum; c) both a. and b.

c) both a & b

430. At the end of the "plateau" phase of the action potential in cardiac myocytes, the membrane permeability changes for this type of ions: a) sodium ions; b) potassium ions; c) calcium ions.

c) calcium ions.

497. Which of the following is a necessary condition for direct electrical communication between cells? a) cells must be of the same type; b) cells must be submerged in electrolyte solution; c) cellular membranes must be connected.

c) cellular membranes must be connected.

106. Contraction of skeletal muscles begins after (choose the best): a) Ca2+ influx through the sarcolemma; b) Na+ influx from the sarcoplasmic reticulum; c) certain latent period.

c) certain latent period.

216. In neurons, the action potential is initiated by: a) change of the membrane conductivity for Cl- ions; b) change of the membrane conductivity for K+ ions; c) change of the membrane conductivity for Na+ ions.

c) change of the membrane conductivity for Na+ ions.

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.

c) complete or incomplete tetanus

168. When the frequency of electrical stimulation is increased significantly, skeletal muscles will respond with: a) a muscle twitch; b) muscle relaxation; c) complete tetanus.

c) complete tetanus.

289. What is the approximate shape of the phospholipid molecules building the biological membranes? a) conical shape: small heads and relatively large volumed tails; b) inverse cone: large heads and relatively narrow tails; c) cylindrical: the cross-sectional area of the head and the tails is similar.

c) cylindrical: the cross-sectional area of the head and the tails is similar.

165. Ionic and dipole polarizations: a) occur predominately in bone tissue; b) cause heating in soft tissue; c) decrease the magnitude of currents passing through soft tissue.

c) decrease the magnitude of currents passing through soft tissue.

486. To decrease the inflow of extracellular information, cells use the following mechanism: a) migration toward locations with smaller information inflow; b) passing the information overflow to neighbouring cells; c) decreasing the number of membrane receptors, responsible for the specific information.

c) decreasing the number of membrane receptors, responsible for the specific information.

416. the part of the rheogram showing an increase of the blood volume in the beginning of the diastole is called: a) anacrota; b) catacrota; c) dicrotic wave.

c) dicrotic wave.

245. The repolarization phase of the axonal action potential is due to: a) diffusion of sodium in to the cell; b) active transport of potassium out of the cell; c) diffusion of potassium out of the cell.

c) diffusion of potassium out of the cell.

144. Which of the following terms is NOT one of the known types of tissue-polarization due to application of an external electric current? a) electronic polarization; b) electrode polarization; c) electret polarization.

c) electret polarization.

387. What is the path of the electric current in suspension of cells in electrolyte solution, if the applied current is DC? a) electric current flows through the cells and in the spaces between the cells; b) electric current flows mostly in the spaces between the cells; c) electric current flows only when there is charge accumulation on the membranes of the cells, after that there is low current in the electrolyte medium.

c) electric current flows only when there is charge accumulation on the membranes of the cells, after that there is low current in the electrolyte medium.

91. Trans-membrane ion transport through ion channels is driven by: a) osmotic gradients; b) equilibrium potentials; c) electrochemical gradients.

c) electrochemical gradients.

346. The quantity μ = v/E is defined as: a) the electric potential between adsorption and defuse layers; b) the coefficient of friction for particles in dispersion medium; c) electrophoretic mobility.

c) electrophoretic mobility.

481. Membrane receptors are: a) information signaling molecules; b) vesicles filled with neurotransmitters; c) element of the chemical information system of the body.

c) element of the chemical information system of the body.

499. Which of the following terms dos not refer to a type of inter-cellular communication? a) paracrine; b) autocrine; c) endogenic.

c) endogenic.

398. What type of electrical impedance (resistance or reactance) is measured with the rheographic equipment? a) capacitive reactance, because it changes with the change of blood volume; b) (active) resistance, because it is inversely proportional to the blood filling of a given organ; c) reactive impedance, because it changes with the electrolyte content of the blood.

b) (active) resistance, because it is inversely proportional to the blood filling of a given organ;

374. Which of the following components of the electrical impedance of a circuit with biological tissue does not depend on the frequency of the applied electric current? a) capacitive reactance; b) (ohmic) resistance; c) inductive reactance.

b) (ohmic) resistance;

190. The isotonic factor of Van't Hoff for non-electrolytes is: a) 0; b) 1; c) 2.

b) 1

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.

b) 2 types of contractile proteins

469. The electrogenic mode of operation of the Na+/K+ pump is as follows: a) 2 Na+ ions move out, for 3 K+ ions moving in; b) 3 Na+ ions move out, for 2 K+ ions moving in; c) 3 Na+ ions move in, for 2 K+ moving out;

b) 3 Na+ ions move out, for 2 K+ ions moving in;

28. In smooth muscles fibers the ratio between actin and myosin (thin/tick) fibers is: a) random; b) 5:1 to 13:1; c) always 6:1.

b) 5:1 to 13:1 c)-> stiated muscle

185. This scientist have contributed to the laws of diffusion: a) Paul Dirac; b) Adolf Fick; c) Fridtj of Nansen.

b) Adolf Fick;

54. Smooth muscle contraction is triggered by increased intra-cellular concentration of this type of ions: a) K+; b) Ca2+; c) Na+.

b) Ca2+

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.

b) Ca2+ influx → depolarization, K+ efflux → repolarization;

119. What is the role of Ca2+ in the contraction of striated muscles? a) Ca2+ activates the cellular enzyme myosin light chain kinase (MLCK), which phosphorylates troponin I, attached to the actin filament, and allows the formation of cross-bridges with myosin; b) Ca2+ ions (at most 4) bond to troponin C, cause a conformational change which allows myosin to bond to actin and form cross-bridges; c) Ca2+ interacts with the myosin molecule, increasing its affinity for the actin, and allowing the formation of cross-bridges.

b) Ca2+ ions (at most 4) bond to troponin C, cause a conformational change which allows myosin to bond to actin and form cross-bridges;

125. What facilitates the Ca2+ transport from the sarcoplasm into the sarcoplasmic reticulum? a) ion channels; b) Ca2+ pumps; c) diffusion.

b) Ca2+ pumps;

