Primary FRCA Course Neurophysiology Exam Prep Questions Flashcards
The membrane potential of a nerve fibre:
Is directly proportional to the diameter of the fibre
False. It is conduction velocity that is directly proportional to the diameter of the fibre.
The membrane potential of a nerve fibre:
Is measured conventionally as negative on the inside
True.
The membrane potential of a nerve fibre:
Represents an imbalance of charge across the two sides of a semi-permeable membrane
True. In a nerve cell the concentration of potassium ions is much greater intracellularly than extracellularly (brought about by the sodium-potassium ATPase pump).
The membrane potential of a nerve fibre:
Reverses its polarity during an action potential
True.
The membrane potential of a nerve fibre:
Can be calculated from the Nernst equation
False. The Goldman constant-field equation is required to calculate the value of the overall membrane potential as it takes into account sodium, chloride and potassium. Nernst equation can be applied to calculate the membrane potential for this individual ion.
Compared with plasma, CSF contains:
Less sodium
True. Sodium concentrations are higher in the plasma.
Compared with plasma, CSF contains:
Lower osmolality
False. Both have an osmolality of around 290 mOsmol/l.
Compared with plasma, CSF contains:
More hydrogen ions
True. CSF has a pH of 7.32.
Compared with plasma, CSF contains:
A higher PCO2
True. 6.6kPa vs 5.3 kPa in plasma.
Compared with plasma, CSF contains:
More urea
False. Urea concentrations are higher in the plasma.
Concerning cerebral blood flow:
Blood flow in the grey matter may be twice that in the whites matter
True.
Concerning cerebral blood flow:
Is inversely proportional to PaCO2
False. It is directly proportional to PCO2 between the range of approx 2.5 and 10.5 kPa.
Concerning cerebral blood flow:
Is predominantly provided by the external carotid artery
False. The vast majority of cerebral blood flow is provided by the internal carotid arteries with a relatively small fraction being carried by the vertebral arteries.
Concerning cerebral blood flow:
Is reduced with acidosis
False. A reduced pH causes cerebral vasodilataion.
Concerning cerebral blood flow:
It is equal to 10% of cardiac output
False. Cerebral blood flow accounts for approximately 15-20% of cardiac output.
The knee jerk reflex:
Is due to stimulation of receptors in the patellar tendon
False. It is due to stretching of muscle spindles in the quadriceps muscle, caused by a tap on the patellar tendon.
The knee jerk reflex:
Has a reflex arc which involves a single interneurone
False. It has a single synapse.
The knee jerk reflex:
The afferent pathway is via A delta fibres
False. It is via A gamma fibres. The efferent pathway is the A delta motor neuron.
The knee jerk reflex:
Hypereflexia of the patellar is known as Westphal’s sign
False. Westphal’s sign is the absence or decrease of this reflex.
The knee jerk reflex:
Is abolished immediately after transection of the spinal cord at T6
True. Transection of the cord is followed by a variable degree of spinal shock where all reflexes are depressed or absent. Recovery of reflexes may take up to 6 weeks.
These modalities correspond to their correct pathways:
Temperature and pain via the ipsilateral spinothalamic tracts
False. Temperature and pain sensations travel in the contralateral spinothalamic tracts.
These modalities correspond to their correct pathways:
Fibres subserving fine touch form the gracile and cuneate nuclei
True. Fine touch is transmitted in the posterior white column in the medial and lateral fasiculi, which each connect to their respective cuneate and gracile nuclei.
These modalities correspond to their correct pathways:
Proprioception via the dorsal columns
True. The dorsal columns transmit fine touch and proprioception.
These modalities correspond to their correct pathways:
Spinocerebellar tracts relay information from muscles
True. Spinocerebellar tracts relay information from muscles and joints to the cerebellum.
When the nerve cell membrane is depolarised:
Sodium permeability falls slowly, producing an action potential.
False. There is a sudden, sharp rise in sodium conductance.
These modalities correspond to their correct pathways:
Pain and the spinotectal tract
True. The spinotectal tract transmits pain, temperature and touch sensation to the midbrain.
When the nerve cell membrane is depolarised:
Sodium permeability is raised until the resting membrane potential is restored.
False. The rise in sodium permeability is transient, with the resting membrane potential being restored by an increase in potassium conductance.
When the nerve cell membrane is depolarised:
Increased calcium permeability produces a plateau phase.
False. This is seen in cardiac muscle, not nerve cells.
When the nerve cell membrane is depolarised:
The change in sodium permeability is directly responsible for impulse transmission
True.
When the nerve cell membrane is depolarised:
Sodium efflux is self limiting
True. Three factors limit depolarisation speed, first the temporary opening of the sodium channels, secondly with increasing intracellular electropositivity the initial sodium gradient reduces, and finally there is an increase in potassium conductance.
The nerve action potential:
Transmission is “saltatory” between the nodes of Ranvier
True.
The nerve action potential:
Is conducted slower in myelinated fibres
False. Myelinated fibres transmit the action potential 50 times faster than unmyelinated fibres.
