5 NEUROMUSCULAR SYSTEM 115

MCQs

MCQ
Questions 261–266
261. A reflex action
A. Is initiated at a sensory receptor organ.
B. May result in endocrine secretion.
C. Involves transmission across at least two central nervous synapses in series.
D. May be excitatory or inhibitory.
E. Is independent of higher centres in the brain.

262. In skeletal muscle neuromuscular junctions

A. The motor end plate is the motor nerve terminal.
B. Spontaneous (miniature) potentials may be recorded in the motor nerve terminal.
C. Motor nerve terminals have vesicles containing acetylcholine.
D. There is a high concentration of acetylcholinesterase.
E. Transmission is facilitated by botulinum toxin.

263. Cerebrospinal fluid

A. Is formed in the arachnoid granulations.
B. Provides the brain with most of its nutrition.
C. Protects the brain from injury when the head is moved.
D. Has a lower pressure than that in the cerebral venous sinuses.
E. Flow around the adult brain is around half a litre per day.

264. A skeletal muscle fibre

A. Membrane is negatively charged on the inside with respect to the outside at rest.
B. Contains intracellular stores of calcium ions.
C. Is normally innervated by more than one motor neurone.
D. Becomes more excitable as its resting membrane potential falls.
E. Becomes less excitable as the extracellular ionized calcium levels fall.

265. In sensory receptors

A. Stimulus energy is converted into a local depolarization.
B. The generator potential is graded and self-propagating.
C. A generator potential can be produced by only one form of energy.
D. The frequency of action potentials generated doubles when the strength of the stimulus
doubles.
E. Serving touch sensation, constant suprathreshold stimulation causes action potentials to be
generated at a constant rate.

266. A somatic lower motor neurone

A. Innervates fewer fibres in an eye muscle than does one innervating a leg muscle.
B. Conducts impulses at a speed similar to that in an autonomic postganglionic neurone.
C. Is unmyelinated.
D. Conducts impulses which cause relaxation in some skeletal muscles.
E. Synapse with skeletal muscle but not with other neurones.
 116 Neuromuscular system – answers

Answers
MCQ

261.
A. TrueStimulation of the receptor generates impulses in the afferent limb.
B. TrueStimulation of osmoreceptors reflexly modifies ADH output from the posterior pituitary
gland.
C. False The knee jerk reflex arc contains only one central nervous synapse.
D. TrueIn the knee jerk extensors of the knee contract, while flexors relax (reciprocal
inhibition).
E. False Higher centres can facilitate or inhibit many reflex actions such as micturition.

262.
A. False It is the modified muscle membrane adjacent to the nerve terminal.
B. False They may be recorded at the motor end plate.
C. TrueThis neurotransmitter, released by exocytosis, excites the end plate membrane.
D. TrueThis makes acetylcholine’s action transient.
E. False Botulinum toxin blocks transmission by an action on the motor nerve terminals.

263.
A. False It is formed in choroid plexuses by active and passive processes.
B. False Most of the brain’s nutrition comes from the blood.
C. TrueThis is its main function and it does so through cushioning and buoyancy.
D. False Its higher pressure allows drainage by filtration to the dural venous sinuses via the
arachnoid villi.
E. TrueThis is about four times its volume.

264.
A. TrueThis ‘resting membrane potential’ is about 290 mV.
B. TrueThese are released on excitation.
C. False A single neurone supplies a group of muscle fibres.
D. TrueIt becomes more excitable as its membrane potential approaches the firing threshold
(about 270 mV).
E. False Decreasing extracellular Ca21 increases excitability and may lead to spontaneous
contractions (tetany), possibly by increasing sodium permeability.

265.
A. TrueThis is the generator potential.
B. False It is graded but not propagated.
C. False But sensitivity is greatest to one form of energy – the ‘adequate stimulus’.
D. False Frequency is related to the logarithm of the strength of the stimulus.
E. False Frequency falls with time due to adaptation.

266.
A. TrueThe more precise the movement required, the fewer the fibres supplied by one motor
neurone.
B. False Somatic motor neurones conduct at 60–120 m/sec; autonomic at about 1 m/sec.
C. False Fast-conducting fibres are large and myelinated.
D. False Impulses carried by somatic motor neurones are excitatory to skeletal muscle.
E. False Some carry impulses to inhibitory (Renshaw) cells in the anterior horn.
 Neuromuscular system – questions 117

Questions 267–272

MCQ
267 Impulses serving pain sensation in the left foot are relayed
A. Across synapses in the left posterior root ganglion.
B. By fibres in the left spinothalamic tract.
C. By the same spinal cord tract which serves heat and cold sensation.
D. To the thalamus on the right side.
E. To the cerebral cortex before entering consciousness.

268. An excitatory post-synaptic potential

A. Is the depolarization of a post-synaptic nerve cell membrane that occurs when a pre-synaptic
neurone is stimulated.
B. Involves reversal of polarity across the post-synaptic nerve cell membrane.
C. May be recorded from a posterior root ganglion cell.
D. Is propagated at the same rate as an action potential.
E. Is caused by the electrical field induced by activity in the pre-synaptic nerve terminals.
269. The ascending reticular formation
A. When stimulated tends to increase alertness.
B. Transmits impulses to higher centres via a multisynaptic pathway.
C. Is activated by collateral branches of sensory neurones.
D. Neurones project to most parts of the cerebral cortex.
E. Increases its activity during deep sleep.

270. The cerebellum

A. Modifies the discharge of spinal motor neurones.
B. Is essential for finely coordinated movements.
C. Has an afferent input from the motor cortex.
D. Has an afferent input from muscle proprioceptors.
E. Has an afferent input from the vestibular system.

271. During deep sleep there is a fall in

A. Hand skin temperature.
B. Arterial PCO2.
C. Blood growth hormone/cortisol ratio.
D. Metabolic rate.
E. Urine formation.

272. Sympathetic
A. Ganglionic transmission is mediated by acetylcholine.
B. Neuromuscular transmission at the heart is mediated by adrenaline.
C. Neuromuscular transmission in hand skin arterioles is mediated by acetylcholine.
D. Neuroglandular transmission at sweat glands is mediated by noradrenaline.
E. Neuromuscular transmission at the iris is mediated by noradrenaline.
 118 Neuromuscular system – answers

Answers
MCQ

267.
A. False The ganglion contains sensory cell bodies but no synapses; primary pain fibres
carrying these impulses synapse with secondary neurones in the left posterior horn.