173. Choose the INCORRECT statement regarding the conductance of direct current (DC) through biological tissues: a) DC does not flow through cells, only in the extracellular fluid; b) DC flows through the cells; c) DC decreases exponentially with time, regarding of the applied constant voltage.

b) DC flows through the cells;

343. Which of the following statements is incorrect? a) Debye length of screening is equal to the length of the diffuse layer; b) Debye length of screening is equal to the distance from the surface where the potential decreases by 10 times; c) Debye length of screening is equal to the distance from the surface where the potential decreases etimes (where e = 2.71).

b) Debye length of screening is equal to the distance from the surface where the potential decreases by 10 times;

255. The resting potential for most excitable cells falls in the region between: a) E = (-10 / -30) mV; b) E = (-60 / -90) mV; c) E = (-30 / +50) mV;

b) E = (-60 / -90) mV;

213. During the repolarization phase of the action potential in neurons, the negative ion current is due to: a) Na+ influx; b) K+ efflux; c) Ca2+ influx.

b) K+ efflux;

447. The slow depolarization phase of the action potential in first-order pacemaker cells is due to: a) Ca2+ influx; b) Na+ influx; c) K+ efflux.

b) Na+ influx;

228. What is the ion composition of local longitudinal currents, that flow near the cellular membrane, and allow for the propagation of action potentials along the length of myelinated axons? a) K+ ions; b) Na+ ions; c) Ca2+ ions.

b) Na+ ions;

250. During the depolarization stage in neurons there is influx of: a) Ca2+ ions; b) Na+ ions; c) K+ ions.

b) Na+ ions;

285. During the resting state of the axonal membrane the ratio of the ion permeabilities for potassium and sodium is PK : PNa = 1 : 0.04. During the depolarization phase of the action potential this ratio changes as follows: a) PK : PNa = 1 : 0.0004; b) PK : PNa = 1 : 20; c) PK : PNa = 20 : 0.04.

b) PK : PNa = 1 : 20;

444. Choose the correct order of excitation of components of the electrical conducting system of the heart. a) bundle of His; b) SA-node; c) Purkinje fibers; d) AV-node; e) atrial myocytes; f) ventricular myocytes.

b) SA-node e) atrial myocytes d) AV-node a) bundle of His c) Purkinje fibres f) ventricular myocytes

103. The three types of Troponin found in striated muscles are? a) A-, M-, and I-type; b) T-, C-, and I-type; c) T-, H-, and Z-type.

b) T-, C-, and I-type;

377. Which of the following formulas refers to the capacitive reactance (Xc)? a) Xc = ω∙C; b) Xc = 1/(ω∙C); c) Xc = √(ω∙C). Where: ω = 2πf is the angular frequency (of electric field oscillation), and C is the capacitance

b) Xc = 1/(ω∙C);

378. Which of the following formulas refers to the impedance (Z) of biological tissue? a) Z = √(R^2 −Xc^2); b) Z = √(R^2 +Xc^2); c) Z^2 = R^2 −Xc^2. Where: Z is impedance, R is resistance, and Xc is capacitive reactance

b) Z = √(R^2 +Xc^2);

235. What is the "resting potential", and what cause is it? a) a self-sustained fluctuation in the membrane potential of excitable cells, caused by the sequential activation of different ion channels; b) a characteristic value of the membrane potential of excitable cells in the absence of external stimuli, caused by the selective ion permeability of the membrane and the electrogenic work of the sodiumpotassium pump; c) the membrane potential of excitable cells, after depolarization, when the voltage across the membrane is zero due the equilibrium of concentration and electrical gradients.

b) a characteristic value of the membrane potential of excitable cells in the absence of external stimuli, caused by the selective ion permeability of the membrane and the electrogenic work of the sodiumpotassium pump;

311. What conditions are necessary for the generation of diffusion potential? a) a semipermeable membrane and two types of ion species; b) a concentration gradient and ion species with different mobility; c) a non-selective membrane and ions species with equal mobility.

b) a concentration gradient and ion species with different mobility;

300. Viscosity of biological membranes is: a) an electrical property; b) a mechanical property; c) chemical property.

b) a mechanical property;

197. Osmosis is defined as: a) an active transport of solvent molecules across a semipermeable membrane from area of low concentration into area of high concentration; b) a passive transport of solvent molecules across a semipermeable membrane from area of higher concentration into an area of lower concentration; c) an active transport of solute molecules across a semipermeable membrane from an area of low concentration into an area of high concentration.

b) a passive transport of solvent molecules across a semipermeable membrane from area of higher concentration into an area of lower concentration;

191. Which of the following is a necessary condition for osmosis? a) a non-permeable membrane; b) a semi-permeable membrane; c) ATP energy source.

b) a semi-permeable membrane;

175. Tetanic muscle contractions are the result of: a) a series of sub-threshold stimuli; b) a series of over-threshold stimuli; c) a series of fast local responses.

b) a series of over-threshold stimuli;

537. What is neurotransmitter quantum? a) the quantity of neurotransmitter molecules contained in one vesicle and released at once; b) a single neurotransmitter molecule that bonds to a receptor; c) an energy quantum released from the presynaptic membrane.

b) a single neurotransmitter molecule that bonds to a receptor;

535. Mediators of neuronal excitation are: a) prostaglandins, adrenalin; b) acetylcholine, noradrenalin, serotonin; c) amikine, enterin, piperidine.

b) acetylcholine, noradrenalin, serotonin;

25. The basis of the thin myofilaments in smooth muscle tissue is the protein: a) myosin; b) actin; c) troponin.

b) actin

29. Thin myofilaments in smooth muscle tissues are build of the following proteins: a) myosin, actin, titin, and troponin; b) actin and tropomyosin; c) actin, titin, and calmodulin.

b) actin and tropomyosin;

130. In striated muscles the regulation of contractions with Ca2+ ions can be classified as: a) myosin-based regulation; b) actin-based regulation; c) neuronal-based regulation.

b) actin-based regulation;

97. The major protein component of the thin myofilaments in striated muscle cells is: a) myosin; b) actin; c) troponin.

b) actin;

39. What is a spike potential? a) a rapid change in the membrane potential due to a slow wave; b) action potential in certain smooth muscle cells; c) electric phenomenon due to re-orientation of the myofilaments in the smooth muscle cell.

