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Neuroscience II Exam II > Neurophysiology Review > Flashcards

Neurophysiology Review Flashcards

1
Q

T/F: L-dopa is produced when dopamine is broken down by neurons

A

False

L-dopa is produced from tyrosine and then converted to dopamine

Clinical relevance: Parkinson disease/mood/affect/emotional experience; binds 2 metabotropic receptors

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2
Q

T/F: the circumventricular organs are characterized by the absence of glial endfeet surrounding the cerebral capillaries

A

True

The circumventricular organs are regions where the BBB is “incomplete”. Tight junctions between capillary endothelial cells are not present

These regions all require exposure to plasma constituents to do their job — area postrema (vomiting), OVLT and SFO (ADH release), posterior pituitary (ADH and oxytocin release)

These areas are also more sensitive to damage d/t toxins in the blood, and drugs will cross into these regions

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3
Q

T/F: influx of calcium into a neuron can elicit apoptosis in a susceptible neuron

A

True

Calcium influx via the NMDA receptor initiates apoptosis in any cell receiving synaptic input from the overactive cell, even if the cell isn’t impacted by the original insult

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4
Q

T/F: full consciousness is produced by the release of ACh and glutamate (EAA) from medullary and pontine regions

A

False

These systems are sufficient to be considered “awake”, but full awareness/consciousness requires serotonergic, noradrenergic, and dopaminergic signaling as well

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5
Q

T/F: P-glycoprotein is required for the movement of glucose from the plasma into the CSF

A

False

Glucose requires a specific transporter (GLUT1) that is insulin inependent

P-glycoprotein is responsible for moving many drugs or other substances from the CSF to the blood

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6
Q

T/F: the ability to recognize an object by feel alone (stereognosis) is completed in somatosensory cortex 1

A

False

This is done by S2 which also is able to compare 2 objects and ties to memory

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7
Q

T/F: damage to the insular cortex abolishes the ability to feel pain

A

False

The insular cortex coordinates autonomic responses. Damage produces asymbolia - painful inputs are recognized as painful, but not perceived as unpleasant

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8
Q

T/F: damage to the dorsal visual pathway impairs the ability to use visual info in motor actions

A

True

The dorsal visual pathway involves the use of visual information in motion while the venral visual pathway involves higher cognitive processing using visual info (naming objects, etc…)

Because of the 2 pathways, the ability to name an object can be divorced from the ability to copy the object

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9
Q

T/F: activation of the saccule will give rise to the sensation of falling forward

A

False

The utricle senses horizontal linear acceleration, while the saccule senses vertical linear acceleration.

Falling forward is sensed by the anterior semicircular canals! Falling backward would be the posterior canals, and turning in circles would be horizontal canals

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10
Q

T/F: Spasticity results from increased gamma-motor neuron activity in the muscle spindle

A

True

Spasticity results from damage to the cortical regions that activate the brainstem inhibitory area, which usually inhibits gamma motoneurons. Thus if this area is damaged, there will be un-inhibited gamma-motorneuron activity in the muscle spindle

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11
Q

What creates and maintains the membrane potential?

A

Created by Na/K ATPase (3 sodium out for every 2 potassium in)

Maintained by the selective permeability of the membrane via K+ leak channels and ClC1 chloride channel

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12
Q

The source of myelin is different in central vs. peripheral neurons.

____ provide myelination in CNS while _______ provide mylination in the PNS

A

Oligodendrocytes = central

Schwann cells = peripheral

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13
Q

Release of NT onto a postsynaptic cell results in different actions depending on if it is ionotropic or metabotropic

If it is ionotropic, and the signal is _____ or ______ -the cell depolarizes and an EPSP occurs

If it is ionotropic, and the signal is _____ or ______ -the cell hyperpolarizes and an IPSP occurs

A

Calcium; sodium

Chloride; potassium

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14
Q

Release of NT onto a postsynaptic cell results in different actions depending on if it is ionotropic or metabotropic

What are some examples of types of G proteins that impact intracellular response?

A

Gs = stimulation of AC activity

Gi = inhibition of AC activity

Gq = activation of IP3/DAG

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15
Q

What monoamine NTs are derived from tyrosine

A

Dopamine — binds 2 metabotrobic receptors

Catecholamines: epinephrine and norepinephrine — binds alpha and beta adrenergic receptors

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16
Q

What monoamine NT is derived from histidine

A

Histamine — involved in wakefulness, binds H1 and H2 receptors

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17
Q

What monoamine NT is derived from tryptophan

A

Serotonin (5-HT)

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18
Q

Serotonin (5HT) binds multiple receptor subtypes. Most are metabotropic, but one is ionotropic. What is the significance of the ionotropic receptor for serotonin — what is the physiologic response?

A

The ionotropic receptor is found in area postrema and triggers vomiting

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19
Q

GABA is an inhibitory NT involving chloride entrance into the cell. It binds 2 receptors, GABA-A which is ______ and GABA-B which is ______

A

Ionotropic; metabotropic

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20
Q

Almost all spinal inhibitor reflexes rely on what NT? What type of receptor?