B. False They cross to the right spinothalamic tract.

C. TruePain and temperature fibres travel together.
D. TrueSensations other than smell are relayed in the thalamus.
E. False They enter consciousness at a subcortical level.

268.
A. TrueAn inhibitory potential is a hyperpolarization.
B. False It is a transient (about 5 msec), small (about 5 mV) depolarization towards the
threshold for firing.
C. False It may be recorded from a motor neurone.
D. False It is not propagated.
E. False It is caused by transmitters changing permeability in post-synaptic membranes.

269.
A. TrueAssociated with increased electrical activity in cortical regions.
B. TrueDiffuse cortical activity following sensory stimulation occurs later than local
postcentral gyrus activity.
C. TrueSensory fibres ascending to the thalamus send collaterals to reticular nuclei.
D. TrueThe diffuse cortical activity following sensory stimulation is abolished by damage to
the reticular formation.
E. False Decreased activity leads to a higher arousal threshold during sleep.

270.
A. TrueHence it influences skeletal muscle activity.
B. TrueDamage to it leads to movements being clumsy (ataxia).
C. TrueThis provides information of the desired movement.
D. TrueThis provides information of the actual movement.
E. TrueIt has an important role in maintaining balance.

271.
A. False Skin temperature rises due to vasodilation.
B. False The level rises due to hypoventilation.
C. False Growth hormone level is higher, cortisol lower in sleep.
D. TrueDue to slowing of metabolism and a fall in catecholamine level.
E. TrueThe antidiuretic hormone level is higher in sleep.

272.
A. TrueThis applies to parasympathetic ganglia also.
B. False The transmitter is noradrenaline.
C. False The transmitter is noradrenaline here also.
D. False These sympathetic fibres are cholinergic.
E. TrueSympathetic adrenergic fibres innervate radial muscle in the iris; cholinergic
parasympathetic fibres innervate the circular muscle.
 Neuromuscular system – questions 119

Questions 273–278

MCQ
273. The blood–brain barrier
A. Slows equilibration of solutes between blood and brain tissue fluids.
B. Is a more effective barrier for fat-soluble substances than water-soluble substances.
C. Is a more effective barrier in infants than in adults.
D. Is a more effective barrier for CO2 than for O2.
D. Permits hydrogen ions to pass freely.

274. Nerve impulses

A. Can travel in one direction only in a nerve fibre.
B. Can travel in one direction only across a synapse.
C. Travel at the speed of an electric current.
D. Correspond in duration to that of the nerve refractory period.
E. Can be transmitted at higher frequencies in autonomic than in somatic nerves.

275. In skeletal muscle

A. Contraction occurs when its pacemaker cells depolarize sufficiently to reach the thresh-old
for firing.
B. Calcium is taken up by the sarcotubular system when it contracts.
C. Actin and myosin filaments shorten when it contracts.
D. The sarcomeres shorten during contraction.
E. Contraction strength is related to initial length of the muscle fibres.
276. The electroencephalogram normally shows voltage waves
A. Whose amplitude is related to intelligence.
B. Of smaller amplitude during deep sleep than during alert wakefulness.
C. Of lower frequency during deep sleep than during alert wakefulness.
D. Of greater amplitude than those of the electrocardiogram.
E. Which are bilaterally symmetrical.

277. Saltatory conduction

A. Occurs only in myelinated fibres.
B. Does not depend on depolarization of the nerve membrane.
C. Has a slower velocity in cold than in warm conditions.
D. Is faster than non-saltatory conduction in nerve fibres with diameters around 10 mm.
E. Transmits impulses with a velocity proportional to fibre diameter.

278. Parasympathetic nerves

A. Have opposite effects to sympathetic nerves on intestinal smooth muscle.
B. Have opposite effects to sympathetic nerves on iris smooth muscle.
C. Cause vasodilatation in skeletal muscle during prolonged exercise.
D. Cause sweat secretion in skin when body temperature rises.
E. Have longer postganglionic than preganglionic fibres.
 120 Neuromuscular system – answers

Answers
MCQ

273.
A. TrueCapillary permeability is lower in the brain than in other tissues.
B. False Fat-soluble substances cross readily due to the lipid in cell membranes.
C. False The reverse is true; bilirubin, which cannot pass in the adult, does so in infants.
D. False Both CO2 and O2 cross the blood–brain barrier easily.
E. False This protects brain tissues against sudden changes in the pH of blood.

274.
A. False In axons, impulses travel in both directions from a point of electrical stimulation.
B. TrueThe transmitter vesicles are in the pre-synaptic terminal.
C. False Impulse propagation is a different process and much slower than electrical cur-rent.

D. TrueNerves cannot be re-excited while their membrane polarity is reversed.

E. False The shorter refractory periods in somatic nerves allow higher frequencies.

275.
A. False Skeletal muscle has no pacemaker cells and shows no spontaneous activity.
B. False Calcium is released from intracellular stores when it contracts.
C. False The filaments do not shorten but slide together over one another.
D. TrueThere is greater overlap of the actin and myosin fibrils.
E. TrueModerate stretch increases contraction strength as in the heart.

276.
A. False EEG is no index of intelligence.
B. False High amplitude waves occur in deep sleep; the reverse is true of wakefulness.
C. TrueThe high amplitude waves in sleep are of low frequency; the reverse is true of the low
amplitude waves in wakefulness.
D. False EEG voltages are much smaller than ECG voltages.
E. TrueAsymmetry is a sign of disease.

277.
A. TrueExcitation leaps from node to node across the myelinated segments.
B. False The membrane does depolarize at the nodes.
C. TrueCooling slows sodium conductance at the nodes.
D. TrueTheoretically, saltatory conduction becomes the slower in nerve fibres with dia-meters
less than 1 mm.
E. TrueAnd to the distance between nodes.

278.
A. TrueParasympathetic nerves stimulate, and sympathetic nerves inhibit, intestinal smooth
muscle contractions.
B. False Both contract iris smooth muscle; however parasympathetics constrict the pupil by
contracting circular muscle, sympathetics dilate it by contracting radial muscle.