b) action potential in certain smooth muscle cells;

232. Which of the following membrane potentials propagates without attenuation (decrease in amplitude) along the length of the membrane? a) trace potential; b) action potential; c) electrotonic potential.

b) action potential;

488. Desensitisation of a receptor is the condition where: a) the cell does not synthesise a sufficient number of given type of receptors; b) activated receptors generate less than the usual number of second messengers; c) there is a structural degradation of membrane receptors.

b) activated receptors generate less than the usual number of second messengers;

538. What is the role of Ca2+ for the release of neurotransmitters? a) opens ion channels that release neurotransmitters; b) activates the membrane enzyme phospholipase C; c) removes the polar heads of membrane lipid molecules and provides contact area for the vesicles.

b) activates the membrane enzyme phospholipase C;

95. The sarcomere is: a) a protein involved in the contraction of striated muscle fibres; b) an element of the striated muscle fiber, located between two Z-discs; c) a structure that produces second messengers in muscle cells.

b) an element of the striated muscle fiber, located between two Z-discs;

475. The bi-directional secondary active transport is called: a) simport; b) antiport; c) uniport.

b) antiport;

502. Upon activation by a ligand, receptor tyrosine kinase (RTK) will: a) activate Ca2+ ion channels; b) auto-phosphorylate and trigger cytosolic signaling cascade; c) depolarise the membrane and cause action potential.

b) auto-phosphorylate and trigger cytosolic signaling cascade;

53. Why are smooth muscles (SM) called autonomous? a) because SM react to external stimuli; b) because excitations can be generated within the SM tissue; c) because SM can remain de-excited for long periods.

b) because excitations can be generated within the SM tissue;

220. Local responses in neurons are caused by: a) spontaneously; b) below-threshold stimulus; c) above-threshold stimulus.

b) below-threshold stimulus;

531. Choose the correct statement. Neurotransmitters are exchanged: a) only between neurons; b) between neurons and adjacent cells; c) between two adjacent cells, which may not be neurons.

b) between neurons and adjacent cells;

436. The action of the anti-arrhythmic pharmaceutical "verapamil" is related to: a) blockage of Na+ influx; b) blockage of Ca2+ influx; c) blockage of Mg2+ influx.

b) blockage of Ca2+ influx;

563. The transport antibiotic gramicidin A: a) bonds K+ ions; b) builds a complex with Na+; c) can transport Na+, Ca2+, and K+.

b) builds a complex with Na+;

431. The fast depolarisation phase of the action potential of cardiac pacemaker cells is due to: a) sodium influx; b) calcium influx; c) potassium efflux.

b) calcium influx

507. When acetylcholine bonds to a muscarinic cholinergic receptor of the membrane of smooth muscles, the following ions are released into the cells: a) sodium ions; b) calcium ions; c) potassium ions.

b) calcium ions;

435. The so called "plateau" phase is found in the action potential of this type of cells: a) pacemaker cells; b) cardiac muscle cells; c) sinoatrial node.

b) cardiac muscle cells

413. The declining part of the rheographic curve is called: a) anacrota b) catacrota c) incisura

b) catacrota

156. What causes the capacitive properties of biological tissue? a) extra- and intra-cellular fluids; b) cellular and intra-cellular membranes; c) the free movement of ions.

b) cellular and intra-cellular membranes;

370. What causes the capacitive reactance of biological tissues? a) the intracellular fluids; b) cellular and intracellular membranes; c) the extracellular fluids.

b) cellular and intracellular membranes;

512. What is the first process that follows the docking of a ligand to a receptor? a) change of the conformation state of the ligand; b) change of the conformational state of the receptor; c) the receptor updating its status on facebook.

b) change of the conformational state of the receptor;

360. Increasing the electrophoretic mobility of the dispersed phase cannot be achieved through: a) change of the pH of the medium; b) change of the volume of the electrophoretic tank; c) change of the applied electric field.

b) change of the volume of the electrophoretic tank;

498. Connexons (gap junctions) allow for: a) electrical communication between cells; b) chemical and electrical communication between cells; c) chemical communications between cells.

b) chemical and electrical communication between cells;

479. Endocrine system communication belongs to the class of: a) mechanical inter-cellular communication; b) chemical inter-cellular communication; c) electrical inter-cellular communication.

b) chemical inter-cellular communication;

87. The default state of ion channels is: a) open; b) closed (deactivated); c) inactivated.

b) closed (deactivated)

196. Passive membrane transport of uncharged particles is driven by: a) electrical gradient b) concentration gradient c) temperature gradient

b) concentration gradient

183. What is the necessary condition for ion diffusion across a semipermeable membrane? a) energy supplied from ATP molecules; b) concentration gradient across the membrane; c) electrical gradient across the membrane.

b) concentration gradient across the membrane;

171. Electro-muscular stimulation is used for: a) observation of the spontaneous contractions in smooth muscles of the gastrointestinal tract; b) conditioning mostly of skeletal muscles; c) stimulation of the peripheral nerves.

b) conditioning mostly of skeletal muscles;

440. What type of cells are cardiac myocytes? a) pacemaker cells; b) contractile cells; c) they have both, contractile and pacemaker functions.

b) contractile cells;

59. In smooth muscle cells, all intra-cellular factors that activate myosin light chain kinase (MLCK) will cause: a) relaxation; b) contraction; c) neither

b) contraction

466. Antiport is defined as: a) coupled membrane transport, where substances move in the same direction; b) coupled membrane transport, where substances move in opposite directions; c) ion channel that allows ions to move only in one direction.

b) coupled membrane transport, where substances move in opposite directions;

149. What happens to the current passing through living tissue, when a constant DC voltage is applied across? a) current increases continuously; b) current decreases exponentially; c) current remains constant.

b) current decreases exponentially;

49. Ca2+ pumps work to: a) increase Ca2+ concentrations in the cytosol; b) decrease Ca2+ concentrations in the cytosol; c) do not affect cytosol concentrations of Ca2+.

b) decrease Ca2+ concentrations in the cytosol;

247. Choose the correct sequence of events during the evolution of an action potential: a) hyperpolarization, repolarization, depolarization; b) depolarization, repolarization, hyperpolarization; c) depolarization, hyperpolarization, repolarization.

