Neurophysiology Flashcards
What is the purpose of the retinal ON- and OFF-pathways?
Decrease glutamate release.
Increase visual contrast.
Increase light sensitivity.
Improve color vision.
Increase visual contrast.
The most important area for the coordination of autonomic output and endocrine processes is:
the limbic system
the amygdala
the hypothalamus
the hippocampus
the hyppothalamus
The sequence of motor unit recruitment:
depends the force needed for the task.
starts from small to large motor units.
is determined by the muscle fiber type
starts from small to large motor units
Which of the following statements about the transduction of taste modalities by activation of G-protein-coupled receptors is true?
The signaling pathway leads to the opening of non-specific cation channels.
The G-protein-coupled receptors have ion channels in the receptor molecule.
The receptor potential triggers an action potential in the chemoreceptor cell.
The signaling pathway leads to the opening of non-specific cation channels.
A research assistant accidentally inhales a high dose of hexamethonium, a blocker of nicotinic acetylcholine receptors. What is the likely effect of this drug on autonomic activity?
Parasympathetic activity will be higher than normal.
Sympathetic and parasympathetic activity will increase.
All autonomic activity will be inhibited.
Sympathetic activity will be higher than normal.
All autonomic activity will be inhibited.
The anterolateral column includes:
Polymodal receptors selective for high temperature.
Ib fibers that convey the sensation of sharp pain.
Thermal nociceptors that signal heat below 25°C.
C fibers that convey the sensation of dull pain.
C fibers that convey the sensation of dull pain.
How is angular acceleration (head rotations) detected by the vestibular system?
The crista ampullaris in the saccule is deflected by the acceleration.
The inertia of the otoconia deflects the stereocilia of vestibular hair cells.
Perilymph displaces the otolithic membranes in the saccule and utricle.
Endolymph deflects the stereocilia of hair cells in the semicircular canals.
Endolymph deflects the stereocilia of hair cells in the semicircular canals.
The muscarinic acetylcholine receptor is a metabotropic receptor. This means that:
It is a selective cation channel.
The receptor is not a ligand-gated channel.
All the options are correct.
It is a non-specific ion channel.
The receptor is not a ligand-gated channel.
If we apply a depolarizing stimulus to a dendrite in a typical neuron, and record the change in membrane potential at different points between the dendrite and the axon hillock, which tracing in the figure above shows the change in membrane potential as a function of distance from the stimulation point?
Stimulus is slowly decreasing.
Both long-term potentiation and depression are Ca2+-dependent processes. However, they have the opposite effect on synaptic function. What is the key initial factor that determines which process is activated?
The specific neurotransmitter.
Voltage-gated ion channels.
The stimulation frequency.
Ca2+-sensitive proteins.
The stimulation frequency.
Which of the following is not influenced by the basal ganglia?
Motor learning
Motor activity
Affective function
Cognitive function
Motor learning.
Which of the following mechanisms allows us to discriminate spatially between two fingers poking on the back of the neck?
The size of the sensory receptor fields.
The diversity of sensory receptor types.
The axonal myelination of sensory neurons.
The firing frequency of the sensory neurons.
The size of the sensory receptor fields.
The voltage-gated Ca2+ channels are inhibited in neuron 4 of the figure above. What happens to synaptic transmission?
Neurotransmitter release decreases.
There will not be a presynaptic action potential.
Neurotransmitter release will be increased.
The postsynaptic neurons will fire action potentials.
Neurotransmitter release decreases.
As you know, myelin is analogous to the insulation of an electrical cable. Which of the following statements about myelin in the central nervous system is true:
it is formed by layers of modified lipids.
myelin is produced by oligodendrocytes.
its presence increases axonal cytoplasmic resistance.
myelin surrounds dendritic segments at regular intervals.
Myelin is produced by oligodendrocytes.
In this figure of the CNS, which structure is involved in equilibrium, motor coordination, and learning of motor tasks?
hypothalamus
How are postsynaptic potentials different from action potentials?
Postsynaptic potentials are graded membrane potentials.
Postsynaptic potentials are all-or-nothing responses.
Postsynaptic potentials are membrane hyperpolarizations.
Postsynaptic potentials do not open voltage-gated channels.