C. False Skeletal muscle has no parasympathetic nerve supply; local metabolites are responsible
for the vasodilatation.
D. False Skin has no parasympathetic innervation; sympathetic cholinergic nerves are
responsible for the increase in sweating when body temperature rises.
E. False The reverse is the case.
 Neuromuscular system – questions 121

Questions 279–284

MCQ
279. a (alpha) adrenoceptors
A. Are located on myofilaments in smooth muscle cells.
B. Are distinguishable from b (beta) receptors using electron microscopy.
C. Can be stimulated by both adrenaline and noradrenaline.
D. Are involved in the vasoconstrictor responses in skin to adrenaline.
E. Are involved in the heart rate responses to noradrenaline.

280. Neurones serving conscious muscle proprioception

A. Conduct impulses at a similar rate to somatic motor neurones.
B. Have their cell bodies in the ipsilateral posterior horn of the spinal cord.
C. Use a different pathway from the primary neurones serving unconscious proprioception.
D. Synapse with secondary neurones whose axons project up the ipsilateral posterior (dorsal)
columns of the spinal cord.
E. Synapse with neurones which cross the midline of the body in the brainstem.
281. The a (alpha) rhythm of the electroencephalogram
A. Disappears when the eyes are closed.
B. Is an electrical potential with an amplitude around one millivolt.
C. Has a frequency of 8–12 Hz.
D. Has a lower frequency than the d (delta) rhythm.
E. Indicates that the subject is awake.

282. Nerve fibres continue to conduct impulses when

A. Extracellular sodium is replaced by potassium.
B. Extracellular sodium is replaced by a non-diffusible cation.
C. Temperature is lowered from 37 to 30oC.
D. Temperature is lowered to below 0oC provided freezing does not occur.
E. The sodium-potassium pump is inactivated.

283. The primary sensory ending of a muscle spindle is stimulated by

A. Shortening of an antagonist muscle.
B. Relaxation of the muscle concerned when under load.
C. Shortening of the extrafusal fibres.
D. Stimulation of the gamma efferent fibres.
E. Striking the appropriate tendon with a tendon hammer.

284. In the spinal cord

A. Pain impulse traffic may be modulated in the posterior horn.
B. Autonomic motor neurones arise in the lateral horn.
C. Gamma-aminobutyric acid may act as an excitatory neurotransmitter.
D. Reflex centres are normally inhibited by descending impulses from supra-spinal centres.
E. Post-synaptic excitation may be mediated by amino acid derivatives acting as neuro-
transmitters.
 122 Neuromuscular system – answers

Answers
MCQ

279.
A. False They are located in the cell membranes.
B. False They cannot be visualized; chemical evidence suggests their structure is similar.
C. TrueAlso by drugs such as ephedrine which has a similar structure.
D. TrueAlpha receptors predominate in skin arterioles.
E. False Cardiac adrenoceptors are predominantly beta receptors.

280.
A. TrueBoth are fast fibres and reflexes involving them have a short reflex delay.
B. False They are in the posterior root ganglion.
C. TrueUnconscious proprioception impulses travel in the spino-cerebellar tracts.
D. False The primary neurone axons pass up the ipsilateral posterior columns before syn-apsing
with secondary neurones at the top of the spinal cord.
E. TrueThe secondary neurones cross in the medulla oblongata.

281.
A. False It is best seen when the subject’s eyes are closed.
B. False It is much smaller, at around 50 microvolts.
C. TrueIt is described in terms of frequency and amplitude.
D. False The upper limit of the delta rhythm is 3.5 Hz.
E. TrueIt disappears with the onset of sleep.

282.
A. False This would depolarize the fibres completely.
B. False Influx of cations is essential for depolarization.
C. TrueHowever, conduction is slowed.
D. False Nerve fibres stop conducting before tissue freezing occurs.
E. TrueThey continue to conduct until the electrochemical gradients created by the pump
decline.

283.
A. TrueThis stretches the agonist and its spindles.
B. TrueThis also stretches the spindles.
C. False This reduces the stretch of the spindle.
D. TrueMuscle contraction at each end of the spindle stretches the nuclear bag.
E. TrueThe knee jerk is initiated by striking the patellar tendon which stretches spindles in the
quadriceps muscle.

284.
A. TrueIn the substantia gelatinosa; endorphins may inhibit pain impulse transmission.
B. TrueThese are the preganglionic autonomic motor neurones.
C. False It is an inhibitory transmitter thought to be responsible for IPSPs at post-synaptic
membranes.
D. False Loss of supraspinal facilitation is responsible for the areflexia in spinal shock.
E. TrueGlutamate and aspartate are thought to be responsible for much of excitatory
transmission in the CNS.
 Neuromuscular system – questions 123

Questions 285–289

MCQ
285. In the cerebral cortex
A. Neuronal connections are innate and immutable.
B. Language and non-language skills are represented in different hemispheres.
C. The areas concerned with emotional behaviour are concentrated in the frontal lobes.
D. The cortical area devoted to sensation in the hand is larger than that for the trunk.
E. Stimulation of the motor cortex causes contractions of individual muscles on the oppo-site
side of the body.

286. When a nerve cell membrane is depolarized by 5 mV

A. Its permeability to sodium increases.
B. Sodium ions move into the cell to cause further depolarization.
C. Potassium ions move outwards down their electrochemical gradient.
D. Chloride ions move inwards down their electrochemical gradient.
E. An action potential is generated.

287. Generalized sympathetic activity is characterized by

A. Contraction of the radial muscle in the iris.
B. Increased urinary excretion of catecholamines.
C. Lipolysis in adipose tissue.
D. Decreased conduction rate in the atrio-ventricular bundle.
E. Relaxation of sphincteric smooth muscle in the alimentary tract.

288 Stimulation of the vagus nerves causes

A. A reduction in the strength of ventricular contraction.
B. Secretion and vasodilatation in the salivary glands.
C. Mucous secretion from bronchial mucosal cells.
D. The spleen to contract.
E. The gallbladder to contract.

289. An action potential in a nerve fibre

A. Occurs when its membrane potential is hyperpolarized to a critical level.
B. Is associated with a transient increase in membrane permeability to sodium.
C. Is associated with a transient decrease in membrane permeability to potassium.
D. Induces local electrical currents in adjacent segments of the fibre.
E. Has an amplitude which varies directly with the strength of stimulus.
 124 Neuromuscular system – answers

Answers
MCQ

285.
A. False The connections of brain neurones can be changed fairly rapidly to reflect new patterns
of activity and sensory experience; this is referred to as neuronal plas-ticity.