A

Glycine — ionotropic receptor (chloride)

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21
Q

Which NT receptor involves calcium influx and is especially active after seizure/stroke/TBI?

A

NMDA receptor

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22
Q

The CSF in the CNS is produced by the ___ ____ and membranes lining the ventricles

Describe its content in comparison to plasma

A

Choroid plexus

Low protein, glucose, and K content relative to blood

Mg content higher than plasma

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23
Q

2 components of BBB

A

Tight junctions between capillary endothelial cells

Podocytes from glial cells cover capillaries to reduce surface area

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24
Q

What happens to cerebral blood flow if systemic BP goes too high?

A

Activation of alpha-adrenergic receptors on cerebral vasculature

Vasoconstriction

Prevents high BP from damaging capillaries (where BBB is — so protects the BBB as much as possible)

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25
Q

What happens if cerebral blood flow is compromised?

A

Brain will activate pressor regions in the medulla, driving systemic pressure up to force blood through to the brain

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26
Q

The vasculature in the brain is innervated with ______, meaning if the vasculature is distended, torqued, or twisted, _____ is perceived

A

Nociceptors; pain

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27
Q

What effect do intracranial bleeds have on BP?

A

Increased intracranial pressure can lead to tremendous increases in systemic BP as the brain tries to maintain perfusion

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28
Q

To be considered “awake” what 2 components are required?

A

Medullary RAS and parabrachial nuclei (glutamate)

Pedunculopontine tegmental nucleus and laterodorsal n. (ACh)

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29
Q

Differentiate S1 from S2 in sensory processing

A

S1 = initial processing - identify characteristics of what activated receptors

S2 = stereognosis (ability to recognize an unseen object by touch); comparing 2 objects

30
Q

Role of PTO in sensory processing

A

Association cortex; involved in naming objects

31
Q

Nociception involves slightly myelinated _____ fibers, or unmyelinated ____fibers

The peripheral ending can be activated by numerous chemicals, including ____ and _____ - leading to increased amount of pain perceived

A

A delta; C

Bradykinin; substance P

32
Q

Spinal processing is different for A vs C pain fibers

_____ path is likely for fast/sharp pain via A delta fibers

_____ path islikely for slow/dull pain via C fibers

A

Spinothalamic

Spinoreticulothalamic

33
Q

The spinoreticulothalamic path for C type pain is important because there is a synapse in the spinal cord at the level where the afferent enters the spinal cord

This synapse is where what 2 events happen?

A

The gating mechanism — non-nociceptive input from a-beta fibers (cutaneous) inhibits painful inputs via presynaptic inhibition

Descendign opioid inputs via the raphe nuclei also act to decrease transmission at this synapse

34
Q

What causes chronic, or neuropathic, pain?

A

Changes in periphery leading to sensitization of the nociceptors themselves, or changes in spinal cord sensitivity to nociceptive input

35
Q

In terms of focusing image onto the retina, the ____ involves the most refraction of light while the ____ has variable refraction

A

Cornea

Lens

[more round lens/more bending = close vision; flatter lens/less bending = far vision]

36
Q

Condition characterized by cloudiness in the lens interfering with light passage

A

Cataract

37
Q

Condition characterized by inability to change the shape of the lens (stiffness or inflexibility)

A

Presbyopia

38
Q

The mechanism of photoreceptors involve light hitting the photoreceptor, causing it to hyperpolarize, reducing ____ release

A

Glutamate

39
Q

Disruptions in the _____ ___ ____ disrupt the ability of the eyes to move together; also involved in focus, detection of motion, and initial processing

A

Lateral geniculate body

40
Q

Significance of primary visual cortex

A

Initial processing; columns devoted to orientation of the lines in the visual field

Job is to create a contour map of the visual field

Blobs involved in initial color processing

41
Q

What do V2 and V4 do in visual processing?

A

V2 = depth perception

V4 = color perception

42
Q

Endolymph vs. perilymph contents

A

Endolymph surrounds hair cells; high in K+, low in Na+

Perilymph is similar to plasma/ECF; high in Na+, low in K+

43
Q

Basilar membrane vs tectorial membrane

A

Hair cells arise from organ of Corti in basilar membrane; basilar membrane bends based on wavelength of sound. High pitched sounds cause maximal bending close to oval window; low pitched sounds cause maximal bending at helicotrema

Tip of hair cells insert into tectorial membrane

44
Q

Pathway of sound to the brain

A

Superior olive (localization of sound source) — medial detects intraural time differences; lateral detects intraural volume differences

Inferior colliculus suppresses info from echoes

Superior colliculus creates 3D map of where sound is

Primary auditory cortex creates tonotopic map of sound, loudness, etc

Auditory association cortex makes complex map of sound, including harmonies, etc.

