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Score — click each question to reveal the answer
Q1
Transmitter release at a chemical synapse is triggered by influx of:
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A. Ca²⁺
B. Na⁺
C. K⁺
D. Cl⁻
✅ Answer: A. Ca²⁺
Depolarization opens voltage-gated Ca²⁺ channels in the terminal; Ca²⁺ entry triggers vesicle fusion and transmitter release.
Q2
An excitatory postsynaptic potential (EPSP) is produced by:
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A. Cl⁻ influx
B. Na⁺ (±Ca²⁺) influx causing depolarization
C. K⁺ efflux
D. closing of Na⁺ channels
✅ Answer: B. Na⁺ (±Ca²⁺) influx causing depolarization
EPSP = a depolarizing graded potential (Na⁺/Ca²⁺ influx) that brings the neuron toward threshold. IPSP = hyperpolarizing (Cl⁻ in / K⁺ out).
Q3
A single subthreshold EPSP can reach threshold by:
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A. the all-or-none law
B. the refractory period
C. temporal and spatial summation
D. saltatory conduction
✅ Answer: C. temporal and spatial summation
Repeated input from one synapse (temporal) or simultaneous input from many synapses (spatial) summate to reach threshold.
Q4
Which is an INHIBITORY neurotransmitter?
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A. glutamate
B. acetylcholine
C. noradrenaline
D. GABA
✅ Answer: D. GABA
GABA (and glycine) open Cl⁻ channels → IPSP → inhibition. Glutamate is the main excitatory CNS transmitter.
Q5
The knee-jerk (stretch / myotatic) reflex is:
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A. monosynaptic
B. polysynaptic
C. autonomic
D. a withdrawal reflex
✅ Answer: A. monosynaptic
The stretch reflex is monosynaptic: muscle spindle (Ia afferent) → directly onto the α-motor neuron → muscle contraction.
Q6
Muscle stretch is sensed by the:
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A. Golgi tendon organ
B. muscle spindle
C. Pacinian corpuscle
D. free nerve ending
✅ Answer: B. muscle spindle
The muscle spindle (Ia afferent) senses muscle length/stretch and drives the stretch reflex. The Golgi tendon organ (Ib) senses tension.
Q7
When an agonist muscle is reflexly contracted, its antagonist is simultaneously relaxed. This is:
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A. recruitment
B. summation
C. reciprocal inhibition
D. the inverse stretch reflex
✅ Answer: C. reciprocal inhibition
Reciprocal inhibition: an inhibitory interneuron relaxes the antagonist (IPSP) while the agonist contracts, allowing smooth movement.
Q8
The dorsal column–medial lemniscus (DCML) pathway carries:
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A. pain and temperature
B. motor commands
C. crude touch only
D. fine touch, vibration and conscious proprioception
✅ Answer: D. fine touch, vibration and conscious proprioception
DCML carries fine touch, vibration and proprioception; it decussates in the medulla. Pain/temperature go in the spinothalamic tract.
Q9
The spinothalamic (anterolateral) tract decussates:
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A. in the spinal cord, within 1–2 segments of entry
B. in the medulla
C. in the thalamus
D. it does not cross
✅ Answer: A. in the spinal cord, within 1–2 segments of entry
Pain/temperature fibres cross at the spinal level soon after entering — important for localising cord lesions (vs DCML which crosses in the medulla).
Q10
Fast, sharp, well-localised pain is carried by:
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A. unmyelinated C fibres
B. myelinated Aδ fibres
C. Ia afferents
D. autonomic fibres
✅ Answer: B. myelinated Aδ fibres
Aδ fibres = fast, sharp pain. C fibres (unmyelinated) = slow, dull, aching pain (transmitter substance P).
Q11
The 'gate control theory' explains why:
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A. pain is always perceived
B. C fibres are myelinated
C. rubbing an injured area reduces pain
D. pain crosses in the medulla
✅ Answer: C. rubbing an injured area reduces pain
Non-painful touch (Aβ) input 'closes the gate' in the dorsal horn, reducing transmission of the pain signal.
Q12
Cardiac ischaemic pain felt in the left arm is an example of:
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A. phantom pain
B. neuropathic pain
C. fast pain
D. referred pain
✅ Answer: D. referred pain
Referred pain: visceral afferents converge with somatic afferents at the same spinal segment, so the brain mislocates the visceral pain to a dermatome.
Q13
The corticospinal (pyramidal) tract mostly decussates at the:
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A. medullary pyramids
B. spinal cord level of entry
C. thalamus
D. internal capsule
✅ Answer: A. medullary pyramids
~85% of corticospinal fibres cross at the medullary pyramids (lateral corticospinal tract), so each motor cortex controls the contralateral body.