b) depolarization, repolarization, hyperpolarization;

520. What will happen to the membrane potential if the Na+/K+ pump stops working? a) hyperpolarization; b) depolarization; c) no change.

b) depolarization;

203. Osmosis across semipermeable membrane occurs due to: a) difference in hydrostatic pressure; b) different concentrations of solute; c) different volume of solvent.

b) different concentrations of solute;

368. A necessary condition for separation of protein fractions with electrophoresis is: a) different concentration of the elements of the fraction; b) different electrokinetic potential; c) different solubility.

b) different electrokinetic potential;

199. The directed motion of solute particles, leading to equalization of concentrations across a permeable membrane, without the use of external forces is: a) osmosis; b) diffusion; c) reabsorption.

b) diffusion;

379. Considering that cellular membranes have dielectric properties (capacitors), what type of electric current can pass through them? a) conduction current; b) displacement current; c) inductive current.

b) displacement current;

341. The surface electric charge of bio-objects is generated by: a) dephosphorylation of ions on the surface of the bio-objects; b) dissociation of ionogenic groups from the surface of the bio-objects; c) association of organic molecules from the environment and their chemical interaction with surface molecules of the cellular membrane.

b) dissociation of ionogenic groups from the surface of the bio-objects;

385. What is the path of the electric current in suspension of cells in electrolyte solution, if the frequency of the current is low? a) electric current flows in equal amounts through the cells and in the spaces between the cells; b) electric current flows mostly in the spaces between the cells; c)electric current flows only when there is charge accumulation on the membranes of the cells

b) electric current flows mostly in the spaces between the cells;

361. Streaming potential is the inverse effect of: a) electrophoresis; b) electroosmosis; c) sedimentation potential.

b) electroosmosis;

546. Which of the following defines best an "open thermodynamic system"? a) exchange of energy with the surrounding environment; b) exchange of energy and matter with the surrounding environment; c) exchange of matter with the surrounding environment.

b) exchange of energy and matter with the surrounding environment;

316. Choose the correct statement regarding the relative electric load between the extra and the intracellular environments during the resting state of the cell: a) intracellular space is positive relative to the extracellular space; b) extracellular space is positive relative to the intracellular space; c) extracellular space is electro-neutral relative to the intracellular space.

b) extracellular space is positive relative to the intracellular space;

277. For their experimental model Hodgkin and Huxley used the method of the: a) generated voltage; b) fixed voltage; c) sinusoidal voltage.

b) fixed voltage;

556. Which type of internal energy in a thermodynamic system can be used to do work: a) energy of bonds; b) free energy; c) concentration energy.

b) free energy;

362. Sedimentation potential is formed due to: a) electrical forces; b) gravitational force; c) magnetic force.

b) gravitational force;

326. In a thermodynamic system under constant external conditions, the diffusion potential: a) approaches the membrane potential; b) has a different maximum value depending on temperature; c) has a maximum value that does not depend on the mobility ion species.

b) has a different maximum value depending on temperature;

327. The magnitude of the membrane potential in a thermodynamic system under constant external conditions: a) is a model version of the diffusion potential; b) has a different value under different temperature; c) has a maximum value depending on the mobility of potential-generating ions.

b) has a different value under different temperature;

296. The molecules of the membrane lipid bi-layer: a) participate directly in the ion transport; b) have a long double chain fatty acid tails; c) are part of the peripheral protein complexes.

b) have a long double chain fatty acid tails;

135. The cross sectional arrangement of actin and myosin filaments in the sarcomere of skeletal muscles is: a) tetragonal; b) hexagonal; c) pentagonal.

b) hexagonal;

184. When placed in the following type of solution, cells will retain water and will inflate: a) isotonic solution; b) hypotonic solution; c) hypertonic solution.

b) hypotonic solution;

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 directly; c) in discrete smooth muscles, found in hollow organs, fibers are innervated together in bundles, and individual cells communicate via nexuses (gap junctions).

b) in discrete smooth muscles each cell is innervated individually, thus cells do not communicate directly;

107. Troponin I in skeletal muscles: a) bonds to Ca2+ and starts the muscle contraction; b) in the absence of Ca2+ it blocks the site of actin than bonds to myosin, and thus it inhibits the formation of actin-myosin cross-bridges; c) it slides against the thin filament, producing heat which is converted into mechanical work during contraction.

b) in the absence of Ca2+ it blocks the site of actin than bonds to myosin, and thus it inhibits the formation of actin-myosin cross-bridges;

411. As the blood volume in certain tissue decreases, the resistance: a) decreases; b) increases; c) remains the same.

b) increases;

284. During the voltage clamp method, the voltage across the membrane is fixed and the current passing through the membrane is measured: a) directly, using sensitive voltmeter across the membrane; b) indirectly, by the input current required to keep the voltage fixed; c) current is not measured but calculated using Ohm's law.

b) indirectly, by the input current required to keep the voltage fixed;

393. Which component of the electrical impedance is not present in the human body? a) capacitive; b) inductive; c) resistive.

b) inductive;

195. Cytotoxic cerebral edema is characterised by: a) inflation of the extracellular spaces; b) inflation of the intracellular spaces; c) loss of water.

b) inflation of the intracellular spaces;

540. Which of the following is not characteristic for the synaptic neurotransmitter communication? a) unidirectionality of transduction; b) information exchange through bivalent ions; c) lower conduction speed than electrical signaling.

b) information exchange through bivalent ions;

215. The action potential phenomenon is found: a) inmost human cells; b) inmuscle and nerve cells; c) only innerve cells.

b) inmuscle and nerve cells;

67. What prevents inorganic ions from moving through the phospholipid membrane? a) the equal concentrations of ion species on both sides of the membrane (isotonicity); b) inorganic ions are water-soluble. The phospholipid bilayer does not permit the passage of watersoluble substances; c) the ion passage is prevented by the higher hydrostatic pressure inside the cell.

b) inorganic ions are water-soluble. The phospholipid bilayer does not permit the passage of watersoluble substances;

66. What activates ligand-gated (receptor-regulated) ion channels? a) changes in the membrane potential; b) interaction between the corresponding ligand and the receptor, regulating the ion channel; c) the process of internalization of the receptor.

b) interaction between the corresponding ligand and the receptor, regulating the ion channel;

