Signaling In The Nervous System

Question 1

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

Answer 1

Intracellular (around 120mM)

• Think of a banana floating in ocean

Question 2

Nerst Equation (pertains to a SINGLE ion)

Answer 2

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

z= charge on ion

Question 3

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

Answer 3

Ion gradients

Relative permeability of membrane to those ions

Question 4

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

Answer 4

-85 mV

Question 5

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

Answer 5

+60 mV

Question 6

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

Answer 6

Goldman Equation

Question 7

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

Answer 7

30

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

Question 8

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

Answer 8

-40 to -85 mV

Question 9

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

Answer 9

Na+ (specifically influx)

Question 10

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

Answer 10

K+ (specifically efflux)

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

Question 11

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

Answer 11

Na+

*specifically, they “inactivate” very rapidly

Question 12

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

Answer 12

K+

*cause of hyperpolarization

Question 13

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

Answer 13

Na+ channels “inactivated”

K+ channels opened

Question 14

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

Answer 14

Absolute

*so no action potential can be triggered at this time

Question 15

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

Answer 15

Relative

*so a strong enough stimulus could trigger another action potential

Question 16

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

Answer 16

Dec. resistance

Faster conduction

Question 17

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

Answer 17

Larger

Question 18

Myelinated neurons conduct action potentials (faster/slower)

Answer 18

Faster

Question 19

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

Answer 19

A fibers

Question 20

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

Answer 20

B fibers

Question 21

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

Answer 21

C fibers

Question 22

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

Answer 22

Connexons (each made of 6 connexins)

Question 23

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

Answer 23

Calcium

Question 24

Synaptic vesicles at Neuromuscular junctions have what NTs

Answer 24

ACh

Question 25

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

Answer 25

Top of junctional folds

Question 26

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

Answer 26

Bottoms of junctional folds and on longitudinal surfaces

Question 27

EPSP

Answer 27

Excitatory Post-Synaptic Potential

Question 28

EPP

Answer 28

End Plate Potential * Specific EPSP occurring at the NMJ

Question 29

IPSP

Answer 29

Inhibitory Post-Synaptic Potential

Question 30

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

Answer 30

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

Question 31

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

Answer 31

Long-Term Potentiation

Question 32

What Amino Acids can act as NTs (3 total)

Answer 32

Glutamate Glycine GABA

Question 33

Amino-Acid Derived NTs (3 total)

Answer 33

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

Question 34

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

Answer 34

Basal Ganglia

Question 35

ACh is released by what neurons in ANS

Answer 35

Sympathetic NS: Preganglionic neuron Parasympathetic NS: both pre and post-ganglionic neurons

Question 36

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

Answer 36

Nicotinic

Question 37

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

Answer 37

Muscarinic

Question 38

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

Answer 38

Basal Nucleus of Meynert

Question 39

ACh can be used clinically to treat what?

Answer 39

Alzheimer's Dementia

Question 40

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)

Answer 40

Glutamate

Question 41

Which NT is often implicated in "excitotoxicity"

Answer 41

Glutamate

Question 42

Disease associated with excess Glutamate

Answer 42

Lou Gehrig's Disease (ALS) *excitotoxicity causes neurons to die

Question 43

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

Answer 43

GABA

Question 44

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

Answer 44

Glycine

Question 45

Two main inhibitory NT in the CNS

Answer 45

GABA (brain) | Glycine (SC

Question 46

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

Answer 46

Serotonin

Question 47

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

Answer 47

Norepinephrine

Question 48

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

Answer 48

Dopamine

Question 49

Examples of Neuropeptides *they are neuroMODULATORS

Answer 49

Enkephalin, Substance P, CCK *can be excitatory, inhibitory, or both

Question 50

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

Answer 50

Nitric Oxide | Cannabinoids

Question 51

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

Answer 51

True

Question 52

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

Answer 52

axon hillock (1st node of Ranvier)

Question 53

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

Answer 53

Temporal Summation

Question 54

SEVERAL different presynaptic neurons firing at different synapses at same time

Answer 54

Spatial Summation

Question 55

(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)

Answer 55

Presynaptic inhibition

Question 56

(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

Answer 56

Postsynaptic (direct) inhibition

Question 57

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

Answer 57

Ach

Question 58

What enzyme synthesizes catecholamines from tyrosine?

Answer 58

Tyrosine Hydroxylase