Q14
A spastic limb with hyper-reflexia and a positive Babinski sign indicates a lesion of the:
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A. lower motor neuron
B. upper motor neuron
C. muscle
D. sensory nerve
✅ Answer: B. upper motor neuron
UMN lesion = spasticity, hyper-reflexia, clonus, up-going toe (Babinski +). LMN lesion = flaccid, areflexic, atrophy + fasciculations.
Q15
Marked muscle atrophy with fasciculations and flaccid weakness suggests a lesion of the:
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A. upper motor neuron
B. cerebellum
C. lower motor neuron
D. basal ganglia
✅ Answer: C. lower motor neuron
Denervation (LMN lesion) → flaccid paralysis, hypo-/areflexia, atrophy and fasciculations.
Q16
A cerebellar lesion produces signs on which side of the body?
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A. contralateral
B. bilateral always
C. no motor signs
D. ipsilateral (same side)
✅ Answer: D. ipsilateral (same side)
Cerebellar signs (ataxia, intention tremor, dysmetria, dysdiadochokinesia, nystagmus) are ipsilateral to the lesion.
Q17
Resting tremor, rigidity and bradykinesia result from loss of dopaminergic neurons in the:
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A. substantia nigra (basal ganglia)
B. cerebellum
C. motor cortex
D. thalamus
✅ Answer: A. substantia nigra (basal ganglia)
Parkinson disease = degeneration of substantia nigra dopamine neurons → a hypokinetic basal-ganglia disorder.
Q18
The sympathetic nervous system arises from the ___ spinal cord and its post-ganglionic transmitter is usually ___.
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A. craniosacral; acetylcholine
B. thoracolumbar; noradrenaline
C. thoracolumbar; acetylcholine
D. craniosacral; noradrenaline
✅ Answer: B. thoracolumbar; noradrenaline
Sympathetic = thoracolumbar (T1–L2), short pre-/long post-ganglionic, post-ganglionic noradrenaline (except sweat glands = ACh).
Q19
Parasympathetic post-ganglionic fibres act on target organs via:
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A. nicotinic receptors
B. α-adrenergic receptors
C. muscarinic ACh receptors
D. β-adrenergic receptors
✅ Answer: C. muscarinic ACh receptors
Parasympathetic targets use ACh on muscarinic receptors. (All autonomic ganglia and the NMJ use ACh on nicotinic receptors.)
Q20
The adrenal medulla is best described as:
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A. a parasympathetic ganglion
B. an endocrine part of the cortex
C. a sensory ganglion
D. a modified sympathetic ganglion releasing catecholamines into the blood
✅ Answer: D. a modified sympathetic ganglion releasing catecholamines into the blood
Pre-ganglionic sympathetic (ACh) fibres stimulate the adrenal medulla to release adrenaline/noradrenaline as hormones.
1Synapse+
The functional junction where one neuron communicates with another cell. At a chemical synapse, an action potential triggers Ca²⁺-dependent transmitter release across the cleft to receptors on the postsynaptic cell — giving one-way conduction, synaptic delay and summation.
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2Excitatory postsynaptic potential (EPSP)+
A graded depolarization of the postsynaptic membrane (Na⁺/Ca²⁺ influx) that moves the neuron toward threshold. EPSPs summate temporally and spatially; an IPSP is the opposite (hyperpolarizing) event.
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3Stretch (myotatic) reflex+
A monosynaptic spinal reflex in which stretching a muscle excites its spindle (Ia afferent), which directly drives the α-motor neuron to contract the same muscle (e.g. the knee jerk). It maintains muscle tone and tests segmental integrity.
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4Reciprocal inhibition+
The reflex relaxation of an antagonist muscle (via an inhibitory interneuron, IPSP) at the same time as its agonist is reflexly contracted, allowing smooth, coordinated movement.
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5Referred pain+
Visceral pain perceived in a somatic region (dermatome) that shares the same spinal segment, because visceral and somatic afferents converge on the same second-order neurons — e.g. cardiac pain referred to the left arm.
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6Autonomic nervous system+
The involuntary motor system controlling smooth muscle, cardiac muscle and glands, divided into the sympathetic (thoracolumbar, 'fight-or-flight') and parasympathetic (craniosacral, 'rest-and-digest') divisions, with the enteric system.
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Essay 1
Describe chemical synaptic transmission and the properties of a chemical synapse.
10 marks
Transmission
- The action potential reaches the presynaptic terminal → opens voltage-gated Ca²⁺ channels.
- Ca²⁺ influx triggers exocytosis of neurotransmitter into the synaptic cleft.
