NERVE, MUSCLE, SYNAPTIC PHYSIOLOGY AND NEUROTRANSMISSION mcqs

1.            Most of the ATP generated in nerve cells is utilized to energize the:

A.            Na-Ca exchanger

B.            H-ATPase in the cell membrane

C.            Na-K ATPase

D.            synthesis of proteins

2.            Fast anterograde transport occurs at a rate of about:

A.            40 mm/day

B.            400 mm/day

C.            1 mm/day

D.            10 mm/day

3.            The largest known axons are found in:

A.            humans

B.            whales

C.            squids

D.            ostriches

4.            The normal resting cardiac muscle cell is most permeable to:

A.            Na

B.            K

C.            Ca

D.            Cl

5.            The membrane potential at which net flux of an ion across the membrane is zero is called:

A.            resting membrane potential

B.            spike potential

C.            threshold potential

D.            electrotonic potential

E.            equilibrium potential of that ion

6.            The resting membrane potential of ventricular cardiomyocytes is closest to the equilibrium potential for:

A.            sodium

B.            chloride

C.            potassium

D.            calcium

7.            The Nernst potential (also called equilibrium potential) is positive for:

A.            Na and Cl

B.            Na and K

C.            Na and Ca

D.            K and Cl

8.            The equilibrium potential of chloride in mammalian spinal motor neurons is typically about:

A. + 20 mV

B.            minus 40 mV (inside negative)

C.            minus 70 mV (inside negative)

D.            minus 90 mV (inside negative)

9.            The resting membrane potential of some neurons is equal to the equilibrium potential of:

A.            Na

B.            K

C.            Cl

D.            Ca

10.          If intracellular and extracellular potassium concentrations are approximately 140 mmol/L and 14 mmol/L respectively, the equilibrium potential for potassium is approximately:

A.            minus 30 mV inside negative

B.            minus 60 mV inside negative

C.            minus 90 mV inside negative

D.            minus 120 mV inside negative

11.          Which one of the following increases excitability of cardiac muscle?

A.            Increase in ECF [K+] from 5 to 10 mM

B.            Increase in ECF [K+] from 5 to 70 mM

C.            Decrease in ECF [K+] from 5 to 1.4 mM

12.          Hypokalemia would be expected to result in:

A.            increased neuronal excitability

B.            a more negative RMP

C.            no change in RMP

D.            a decrease in firing level of neurons

13.          The membrane potential of cardiac muscle cells is most affected by even a small change in plasma concentration of:

A.            Na

B.            K

C.            Cl

D.            Ca

14.          Which of the following would justify excluding sodium conductance from the equation for estimating resting membrane potential in skeletal muscle fibers?

A.            Extracellular [Na] is higher than ICF [Na]

B.            Na-K pump extrudes 3 Na for 2 K pumped in

C.            Negligible Na permeability of the resting membrane

D.            Unexcited cells are equally permeable to Na and K

15.          Excitability, in neurophysiology, is defined as:

A.            presence of a resting membrane potential

B.            use of more than 30% of ATP synthesized for powering the Na-K ATPase

C.            response to a threshold stimulus with a propagated action potential

D.            presence of voltage gated ion channels in a tissue

16.          Physiologically, the site of origin in motor neurons of conducted impulses is the:

A.            dendritic zone

B.            axon hillock

C.            node of Ranvier

D.            terminal buttons

17.          In motor neurons, the portion of the cell with the lowest threshold for the production of a full- fledged action potential is:

A.            initial segment

B.            soma

C.            dendritic zone

D.            node of Ranvier

18.          In the CNS, the membranes that wrap around myelinated neurons are those of:

A.            Schwann cells

B.            oligodendroglia

C.            endothelial cells

D.            astrocytes

19.          The number of Na channels per square micrometer of membrane in myelinated mammalian neurons is maximum in the:

A.            cell body

B.            dendritic zone

C.            initial segment

D.            node of Ranvier

20.          Action potential conduction velocity is influenced by:

A.            axon diameter

B.            temperature

C.            myelination

21.          Which one of the following statements about electrotonic potentials is incorrect?

A.            They are graded responses.

B.            They are local (non-propagated) responses.

C.            They may be depolarizing or hyperpolarizing.

D.            They are produced by a threshold stimulus.

22.          A stronger than normal stimulus can cause excitation of nerve or muscle during the:

A.            absolute refractory period

B.            relative refractory period

C.            spike potential

D.            overshoot

23.          An excitable cell has an RMP of -70 mV and a firing level of – 50 mV. This cell would be inexcitable when its membrane potential is:

A.            – 30 mV

B.            – 55 mV

C.            – 70 mV

D.            – 90 mV

24.          For the same conditions (as in the above question), the cell would be most excitable when its membrane potential is:

A.            – 30 mV

B.            – 55 mV

C.            – 70 mV

D.            – 90 mV

25.          The duration of action potential in a nerve is typically closest to:

A.            2 ms

B.            20 ms

C.            200 ms

D.            2000 ms

26.          Is conduction of nerve impulse in motor axons unidirectional or bidirectional?

27.          A traveling nerve impulse does not depolarize the area immediately behind it because:

A.            it is hyperpolarized

B.            the area immediately behind is refractory

C.            it is not self-propagating

D.            the conduction is always orthodromic

28.          The nerve fiber type most susceptible to conduction block by pressure is:

A.            type A

B.            type B

C.            type C

29.          Which of the following nerve fibers is most susceptible to hypoxia?

A.            Somatic motor neurons

B.            Nociceptive afferents

C.            Preganglionic autonomic neurons

D.            Fibers transmitting touch sensation

30.          Which nerve fiber type is most susceptible to conduction block by local anesthetics?

A.            Type A

B.            Type B

C.            Type C

31.          In spinal anesthesia, which of the following is lost first?

A.            Sympathetic tone

B.            Sensation in the lower limbs

C.            Motor function

D.            Proprioception

32.          Nociceptors (nerve endings signaling pain) signal through:

A.            Aα fibers

B.            Aβ fibers

C.            Aγ fibers

D.            Aδ fibers

E.            C fibers

33.          The duration of action potential in a skeletal muscle fiber is typically:

A.            5 ms

B.            25 ms

C.            100 ms

D.            250 ms

34.          When heart rate is about 75 beats per minute, the mean duration of action potential in ventricular muscle cells is approximately:

A.            5 ms

B.            25 ms

C.            100 ms

D.            250 ms

35.          Though the equilibrium potential of Na is + 60 mV, membrane potential does not reach this value during the overshoot of the action potential because:

A.            the concentration gradient of Na is reversed

B.            Na channels undergo inactivation in 1 ms

C.            voltage gated K channels open when membrane potential reaches 0 mV

D.            the membrane is impermeable to Na

36.          In skeletal muscle, thin filaments do not

contain:

A.            actin

B.            myosin

C.            troponin

D.            tropomyosin

37.          Actin is tethered to Z-lines in the sarcomere by:

A.            actinin

B.            titin

C.            nebulin

D.            dystrophin

38.          Ryanodine receptor is located in the:

A.            sarcolemma

B.            T-tubule

C.            terminal cisterns of sarcoplasmic reticulum

D.            cytosol

39.          The ATPase activity of which of the following proteins is altered to regulate skeletal muscle contraction?

A.            Actin

B.            Myosin

C.            Troponin

D.            Tropomyosin

40.          The major source of calcium for contraction of skeletal muscle is:

A.            ECF

B.            cytosol

C.            mitochondria

D.            sarcoplasmic reticulum

41.          Excitation and contraction of skeletal muscle are coupled by:

A.            ATP

B.            myosin

C.            release of calcium into sarcoplasm

D.            calmodulin

42.          Select all correct answers. Which of the following slow skeletal muscle relaxation?

A.            Slow myosin ATPase

B.            Inhibition of Ca-Mg ATPase

C.            ATP depletion

43.          Rigor mortis is due to:

A.            damage to actin and myosin

B.            rapid sequestration of Ca in ER

C.            increased myosin ATPase

D.            ATP depletion

44.          The gene coding which of the following proteins is the largest?

A.            Titin

B.            Dystrophin

C.            Gigantin

D.            Nebulin

45.          Which of the following proteins is absent

from smooth muscle?