117. The major source of Ca2+ for skeletal muscle contraction is: a) the extracellular space where Ca2+ concentration is much greater than in the cytosol; b) intracellular depots located in the sarcoplasmic reticulum; c) simultaneously from both sources (a and b).

b) intracellular depots located in the sarcoplasmic reticulum;

443. Myocardial cells are specialised type of striated muscle cells that contract: a) voluntarily; b) involuntarily; c) depends on the situation.

b) involuntarily;

69. Is ion channel traffic regulated and how? a) no, ion traffic is not regulated; b) ion traffic is regulated through conditional gating mechanisms; c) ion traffic is regulated by pressure gradients.

b) ion traffic is regulated through conditional gating mechanisms;

193. Relative to the blood, physiological solution with 0.9% of NaCl is: a) hypertonic; b) isotonic; c) hypotonic.

b) isotonic;

301. The bending (kink) in one of the hydrocarbon tails of the phospholipid molecule, due to a double carbon bond, has the following implications: a) it aids the rotational motion of the phospholipid heads; b) it eases the transmembrane diffusion of gases and small molecules; c) it facilitates the motion of segments of the molecule.

b) it eases the transmembrane diffusion of gases and small molecules;

137. Order the following processes, related to striated muscle contraction, according to their sequence of occurrence: a) activation of dyhidropyridine receptors at the sarcolemma and ryanodine receptors of the sarcoplasmic reticulum; b) contraction; c) excitation of action potential; d) release of Ca2+ from the sarcoplasmic reticulum; e) calcium regulation of the contraction proteins.

c) excitation of action potential; a) activation of dyhidropyridine receptors at the sarcolemma and ryanodine receptors of the sarcoplasmic reticulum; d) release of Ca2+ from the sarcoplasmic reticulum; e) calcium regulation of the contraction proteins. b) contraction;

500. Receptors are not: a) membrane structures; b) cytosol proteins; c) extracellular structures.

c) extracellular structures.

472. When substances use protein carrier molecules to cross the membrane, the process is described as: a) simple diffusion; b) protein-lipid transport; c) facilitated diffusion.

c) facilitated diffusion.

34. Which intracellular factors lead to a smooth muscle contraction? a) factors that activate the enzyme myosin light chain phosphatase; b) factors that inhibit the enzyme myosin light chain phosphatase; c) factors that activate the enzyme myosin light chain kinase.

c) factors that activate the enzyme myosin light chain kinase.

328. Where in the cell is the potential-generating charge located? a) in the diffusion layer around the cell; b) in the zones of accelerated active transport of small organic molecules; c) fixed on the surface of the cellular membrane.

c) fixed on the surface of the cellular membrane.

239. What type of response is triggered in excitable cells when stimulated with an over-threshold stimulus? a) generation of electrotonic potential; b) generation of Donnan potential; c) generation of action potential.

c) generation of action potential.

304. The amphiphilic lipids of the plasma membrane have: a) certain fixed positions at the membrane; b) lateral and rotational mobility within their layers; c) have lateral, rotational, and trans-layer mobility.

c) have lateral, rotational, and trans-layer mobility.

186. When placed in the following type of solution, cells will lose water and will shrink: a) isotonic solution; b) hypotonic solution; c) hypertonic solution.

c) hypertonic solution.

164. Ionic polarization: a) involves mostly water molecules; b) relates to the formation of a double electric layer; c) increases the electromotive force (EMF) generated in biological tissue.

c) increases the electromotive force (EMF) generated in biological tissue.

364. Which of the following is not a type of macro-electrophoresis? a) analytical macro electrophoresis; b) medical electrophoresis (iontophoresis); c) inductive electrophoresis.

c) inductive electrophoresis.

274. Treatment of tissue with tetraethylammonium (TEA) will result in: a) change of the potassium equilibrium potential; b) inhibition of active potassium transport; c) inhibition of passive potassium transport.

c) inhibition of passive potassium transport.

273. Treatment of tissue with tetrodotoxin (TTX) will result in: a) change of the sodium equilibrium potential; b) change in the extracellular sodium concentration; c) inhibition of passive sodium transport.

c) inhibition of passive sodium transport.

519. For thermodynamic system in equilibrium, there is no change in: a) free energy; b) electrochemical potential; c) internal energy.

c) internal energy.

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.

c) involuntary, slow, low energy expenditure

461. Which of the following statements refer to the primary active transmembrane transport? a) transport of organic molecules; b) uses the energy of the concentration gradient of Na+; c) involves the active transport of: Na+, K+, Ca2+, H+, Mg2+, Cl-, and bicarbonate ions.

c) involves the active transport of: Na+, K+, Ca2+, H+, Mg2+, Cl-, and bicarbonate ions.

280. The depolarization phase of the axonal action potential is contributed to the: a) inward Na+ current due to the electrogenic work of the sodium-potassium pump; b) inward Na+ current due to the non-electrogenic work of the sodium-potassium pump; c) inward Na+ current due to the activation of voltage-gated sodium channels.

c) inward Na+ current due to the activation of voltage-gated sodium channels.

202. Which of the following membrane transports is NOT passive? a) aquaporins; b) ion channels; c) ion pumps.

c) ion pumps.

474. The primary active membrane transport is carried by: a) aquaporins; b) ion channels; c) ion pumps.

c) ion pumps.

36. What is the role of the enzyme myosin light chain phosphatase (MLCP) in the smooth muscle relaxation? a) after contraction, it lengthens the thick myofilaments; b) it de-phosphorylates the 20-kDa myosin light chain (MLC 20) of the myosin molecule, disrupting the bonding of myosin with the dense bodies of the membrane; c) it de-phosphorylates the 20-kDa myosin light chain (MLC 20) of the myosin molecule, disrupting the cross-bridge formation between thin and thick fibres.

c) it de-phosphorylates the 20-kDa myosin light chain (MLC 20) of the myosin molecule, disrupting the cross-bridge formation between thin and thick fibres.

339. What happens to the zeta potential when the ionic strength of the dispersion medium is increased? a) it increases; b) it stays the same; c) it decreases.

c) it decreases.