- Transmitter binds postsynaptic receptors → a graded potential: EPSP (Na⁺/Ca²⁺ in, depolarizing) or IPSP (Cl⁻ in / K⁺ out, hyperpolarizing).
- The neuron integrates EPSPs − IPSPs; if threshold is reached it fires an action potential.
- Transmitter is removed (enzymatic breakdown, reuptake or diffusion).
Properties
One-way conduction (Dale), synaptic delay (~0.5 ms), temporal and spatial summation, fatigue, and high sensitivity to drugs, hypoxia and pH.
Marking guide (10 marks): AP → Ca²⁺ influx → transmitter release 3 · EPSP vs IPSP 2 · integration/threshold 1.5 · transmitter removal 1 · properties (one-way, delay, summation, fatigue) 2.5
Essay 2
Compare the two major ascending sensory pathways (dorsal column–medial lemniscus vs spinothalamic).
10 marks
Dorsal column–medial lemniscus (DCML)
- Carries: fine touch, vibration, conscious proprioception.
- Course: ascends ipsilaterally in the dorsal columns and decussates in the medulla.
Spinothalamic (anterolateral)
- Carries: pain, temperature, crude touch.
- Course: decussates in the spinal cord within 1–2 segments of entry, then ascends.
Common features
Both are 3-neuron chains relaying in the thalamus (VPL) → primary somatosensory cortex (postcentral gyrus, somatotopic homunculus).
Clinical value
The different crossing levels let a cord hemisection (Brown-Séquard) be localised: ipsilateral loss of fine touch/proprioception below + contralateral loss of pain/temperature.
Marking guide (10 marks): DCML modalities + medullary crossing 3 · spinothalamic modalities + cord crossing 3 · 3-neuron / thalamus / cortex 2 · clinical localisation 2
Essay 3
Distinguish upper motor neuron (UMN) from lower motor neuron (LMN) lesions.
10 marks
The pathway
The UMN (corticospinal tract) runs from the motor cortex, decussates at the medullary pyramids, to the LMN in the anterior horn; the LMN runs to the muscle.
UMN lesion signs
- Increased tone — spasticity; hyper-reflexia and clonus.
- Positive Babinski (up-going toe).
- Little atrophy (disuse only); no fasciculations.
LMN lesion signs
- Decreased tone — flaccid paralysis; hypo-/areflexia.
- Marked muscle atrophy and fasciculations.
- Negative Babinski.
Marking guide (10 marks): pathway 2 · UMN: spastic, hyper-reflexia, Babinski + 3 · LMN: flaccid, areflexia, atrophy + fasciculations 3 · table-style contrast / clarity 2
Essay 4
Describe the functions of the cerebellum and the features of a cerebellar lesion.
10 marks
Functions
The cerebellum does not initiate movement; it coordinates movement by comparing the intended with the actual movement and correcting it. It controls timing and smoothness of voluntary movement, balance and posture (via the vestibulocerebellum), and motor learning.
Lesion features (ipsilateral)
- Ataxia — incoordination, broad-based gait.
- Intention tremor — tremor that worsens on approaching a target.
- Dysmetria — past-pointing (finger–nose test).
- Dysdiadochokinesia — impaired rapid alternating movements.
- Nystagmus, scanning speech, hypotonia.
All signs occur on the same side as the lesion.
Marking guide (10 marks): functions (coordination, comparator, balance, motor learning) 4 · ataxia 1 · intention tremor 1 · dysmetria 1 · dysdiadochokinesia 1 · ipsilateral 2
Essay 5
Compare the sympathetic and parasympathetic divisions of the autonomic nervous system.
10 marks
Origin
Sympathetic = thoracolumbar (T1–L2); parasympathetic = craniosacral (CN III, VII, IX, X and S2–S4).
Fibres/ganglia
Sympathetic: short pre-, long post-ganglionic (ganglia near the cord). Parasympathetic: long pre-, short post-ganglionic (ganglia near the organ).
Transmitters/receptors
All ganglia and the NMJ: ACh on nicotinic receptors. Sympathetic post-ganglionic: noradrenaline on α/β receptors (except sweat glands = ACh). Parasympathetic post-ganglionic: ACh on muscarinic receptors.
Overall effects
Sympathetic = 'fight or flight' (↑HR, pupils dilate, bronchodilate, ↓gut). Parasympathetic = 'rest and digest' (↓HR, pupils constrict, ↑gut). The adrenal medulla is a modified sympathetic ganglion.
Marking guide (10 marks): origin (thoracolumbar vs craniosacral) 2 · fibre/ganglion length 2 · transmitters/receptors (nicotinic ganglia, NE vs muscarinic) 3 · overall effects 2 · adrenal medulla 1