A.            Actin

B.            Myosin

C.            Troponin

D.            Tropomyosin

46.          The activity of which contractile protein is altered to regulate smooth muscle contraction?

A.            Actin

B.            Myosin

C.            Calmodulin

D.            Tropomyosin

47.          The calcium-binding protein that plays a key role in the regulation of smooth muscle cell contraction is:

A.            dystrophin

B.            calmodulin

C.            troponin C

D.            calcineurin

48.          Which of the following statements about visceral smooth muscle is incorrect?

A.            Neighboring cells are electrically coupled by means of gap junctions.

B.            Contraction can occur in the absence of extrinsic neural innervation.

C.            Twitch duration is typically longer when compared to skeletal muscle.

D.            Force is graded by varying intracellular calcium.

E.            Stretch of smooth muscle consistently increases active tension.

49.          An example for multi-unit (nonsyncytial) smooth muscle is:

A.            stomach

B.            uterine myometrium

C.            iris

D.            ureters

Questions 50-52. True/False

50.          Type I skeletal muscle fibers:

A.            They are called slow, oxidative fibers.

B.            They are innervated by slow motor units.

C.            They have slow myosin ATPase activity.

D.            They contain myoglobin.

E.            They have high oxidative capacity.

51.          Type IIA skeletal muscle fibers:

A.            They are called fast oxidative, glycolytic fibers.

B.            They are innervated by fast motor units resistant to fatigue.

C.            They have fast myosin ATPase activity.

D.            They have some myoglobin.

E.            They have moderate oxidative capacity.

52.          Type IIB skeletal muscle fibers:

A.            They are called fast glycolytic fibers.

B.            They have little to no myoglobin.

C.            They are innervated by fast motor units that are fatigable.

D.            They have fast myosin ATPase activity.

E.            They have low oxidative capacity.

53.          Oxidative capacity is highest in:

A.            type I muscle fibers

B.            type IIA muscle fibers

C.            type IIB muscle fibers

54.          Which of the following statements is

incorrect?

A.            Contraction can occur without an appreciable decrease in the length of the muscle.

B.            Contraction against a constant load with approximation of the ends of the muscle is called isotonic contraction.

C.            Muscles can lengthen while doing work.

D.            Isometric contractions do work whereas isotonic contractions do not.

55.          When a heavy object in hand is lowered, the extension at the elbow is brought about by:

A.            active shortening of the extensors

B.            passive shortening of the extensors

C.            active lengthening of the flexors

D.            active shortening of the flexors

56.          The total tension generated during skeletal muscle contraction is highest when the muscle:

A.            is appreciably shorter than resting length

B.            contracts isometrically at resting length

C.            is stretched beyond its resting length

57.          The smallest amount of muscle that can contract in response to excitation of a single motor neuron is:

A.            1 muscle fiber

B.            a muscle fasciculus

C.            the entire muscle

D.            all muscle fibers supplied by that neuron

58.          The number of muscle fibers innervated by a motor axon is smallest in:

A.            gastrocnemius

B.            orbicularis oculi

C.            single-unit smooth muscle

D.            soleus

59.          Staircase phenomenon (Treppe) is due to:

A.            increased availability of intracellular calcium

B.            synthesis of stable troponic C molecules

C.            summation

D.            tetanus

E.            increased excitability

60.          The force of muscle contraction cannot be increased by:

A.            increasing the frequency of activation of motor units

B.            increasing the number of motor units activated

C.            recruiting larger motor units

D.            asynchronous firing of motor units

E.            increasing the amplitude of action potentials in motor neurons

F.            varying release of calcium from SR

61.          The term ‘size principle’ refers to the fact that:

A.            chronically denervated skeletal muscle decreases in size due to reduced release of growth factors from motor neurons

B.            neurons in small motor units conduct slowly

C.            small motor units are recruited for more forceful contractions

D.            large, fast motor units are recruited after small, slow motor units

62.          Recruitment and activation of motor units is investigated by:

A.            electromyography

B.            electroencepaholgraphy

C.            nerve action potential recordings

D.            clinical examination of tendon jerks

63.          The minimum stimulus intensity that produces a compound action potential in nerve or muscle is called (or equal to):