B. TrueThe left hemisphere is dominant for speech in most people and the right is dom-inant
for skills requiring appreciation of time and space relationships.
C. False They are found mainly in the limbic cortex.
D. TrueThe cortical area given to a particular skin area is related to the richness of its sensory
innervation, not its anatomic size.
E. False Stimulation causes integrated movements not individual muscle contractions.

286.
A. TrueDepolarization opens sodium channels in the membrane.
B. TruePositively charged sodium ions move down their electrochemical gradient making the
inside of the fibre more positive.
C. TrueThe fall in membrane potential increases the outward electrochemical gradient for the
positively charged potassium ions; their exit tends to stabilize the mem-brane potential.
D. TrueThe fall in membrane potential increases the inward electrochemical gradient for
chloride; this again tends to restore the resting membrane potential.
E. False Not unless it reaches the threshold for firing.

287.
A. TrueThis dilates the pupil.
B. TrueDerived from activity in the adrenal medulla and sympathetic nerve endings.
C. TrueThis provides fatty acids for energy production.
D. False It increases and the PR interval shortens; higher heart rates are made possible.
E. False Sympathetic activity inhibits most smooth muscle in gut but contracts the sphincters.

288.
A. False Ventricles have little vagal innervation.
B. False The vagus does not supply parasympathetic nerves to the salivary glands.
C. TrueIt also contracts bronchial smooth muscle.
D. False It is sympathetic activity that causes the spleen to contract.
E. TrueThis together with relaxation of the sphincter of Oddi drives bile into the duo-denum.

289.
A. False It occurs when the membrane potential is reduced to its threshold for firing.
B. TrueThis leads to rapid depolarization towards the sodium equilibrium potential.
C. False Permeability to K1 increases and the resulting K1 efflux contributes to membrane
repolarization.
D. TrueThis depolarizes the adjacent axon and leads to propagation of the impulse.
E. False Because of the ‘all or none’ law, impulse configuration is independent of stimu-lus
strength.
 Neuromuscular system – questions 125

Questions 290–294

MCQ
290. Non-myelinated axons differ from myelinated axons in that they are
A. Not sheathed in Schwann cells.
B. Not capable of regeneration after section.
C. Found only in the autonomic nervous system.
D. Less excitable.
E. Refractory for a longer period after excitation.

291. Resting nerve cell membranes are more permeable to

A. Organic anions than to Cl2 anions.
B. K1 ions than to Cl2 ions.
C. Na1 ions than to K1 ions.
D. Oxygen molecules than to glucose molecules.
E. Water molecules than to H1 ions.
292. Acetylcholine
A. Acts on the same type of receptor on postganglionic fibres in sympathetic and parasym-
pathetic ganglia.
B. Acts on the same type of receptor on target organs at cholinergic sympathetic and para-
sympathetic nerve terminals.
C. Acts on the same type of receptor at autonomic ganglia and at somatic neuromuscular
junctions.
D. Acts as an excitatory transmitter in the basal ganglia.
E. In blood is hydrolyzed by the same cholinesterase as is found at neuromuscular junc-tions.

293. Visceral smooth muscle differs from skeletal muscle in that

A. It contracts when stretched.
B. It is not paralyzed when its motor nerve supply is cut.
C. Its cells have unstable resting membrane potentials.
D. It contains no actin or myosin.
E. Excitation depends more on influx of extracellular calcium than release of calcium from
endoplasmic reticulum.

294. An inhibitory post-synaptic potential

A. May be recorded in a post-ganglionic sympathetic neurone.
B. May be recorded in an anterior horn motor neurone.
C. Does not exceed one millivolt in amplitude.
D. Moves membrane potential towards the equilibrium potential for potassium.
E. May summate in space and time with other excitatory and inhibitory potentials in the same
neurone.
 126 Neuromuscular system – answers

Answers
MCQ

290.
A. False Both types have Schwann cell sheaths.
B. False Following section, the central end of the axon buds and grows down the Schwann cell
sheath until it reaches its target organ.
C. False Some sensory fibres serving pain and temperature are unmyelinated C fibres.
D. TrueMyelinated fibres have a lower threshold for stimulation.
E. True2 ms compared with 0.5 ms in well myelinated nerves; myelinated fibres can transmit
impulses at higher frequencies than unmyelinated nerves.

291.
A. False Organic anions cannot cross the membrane readily.
B. False The permeability to Cl2 is about twice that to K1.
C. False K1 permeability is about 100 times that of Na1.
D. TrueO2, being a small, nonpolar, lipophilic molecule dissolves in the membrane lipid and
crosses more easily than the larger glucose molecule.
E. TrueThe bilipid layer is more permeable to water than to the charged hydrogen ion.

292.
A. TrueThese are ‘nicotinic’ receptors and the action is blocked at both sites by drugs such as
hexamethonium.
B. TrueThese are ‘muscarinic’ receptors and the action is blocked at both sites by atro-pine.

C. False The receptors are different; curare blocks transmission at somatic neuromuscular
junctions but not at ganglia.
D. TrueAnticholinergic drugs are sometimes useful in the treatment of muscle rigidity in
Parkinsonism.
E. False The ‘pseudocholinesterase’ found in blood differs from the ‘true cholinesterase’ found
near neuromuscular junctions.

293.
A. TrueThe intrinsic ‘myogenic’ response in smooth muscle opposes stretch; skeletal muscle
requires a nerve reflex arc for this type of response.
B. TrueIt continues to contract due to local pacemakers.
C. TrueThey show spontaneous depolarization between contractions.
D. False In smooth muscle, actin and myosin filaments occur but are less obvious on
microscopy.
E. TrueSmooth muscle has a less well-developed sarcoplasmic reticulum.

294.
A. False No such potentials have been recorded here.
B. TrueThe hyperpolarization of the anterior horn cell reduces the likelihood of the cell firing
action potentials by moving the membrane potential further from the firing threshold.
C. False Its amplitude is about 5 mV and its duration about 5 msec.
D. TrueIt may be produced by increased permeability to potassium or to chloride ions.
E. TrueIn this way the post-synaptic cell integrates the various signals it receives.
 Neuromuscular system – questions 127

Questions 295-300

MCQ
295. A volley of impulses travelling in a pre-synaptic neurone causes
A. An identical volley in the post-synaptic neurone.
B. An increase in the permeability of the pre-synaptic nerve terminals to calcium.
C. Vesicles in the nerve endings to fuse with the cell membrane and release their contents.
D. The generation of at least one action potential in the post-synaptic neurone.
E. Neurotransmitter to travel down the nerve axon.