251. Choose the INCORRECT statement regarding Nernst equation for potassium ions across the membrane: Ek= (RT/zF)ln ([K+]out/[K+]in) a) its good approximation for the resting potential; b) considers the membrane permeable only for one ion species (K+); c) it models the membrane potential during the action potential.

c) it models the membrane potential during the action potential

484. Is it possible for a given type of signaling molecule to interact with multiple types of receptors? a) not possible; b) a given signaling molecule can activate all membrane receptors; c) its common for a ligand to interact with several types of receptors.

c) its common for a ligand to interact with several types of receptors.

548. Which of the following defines best an "isolated thermodynamic system"? a) exchange of energy with the surrounding environment; b) exchange of matter with the surrounding environment; c) lack of any exchange (energy or matter) with the surrounding environment.

c) lack of any exchange (energy or matter) with the surrounding environment.

492. Nicotinic acetylcholine receptors (nAChR) function as: a) ligand-gated Ca2+ ion pumps; b) voltage-gated Na+ channels; c) ligand-gated Na+ channels.

c) ligand-gated Na+ channels.

127. The resting potential of the sarcolemma is: a) more positive than Na+ equilibrium potential; b) more positive than the excitation threshold potential; c) more positive than the K+ equilibrium potential.

c) more positive than the K+ equilibrium potential.

167. Electro-muscular stimulation is used in the following condition: a) epilepsy; b) arrhythmia; c) muscle atrophy.

c) muscle atrophy.

118. Choose the correct statement regarding striated muscles: a) muscle contraction (mechanical event) comes first, and it triggers an action potential (electrical event) in the membrane of the contracting cell; b) muscle contraction and action potential are independent, concurrent processes and do not affect each other; c) muscle contraction (mechanical event) comes second, and it is triggered by an action potential (electrical event) in the membrane of the contracting cell.

c) muscle contraction (mechanical event) comes second, and it is triggered by an action potential (electrical event) in the membrane of the contracting cell.

139. Myofilaments of the striated muscle cells are composed of the proteins: a) actin and myosin; b) actin, troponin, tropomyosin; c) myosin, actin, troponin, tropomyosin.

c) myosin, actin, troponin, tropomyosin.

550. Can a natural process be perfectly reversible? a) depends on the thermodynamic system; b) all natural process are reversible; c) natural processes are not perfectly reversible.

c) natural processes are not perfectly reversible.

62. Is it possible for Cl- ions to pass through a Ca2+ ion channel? a) no, because Cl- ions are too large to fit the narrow channel; b) yes, they can; c) no, because the Ca2+ ion channel has an electrostatic selectivity filter with negative charge.

c) no, because the Ca2+ ion channel has an electrostatic selectivity filter with negative charge.

557. Can heat energy be converted completely into work? a) yes; b) only in isolated thermodynamic system; c) no.

c) no.

15. The sarcoplasmic reticulum of smooth muscle cells can be characterized as: a) very elaborate; b) moderately developed; c) not elaborate.

c) not elaborate

89. What is the electric charge of the narrow tunnels in ion channels? a) positive; b) negative; c) opposite to the electric charge of the ion species that pass through the channel.

c) opposite to the electric charge of the ion species that pass through the channel.

267. Which of the following currents is responsible for the repolarization phase of the axonal action potential? a) inward sodium ion current; b) inward calcium ion current; c) outward potassium ion current.

c) outward potassium ion current.

433. Which cardiac cells exhibit the spontaneous diastolic depolarization? a) myocytes of the right atrium; b) myocytes of the left ventricle; c) pacemaker cells.

c) pacemaker cells.

201. What are the two types of membrane transport according to the energy requirements? a) diffusion and osmoses; b) passive transport an facilitated diffusion; c) passive and active transport.

c) passive and active transport.

82. Ion transport through the ion channels is: a) unidirectional; b) active; c) passive.

c) passive.

43. Spike potentials are found in: a) hepatocytes; b) cardiac contractions; c) phasic smooth muscle contractions.

c) phasic smooth muscle contractions.

283. What kind of ion current flows across the axonal membrane during the repolarization phase of the action potential? a) negative Na+ current; b) positive Na+ current; c) positive K+ current.

c) positive K+ current.

240. What is the electric potential on the outside of the membrane relative to the inside, during the resting state of the cell? a) negative; b) zero; c) positive.

c) positive.

236. The resting membrane potential in excitable cells is close to the equilibrium potential of this ion species: a) sodium; b) calcium; c) potassium.

c) potassium.

70. Which of the following descriptions refers to ion channels? a) a random, temporary formation of pores in the lipid bilayer; b) protein structures that transport ions across the membrane with the expense of energy; c) protein structures that allow passive transport of inorganic ions.

c) protein structures that allow passive transport of inorganic ions.

529. Does temperature have an effect on the level of radiation damage of biological tissue? a) temperature does not influence the effects of ionizing radiation; b) radiation damage is weaker for higher temperature; c) radiation damage is stronger for higher temperature

c) radiation damage is stronger for higher temperature

463. The Na+/I- symporter, which transports iodine into the thyroid gland, cannot distinguish between non-radioactive (I-127) and radioactive (I-131) iodine. How could this be explained? a) radioactive and non-radioactive iodine have the same physical properties; b) radioactive and non-radioactive iodine have the same number of neutrons; c) radioactive and non-radioactive iodine have the same chemical properties.

c) radioactive and non-radioactive iodine have the same chemical properties.

114. When an over-threshold stimulus reaches the striated muscle cell, the following events take place: a) activation of the myosin light chain kinase; b) communication between adjacent cells; c) release of calcium from the sarcoplasmic reticulum.

c) release of calcium from the sarcoplasmic reticulum.

464. What type of membrane transport delivers iodide into the thyroid gland? a) passive transport; b) primary active transport; c) secondary active transport.

c) secondary active transport.

470. Transmembrane transport of substances against their electrochemical gradient, that does not use direct coupling of ATP is called: a) passive transport; b) primary active transport; c) secondary active transport.

c) secondary active transport.

417. What causes the appearance of the dicrotic wave? a) non-linear elastic changes of the aortic arc; b) the appearance of extra-systolic activity and parallel increase of the heart rate; c) secondary increases of blood inflow in the aortic region, as a result of its reflection off the closed aortic valve at the end of the systole.

c) secondary increases of blood inflow in the aortic region, as a result of its reflection off the closed aortic valve at the end of the systole.