The nerve action potential:
Is propogated exponentially
False. The action potential is propagated in a linear fashion in unmyelinated fibres.
The nerve action potential:
Is approximately 35 mV above the resting potential
False. During the action potential the membrane potential changes from -70 to +35 mV, a 105 mV difference.
The nerve action potential:
Is initiated by sodium influx
True. It is initiated by sodium influx.
In complete cord transection:
Arterial blood pressure becomes labile
True. Due to autonomic hyperactivity.
In complete cord transection:
Autonomic hypereflexia occurs within the first few days
False. Elfh does not give an actual time frame, but some google sources suggested 1 month to 1 year, and wikipedia says normally within the first year.
In complete cord transection:
Tendon reflexes are the first to recover
False. The first reflexes to return are flexor reflexes to touch and anogenital reflexes.
In complete cord transection:
Recovery of reflexes occurs at around 6 months
False. Recovery of reflexes occurs at around 2 weeks, though can be delayed for up to 6 weeks.
In complete cord transection:
There is total loss in sensation from dermatomes below the level of injury
True.
Cerebral blood flow (CBF):
A high PaO2 causes cerebral vasoconstriction
True. And a low PaO2 causes cerebral vasodilatation.
Cerebral blood flow (CBF):
The normal jugular venous saturation is about 65%
True.
Cerebral blood flow (CBF):
Can be estimated by doppler
True. Cerebral blood flow can be estimated by the Kety method (an application of the Fick principle), Scintillography. Doppler is a crude but readily available method.
Cerebral blood flow (CBF):
Acidosis induced cerebral vasodilatation is independent to PaCO2
True.
Cerebral blood flow (CBF):
A decrease in arterial pressure causes vasoconstriction of cerebral vessels
False. Autoregulation would have the opposite effect.
The conduction velocity along a nerve:
Is increased by myelination
True.
The conduction velocity along a nerve:
Increases when the serum potassium is low
False. Conduction is slowed by hypokalaemia. Think about widening the gap between the resting concentrations and therefore hyperpolarising the membrane.
The conduction velocity along a nerve:
Increases with diameter
True. Increasing diameter and myelination increases conduction velocity.
The conduction velocity along a nerve:
Is greater in delta than alpha fibres
False. Both are myelinated, but alpha are much larger in diameter.
The conduction velocity along a nerve:
Is greater in motor than in sensory nerves
True. Motor neurones tend to be A alpha neurons. As they have the largest diameter and are myelinated, they have the fastest conduction velocity.
The action potential:
Depolarization is caused by the transfer of sodium ions across the membrane
True.
The action potential:
In the resting state the potential inside the nerve fibre is +85 mV
False. It is -70mV.
The action potential:
Is generated by differing ionic concentrations of sodium and potassium
True.
The action potential:
Occurs when the membrane depolarises by 15mV
True. Once membrane potential rises from -70mV to -55mV, threshold is reached.
The action potential:
Has 4 phases
False. It has 5 phases. Phases 0,1,2,3 and 4. 0 - resting; 1 - stimulus towards threshold potential; 2 - depolarisation, 3 - repolarisation; 4 - hyperpolarisation.
Stimulation of the parasympathetic nervous system causes:
Bladder relaxation
False. The parasympathetic system stimulates the GIT inc the stomach and bladder.
Stimulation of the parasympathetic nervous system causes:
Gall-bladder contraction
True.
Stimulation of the parasympathetic nervous system causes:
Bronchodilatation
False. It causes bronchoconstriction.
Stimulation of the parasympathetic nervous system causes:
Miosis
True.
Stimulation of the parasympathetic nervous system causes:
Decreased insulin secretion
False. Insulin secretion is increased.
Concerning intracranial pressure (ICP):
Tonsillar (cerebellar) herniation causes ipsilateral pupillary dilatation
False. Tonsillar herniation causes neck stiffness and Cheyne-Stoke breathing.
Concerning intracranial pressure (ICP):
The effect of hypocapnoea-induced cerebral vasoconstriction is maintained for 12 hours or more
False. Hypocapnoea-induced cerebral vasoconstriction lessens demonstrably between 6 to 10 hours.
Concerning intracranial pressure (ICP):
Normal ICP is 10-20 mmHg
False. 5-15 mmHg is the standard normal range, although it varies with arterial pulsation, respiration, coughing and straining.
Concerning intracranial pressure (ICP):
ICP increases linearly with increasing cerebral blood volume
False. Initially, a change in volume of one brain compartment (solid matter, tissue fluid, blood and CSF) is accompanied by a reciprocal change in the other compartment (the Munro-Kellie doctrine).
Concerning intracranial pressure (ICP):
Lundberg B pressure waves may be a normal finding
False. Lundberg A (interval 5 to 20 min, ICP 50 to 100mmHg) and B (interval about 1min, ICP up to 50mmHg) waves are always superimposed on an elevated ICP and indicate failed compensatory mechanisms. C waves (0.1Hz up to 20 mmHg) may also be pathological but can occur in normal patients.