296. Pain receptors are

A. Similar in structure to Pacinian corpuscles.
B. Stimulated by a rise in the local K1 concentration.
C. Quick to adapt to a constant stimulus.
D. More easily stimulated in injured tissue.
E. Stimulated in the wall of the gut by agents which damage the tissues.

297. A property shared by

A. Skeletal and cardiac muscle is their striated microscopical appearance.
B. Skeletal and multiunit smooth muscle is that they are paralysed when their motor nerves are
cut.
C. Cardiac and visceral smooth muscle is their spontaneous activity when denervated.
D. Skeletal and cardiac ventricular muscle is their stable resting membrane potential.
E. All varieties of muscle is that contraction strength is related to their initial length.
298. The equilibrium potential (E ) for
A. An ion species is the membrane potential observed when its concentrations on each side of
the membrane are in equilibrium.
B. Na1 is about 250 mV in squid axon.
C. An ion species depends on the ratio of the concentrations of the ion outside (I o) and inside (Ii)
the cell.
D. An ion species is the potential the membrane potential would approach if it became freely
permeable to that ion.
E. An ion species would be zero if the concentrations of the ion on each side of the mem-brane
were equal.

299. Histological and physiological study of skeletal muscle shows that the
A. Distance between two Z lines remains constant during contraction.
B. Width of the anisotropic A band is constant during contraction.
C. Tension developed is maximal when actin and myosin molecules just fail to overlap.
D. Stimulus needed to cause contraction is minimal when applied at the Z line.
E. The T system of transverse tubules opens into the terminal cisterns of the sarcoplasmic
reticulum.

300. Rapid eye movement (REM) sleep differs from non-REM sleep in that
A. The EEG shows waves of higher frequency.
B. Muscle tone is higher.
C. Heart rate and respiration are more regular.
D. Secretion of growth hormone is increased.
E. Dreaming is more common.
 128 Neuromuscular system – answers

Answers
MCQ

295.
A. False The synapse may amplify or attenuate the signal.
B. TrueThe uptake of Ca21 by the nerve ending facilitates release of transmitter.
C. TrueThe neurotransmitter contained in the vesicles is released by exocytosis.
D. False The impulses may be inhibitory; even if they are excitatory, the post-synaptic
neurone may be strongly inhibited by inputs from other pre-ganglionic neurones.
E. TrueNeurotransmitter is thought to be synthesized and packaged in the Golgi appara-tus in
the neurone cell body before travelling down the axon to the nerve termi-nals.

296.
A. False They are bare nerve endings.
B. TrueK1 salts cause pain when applied to the base of an ulcer.
C. False Pain receptors adapt very slowly; this protects the tissues against damage.
D. TrueThe sensitivity of pain receptors is increased by local tissue injury (hyperalgesia).
E. False Damage to the gut wall by stimuli such as cutting or burning is painless.

297.
A. TrueBoth have highly organized actin and myosin filaments.
B. TrueThe iris is an example of multiunit smooth muscle.
C. TrueIsolated hearts and gut segments show spontaneous activity in the organ bath.
D. TrueOnly the pace maker cells in the heart have unstable membrane potentials.
E. TrueThe Frank–Starling relationship describes this with respect to cardiac muscle.

298.
A. False It is the membrane potential that would be required to balance the concentration
gradient for that ion.
B. False A positive membrane potential of about 165 mV is required to balance the Na1
concentration gradient.
C. TrueIt can be calculated using the Nernst equation:
E561.5 log10 [Io] [Ii].valence21 at 37°C.
D. TrueMembrane potential approaches 165 mV when freely permeable to Na1.
E. TrueFrom the Nernst equation (log1015O).
299.
A. False This is sarcomere length and it shortens with contraction.
B. TrueIts width is the length of the myosin molecule.
C. False It is maximal when action and myosin overlap maximally and when adjoining actin
molecules just fail to overlap.
D. TrueThis is where the transverse tubules penetrate the muscle fibre.
E. False They are adjacent but are not directly connected.

300.
A. TrueWave amplitude is reduced also.
B. False Surprisingly, muscle tone is low.
C. False They are much more irregular.
D. False It is inhibited during REM sleep.
E. TrueSubjects woken at the end of REM sleep give vivid accounts of dreams.
 Neuromuscular system – questions 129

Questions 301–307

MCQ
301. Hemisection of the spinal cord at C7 on the right side would cause
A. Greater loss of pain sensation in the right foot than in the left foot.
B. Greater loss of motor power in the right leg than in the left leg.
C. Greater loss of conscious proprioception in the right than in the left leg.
D. Respiratory failure
E. Loss of the micturition reflex.

302. The ankle jerk reflex is exaggerated

A. When the arm muscles are voluntarily contracted.
B. Immediately after complete spinal cord transection at the cervical level.
C. On the left side some months after damage to the tracts in the right internal capsule.
D. In extrapyramidal system disorders such as Parkinsonism.
E. When cerebellar function is lost.

303. Delta (d) wave activity in the electroencephalogram

A. Is low in frequency and amplitude.
B. Suggests that the patient is alert and concentrating.
C. When unilateral suggests a brain abnormality.
D. Is a feature of petit mal epilepsy.
E. Is more common in children than in adults while they are awake.

304. Increased intracranial pressure may cause

A. Cranial enlargement in children.
B. Squinting and loss of smell sensation in children.
C. Cupping of the optic disc.
D. An increase in cerebral blood flow.
E. Arterial hypertension.

305. Pain receptors in the gut and urinary tract may be stimulated by
A. Cutting through their wall with a sharp scalpel.
B. Distention.
C. Inflammation of the wall.
D. Acid fluid.
E. Vigorous rhythmic contractions behind an obstruction.

306. Signs of brainstem death include

A. Unconsciousness.
B. Loss of pupillary reaction to light.
C. Loss of tendon jerks in the arms and legs.
D. Loss of respiratory response to CO2 in the absence of hypoxia.
E. Nystagmus in response to cold water in the external auditory canal.
307. Spasm of digital vessels in the hands in response to cold (Raynaud’s
phenomenon) may be relieved by
A. Cutting sympathetic nerves to the hand.
B. Stimulating parasympathetic nerves to the hand.
C. Alpha (a) adrenoceptor blockade.
D. Beta (b) adrenoceptor agonists.
E. Wearing gloves.
 130 Neuromuscular system – answers

Answers
MCQ

301.
A. False The left would be more affected; pain fibres cross the midline shortly after enter-ing
the cord.
B. TrueThe main motor tract to the right leg would be severed.
C. TrueThe fibres serving proprioception cross at the top of the spinal cord.
D. False Diaphragmatic and some intercostal activity would remain intact.
E. False The reflex centres for micturition are in the sacral cord.

