The action potential of a nerve cell
Results from a large increase in membrane permeability to Na+ ions
Can summate with one another
May vary considerably in amplitude
Become larger as stimulus strength increase
Follow from a decrease in membrane permeability for K+ ions
At neuromuscular junction:
the muscle membrane possesses muscarinic receptors
the motor nerve endings secrete norepinerphrine
curare leads to prolongation of neuromuscular transmission
the motor nerve endings secrete acetylcholine
none of the above
The nervous system is compromised of:
Neurons
Neurotubules
Neurofibrils
Axons
Dendrites
The unique property of the neuron is:
Communication
Contraction
Secretion
Energy production
Excitation
Most axons are covered by a fatty sheath called:
Neurilema
The nodes of Ranvier
Myelin
Neural adipose
Sacrolema
Receptors which respond in a stretch reflex are:
Carotid baroreceptors
Free nerve endings
Ruffini's endings
Oligodendrocytes
Pacinan corpuscles
Select the excitatory neurotransmitter:
GABA
Dopamine
Norepinerphrine
Glycine
None of them
Laws of transmission in chemical synapses
One way conduction
Amplitude coding of postsynaptic membrane
Delayed transmission
Summation
All of the above
Which are the most important EEG waves during wakefulness with opened eyes
Gamma (γ)
Alpha (α)
Beta (β)
Delta (δ)
Alpha (α) and Delta (δ)
The adrenergic receptors:
Alpha
Muscarinic
Beta
Nicotinic
Alpha and Beta
Which one of the following is characteristic of type A nerve fibers:
Nociception
Slower conduction than C fibers
Myelinated
Substance P
Sensory only
Electroencephalogram (EEG) registers the activity of the
reticular activating system
limbic system
thalamus
cortex
brain stem
Sensory neurons have:
a short dendrite and a long axon
a short dendrite and a short axon
a long dendrite and a short axon
along dendrite and a long axon
their axons and dendrites may be either long or short
The medulla oblongata helps regulate which of the following
breathing
heartbeat
sneezing
vomiting
all of the above
What anatomical region of a multipolar neuron has the lowest threshold for generating an action potential?
soma
dendrites
axon hillock
distal axon
proximal axon
What do the dorsal root ganglia contain?
cell bodies of somatic motor neurons
axon terminal of somatic motor neurons
cell bodies of autonomic motor neurons
axon terminal of sensory neurons
cell bodies of sensory neurons
Prevertebral sympathetic ganglia are involved with the innervation of the
abdominal organs
thoracic organs
head
m. errector pili
A reflex action:
is initiated at sensory receptors
always results in endocrine secretion
involves transmission across at least two central nervous synapses in series
is always inhibitory
is independent of higher centres in the brain
In skeletal muscle neuromuscular junctions:
the motor end plate is the motor nerve terminal
spontaneous (miniature) potentials may be recorded in the motor nerve terminal
motor nerve terminals have vesicles containing acetylcholine
there is a high concentration of curare
transmission is facilitated by botulinum toxin
Cerebrospinal fluid:
is formed in the arachnoid granulations
provides the brain with most of its nutrition
protects the brain from injury when the head is moved
has a lower pressure than that in the cerebral venous sinuses
flows around the adult brain and is around 5 litres per day
An excitatory post-synaptic potential:
is the depolarization of a post-synaptic nerve cell membrane that occurs when a presynaptic neurone is stimulated
involves reversal of polarity across the post-synaptic nerve cell membrane
may be recorded from a posterior root ganglion cell
is propagated at the same rate as an action potential
is caused by the electrical field induced by activity in the pre-synaptic nerve terminals
The ascending reticular formation:
when stimulated tends to increase alertness
transmits impulses to higher centres via a multisynaptic pathway
is activated by collateral branches of sensory neurones
neurones project to most parts of the cerebral cortex
The cerebellum:
modifies the discharge of spinal motor neurones
is essential for finely coordinated movements
has an afferent input from the motor cortex
has an afferent input from muscle proprioceptors
During deep sleep there is a fall in:
hand skin temperature
arterial pCO2
blood growth hormone/cortisol ratio
metabolic rate
pH
Sympathetic:
ganglionic transmission is mediated by acetylcholine
neuromuscular transmission in the heart is mediated by acetylcholine
neuromuscular transmission in hand skin arterioles is mediated by acetylcholine
neuroglandular transmission in sweat! glands is mediated by noradrenaline
neuromuscular transmission in the iris is mediated by acetylcholine
The blood-brain barrier:
slows equilibration of solutes between blood and brain tissue
is more effective barrier for fat-soluble substances than water-soluble substances
is more effective barrier in infants than in adult
is more effective barrier far CO2 than for 02
permits hydrogen ions to pass freely
The electroencephalogram normally shows voltage waves:
whose amplitude is related to intelligence
of lower frequency during deep sleep than during alert wakefulness
of smaller amplitude during deep sleep than during alert wakefulness
of greater amplitude than those of the electrocardiogram
which are bilaterally unsymmetrical
Parasympathetic nerves:
have effects on intestinal smooth muscle opposite to sympathetic nerve
have no effect on lacrimation
cause vasodilatation in skeletal muscle during prolonged exercise
cause sweat secretion in skin when body temperature rises
have longer postganglionic than preganglionic fibres
α (alpha) adrenoceptors:
are located on myofilaments in smooth muscle cells
are distinguishable from β (beta) receptors using electron microscopy
can be stimulated by both adrenaline and noradrenaline
are involved in the vasodilation responses to adrenaline in skin
are involved in heart rate responses to noradrenaline
The α (alpha) rhythm of the electroencephalogram:
disappears when the eyes are closed
is an electrical potential with an amplitude around one millivolt
has a frequency of 8-12 Hz
has a lower frequency than the δ (delta) rhythm
indicates that the subject is sleeping
The primary sensory ending of a muscle spindle is stimulated by:
shortening of an antagonist muscle
relaxation of the muscle concerned when under load
stimulation of the gamma efferent fibres
striking the appropriate tendon with a tendon hammer
In the spinal cord:
pain impulse traffic may be modulated in the posterior horn
autonomic motor neurones arise in the lateral horn
glycin acts as inhibitory neurotransmitter
post-synaptic excitation may be mediated by amino acid derivatives acting as neurotransmitters
In the cerebral cortex
neuronal connections are innate and immutable
language and now-language skills are represented in the same hemisphere
the areas concerned with emotional behavior are concentrated in the lobes
the cortical area devoted to sensation in the hand is larger that for the trunk
stimulation of the motor cortex causes contractions of individual muscles on the opposite side of the body
Generalized sympathetic activity is characterized by:
contraction of the radial muscle in the iris
increased urinary excretion of catecholamines
lipolysis in adipose tissue
increased conduction rate in the atrio-ventricular bundle
Acetylcholine:
acts on the same type of receptor on postganglionic fibres in sympathetic and parasympathetic ganglia
acts on the different type of receptor on target organs at cholinergic sympathetic and parasympathetic nerve terminals
acts on the same type of receptor at autonomic ganglia and at somatic neuromuscular junctions
acts on alpha and beta receptors
in blood is hydrolyzed by the same cholinesterase as is found at neuromuscular junctions
An inhibitory post-synaptic potential:
may be recorded in a post-ganglionic sympathetic neurone
may be recorded in an axon
does not exceed one millivolt in amplitude
moves membrane potential towards the equilibrium potential for sodium
may summate in space and time with other excitatory and inhibitory potentials in the same neurone
A valley of impulses travelling in a pro-synaptic neurone causes:
an identical volley in the post-synaptic neurone
summation of action potentials
an increase in the permeability of the pare-synaptic nerve terminals to calcium
the generation of at least one action potential in the post-synaptic neurone
endocytosis of neurotransmitter
Pain receptors are:
similar in structure to Pacinian corpuscles
stimulated by a rise in the local K+ concentration
quick to adapt to a constant stimulus
more easily stimulated in intact than in injured tissue
stimulated in the wall of the gut by agents which damage the tissues
Rapid eye movement (REM) sleep differs from non-REM sleep in that:
the EEG shows waves of higher frequency
muscle tone is higher
heart rate and respiration are more regular
secretion of growth hormone is increased
not possible
Delta (δ) wave activity in the electroencephalogram:
is low in frequency and amplitude
suggests that the patient is alert and concentrating
suggests that the patient is with opened eyes
is a feature of petit mal epilepsy
is more common in children than in adults while they are awake
Signs of brainstem death include:
unconsciousness
normal pupillary reaction to light
loss of tendon jerks in the arms and legs
loss of respiratory response to CO2 in the absence of hypoxia
