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Neurology-Week 1 > Signaling In The Nervous System > Flashcards

Signaling In The Nervous System Flashcards

1
Q

There is more Potassium (K+) in the (extra/intra)cellular fluid

A

Intracellular (around 120mM)

  • Think of a banana floating in ocean
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2
Q

Nerst Equation (pertains to a SINGLE ion)

A

E= (60/z) x log (Xout/Xin)

z= charge on ion

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3
Q

What are the 2 Major Determinants of the Membrane Potential at any given time

A

Ion gradients

Relative permeability of membrane to those ions

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4
Q

What is the Equilibrium Potential (Eion) for Potassium (K+)

A

-85 mV

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5
Q

What is the Equilibrium Potential (Eion) for Sodium (Na+)

A

+60 mV

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6
Q

The (Nerst/Goldman) equation takes into account multiple ions and their permeabilities

A

Goldman Equation

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7
Q

At rest, the permeability of neuron membranes to K+ is about ________ times that of Sodium

A

30

*thus the membrane potential lies closer to Equilibrium potential of K+ (-85mV) to keep them inside

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8
Q

What is the resting membrane potential of neurons and skeletal muscle cells

A

-40 to -85 mV

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9
Q

(Na+/K+) movement is responsible for the upstroke and depolarizing a neuron

A

Na+ (specifically influx)

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10
Q

(Na+/K+) movement is responsible for the repolarization and hyperpolarization of a neuron

A

K+ (specifically efflux)

*result in hyperpolarization due to being slow to close, so too much leaves

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11
Q

(Na+/K+) channels open and close very rapidly

A

Na+

*specifically, they “inactivate” very rapidly

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12
Q

(Na+/K+) channels open and close very slowly

A

K+

*cause of hyperpolarization

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13
Q

Describe the action of the Na+ and K+ channels during repolarization

A

Na+ channels “inactivated”

K+ channels opened

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14
Q

The (absolute/relative) refractory period is when ALL Na+ channels are either open or inactivated

A

Absolute

*so no action potential can be triggered at this time

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15
Q

The (absolute/relative) refractory period is when K+ permeability is elevated and SOME Na+ are still inactivated

A

Relative

*so a strong enough stimulus could trigger another action potential

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16
Q

Increasing the axon diameter (inc./dec.) the resistance of current and makes conduction (faster/slower)

A

Dec. resistance

Faster conduction

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17
Q

A (larger/smaller) axon is more likely to be myelinated

A

Larger

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18
Q

Myelinated neurons conduct action potentials (faster/slower)

A

Faster

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19
Q

(A/B/C) fibers are large-diameter myelinated axons; conduct very rapidly; used for proprioception, touch, pressure, fast pain, and skeletal muscle

A

A fibers

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20
Q

(A/B/C) fibers are smaller BUT myelinated; conduct adequately; used for preganglionic autonomic nerves

A

B fibers

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21
Q

(A/B/C) fibers are small and thinly/unmyelinated; very slow conduction; used for POSTganglionic sympathetics and slow pain/temp

A

C fibers

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22
Q

Electrical synapses have gap junctions, which are made by ___ for rapid communication b/w cells.

A

Connexons (each made of 6 connexins)

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23
Q

A rise in _______ in the axon terminal triggers the fusion of synaptic vesicles with the membrane, releasing NTs into the synapse

A

Calcium

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24
Q

Synaptic vesicles at Neuromuscular junctions have what NTs

A

ACh

25
Q

ACh receptors (nicotinic receptors) in the NMJ are where?

A

Top of junctional folds

26
Q

Voltage-gated Na+ channels at the NMJ are where?

A

Bottoms of junctional folds and on longitudinal surfaces

27
Q

EPSP

A

Excitatory Post-Synaptic Potential

28
Q

EPP

A

End Plate Potential

  • Specific EPSP occurring at the NMJ
29
Q

IPSP

A

Inhibitory Post-Synaptic Potential

30
Q

What determines whether or not a post synaptic response is Excitatory or Inhibitory

A

NT released
Receptor
Ion channels open or close
Selectivity of ion channels

31
Q

The ability of synapses in the CNS to produce a long-lasting increase in synaptic strength; can last days to weeks, selective for active synapses only and may underlie learning and memory at the synaptic level

A

Long-Term Potentiation

32
Q

What Amino Acids can act as NTs (3 total)

A

Glutamate
Glycine
GABA

33
Q

Amino-Acid Derived NTs (3 total)

A
  1. Serotonin (Tryptophan)
  2. NE*
  3. Dopamine*
    * Catecholamines (all Tyrosine-derived)
34
Q

ACh is used as a modulator of motor coordination where in the brain?