The following are parasympathetic ganglia:
Ciliary ganglion
True.
The following are parasympathetic ganglia:
Otic ganglion
True.
The following are parasympathetic ganglia:
Stellate ganglion
False. The stellate and coeliac ganglia are sympathetic ganglia.
The following are parasympathetic ganglia:
Gasserian ganglion
False. The gasserian ganglion is the fifth cranial nerve ganglion.
The following are parasympathetic ganglia:
Coeliac ganglion
False. The stellate and coeliac ganglia are sympathetic ganglia.
The chemical mediator released at the following sites is acetylcholine:
Parasympathetic preganglionic neurones
True.
The chemical mediator released at the following sites is acetylcholine:
Parasympathetic postganglionic neurones
True.
The chemical mediator released at the following sites is acetylcholine:
Sympathetic postganglionic neurones which innervate the heart
False. The cholinergic sympathetic postganglionic neurones are those which innervate the sweat glands and those ending on skeletal muscle blood vessels (causing vasodilataion).
The chemical mediator released at the following sites is acetylcholine:
Sympathetic preganglionic neurones
True.
The chemical mediator released at the following sites is acetylcholine:
Sympathetic postganglionic neurones which innervate sweat glands
True.
The autoregulation of cerebral blood flow:
Curve shows a shift to the left in chronic hypertension
False. It is shifted right in chronic hypertension and thus a higher mean arterial pressure must be maintained in these patients.
The autoregulation of cerebral blood flow:
Is maintained under hypoxic conditions
False. Autoregulation is impaired by hypoxia and hypercapnia.
The autoregulation of cerebral blood flow:
Remains constant over a range of systolic blood pressures from 60 to 140 mmHg
False. This is the approximate range for mean, not systolic blood pressure.
The autoregulation of cerebral blood flow:
Is impaired in hypercapnia
True.
The autoregulation of cerebral blood flow:
Is altered in the acute phase following subarachnoid haemorrhage
True. Autoregulation is lost around areas of intracerebral pathology.
The pathways of pain sensation include:
C fibres which release histamine and serotonin
False. The C fibres release glutamate and substance P principally in laminae II and III.
The pathways of pain sensation include:
A-delta fibres which terminate in lamina I of the dorsal horn
True.
The pathways of pain sensation include:
A-gamma fibres synapsing in in the dorsal horn
False. A-gamma fibres are motor neurons.
The pathways of pain sensation include:
Second order neurones which ascend in the ipsilateral spinothalamic tracts
False. They ascend in the contralateral spinothalamic tracts.
The pathways of pain sensation include:
Descending pathways in the dorsolateral columns
True.
In the autonomic nervous system:
Parasympathetic nervous system stimulation produces coronary vasodilatation
True. The coronary vasculature is dilated (beta2), and constricted (alpha1), by the adrenergic system. In addition, in the presence of an intact endothelium parasympathetic stimulation leads to a dilatation via the actions of nitric oxide.
In the autonomic nervous system:
The stellate ganglia impair myocardial contractility
False. The paired stellate ganglia send postganglionic fibres to the heart. Stimulation via the right leads to increased heart rate while via the left leads to increased contractility.
In the autonomic nervous system:
Post-ganglionic sympathetic nerves increase catecholamine release from the adrenal glands
False. Sympathetic nerves reaching the adrenals are pre-ganglionic.
In the autonomic nervous system:
All preganglionic neurones are cholinergic
True.
In the autonomic nervous system:
Alpha-2 stimulation modifies intracellular cGMP levels
False. Alpha2 mediated negative feedback functions by reducing intra-cellular levels of cAMP.
Acetylcholine:
Is the neurotransmitter at all parasympathetic postganglionic nerve endings
True. Along with sympathetic supply to sketetal muscle blood vessels and sweat glands and all preganglionic neurones.
Acetylcholine:
Is generated from choline synthesized within the axoplasm
False. It is synthesived in the nerve ending.
Acetylcholine:
Its synthesis is catalysed by the enzyme choline acetylesterase
False. It is catalysed by the enzyme choline acetytransferase.
Acetylcholine:
Is an ester
True. Being broken down by acetylcholinesterase.
Acetylcholine:
Raises the membrane permeability to sodium and calcium in the heart
False. Ach raises the membrane permeability to Na, K, and Ca in most tissues, but in the heart only K permeability is increased.
Regarding the cerebral circulation:
The circle of Willis is formed from the internal carotid and vertebral arteries only
True.
Regarding the cerebral circulation:
The middle cerebral artery is most commonly affected by a CVA
True.
Regarding the cerebral circulation:
The anterior spinal artery is a branch of the vertebral artery
True.
Regarding the cerebral circulation:
The posterior spinal artery is a branch of the vertebral artery
True. It can originate either directly from the vertebral artery or from the posterior inferior cerebellar artery which is the largest branch of the vertebral artery.
Regarding the cerebral circulation:
The anterior cerebral artery supplies the superior and medial parts of the cerebral hemisphere
True.