302.
A. False It is not exaggerated but contraction of arm muscles reinforces the reflex.
B. False Immediately after cord transection, reflexes below the level of the lesion are lost in the
stage of ‘spinal shock’.
C. TrueMuscle tone increases following contralateral internal capsular lesions.
D. False Though muscle tone is increased, tendon jerks are not exaggerated.
E. False Muscle tone is low following cerebellar damage and the knee jerk ‘pendular’.

303.
A. False Delta waves have slow frequency and large amplitude.
B. False It is associated with deep sleep.
C. TrueDelta waves may indicate brain damage as well as deep sleep.
D. False This produces a characteristic spike and wave pattern in the EEG.
E. TrueDelta wave activity is seen occasionally in the EEGs of normal awake children.

304.
A. TrueHydrocephaly occurs because the cranial bone sutures have not closed.
B. TrueThe cranial deformity in hydrocephalus may damage cranial nerves.
C. False It causes papilloedema – bulging in the opposite direction.
D. False Vessel compression may reduce cerebral flow severely.
E. TrueThis reflex response helps to maintain cerebral blood flow.

305.
A. False The intestine may be cut painlessly during operations under local anaesthesia.
B. TrueStretch is an adequate stimulus for these receptors.
C. TrueChemicals released in inflammation lower the pain threshold (hyperalgesia).
D. TrueAs with a peptic ulcer.
E. TrueThis is the cause of the intermittent pain known as colic.

306.
A. False Consciousness is a function of the cerebral cortical neurones.
B. TrueThe coordinating centres for pupillary reflexes are in the brainstem.
C. False The reflex centres for tendon jerks are in the spinal cord.
D. TrueRespiratory reflexes are coordinated in the brainstem.
E. False Nystagmus is the normal reflex response of brainstem centres to this stimulus.

307.
A. TrueSympathetic nerves to digital vessels are tonic vasoconstrictor nerves.
B. False The hand does not have a parasympathetic nerve supply.
C. TrueAlpha receptors mediate sympathetic vasoconstriction.
D. False Digital vessels have few beta receptors.
E. False Raynaud’s phenomenon is triggered by cold and wearing gloves may prevent cooling
to the threshold temperature.
 Neuromuscular system – questions 131

Questions 308–314

MCQ
308. Muscle tone is reduced by
A. Curare-like drugs.
B. Lower motor neurone lesions.
C. Upper motor neurone lesions.
D. Cerebellar lesions.
E. Gamma efferent impulses to muscle spindles.

309. Effective treatments for severely raised intracranial pressure include

A. Removal of cerebrospinal fluid by lumbar puncture.
B. Reduction of extracellular fluid by diuretics.
C. Creating an anastomosis between a cerebral ventricle and a neck vein.
D. Creating an anastomosis between intracranial subdural space and the peritoneal cavity.
E. Placing the patient recumbent with the legs raised.

310. Disease of the extrapyramidal motor system in Parkinsonism causes

A. Tremor which is more obvious when the patient is performing skilled movements.
B. Muscle paralysis.
C. Increased muscle tone throughout the range of passive movement.
D. Increased involuntary facial movements during speech.
E. An unusual gait with small fast regular steps.

311. Lower motor neurone disease

A. Causes loss of voluntary movements but not of reflex movements.
B. Is a later stage of upper motor neurone disease.
C. Causes eventual wasting of the muscles concerned.
D. Does not affect ventilation of the lungs.
E. Is associated with involuntary twitchings of small fasciculi in the affected muscles.

312. Blockade of a (alpha) adrenoceptors is likely to cause a reduction in

A. Sweat production.
B. Bronchus diameter.
C. Gastrointestinal motility.
D. Total peripheral resistance.
E. Heart rate.
313. Bulging of the optic disc into the vitreous humour (papilloedema) is
caused by
A. Raised intraoccular pressure (glaucoma).
B. Blockage of absorption of the aqueous humour.
C. A rise in intracranial pressure.
D. Inflammation of the optic nerve.
E. Interference with the venous drainage of the eye.

314. Atropine (which blocks muscarinic receptors) causes

A. Paralysis of accommodation for near vision in the eye.
B. Constriction of the pupil.
C. Constriction of the bronchi.
D. Diarrhoea.
E. Difficulty with micturition.
 132 Neuromuscular system – answers

Answers
MCQ

308.
A. TrueThese paralyse muscle by blocking transmission at neuromuscular junctions.
B. TrueLower motor neurones also paralyse skeletal muscle.
C. False Loss of supraspinal influences results in spasticity of the affected muscles.
D. TrueThe cerebellum helps to maintain normal muscle tone.
E. False These increase spindle sensitivity to stretch and hence muscle tone.
309.
A. False This may cause fatal compression of the brainstem if the medulla is forced (coned) into
the foramen magnum.
B. TrueThis reduces formation of cerebrospinal fluid.
C. TrueThis facilitates drainage of cerebrospinal fluid.
D. False CSF is in the subarachnoid space.
E. False This would increase intracranial pressure due to gravitational effects and impair CSF
drainage by raising pressure in the venous sinuses.
310.
A. False Parkinsonism causes tremor which is more obvious when the patient is at rest.
B. False Paralysis is not a feature of the condition.
C. TrueThis is ‘cogwheel’ or ‘lead pipe’ rigidity.
D. False The face is mask-like; there is poverty of facial movements.
E. TrueThe body’s centre of gravity is shifted forward.
311.
A. False The muscles are paralysed and not capable of voluntary or reflex movements.
B. False It is totally independent of upper motor neurone disease.
C. TrueIt leads to ‘disuse atrophy’.
D. False Ventilation will be affected if the phrenic and intercostal nerves are involved.
E. True‘Fasciculation’ is due to denervation hypersensitivity; muscles become ultra-sensitive to
small amounts of acetylcholine released from the degenerating nerve terminals.
312.
A. False Sweating is mediated by cholinergic nerves.
B. False Bronchial smooth muscle has few alpha receptors; beta blockade tends to cause
bronchoconstriction.
C. False Stimulation of alpha or beta adrenoceptors inhibits the gut.
D. TrueAlpha receptors mediate vasoconstriction.
E. False The heart has few alpha receptors; beta receptor blockade slows the heart.
313.
A. False Glaucoma causes depression (‘cupping’) of the optic disc.
B. False This is a cause of glaucoma.
C. TruePapilloedema is an important sign of raised intracranial pressure.
D. TrueOptic neuritis causes swelling of the optic disc.
E. TrueThis causes local oedema involving the disc.
314.
A. TrueBy paralysing the ciliary muscles.
B. False It causes pupillary dilatation by paralysing circular muscle in the iris.
C. False It tends to dilate the bronchi by blocking vagal effects.
D. False It causes constipation by suppressing bowel activity.
E. TrueMicturition depends on cholinergic nerves.
 Neuromuscular system – questions 133