A

Basal Ganglia

35
Q

ACh is released by what neurons in ANS

A

Sympathetic NS: Preganglionic neuron

Parasympathetic NS: both pre and post-ganglionic neurons

36
Q

Sympathetic and Parasympathetic preganglionic neurons secrete ACh to postganglionic neurons that express what receptor

A

Nicotinic

37
Q

Parasympathetic postganglionic neurons secrete ACh to target tissues that express what receptor

A

Muscarinic

38
Q

Part of forebrain that synthesizes ACh, projects widely into the cortex and facilitates memory

A

Basal Nucleus of Meynert

39
Q

ACh can be used clinically to treat what?

A

Alzheimer’s Dementia

40
Q

Major excitatory NT in CNS for cognition, motor and sensory function; found everywhere in the brain, can cause “excitotoxicity” in which neurons under stress die when overly excited (like in Lou Gehrig’s Disease; aka ALS)

A

Glutamate

41
Q

Which NT is often implicated in “excitotoxicity”

A

Glutamate

42
Q

Disease associated with excess Glutamate

A

Lou Gehrig’s Disease (ALS)

*excitotoxicity causes neurons to die

43
Q

Major inhibitory NT in CNS for cognition, motor and sensory function; found predominantly on interneurons; causes sedation, muscle relaxation, etc.; used to treat anxiety

A

GABA

44
Q

Inhibitory NT in the CNS (spinal cord) for spinal cord inhibition; used to treat spasticity

A

Glycine

45
Q

Two main inhibitory NT in the CNS

A

GABA (brain)

Glycine (SC

46
Q

NT majorly found in the Raphe nuclei and pineal gland; role in limbic function and sleep (sleep, arousal, pain perception, food intake, emotions, temperature and mood); used to treat Depression via SSRIs

A

Serotonin

47
Q

Catecholamine used in the ANS (released by postganglionic neurons) and Locus Ceruleus; role in limbic function (arousal, attention and anxiety); used to treat ADHD

A

Norepinephrine

48
Q

Catecholamine synthesized in the Substantia nigra; found in brainstem (reward, pleasure, addiction) and hypothalamus (inhibition of prolactin release); role in basal ganglia function; too little = Parkinson’s, too much = Schizophrenia

A

Dopamine

49
Q

Examples of Neuropeptides

*they are neuroMODULATORS

A

Enkephalin, Substance P, CCK

*can be excitatory, inhibitory, or both

50
Q

Examples of Gases or Lipid Soluble compounds that can modulate the release of NTs; freely diffuse across membranes; often used to treat acute pain

*they are neuroMODULATORS

A

Nitric Oxide

Cannabinoids

51
Q

True/False: Synapses on the same neuron can be either EPSP or IPSP

A

True

52
Q

Integration of synaptic events (EPSPs and/or IPSPs) can initiate action potentials at the _________

A

axon hillock (1st node of Ranvier)

53
Q

ONE presynaptic neuron firing EPSPs (or IPSPs) multiple times in close succession

A

Temporal Summation

54
Q

SEVERAL different presynaptic neurons firing at different synapses at same time

A

Spatial Summation

55
Q

(Presynaptic Inhibition or Postsynaptic Inhibition)

Amount of excitatory NT released is decreased by effects of second neuron, whose axon makes synapses with first neuron’s axon (axo-axonic synapses).

  • Acts by either reducing Ca+ channels or activating K+ channels in the pre-synaptic neuron (to decrease 1st neuron’s release of excitatory NT)
A

Presynaptic inhibition

56
Q

(Presynaptic Inhibition or Postsynaptic Inhibition)

Inhibitory NT is released by presynaptic neuron to hyperpolarize postsynatpic membrane.

  • Acts by increasing permeability of postsynaptic K+ or Cl- channels
A

Postsynaptic (direct) inhibition

57
Q

What NT is important in motor function, autonomic function, and memory

A

Ach

58
Q

What enzyme synthesizes catecholamines from tyrosine?

A

Tyrosine Hydroxylase

Neurology-Week 1 (9 decks)

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