Postsynaptic potentials are graded membrane potentials
In the figure above, neurons 1 and 2 are excitatory, and neuron 3 is inhibitory. All of them synapse onto neuron 4, and neuron 3 has twice the synaptic strength of neurons 1 and 2 combined. If neurons 1, 2, and 3 fire at the same time, what would be the likely effect on neuron 4?
Spatial summation: neuron 4 would hyperpolarize.
Temporal summation: neuron 4 would depolarize.
Neurons 1, 2, and 3 cancel each other out.
Synaptic block: neuron 4 would not change.
Spatial summation: neuron 4 would hyperpolarize
Which of the following is not a step in an action potential?
All options are correct
Inactivation of voltage-gated K+ channels
A cycle of voltage-gated Na+ channel openings
A graded membrane hyperpolarization
Inactivation of voltage-gated K+ channels
In a typical neuron at rest, what are the intra- and extracellular concentrations of chloride ([Cl-]) and calcium ([Ca++])?
Intracellular [Ca++] and [Cl-] are greater than extracellular [Ca++] and [Cl-].
Intracellular [Cl-] is the same as in the plasma.
The [Ca++] is greater inside the cell than outside.
The intracellular [Cl-] is higher than the intracellular [Ca++].
The intracellular [Cl-] is higher than the intracellular [Ca++].
When we compare “large” and “small” motor units, we are talking about:
the number of muscle fibers innervated by one motor neuron.
the number of neuromuscular junctions present in a muscle fiber.
the number of muscle fibers available in a skeletal muscle.
the number of motor neurons present in the spinal cord.
the number of muscle fibers innervated by one motor neuron
Which of the following are characteristics of rods and cones?
Only cones contain rhodopsin and opsin.
Rods are more sensitive to light, cones detect colors.
Cones are more sensitive to light, rods detect colors.
Only rods have outer and inner segments.
Rods are more sensitive to light, cones detect colors.
The nicotinic acetylcholine receptors are _________________ in the membrane of ________________.
metabotropic receptors — preganglionic cells
G-protein-coupled receptors — preganglionic cells
voltage-gated Na+ channels — postganglionic cells
ionotropic receptors — postganglionic cells
ionotropic receptors — postganglionic cells
Central pattern generators are:
motor timing signals that originate in the motor cortex.
cerebellar integrators of sensory and motor information.
neural circuits that underlie rhythmic motor activities.
reflexive motor activities triggered by sensory inputs.
Neural circuits that underlie rhythmic motor activities
The auditory hair cells are mechanoreceptors that are stimulated by pressure waves. How is sound transduced to receptor potentials when the hair bundles move away from the longer stereocilia?
Stereocilia open Ca2+ channels in the basolateral membrane.
Tip links open nonselective cation channels in the stereocilia.
Hair cell hyperpolarization inhibits glutamate release.
The depolarization triggers an action potential in the hair cell.
Hair cell hyperpolarization inhibits glutamate release
Taste transduction of salty and sweet is different because:
they use different chemoreceptors in the same taste cell.
only the taste for sweet results in a hyperpolarizing receptor potential.
the taste molecules are different ions that depolarize the taste receptors.
the transduction process does not include the activation of G-proteins in both
the transduction process does not include the activation of G-proteins in both
Where does the action potential travel to under normal conditions?
axon hillock
In Parkinson’s disease, loss of motor activation leads to:
tremor during movement.
exaggerated movements.
cognitive impairment.
slower movements.
slower movements
What is the explanation for “referred pain”?
Descending inhibition
Afferent overlap
Signal convergence
Signal convergence
Cerebellar dysfunction is characterized by:
jerky involuntary movements.
tremor during movement.
cognitive dysfunction.
inability to initiate a movement.
tremor during movement
What is the function of an axon hillock?
to initiate an action potential
Which of the following is not a characteristic of action potentials?
Action potentials are all-or-nothing responses
Action potentials are fast transient responses
Action potentials create frequency-encoded signals
Action potentials propagate a short distance
Action potentials propagate a short distance
Which statement about the parasympathetic preganglionic neurons is true?
They release neuropeptides to modulate synaptic function.
Their somas are in the lateral column of the spinal cord gray matter.
Their terminals are found in pre- and paravertebral ganglia.
They use acetylcholine to elicit slow IPSPs on postganglionic cells.