Questions 315–320

MCQ
315. Visceral pain
A. Is poorly localized compared with pain arising in skin.
B. Is often felt in the mid line.
C. May cause reflex contraction of overlying skeletal muscle.
D. May cause reflex vomiting.
E. May cause reflex changes in arterial blood pressure.

316. Posterior column damage in the spinal cord may impair

A. Vibration sense.
B. Pain sensation.
C. The flexor plantar response to stimulation of the sole.
D. Touch sensation.
E. The ability to stand steadily with the eyes closed.

317. Aphasia
A. Is an impairment of language skills without motor paralysis, loss of hearing or vision.
B. Implies impairment of consciousness.
C. Is called motor aphasia if the patient understands what the speech sounds and symbols mean
but lacks the higher motor skills needed to express them.
D. Is called sensory aphasia if the patient does not understand the meaning of the words he
hears, sees and uses.
E. Usually results from right-sided cortical damage.
318. Blockade of parasympathetic activity causes a reduction in
A. Sweat production.
B. Resting heart rate.
C. The strength of skeletal muscle contraction.
D. Salivation.
E. Intestinal motility.

319. Sensory disturbance consisting of

A. Pain, sensory loss and paraesthesiae in one leg suggests a spinal cord lesion.
B. Loss of pain, temperature but not touch sensation in the arms suggests a spinal cord lesion.
C. Loss of two-point discrimination but not touch sensation suggests a lesion in the thala-mus.

D. Loss of all sensations on the left side suggests a right internal capsule lesion.
E. Loss of all sensations in a skin region suggests a peripheral nerve or posterior root lesion.
320. Damage to the cerebral cortex may cause loss of
A. Pain sensation on the opposite side of the body.
B. Reflex thermoregulatory activity.
C. Skilled movements in the absence of paralysis.
D. Ability to identify an object by its tactile characteristics.
E. Vision in one eye only.
 134 Neuromuscular system – answers

Answers
MCQ

315.
A. TrueThis is characteristic of visceral pain.
B. TrueHowever pain from some viscera such as ureters and bile ducts is lateralized.
C. TrueIn the abdomen this is seen as ‘guarding’.
D. TrueVisceral pain is often associated with autonomic side effects.
E. TrueAnother example of autonomic side effects, pressure may increase or decrease.

316.
A. TrueThe fibres carrying this sensation travel in the posterior columns.
B. False The fibres carrying pain sensation travel in the spinothalamic tracts.
C. False The reflex does not depend on posterior column fibres.
D. TrueThe fibres responsible for fine touch sensation travel in the posterior columns.
E. TrueProprioceptive information is important in maintaining balance and it is carried in the
posterior columns.

317.
A. TrueIt is a cortical dysfunction.
B. False Level of consciousness is an independent entity.
C. TrueIt may start with an inability to say the names of familiar objects but end up with loss of
virtually all verbal communication skills.
D. TruePatients with sensory aphasia tend to talk rubbish since they are unaware of the errors in
their use of language.
E. False Language skills are carried in the left hemisphere in right and some left-handed people.

318.
A. False Sweat glands are innervated by sympathetic cholinergic nerves.
B. False Resting heart rate rises due to blockade of vagal tone.
C. False Parasympathetic nerves are not involved in skeletal muscle activity.
D. TrueDryness of the mouth results from blockade of salivary secretion.
E. TrueParasympathetic nerves are motor to intestinal smooth muscle.

319.
A. False Pain is uncommon with spinal cord lesions; the symptoms suggest irritation of a
sensory root or peripheral nerve.
B. TrueThe fibres carrying these sensations run in separate tracts in the spinal cord.
C. False It suggests a parietal cortex lesion where such sensory discriminations are made.
D. False It suggests right-sided brain-stem damage since pain is appreciated at subcorti-cal
level.
E. TrueOnly peripheral nerves and posterior roots carry all modalities of sensation together
from a circumscribed skin area.

320.
A. False The cerebral cortex is not involved in the conscious appreciation of pain.
B. False Reflex thermoregulation is organized in the hypothalamus.
C. TrueSuch loss of skilled movements is called ‘apraxia’.
D. TrueThis ‘asteriognosia’ results from parietal cortex damage.
E. False Damage to the visual cortex causes loss of part of the visual field in both eyes.
 Neuromuscular system – questions 135

Questions 321–326

MCQ
321. In the hemiplegia following a right-sided cerebrovascular accident
(stroke)
A. Left-sided muscle weakness is evident.
B. Muscles in the left side of the body are unable to contract.
C. Muscles which act on both sides of the body, such as respiratory muscles, tend to be spared.
D. Skilled movements are better preserved than unskilled movements.
E. Speech movements are better preserved than swallowing movements.

322. Characteristic features of cerebellar disease include loss of

A. Muscle tone.
B. Muscle strength.
C. Conscious muscle-joint sense.
D. Ability to make precise muscle movements.
E. Ability to fix the gaze steadily on an object.
323. Long-term consequences of transection of the spinal cord in the lower
cervical region include
A. Loss of thermoregulatory sweat production in the legs.
B. Severe flexor spasms when the skin of the legs is stimulated.
C. Paralysis of bladder muscle.
D. Inability to regulate sympathetic tone in leg blood vessels in response to baroreceptor
stimulation.
E. Inability to erect the penis and ejaculate semen.
324. Blockade of b (beta) adrenoceptors is likely to cause
A. Decreased intestinal motility.
B. Worsening of the condition in patients with bronchial asthma.
C. Worsening of the condition in patients in cardiac failure.
D. Inability to increase heart rate during exercise in patients with transplanted hearts.
E. Inability to increase blood flow to exercising muscles.