45. Phasic smooth muscles are characterized by: a) their steady membrane potential; b) their function to maintain the tonus in blood vessels; c) sinusoidal variation in the membrane potential.

c) sinusoidal variation in the membrane potential.

145. How many different types of polarization in living tissue can be accounted for? a) two; b) nine; c) six.

c) six.

404. How is skull bone resistance bypassed during rheographic examination of the brain? a) brain rheography is impossible; b) through skull trepanation and application of electric current through the hole; c) skull bones have low resistance for the midrange frequencies used in rheography.

c) skull bones have low resistance for the midrange frequencies used in rheography.

9. Which of the following muscles do not have an ordered sarcomere structures? a) skeletal muscles; b) cardiac muscle; c) smooth muscles.

c) smooth muscles

122. Which of the following muscles do not have a sarcomere? a) skeletal muscles; b) cardiac muscles; c) smooth muscles.

c) smooth muscles.

427. The autonomous excitation of the heart is contributed to: a) the regular variation of the threshold potential of ventricular myocytes; b) the effect of mechanical pulse waves on the cardiac myocytes; c) special type of ion channels found in the membranes of pacemaker cells.

c) special type of ion channels found in the membranes of pacemaker cells.

113. In striated muscles, myosin heads bond to actin filaments to form cross-bridges: a) after oxidation of the active bonding sites of actin; b) after phosphorylation of tropomyosin I; c) spontaneously.

c) spontaneously.

295. Phospholipids of the membrane double layer are: a) synthesized in the extracellular space; b) gathered from food; c) synthesized in the cytosol.

c) synthesized in the cytosol.

445. Which of the following tissues has pacemaker cells? a) myocytes of the ventricles; b) myocytes of the atria; c) the atrioventricular node.

c) the atrioventricular node.

396. Which parameters of the hemodynamics can be studied with rheographic equipment? a) the sounds generated by the motion of blood in the studied tissue; b) the pressure pulses caused by blood the examined blood vessels; c) the blood filling of tissues in the examined areas.

c) the blood filling of tissues in the examined areas.

105. During contraction muscle cells convert: a) heat into mechanical work; b) the chemical energy of ATP into electrical energy of action potentials, which is converted into mechanical work; c) the chemical energy of ATP into mechanical work.

c) the chemical energy of ATP into mechanical work.

418. Which of the following factors determines the different number of waves, appearing after the incisura (dicrotic notch) of the rheographic curve? a) the cardiac contraction during the systole; b) the wobbling of the heart wall during the closure of the aortic valve; c) the condition of the vascular system.

c) the condition of the vascular system.

132. What is meant by the term "electro-mechanical coupling": a) the release of mediators in synaptic signaling; b) the propagation of slow waves without spike potentials; c) the connection between an electric signal and muscle contraction.

c) the connection between an electric signal and muscle contraction.

160. When pulsed current is applied through biological tissue: a) there will be polarization of the ion channels; b) the conductivity of the cell increases due heating; c) the current decreases with time.

c) the current decreases with time.

159. When direct current (DC) is applied through biological tissue: a) there is polarization of dissolved ions; b) the conductivity of the cell increases due to temperature increase; c) the current will decrease with time.

c) the current will decrease with time.

389. The high resistance of living cells and tissues to the propagation of constant direct current is explained with: a) the dielectric properties of phospholipids; b) the dielectric properties of transmembrane proteins; c) the dielectric properties of membranes.

c) the dielectric properties of membranes.

254. How is the "resting potential" of the cellular membrane defined? a) the intracellular electric potential in close proximity to the membrane during rest; b) the extracellular electric potential in close proximity to the membrane during rest; c) the electric potential difference between the intracellular and extracellular regions in close proximity of the membrane during rest.

c) the electric potential difference between the intracellular and extracellular regions in close proximity of the membrane during rest.

543. The appearance of local longitudinal Na+ currents in the area of initial stimulation in excitable membrane are the result of: a) the high mobility of sodium ions; b) he chaotic thermal motion of the ions; c) the generation of electrical and concentration gradients for Na+ in the vicinity of the initial Na+ influx.

c) the generation of electrical and concentration gradients for Na+ in the vicinity of the initial Na+ influx.

112. Which of the following processes is involved in the bending of the myosin head at 50 degrees after the formation of cross-bridges? a) the release of ADP from the myosin head; b) the sliding of the thin myofilaments towards the middle of the sarcomere; c) the hydrolysis of ATP after bonding to the myosin head.

c) the hydrolysis of ATP after bonding to the myosin head.

131. During the contraction of striated muscles, the length of this feature will shorten: a) the length of thin and think myofilaments; b) the diameter of myosin and actin proteins; c) the length of the sarcomere.

c) the length of the sarcomere.

65. Which of the following combinations of factors determine the activation time of the voltage-gated ion channels? a) the membrane potential and the pH of the cytosol; b) the level of hyper-polarization of the membrane and the specific channel gate kinetics; c) the level of membrane depolarization and the specific ion channel kinetics.

c) the level of membrane depolarization and the specific ion channel kinetics.

80. Choose the correct statement regarding ligand-gated ion channels: a) they are inactivated by complementarity; b) they are activated by changes in the membrane potential; c) the ligand-receptor interaction leads to conformational changes in the protein structure.

c) the ligand-receptor interaction leads to conformational changes in the protein structure.

223. For which of the following scenarios the neuron has the highest excitability? a) the membrane potential is at resting level; b) the membrane is hyper-polarized; c) the membrane is depolarized.

c) the membrane is depolarized.

219. What causes the appearance of trace potentials in neurons? a) the temperature increase due to ionic currents in the intracellular space; b) the membrane structural recovery processes after the action potential; c) the off-equilibrium concentrations of Na+ and K+ ions after the action potential.

c) the off-equilibrium concentrations of Na+ and K+ ions after the action potential.

332. What is the isoelectric point of the zeta potential? a) the extracellular concentration of ions for which the membrane potential is zero; b) the pH of the extracellular fluid for which the diffusion potential is zero; c) the pH of the dispersion medium for which the electrokinetic potential is zero.

c) the pH of the dispersion medium for which the electrokinetic potential is zero.

