Lecture 2: Foundations of Neuroscience II

Question 1

what are neurons

Answer 1

excitable cells that fire APs across a neural network in the nervous system

Question 2

four regions of the neuron

Answer 2

cell body, dendrites, axon, presynaptic terminal

Question 3

cell body properties

Answer 3

nucleus (stores genes), ER (protein synthesis)

Question 4

dendrites function

Answer 4

branch-like structures, receive inputs from other cells

Question 5

axon function

Answer 5

convey electrical signals, reach over 3 meters

Question 6

presynaptic terminal function

Answer 6

electrical signal dictates chemical release to communicate w/ other neurons

Question 7

myelin sheath function

Answer 7

fatty insulating structure; surrounds an axon to increase speed of conduction
- made of Schwann cells/oligodendrocytes

Question 8

how are Na+ and K+ concentrated inside & outside the cell

Answer 8

Na+ more concentrated outside, w/ K+ more concentrated inside

Question 9

when will an AP be initiated

Answer 9

when enough stimuli are received & the neuron reaches threshold
- all or nothing; once it goes, it goes; does not matter how intense stimuli are after it reaches threshold

Question 10

when does neuron depolarize

Answer 10

during AP (voltage inside the cell becomes positive, max of +40 mV)

Question 11

how does the cell depolarize during AP?

Answer 11

stimulus causes Na+ channels to open, allowing Na+ to flow into the cell, making the inside more positive

Question 12

what is repolarization driven by?

Answer 12

efflux of K+ ions

Question 13

what is hyperpolarization caused by

Answer 13

overshoot of K+ ions flowing out of the neuron

Question 14

result of hyperpolarization

Answer 14

makes it harder for another AP to immediately be initiated

Question 15

two ways to increase velocity of conductance

Answer 15

1. increase axon diameter
2. myelinate axon

Question 16

how does increasing axon diameter affect velocity of conductance

Answer 16

causes less resistance to current flow

Question 17

how does myelinating the axon increase velocity of conductance

Answer 17

AP is only produced at Nodes of Ranvier, impulse jumps from node-to-node (saltatory conduction)

Question 18

sensory neuron function

Answer 18

take sensory info from environment & send signal to brain

Question 19

motor neuron function

Answer 19

communicate info from brain –> tissues & organs throughout the body, allowing for movement

Question 20

interneuron function

Answer 20

transmit info b/w sensory & motor neurons; plays a role in learning, memory, & planning

Question 21

where are voltage-gated ion channels found

Answer 21

along the axon; propogate signal directionally

Question 22

what are the most diverse class of voltage-gated ion channels?

Answer 22

K+ channels

Question 23

what is a channelopathy

Answer 23

mutation in genes coding for ion channels that disrupt function
- manifest as neurological & psychiatric disorders

Question 24

what channelopathies does schizophrenia have

Answer 24

mutations in genes encoding Ca2+ & K+ channels

Question 25

what channelopathies does bipolar disorder have

Answer 25

genetic variations in genes involved in formation of Na+ & Ca2+ channels

Question 26

what channelopathies are involved in ASD

Answer 26

mutations encoding Ca2+ channels

Question 27

channelopathies involved in epilepsy

Answer 27

mutations encoding voltage-gated ion channels

Question 28

steps of small molecule neurotransmission

Answer 28

1. synthesis of enzymes in cell body 2. slow axonal transport of enzymes 3. synthesis & packaging of NT 4. release & diffusion of NT 5. transport of precursors into terminal

Question 29

steps of neuropeptide neurotransmission

Answer 29

1. synthesis of NT precursors & enzymes 2. transport of enzymes & pre-peptide precursors down microtubule tracks 3. enzymes modify pre-peptides to produce peptide NT 4. NT diffuses away & is degraded by proteolytic enzymes

Question 30

where do neuropeptides act

Answer 30

at GPCRs - different effects in different areas

Question 31

main function of neuropeptides

Answer 31

affect gene expression, local blood flow, synaptogenesis, & glial cell morphology

Question 32

differences b/w synthesis of neuropeptides & small molecules

Answer 32

peptides are only made in cell body (requires peptide bond formation on ribosomes) & small molecules are synthesized locally in terminals

Question 33

differences b/w storage vesicles for neuropeptides vs small molecule NTs

Answer 33

no uptake mechanism for NPs, but SMs are rapidly concentrated by vesicles

Question 34

diff b/w exocytotic release for NPs vs NTs

Answer 34

NPs are stored in large dense core vesicles & follow regulated secretory pathway; SM vesicles follow constitutive secretory pathway

Question 35

main feature of constitutive secretory pathway

Answer 35

membrane of synaptic vesicles must be processed before being able to release NT - SM NTs

Question 36

what presynaptic effect does low frequency neuronal firing cause?

Answer 36

causes localized elevation in cytoplasmic Ca2+ near the cytoplasmic membrane --> evokes predominant release of classic NTs only

Question 37

what presynaptic effect does high frequency firing cause?

Answer 37

more widespread elevation of Ca2+ --> causes additional release of NP co-transmitters

Question 38

cholinergic system effect

Answer 38

excitatory & modulatory

Question 39

glutamatergic system effect

Answer 39

primarily excitatory

Question 40

GABAergic system effect

Answer 40

inhibitory

Question 41

glycine system effect

Answer 41

inhibitory

Question 42

what are the biogenic amines

Answer 42

dopamine, serotonin, epinephrine, norpinephrine

Question 43

biogenic amines effect

Answer 43

modulatory

Question 44

peptidergic system effect

Answer 44

excitatory & inhibitory

Question 45

what are some drug targets?

Answer 45

transporters, enzymes, ligand-gated ion channels, voltage-gated ion channels, GPCRs

Question 46

what does neuroplasticity involve

Answer 46

changes in strength & efficiency of synapses & formation of new synaptic connections

Question 47

what causes LTP

Answer 47

repeated stimulation of a synapse to increase its strength

Question 48

what causes LTD

Answer 48

reduced stimulation can weaken synapses, making communication less effective

Question 49

function of AMPARs in LTD

Answer 49

trafficking of AMPARs out of the terminal & back inside the cell

Question 50

how does trafficking of AMPARs cause LTD

Answer 50

no more communication @ synapse bc there is no place for binding

Question 51

what is the process of structural changes?

Answer 51

experience --> growth of new dendritic spines / retraction of existing ones, altering neuron's connectivity

Question 52

what is the process of changes in NT release?

Answer 52

reduction of stimulation --> increase/decrease amount of NT release at synapses

Question 53

process of gene expression & protein synthesis

Answer 53

learning & repeated experiences can activate genes that produce proteins involved in synaptic modification & neuron growth

Question 54

function of myelination changes in LTP

Answer 54

neurons that need to make stronger connections have increased thickness of myelin sheaths