325. Cutaneous pain

A. Can be caused by overstimulation of touch receptors.
B. Can be caused by excitation of receptors by chemicals released in injured tissue.
C. Can be elicited more readily if the tissue has been injured recently.
D. Receptors adapt to stimulation more quickly than touch receptors.
E. Transmission at spinal cord level is facilitated by opening of potassium channels in the post-
synaptic membrane.

326. Headache can be produced by

A. Dilatation of intracranial blood vessels.
B. Constriction of extracranial blood vessels.
C. Meningeal irritation.
D. Blood in the cerebrospinal fluid.
E. Loss of cerebrospinal fluid following lumbar puncture.
 136 Neuromuscular system – answers

Answers
MCQ

321.
A. TrueVoluntary movements such as making a handgrip are abnormally weak.
B. False Voluntary control is lost but the muscles can contract in reflex, synergistic and other
involuntary movements.
C. TruePerhaps because they have bilateral cortical representation.
D. False The most affected movements are those requiring high levels of cortical control.
E. False The vocal cord movements required for speech are more highly skilled than those
required for swallowing.

322.
A. TrueMuscle tone depends in part on the integrity of the cerebellum.
B. False Muscle strength does not depend on the cerebellum.
C. False Cerebellar activity depends on unconscious, not conscious, proprioception.
D. TrueLoss of muscular coordination causes ‘intention tremor’.
E. TrueThe jerky eye movement in cerebellar disease when the gaze is fixed on an object is
called ‘nystagmus’.

323.
A. TrueThermoregulatory control is coordinated through the sympathetic nervous system by
centres in the hypothalamus.
B. TrueDue to exaggeration of the spinal withdrawal reflex.
C. False Both micturition and defaecation can occur reflexly (their reflex centres are in the
sacral cord) but are no longer under voluntary control.
D. TrueThis impairs the control of arterial blood pressure, especially in the erect position.
E. False These are spinal reflexes with centres in the lumbosacral region of the spinal cord.

324.
A. False Alpha and beta adrenoceptor stimulation in gut inhibits smooth muscle.
B. TrueBy blocking the bronchodilatory action of adrenaline and noradrenaline.
C. TrueBy several mechanisms including blocking the sympathetic drive to the heart.
D. TrueBy blocking the chronotropic effect of circulating catecholamines.
E. False Increased flow in exercise depends on local metabolites, not beta adrenoceptors.

325.
A. False Pain is due to excitation of specific pain receptors.
B. TrueSuch substances include histamine, bradykinin, 5-hydroxytryptamine, prosta-glandins,
nitric oxide and substance P.
C. TrueChemicals released in the injured tissue reduce the stimulation threshold to cause
hyperalgesia.
D. False Pain receptors adapt much more slowly than touch receptors.
E. False This would inhibit synaptic transmission and may explain how enkephalin and
endorphin modulate transmission of pain impulses in the substantia gelatinosa.

326.
A. TrueProbably due to pain receptors in vessel walls stimulated by stretch.
B. False Dilatation of these extracranial vessels occurs in patients with throbbing migraine-type
headaches that are relieved by certain vasoconstrictor agents.
C. TrueThis causes the severe pain and neck stiffness in early meningitis.
D. TrueSurprisingly, blood also irritates the meninges to cause headache and neck stiff-ness.

E. TrueThe brain tends to sag in the cranium and pull on pain receptors in the meninges.
 Neuromuscular system – questions 137

Questions 327–330

MCQ
327. Depressed brain function causes
A. Disorders of function which are independent of the cause of the depression.
B. Loss of unskilled movements before loss of skilled movements.
C. Restlessness and delirium before stupor and coma.
D. A progressive fall in the amplitude of waves in the EEG.
E. Depression of ventilation before loss of consciousness.

328. Loss of pain sensation in the

A. Feet may lead to skin ulceration.
B. Knee may lead to joint damage.
C. Ears and fingers usually precedes frostbite.
D. Leg follows surgical division of the spinocerebellar tracts in the spinal cord.
E. Face follows surgical division of the facial nerve.

329. Intracranial pressure tends to rise when

A. Cerebral venous pressure rises.
B. Forced expiration is made against a closed glottis.
C. There is a bout of coughing.
D. Cerebral blood flow increases.
E. Arterial PCO2 falls below normal.
330. Severe pain may lead to
A. A fall in blood pressure due to a fall in vascular resistance in skeletal muscle.
B. A fall in heart rate due to an increase in cardiac vagal tone.
C. Vomiting through a reflex centre in the brainstem.
D. Profuse sweating due to activation of sympathetic nerves.
E. Suppression of cortisol secretion.
 138 Neuromuscular system – answers

Answers
MCQ

327.
A. TrueAlcohol, lack of oxygen, low blood sugar and hypothermia all impair cellular function
in the brain and lead to a recognizable syndrome of neurological effects.
B. False Higher critical functions depending on cortical cells are first to go, e.g. driving ability.

C. TrueComa implies that cellular depression has reached the less sensitive cells in the
brainstem mediating consciousness.
D. False Amplitude increases initially to give delta waves in light coma before falling later.

E. False This brainstem function is preserved until the later stages of deep coma.

328.
A. TrueProbably because of failure to protect the foot and letting minor injury persist without
attention.
B. TrueAgain due to loss of the protective effects of pain.
C. TrueNerve fibres stop conducting near freezing point so there is no further warning when
freezing causes tissue damage.
D. False Pain sensation is blocked by surgical division of the spinothalamic tracts.
E. False It is lost following division of the sensory root of the trigeminal nerve.

329.
A. TrueThis distends intracranial veins and hence raises pressure within the cranium.
B. TrueThis (Valsalva) manoeuvre raises cerebral venous pressure.
C. TrueThis also raises cerebral venous pressure.
D. TrueThe vasodilation raises the volume of blood within the cranium.
E. False This constricts cerebral vessels and reduces cerebral blood volume.

330.
A. TrueThis lowers total peripheral resistance.
B. TrueConsciousness may be lost if this is combined with muscle vasodilation in the
‘vasovagal’ syndrome.
C. TrueThe vomiting centre is in the medulla oblongata.
D. TrueSympathetic cholinergic nerves are motor to sweat glands.
E. False Severe pain increases cortisol secretion via the hypothalamus as part of the general
response to trauma.