nystagmus in response to cold water in the external auditory canal
Atropine causes:
paralysis of accommodation for near vision in the eye
constriction of the pupil
constriction of the bronchi
diarrhea
bradycardia
Aphasia:
is an impairment of language skills without motor paralysis loss of hearing or vision
does not mean unconsciousness
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
is called sensory aphasia if the patient does not understand the meaning of the words he hears, sees and uses
Blockade of parasympathetic activity causes a reduction in:
sweat production
resting heart rate
the strength of skeletal muscle contraction
salivation
blood pressure
Blockade of beta (β) adrenoceptors is likely to cause:
disturbance in renal-angiotensin-aldosterone system
worsening of the condition in patients with bronchial asthma
worsening of the condition in patients in cardiac failure
inability to increase heart rate during exercise in patients with transplanted hearts
All of these characteristics belong to postsynaptic potentials, except for:
they have constant magnitude
there are no refractory periods
summation is possible
typically occur at the cell body of a neuron
they are decremental
Compared with the Endocrine System, regulation of the body by the Nervous System provides:
relatively slow but long-lasting responses to stimuli
swift but brief responses to stimuli
swift, long-lasting responses to stimuli
antagonist hormone interactions
relatively slow, short-lived responses to stimuli
Which of these characteristics is not related to the Parasympathetic division of the ANS?
urination
defecation
lacrimation
posturation
Which of the following has slowest conduction:
A alpha
A beta
A gamma
B fibres
C fibres
A man falls into deep sleep with one arm under his head. After awakening the arm is paralyzed but tingling sensation and pain sensation persist. This loss of motor function without the loss of sensory function is due to:
A fibres are more susceptible to hypoxia that B fibers
A fibres are more sensitive to pressure than C fibers
C fibres are more sensitive to pressure than A fibers
sensory nerves are nearer the bone and hence affected by pressure
Saltatory conduction:
is seen only in myelinated nerve fibres
is slower that non saltatory conduction
is not affected if a local anesthetic is applied to the nodes of Ranvie
is seen only in sensory fibers
is seen only in the cortex
Myelin sheath is produced by:
Axoplasm
Mitochondria
Schwann cell
Muscle cell
Endocrine cell
Sleep is associated with:
an alpha rhythm in the electroencephalogram
increased activity in the reticular activating system
a beta rhythm in the EEG
a high level of vagal tone to the heart and grinding movements of the teeth
a rise in central body temperature
From childhood to old age:
there is a steady decrease in total sleeping time per day
deep (stage 4) Sleep decreases as a percentage of total daily sleep
body water as a percentage of body mass decreases
sleep becomes less aggregated into a single sleeping period
The method by which the brain's electrical activity is registered from the scalp is called:
electroneurography (ENG)
electroencephalography (EEG)
electrocardiography (ECG)
electromyography (EMG)
nuclear-magnetic resonance (NMR)
The sympathetic preganglionic neurons of the ANS secrete:
dopamine
L-DOPA
serotonin
histamine
acetylcholine
The adrenergic effect on the bronchial smooth muscle is:
constriction
relaxation
sometimes constriction, sometimes relaxation
of no effect
dose dependent - at low concentrations - constriction, at higher doses - relaxation
reflexes are defined as somatic, visceral and mixed
according to the location of the receptors
according to the type of the reflex arc
according to the effectors
according to the location of the interneurons
according to formation
The adrenal medulla is innervated by:
preganglionic cholinergic neurons
postganglionic cholinergic neurons
preganglionic adrenergic neurons
postganglionic adrenergic neurons
preganglionic dopaminergic neurons
The increased tone of the parasympathetic division leads to:
contraction of the pupils and bronchial smooth muscle fibers
dilation of the pupils and relaxation of the bronchial smooth muscle fibers
contraction of the pupils and relaxation of the bronchial smooth muscle fibers
dilation of the pupils and contraction of the bronchial smooth muscle fibers
Excessive formation of a substance/ secretion in the body is controlled in order to maintain homeostasis by:
+ve feedback mechanism
-ve feedback mechanism
osmosis
haemodynamics
Up-regulation
The sympathetic response to stress includes:
increased blood pressure
increased glycogen breakdown in liver and muscles
increased glycogen synthesis in liver and muscles
increased blood clotting
a, b, and d
