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Flashcards in Neurophysiology Review Deck (71)
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1

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

False

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

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

2

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

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

3

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

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

4

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

False

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

5

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

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

6

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

False

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

7

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

False

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

8

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

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

9

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

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

10

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

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

11

What creates and maintains the membrane potential?

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

12

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

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

Oligodendrocytes = central

Schwann cells = peripheral

13

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

Calcium; sodium

Chloride; potassium

14

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?

Gs = stimulation of AC activity

Gi = inhibition of AC activity

Gq = activation of IP3/DAG

15

What monoamine NTs are derived from tyrosine

Dopamine — binds 2 metabotrobic receptors

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

16

What monoamine NT is derived from histidine

Histamine — involved in wakefulness, binds H1 and H2 receptors

17

What monoamine NT is derived from tryptophan

Serotonin (5-HT)

18

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?

The ionotropic receptor is found in area postrema and triggers vomiting

19

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

Ionotropic; metabotropic

20

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

Glycine — ionotropic receptor (chloride)

21

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

NMDA receptor

22

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


Describe its content in comparison to plasma

Choroid plexus

Low protein, glucose, and K content relative to blood

Mg content higher than plasma

23

2 components of BBB

Tight junctions between capillary endothelial cells

Podocytes from glial cells cover capillaries to reduce surface area

24

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

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)

25

What happens if cerebral blood flow is compromised?

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

26

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

Nociceptors; pain

27

What effect do intracranial bleeds have on BP?

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

28

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

Medullary RAS and parabrachial nuclei (glutamate)

Pedunculopontine tegmental nucleus and laterodorsal n. (ACh)

29

Differentiate S1 from S2 in sensory processing

S1 = initial processing - identify characteristics of what activated receptors

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

30

Role of PTO in sensory processing

Association cortex; involved in naming objects