They release neuropeptides to modulate synaptic function
How does lateral inhibition affect the output of neurons with receptive fields at the edge of a stimulus?
The neurons at the edge stimulate inhibitory interneurons.
The output of excitatory interneurons is inhibited.
The output of neurons at the edge of a stimulus is inhibited.
Inhibitory branches from sensory neurons at the center of the receptive field.
The output of neurons at the edge of a stimulus is inhibited
Schwann cells and oligodendrocytes create the myelin sheaths in myelinated axons. What are the main differences between these two cell types?
Schwann cells and oligodendrocytes are basically the same.
The myelin thickness and their location around vessels.
The type of transporters they express and the myelin composition.
Their location and the number of axons each cell myelinates.
Their location and the number of axons each cell myelinates
During the refractory period, a new action potential is not possible because the voltage-gated are .
relative : Na+ channels : closed
absolute : K+ channels : inactivated
relative : K+ channels : closed
absolute : Na+ channels : inactivated
absolute : Na+ channels : inactivated
What causes hyperpolarization?
slow closing of voltage-gated potassium channels
A patient who complains of changes in her field of vision is seen by an ophthalmologist. It is determined that the visual optics of the eyes are fine, however, there is total loss of vision on the right eye. The underlying cause for this deficit is most likely:
damage to the left optic nerve.
a tumor near the pituitary gland.
damage to the right occipital lobe.
damage to the right optic nerve.
damage to the right optic nerve
A 34 year old male is admitted into the emergency room having fallen down the stairs. He reports that he landed on the bottom step hard with the middle of his back. Neurological exam reveals normal response to touch of both feet and legs, but no sensation of ice being placed on the right foot or leg. With no more information, where can you predict the injury is?
The right anterolateral column of the spinal cord
The right dorsal column of the spinal cord
The brainstem nucleus
The left anterolateral column of the spinal cord
The left anterolateral column of the spinal cord
What would happen to step 2 (depolarization) on the graph below if the presynaptic neuron was releasing GABA instead of glutamate?
It would go down, instead of up.
Consider the vestibulocochlear nerve. The nerve has been damaged during a routine surgical procedure. The patient is unable to hear in his left ear, but he can stand and walk with no problems.
The whole right nerve is damaged.
The left cochlear branch is damaged.
The whole left nerve is damaged.
The left vestibular branch is damaged.
the left cochlear branch is damaged
In the diagram below, there are three neurons synapsing onto one neuron. If A and B both release acetylcholine and C releases GABA, which of the following scenarios would cause the largest graded potential?
Firing A and B together
A fellow classmate panics during her physiology exam and is having a severe asthma attack. Fortunately, she has a rescue inhaler with her. She takes two puffs of the inhaler, and a few minutes later her asthma symptoms have subsided. What is the most likely receptor that the drug in the inhaler has activated?
Alpha-adrenergic receptors
Muscarinic receptors
Beta-adrenergic receptor
Nicotinic receptors
Beta-adrenergic receptor
Myasthenia gravis is a disease often associated with muscle weakness, and due to a decrease in the number of nicotinic receptors on the skeletal muscle. A likely treatment for this condition would be to:
give a calcium channel blocker.
block the action of acetylcholinesterase.
decrease the number of acetylcholine receptors on the postsynaptic membrane.
increase the number of adrenergic receptors on the presynaptic membrane.
block the action of acetylcholinesterase
Trimethaphan is a blocker of ganglionic nicotinic receptors that was used for the treatment of high blood pressure. What do you think is a significant adverse effect of this drug?
It induces an abnormal increase in gastrointestinal motility and secretions.
It blocks ganglionic transmission in the sympathetic and parasympathetic divisions.
It impairs neuromuscular transmission and causes significant muscle weakness.
It causes complete and selective inhibition of the parasympathetic division.
It blocks ganglionic transmission in the sympathetic and parasympathetic divisions
Which of the following cell types are components of the blood-brain barrier?
a) Endothelial cells
b) Oligodendrocytes
c) Ependymal cells
e) Schwann cells
endothelial cells
These gial cells originate in the bone marrow. They are important for immune responses within the CNS, and are also involved in neuronal plasticity:
a) microglia
b) satellite cells
c) oligodendrocytes
d) astrocytes
microglia
What is the region for central autonomic regulation?