A.            rheobase

B.            chronaxie

C.            twice rheobase

D.            twice chronaxie

64.          Which of the following is incorrect about cardiac muscle?

A.            T-system is located at the Z lines.

B.            Adjacent muscle cells are coupled by gap junctions

C.            Intercalated disks are at Z-lines.

D.            Dependence on influx of calcium from ECF for release of calcium from the SR.

E.            It contains myoglobin.

F.            It contains mitochondria.

G.           The twitch duration is shorter compared to type II skeletal muscle fibers.

65.          When heart rate is 75 bpm, the duration of absolute refractory period of cardiac muscle is normally approximately:

A.            50 ms

B.            100 ms

C.            200 ms

D.            300 ms

66.          When heart rate is about 75 beats/min, the duration of ventricular systole is about:

A.            100 ms

B.            200 ms

C.            300 ms

D.            400 ms

67.          Regarding the ionic basis of action potential in working cardiomyocytes, which of the following is incorrect?

A.            Phase 0: Na influx

B.            Phase 1: K influx

C.            Phase 2: Ca influx

D.            Phase 3: K efflux

68.          The shortest phase of the action potential in ventricular cardiomyocytes is:

A.            Phase 0

B.            Phase 1

C.            Phase 2

D.            Phase 3

69.          Which of the following characteristics is unique to skeletal muscle and is not observed in normal cardiac muscle?

A.            Gradation of force production

B.            Refractoriness

C.            Staircase phenomenon

D.            Tetanizability

E.            Conduction of impulse through gap junctions

70.          Which of the following accelerates contraction as well as relaxation of heart muscle?

A.            Norepinephrine

B.            Calcium

C.            Digoxin

D.            Potassium

71.          Under basal conditions, which is the predominant energy substrate utilized by cardiac muscle?

A.            Carbohydrate

B.            Amino acids

C.            Ketones

D.            Fatty acids

72.          Which of the following is not a step in vascular smooth muscle contraction?

A.            Ca binding to troponin C

B.            Activation of calcium-calmodulin dependent myosin light chain kinase

C.            Phosphorylation of myosin

D.            Increased myosin ATPase activity

73.          Resting membrane potential is most unstable in which of the following muscles?

A.            Smooth muscle of the stomach

B.            Gastrocnemius muscle

C.            Orbicularis oculi

D.            Muscle cells in the left ventricle

74.          The addition of which of the following to a preparation of intestinal smooth muscle would most likely increase the frequency of spike potentials in vitro?

A.            Acetylcholine

B.            Epinephrine

C.            Norepinephrine

D.            Nitric oxide

75.          The latch-bridge mechanism in smooth muscle is responsible for:

A.            fast muscle twitch

B.            sustained muscle contraction

C.            excitation-contraction coupling

D.            unstable membrane potential

76.          The repolarizing phase of the action potential in nerve fibers is primarily due to:

A.            Na-K ATPase

B.            sodium influx via voltage gated sodium channels

C.            potassium efflux via voltage gated potassium channels

D.            calcium efflux mediated by Na-Ca exchanger

77.          Denervation hypersensitivity:

A.            is due to upregulation of neurotransmitter receptors in the denervated structure

B.            does not occur in smooth muscle

C.            partly explains the release phenomenon that occurs in neurological diseases

78.          Neuromuscular transmission is impaired in conditions listed below (in List A), however, the pathogenesis of muscle weakness is different in each. Match items in List A with those in List B.

List A

1.            Botulism

2.            Cobra venom intoxication

3.            Lambert-Eaton syndrome

4.            Myasthenia gravis

List B

A.            Antibodies to nicotinic Ach receptors in the motor end plate

B.            Toxin inhibits Ach release from presynaptic nerve terminals in skeletal muscle neuromuscular junction

C.            Competitive blockade of nicotinic Ach receptors in skeletal muscle motor end plate

D.            Antibodies to voltage-gated calcium channels in presynaptic terminals

79.          Kinemyography is a novel technique for monitoring neuromuscular function.

80.          Which of the following is correct with regard to numbers of each of the following in the CNS?

A.            neurons >> glia > synapses

B.            glia >>> synapses >>> neurons

C.            synapses >> glia > neurons

D.            synapses >> neurons >> glia

81.          Which of the following types of cells work as scavenger cells in the CNS?

A.            Microglia

B.            Oligodendroglia

C.            Ependymal cells

D.            Astrocytes

82.          Which of the following cells in the CNS is primarily involved in the reuptake of excitatory neurotransmitters released by neurons?

