Neuroscience 1 HyprPaper 3

When a peripheral nerve is severed, which of the following statements correctly describes the repair of that nerve?

Nissl granules begin to disappear 20 days after the nerve lesion
Regeneration is independent of the number of functional Schwann cells
Schwann cells are important for removing debris from the injured site
Myelin sheath below the injured site starts disintegrating within 24 hours

Which of the following statements regarding the action potentials in mixed nerves is correct?

The amplitude of the action potential is dependent on the stimulus intensity
The number of fibers in the nerve that are excited is independent of the stimulus strength
All fibres contained in the nerve enter the refractory period at the same time with repeated stimulation
All fibres contained in the nerve are excited for the same duration upon application of the threshold stimulus

Which of the following statements best describes the ”motor unit”?

A single muscle fiber which contracts independently of others
A single motor neurone in the motor unit pool that has been excited
A group of muscle fibres interconnected by gap and tight junctions
A motorneurone plus all the muscle fibres which it innervates

A significant decrease in the resting membrane potential of nerves will most likely result from which one of the following ionic states?

Hyperchloremia
Hyperkalaemia
Hypocalcemia
Hyponatremia

Proteins needed for normal neurotransmission will require which one of the following processes?

Anterograde transport
Retrograde transport
Antidromic conduction
Orthrodromic conduction

Which one of the following statements regarding the resting membrane potential of neurones is correct?

A hyperkalaemic state will cause a decrease in the normal value
It is determined by the Nernst potential for potassium ions
It is determined by the extracellular calcium ion concentration
Maintenance of the normal value does not require energy expenditure

Which one of the following statements regarding the autonomic nervous system is correct?

Preganglionic parasympathetic fibres are mostly short and myelinated
Postganglionic sympathetic fibres are mostly short and unmyelinated
The pelvic nerve innervates all regions of the large intestines
The pelvic nerve innervates the urinary bladder but not the kidneys

Which one of the following actions results from stimulating the pelvic nerve?

Contraction of the detrusor muscle of the urinary bladder
Contraction of the internal sphincter of the urinary bladder
Relaxation of the internal and external anal sphincters
Relaxation of the rectal wall and internal anal sphincter

Which of the following actions results from increased sympathetic tone?

Bronchoconstriction
Erection
Defecation
Venoconstriction

Which one of the following effects would result from a unilateral lesion to the superior cervical ganglion?

Dry skin on the affected side of the face
Enopthalmosis on the opposite side of the face
Flushed skin on the opposite side of the face
Myadriaisis on the affected side of the face

Which one of the following actions would most likely result from an increase in circulating epinephrine?

Anhydrosis
Lipolysis
Miosis
Peristalsis

Which one of the following actions will most likely result from a vagotomy?

Decreased gastric acid secretion
Hypertension
Increased lung secretions
Vasodilation

Which of the following nerves would be most susceptible to hypoxia?

Autonomic postganglionic fibers
Fast pain fibers
Motorneurones
White rami communicantes

Saltatory conduction is abnormal in which of the following disorders?

Guillian-Barré syndrome
Hyperkalaemic periodic paralysis
Lambert-Eaton syndrome
Myasthenia Gravis

The adrenal medulla releases epinephrine when stimulated by which one of the following nerves?

Preganglionic cholinergic nerve fibres coursing in the vagus nerve
Postganglionic sympathetic fibres arising from spinal cord segments T5 to T9
The splanchnic nerve that synapses in the coeliac
The splanchnic nerve that arises between spinal cord segments T5 to T9

Which one of the following drugs prolongs the pharmological effects of acetylcholine?

Atropine
Pirenzipine
Scopolamine
Pyridostigmine

Which one of the following drugs will produce an increase in blood pressure and a reflex decrease in heart rate?

Phentolamine
Phenylephrine
Practolol
Prazosin

Which one of the following drugs is a non-selective beta antagonist?

Atenolol
Butoxamine
Phenoxybenzamine
Propranolol

Which one of the following drugs is LEAST likely to constrict the bronchioles?

Nadolol
Metoprolol
Propranolol
Oxprenolol

Which one of the following is a characteristic feature of slow skeletal muscles?

Easy fatiguability
Rich in glycogen
Rich in myoglobin
Short twitch durations

Which one of the following substances accumulates during tetanic contraction of the skeletal muscle?

ATP
Ca2+
K+
Na+

During skeletal muscle contraction, calcium ions perform which of the following functions?

They increase the action potential transmitted along the sarcolemma
They cause ATP to bind to actin filaments
They bind to regulatory proteins on the myosin filaments
They expose myosin binding sites on the actin filaments

Which one of the following mechanisms of action best describes the muscle relaxant effect of d-Tubocurarine?

It competitively inhibits muscarinic receptor activity
It prolongs the activation of sodium ion channels
It prevents acetylcholine binding to nicotinic receptors
It prevents the release of acetylcholine from nerve endings

Which one of the following statements describes the mechanism of action of Succinycholine?

It competitively blocks nicotinic receptors at autonomic ganglia
It competitively blocks nicotinic receptors on skeletal muscle
It depolarizes nicotinic receptors at autonomic ganglia
It depolarizes nicotinic receptors on skeletal muscles

Which one of the following statements describes the mechanism of action of Dantrolene?

It blocks nicotinic receptors on the sarcolemma of the muscle
It opens potassium channels on the skeletal muscle
It inhibits acetylcholine release from the nerve endings
It inhibits calcium release from the sarcoplasmic reticulum

Which one of the following effects is most likely to occur with pseudocholinesterase deficiency?

Decreased potency of succinylcholine
Increased potency of atracurium
Prolonged succinylcholine blockade
Shortened duration of atracurium blockade

Neuroscience 1 HyprPaper 3

Neuroscience 1 HyprPaper 3

January 18, 2021

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