Hypothalamus
The cerebrospinal fluid (CSF) is produced by the choroid plexus and circulates between the brain ventricles and
the subarachnoid space in the CNS. Which of the following is a characteristic of CSF?
a) Protein concentration is higher in CSF than in plasma.
b) Na+ concentration is higher in CSF than in plasma.
c) K+ concentration is higher in CSF than in plasma.
d) CSF has the same composition as plasma.
Na+ concentration is higher in CSF than in the plasma
The term “blood-brain barrier” is given to the structures and processes that regulate the exchange of substances
between the blood and the central nervous system. Among other things, the blood-brain barrier serves to:
a) impede the entry of lipophilic substances from the blood to the brain.
b) ensure the brain’s extracellular fluid has the same composition as plasma.
c) provide the transporters that facilitate the entry of glucose into the brain.
d) none of the options is correct.
provide the transporters that facilitate the entry of glucose into the brain
In a typical neuron, why is the resting membrane potential closer to the equilibrium potential of K + than the
equilibrium potential of Na+ ?
a) Voltage-gated K+ channels are activated.
b) The extracellular Na+ concentration is lower.
c) Cl- is passively distributed across the membrane.
d) There is greater permeability to K+ than to Na + .
There is greater permeability to K+ than to Na+.
What process explains the spread of a graded potential down an axon?
a) Space constant
b) Electrotonic conduction
c) Saltatory conduction
d) All-or-nothing response
Electrotonic conduction
Which of the following conductance (g) changes is least likely to trigger an action potential?
a) gNa increases, and g K decreases
b) gNa increases, and g K increases
c) gNa decreases, and gK increases
d) gNa decreases, and gK decreases
gNa decreases, and gK increases
You discovered a new drug that prevents the closure of voltage-gated K+ channels. What would be the
predicted effect of this drug on neuronal action potentials?
a) The neurons would be unexcitable after 1 action potential.
b) The amplitude of the action potentials would increase.
c) The action potential threshold would decrease.
d) The relative refractory period would be significantly longer.
The relative refractory period would be significantly longer
Multiple sclerosis is a chronic demyelinating disease. A study is done that measures the signal conduction
velocity as part of the diagnostic procedure. With multiple sclerosis, what would you expect to happen to the
conduction velocity?
a) It will decrease.
b) It will increase.
c) It will not change.
d) There will be no conduction.
It will decrease
Inhibition of voltage-gated calcium channels in a presynaptic neuron will result in which of the following?
a) Decreased presynaptic action potential.
b) Increased neurotransmitter release.
c) Impaired impulse conduction along the axon.
d) Decreased neurotransmitter release.
Decreased neurotransmitter release
What is a likely consequence of blocking the potassium leak channels in a postsynaptic neuron?
a) Sodium accumulates inside the postsynaptic neuron.
b) A smaller EPSP is needed to trigger an action potential.
c) The neuron cannot trigger an action potential.
d) The resting membrane potential decreases.
A smaller EPSP is needed to trigger an action potential
In contrast to excitatory postsynaptic potentials (EPSPs), inhibitory postsynaptic potentials (IPSP) will
always:
a) hyperpolarize the membrane.
b) close non-specific cation channels.
c) decrease action potential frequency.
d) increase the membrane potential.
Decrease action potential frequency
Consider the figure above. What is the likely response measured by the recording electrode If synapses A and
B (both excitatory) stimulate the postsynaptic neuron at the same time?
a) An action potential may be triggered.
b) The membrane potential is hyperpolarized.
c) No significant membrane potential change.
d) The membrane potential is unchanged.
An action potential may be triggered
Long-term potentiation and depression are Ca 2+ -dependent processes. However, they have the opposite effect
on synaptic function. What is the key factor that determines which process is activated?
a) The specific neurotransmitter.
b) The stimulation frequency.
c) Ca2+ -sensitive proteins.
d) Voltage-gated ion channels.
the stimulation frequency
Which of the following is a somatosensory modality?
a) Olfaction
b) Vision
c) Pain
d) Smell
Pain
Lateral inhibition and receptor field overlap are two mechanisms that influence our perception of:
a) stimulus frequency.
b) stimulus intensity.
c) stimulus modality.
d) stimulus location.