45
Q

Myotatic refex vs. GTO reflex

A

Myotatic reflex occurs when stretching of muscle spindle leads to contraction of stretched muscle

GTO reflex occurs when too much force is placed on contracting muscle so that strong inhibition stops contraction

46
Q

Role of primary motor cortex and supplementary and premotor cortex in voluntary motion

A

Primary motor cortex = relay the desired action to the lower motoneurons to activate the muscles

Supplementary and premotor cortex = planning of motions, postural control

47
Q

Role of parts of the cerebellum in voluntary motion

A

Spinocerebellum: medial is postural control, lateral is to correct ongoing motion

Cerebrocerebellum involves planning of complex motion; motor memory

Vestibulocerebellum is eye movements/postural movements for future motions

48
Q

Contractile cells of BBB

A

Pericytes

49
Q

Role of Na/K/2Cl transport in BBB

A

Transports ions from CSF to blood

Expression tied to endothelin 1 and 3

Endothelin production tied to astrocyte signals

50
Q

Role of P-glycoprotein in BBB transport

A

Moves drugs that don’t belong that crossed BBB back into blood

51
Q

The NMDA receptor is an ionotropic receptor activated by exogenous N-methyl-D-aspartate. It is also activated by _____ and ______. When activated, it allows _____ influx

A

Glutamate; aspartate; Ca

52
Q

_____ serves as a coagonist at the NMDA receptor and is required for EAA to have an effect, but on its own cannot open the channel

A

Glycine

53
Q

Role of Mg in NMDA receptor

A

Mg binds inside the channel, blocking it

To open the channel, Mg must leave; depolarization forces Mg out of the channel

[PCP binding site is inside the channel, internal to Mg binding site, and blocks the channel]

54
Q

Increased intracellular Ca following NMDAR activation results in what 4 events?

A

Activation of phospholipase A2 — release of arachidonate from membrane and physical damage to membrane; arachidonate acts at ryanodine receptor on ER releasing more Ca from intracellular stores causing unfolded protein response, activation of eIF2a-kinase, impaired mitochondrial function

Activation of calcineurin (phosphatase) - activates NOS, increases NO synthesis

Activation of Mu-calpain (protease) - proteolysis — spectrin, eIF4G, metabolic impairment

Activation of apoptotic pathway - cytochrome C and caspase 9

55
Q

Location of NT: dopamine

A

Substantia nigra, ventral tegmental area

56
Q

Location of NT: EAA

A

Dorsal and ventral pathways (to cortex)

57
Q

Location of NT: NE

A

Locus coeruleus

58
Q

Location of NT: serotonin

A

Raphe nuclei

59
Q

Location of NT: ACh

A

Pedunculopontine tegmental and laterodorsal nuclei

60
Q

Location of NT: histamine

A

Tuberomammilary nucleus of the hypothalamus

61
Q

Which division of the motor cortex determines whether it’s okay to move and identifies the goal and motion required to meet that goal?

A

Premotor cortex

62
Q

Which division of the motor cortex exerts postural control, identifies the specific motor sequence required and plans the motion, changing tactics if necessary?

A

Supplementary motor cortex

63
Q

Which division of the motor cortex codes the individual motions required to reach the goal and activate the muscles?

A

Primary motor cortex

64
Q

The ______ receives input from nearly all of the cerebral cortex and transmits it to the basal ganglia. The output from the basal ganglia (GPi and SNpr) is inhibitory and projects to motor areas in the brainstem and thalamus (releases_____)

A

Striatum; GABA

65
Q

Result of damage to any basal ganglia structure

A

Slowness of voluntary movement, involuntary movements, involuntary posutres, or a combination of these

66
Q

Result of damage to SNpc in basal ganglia

A

Tremor at rest, slowness of movement, rigidity, and postural instability (main features of parkinsons)

67
Q

Components of basal ganglia

A

Striatum (caudate + putamen) — output inhibitory

Globus pallidus (external segment+internal segment)

Substantia nigra (pars compacta+pars reticulata) — dopaminergic; stimulates D1(+) and D2(-) receptors

Subthalamic nucleus — input from frontal lobe, output excitatory to other BG nuclei, kept under tonic inhibition by Gpe

68
Q

Compare/contrast direct pathway vs indirect pathway via basal ganglia

A

Normally direct pathway allows motion and indirect pathway prevents motion

69
Q

What happens in basal ganglia with huntington disease?

A

Indirect pathway is abolished, resulting in excess movement

Loss of ACh tone causes this

70
Q

Noxious stimuli is sensed by TRP receptors, which are ligand-gated non-selective cation channels permeable to Ca, Na, and/or K

What are the following channels for: TRPV1, TRPA1, TRPM8?

A

TRPV1 — capsaicin, heat

TRPA1 — mustard, cool

TRPM8 — menthol, cool

71
Q

4 regions of the brain in which tight junctions are absent (i.e., not included in BBB)

A

OVLT
SFO
Posterior pituitary
Area postrema

Neuroscience II Exam II (5 decks)

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