A.            Astroglial cell

B.            Microglial cell

C.            Oligodendroglial cell

D.            Ependymal cell

83.          Which is the commonest type of synapse in the CNS?

A.            Axosomatic synapse

B.            Axodendritic synapse

C.            Axoaxonal synapse

84.          Which of the following events in postsynaptic neuronal membrane underlie excitatory postsynaptic potentials?

A.            Opening of Na channels

B.            Closure of K channels

C.            Opening of calcium channels

D.            Opening of chloride channels

85.          Which of the following events in postsynaptic neuronal membrane underlie inhibitory postsynaptic potentials? Opening of:

A.            Na channels

B.            Ca channels

C.            Cl channels

86.          Neuron C responds to stimulation of neuron A with a propagated action potential only when neuron B (which terminates only on neuron C) is also simultaneously stimulated. Which of the following inferences is justified?

A.            Neuron C releases glycine.

B.            Neuron B releases an excitatory neurotransmitter.

C.            The synapse between A and C is axosomatic.

D.            The neurotransmitter released by neuron A opens K channels in neuron C.

87.          The minimum time for transmission across one synapse is:

A.            0.5 ms

B.            1 ms

C.            1.5 ms

D.            2 ms

88.          Inhibitory postsynaptic potentials (IPSP) are an example of:

A.            postsynaptic inhibition

B.            presynaptic inhibition

C.            direct inhibition

D.            indirect inhibition

89.          Presynaptic inhibition occurs at:

A.            axoaxonal synapses

B.            axosomatic synapses

C.            axodendritic synapses

90.          Renshaw cell inhibition of alpha-motoneurone is an example of:

A.            feedforward inhibition

B.            negative feedback inhibition

C.            presynaptic inhibition

D.            postsynaptic inhibition

E.            indirect inhibition

F.            direct inhibition

91.          Most excitatory neurotransmission in the brain is believed to be mediated by:

A.            glutamate

B.            glycine

C.            GABA

D.            GnRH

92.          The inhibitory amino acid neurotransmitters in the CNS are:

A.            glutamate and glycine

B.            glutamate and aspartate

C.            GABA and glycine

D.            aspartate and glycine

93.          Which of the following is/are examples of ligand-gated ion channels?

A.            Nicotinic Ach receptor

B.            IP3 receptor

C.            GABA-A receptor

D.            Glycine receptor

94.          IPSPs due to chloride influx are produced by:

A.            acetylcholine

B.            GABA

C.            glycine

D.            glutamate

E.            substance P

95.          Which of the following neurotransmitters has both excitatory and inhibitory effects?

A.            Aspartate

B.            GABA

C.            Glutamate

D.            Glycine

96.          Which of the following toxins inhibits the release of acetylcholine from alpha-motor neurons?

A.            Botulinum toxin

B.            Cholera toxin

C.            Saxitoxin

D.            Tetanus toxin

97.          Which of the following effects is not

produced by stimulation of μ opioid receptor?

A.            Analgesia

B.            Constipation

C.            Diuresis

D.            Euphoria

E.            Miosis

F.            Sedation

98.          Synaptic conduction is mostly orthodromic

because:

A.            dendrites cannot be depolarized.

B.            once repolarized, an area cannot be depolarized.

C.            the strength of antidromic impulses is less.

D.            the neurotransmitter is in the presynaptic terminal.

99.          Which of the following statements about synaptic potentials is incorrect?

A.            They are propagated down the postsynaptic neuron.

B.            They undergo spatiotemporal summation.

C.            They are analogous to generator potentials and end-plate potentials.

D.            IPSP hyperpolarize the postsynaptic neuron.

E.            They are proportional to the amount of transmitter released by the presynaptic neuron.

100.        Following peripheral nerve injuries, which of the following investigations is most useful to assess likelihood of recovery of muscle and nerve function?

A.            Electromyography

B.            Muscle biopsy

C.            Strength-duration curve

Related Posts

Leave a Reply

Your email address will not be published. Required fields are marked *