Stimulus location
Which of the following statements about cold receptors is true?
a) They have a wider response range than warmth receptors.
b) They start firing at temperatures lower than 0°C.
c) They are uniformly distributed throughout the body.
d) They are innervated by Ib nerve endings.
They have a wider range than warmth receptors
Which of the following statements about reflexes is correct?
a) Reflexes require involvement of higher cortical centers.
b) Reflexes are restricted to one side of the body.
c) The brain may be unaware of the initiating event.
d) Interneurons are not involved in reflexes
The brain may be unaware of the initiating event
Which of the following steps takes place during phototransduction?
a) Transducin decreases phosphodiesterase activity.
b) The photoreceptors increase glutamate release.
c) The photoreceptors generate action potentials.
d) cGMP decreases and closes cGMP-gated channels
cGMP decreases and closes cGMP-gated channels
Why does mechanical deformation of stereocilia towards the tallest stereocilium depolarize auditory hair
cells?
a) Calcium enters and increases neurotransmitter release.
b) Tip links stretch and open nonselective cation channels.
c) Voltage-gated calcium channels open.
d) All the answers are correct.
Tip links stretch and open nonselective cation channels
Benign paroxysmal vertigo is the most common cause of dizziness in the general population. The dizziness is
typically triggered when laying down from standing or standing from sitting. Which of the following regions
will be affected?
a) Utricle and saccule
b) Semicircular canals
c) Cochlea
d) Eustachian tubes
Utricle and saccule
Which of the following statements about the transduction of taste modalities by activation of G-protein-
coupled receptors is false?
a) The transduction pathway triggers a graded potential in the taste cell.
b) The G-protein-coupled receptors do not have ion channels in the receptor complex.
c) The signaling pathway leads to the opening of specific anion channels.
The signaling pathway leads to the opening of specific anion channels
Which of the following statements about the sense of smell is correct?
a) Smell receptors are epithelial cells.
b) Smell molecules inactivate a G protein.
c) cAMP opens non-specific anion channels.
d) Smell receptors generate action potentials.
Smell receptors generate action potentials
The mechanism of reciprocal inhibition in the knee jerk reflex refers to the:
a) activation of alpha-motor neurons that innervate antagonistic muscles.
b) stimulation of inhibitory interneurons that relax antagonistic muscles.
c) activation of alpha-motor neurons that innervate agonist muscles.
d) Inhibition of ipsilateral agonist and contralateral antagonist muscles.
stimulation of inhibitory interneurons that antagonistic muscles relax
Which of the following statements about the primary motor cortex is false?
a) Its output is adjusted by the basal ganglia.
b) It includes inputs from the frontal lobe.
c) It initiates all motor activities.
d) Its output is copied to the cerebellum.
It initiates all motor activities
Which of the following is influenced by the basal ganglia?
a) Vestibular function.
b) Motor learning.
c) Memory formation.
d) Cognitive function.
Cognitive function
Which of the following is part of the autonomic nervous system?
a) Enteric nervous system
b) Somatosensory cortex
c) Hippocampus
d) All the options are correct
Enteric nervous system
What is the main difference between the autonomic and somatic motor systems?
a) Somatic motor neurons are in the spinal cord.
b) Autonomic neurons form a 2-synapse pathway.
c) Somatic motor neurons use acetylcholine.
d) Autonomic neurons are in the brainstem.
Autonomic neurons form a 2-synapse pathway
The parasympathetic nervous system:
a) is the only autonomic input to the enteric nervous system.
b) initiates the flight-or-fight response.
c) acts on adrenergic receptors on the target tissues.
d) is absolutely needed for survival.
IS absolutely needed for survival
Which of the following statements about the sympathetic division is true?
a) Adrenergic receptors are inotropic receptors.
b) It relies exclusively on norepinephrine as the final neurotransmitter.
c) It acts on G-protein-coupled metaboreceptors.
d) Adrenergic receptors do not have a tissue-specific distribution.
It acts on G-protein-coupled metaboreceptors
Hypertension (high blood pressure) is often treated pharmaceutically using beta-adrenergic blockers. Which of
the following could be an adverse event of these drugs?
a) Decreased heart rate.
b) Increased blood pressure.
c) Lack of appetite.
d) Decreased urination frequency.
Decreased heart rate