225. The refractory period in excitable cells is: a) the duration of trace potentials following the action potential; b) the period between stimulation and excitation of an action potential; c) the period where new action potential is impossible or more difficult to generate.

c) the period where new action potential is impossible or more difficult to generate.

170. When constant direct current is applied to living tissue, the magnitude of the current will decrease with time. What is the explanation? a) the activation of voltage-gated Ca2+ channels; b) the increase of the active resistance of the skin; c) the polarization of the tissue.

c) the polarization of the tissue.

318. Membrane potential is defined as: a) the potential difference between two points on the external side of, and distant from the cellular membrane; b) the potential difference between two points on the internal side of, and distant from the cellular membrane; c) the potential difference between two points on both sides, and in close proximity, of the cellular membrane.

c) the potential difference between two points on both sides, and in close proximity, of the cellular membrane.

330. Which of the following potential differences the electrokinetic potential of the cell: a) the potential difference between intracellular and extracellular environments; b) the potential difference between the fixed surface charge of the membrane and the extracellular fluid; c) the potential difference in the liquid medium of the cell, between the plane of the adsorption layer. and the bulk of the medium

c) the potential difference in the liquid medium of the cell, between the plane of the adsorption layer. and the bulk of the medium

534. Which of the following structures emit neurotransmitter molecules? a) the postsynaptic membrane; b) any part of the membrane; c) the presynaptic membrane.

c) the presynaptic membrane.

457. Which of the following transport processes is considered an active transport? a) the transfer of substance (molecules, ions) from area with high concentration into area of lower concentration; b) the transfer of substance (molecules, ions) irregardless of the direction of the concentration gradient; c) the transfer of substance (molecules, ions) from area with low concentration into area of higher concentration;

c) the transfer of substance (molecules, ions) from area with low concentration into area of higher concentration;

79. The passive trans-membrane transport of neutral molecules, when possible, is driven by: a) their electrochemical gradient; b) their electrical gradient; c) their concentration gradient.

c) their concentration gradient.

336. The ions of the adsorption and defuse layers are called counter-ions because: a) need to be distinguished from the potential-generating ions; b) because they move in the opposite direction the there is an external electric filed; c) they have the opposite charge to that of the potential-generating ions.

c) they have the opposite charge to that of the potential-generating ions.

511. Which of the following functions is characteristic for the receptors: a) they recognise the complimentary ligands but allow docking only when the cell needs the carried information; b) upon recognition, they allow docking of the type of signaling molecules that are required by the current needs of the cell; c) they interact with complimentary ligands on probabilistic principles (the higher the concentration the higher the chance of interaction).

c) they interact with complimentary ligands on probabilistic principles (the higher the concentration the higher the chance of interaction).

100. The myosin molecule in striated muscles has: a) two active sites: for bonding with Tropomyosin C, and ATP; b) three active sites: for bonding with F - actin, Ca2+, and ATP; c) two active sites: for bonding with F - actin, and ATP.

c) two active sites: for bonding with F - actin, and ATP.

504. Which of the following receptors do not get activated by acetylcholine? a) muscarinic receptors; b) nicotinic receptors; c) tyrosine receptors.

c) tyrosine receptors.

282. What happens when the membrane potential in neurons becomes equal or greater than the critical depolarisation threshold? a) voltage gated Na+ channels become deactivated, and the membrane potential returns to its resting state; b) voltage-gated Na+ channels do not respond to changes in the membrane potential reaching the critical threshold depolarization level; c) voltage-gated Na+ channels open and action potential is initiated.

c) voltage-gated Na+ channels open and action potential is initiated.

423. Under what circumstances the atrioventricular (AV) node takes over the role of leading pacemaker of the heart? a) when there is a dysfunction of heart's innervation; b) when there is ectopic foci; c) when there is a sinoatrial arrest.

c) when there is a sinoatrial arrest.

483. Is it possible for a given receptor to interact with multiple different signaling molecules? a) no, because a given receptor interacts only with one type of ligand; b) yes, because any given receptor can interact with all ligands; c) yes, a given receptor can interact with several signaling molecules, with similar structure.

c) yes, a given receptor can interact with several signaling molecules, with similar structure.

565. Is it possible to change the threshold potential of a neuron? a) yes, it is function of the work of the Na+/K+ pump; b) no, all cells have pre-set threshold potential; c) yes, it depends on the number of voltage-gated Na+ channels that can be activated at the time of stimulation.

c) yes, it depends on the number of voltage-gated Na+ channels that can be activated at the time of stimulation.

506. Can action potentials be used for inter-cellular signaling? a) no, action potentials do not travel through the extracellular medium; b) yes, all cells use action potentials for communications; c) yes, some cell types use it (neurons, visceral smooth muscles, cardiac muscles).

c) yes, some cell types use it (neurons, visceral smooth muscles, cardiac muscles).

524. Is there a significant difference in the biological effects in tissue from exposure of ionising radiation of different types? a) yes, electromagnetic waves are more damaging than particle beams; b) yes, particle beams are more damaging than electromagnetic radiation; c) yes, the effects of different types of radiation are very different on cellular level.

c) yes, the effects of different types of radiation are very different on cellular level.

376. When the frequency of the applied current is very high, the capacitive reactance of the skin will approach the following: a) a very large value; b) it will be equal to the (active) resistance; c) zero.

c) zero.

206. Which of the following equations refers to Osmotic pressure (per Van't Hoff): a) π = CTV; b) π = MTV; c) π = CRT. Where: C-concentration, R-gas constant, T-temperature, V-volume, M-mass.

c) π = CRT

446. Choose the correct order of occurrence of the ion currents that comprise action potentials of the cardiomyocytes: a) K+ efflux; b) Ca2+ influx, K+ efflux; c) K+ efflux, Cl- influx; d) Na+ influx.

d) Na+ influx c) K+ efflux, Cl- influx; b) Ca2+ influx, K+ efflux; a) K+ efflux;

212. During the depolarization phase of the action potential in neurons, the positive ion current is due to: а) Na+ influx; b) K+ efflux; c) Ca2+ influx.

а) Na+ influx;

211. After an excitation of an action potential, the Na+ current across the membrane: а) decreases about 100 times; d) remains constant; с) increases about 500 times.

с) increases about 500 times.