Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

PHGY 209 > nerve/synapse lectures 5-6 > Flashcards

nerve/synapse lectures 5-6 Flashcards

1
Q

what is presynaptic terminal

A

swelling at end of axon
includes active zone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is active zone

A

specialized region
vesicles parked here in active zone
held in place
faces postsynaptic spine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are presynaptic vesicles

A

presynaptic terminals filled with presynaptic vesicles
made out of plasma membrane
packages neurotransmitter - chemical released by presynaptic terminal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is synaptic cleft

A

name of gap between presynaptic terminal and postsynaptic spine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is postsynaptic density

A

in post synaptic membrane
looks dark - many proteins
high density of proteins involved in process of transmitting info from presynaptic terminal to postsynaptic spine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what triggers neurotransmitter release in presynaptic terminal

A

activation of voltage gated calcium channels
ion channels are next to docked synaptic vesicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are ligand gated ion channels

A

postsynaptic receptors for transmission at brain synapses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

describe ligand gated ion channels

A

ion channels open up pore when binds a small messenger molecules
released by presynaptic terminal and activates ion channel in postsynaptic spine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what are ligand gated ion channels AKA

A

neurotransmitter receptors
ionotropic receptors (since they are ion channels)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what does calcium do

A

biochemical signal and causes cell to do things
can cause cells to contract (biochemical signal in skeletal muscle)
triggers sequence of biochemical events in presynaptic terminal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

describe calcium levels inside and outside cell

A

outside cell = low concentration
inside cells and presynaptic terminal = veryyyyy low, so calcium wants to flow in down concentration gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

do neurons want to keep calcium levels high inside the cell

A

wants to keep calcium levels in cell low because calcium is a signalling molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

describe the types of signal transformations during synapse

A

ap = electrical signal then gets to presynaptic terminal and is converted to chemical signal = neurotransmitter and then converted back to electrical signal in postsynaptic cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

name the 3 main steps of chemical synaptic transmission

A

1 = ap invades presynaptic terminal, calcium channels open and result in calcium influx into terminal
2 = synaptic vesicles fuse with presynaptic membrane releasing transmitter into synaptic cleft
3 = transmitter diffuses across the cleft and activates receptors in postsynaptic membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

describe step 1 of chemical synaptic transmission

A

wave of depolarization depolarizes presynaptic terminal and gets more positive
causes voltage gated calcium channels to open
calcium levels increase, small amount flowing in changes the concentration significantly
calcium binds to proteins found in presynaptic terminal and activates them and sequence of biochemical events, so a few vesicles docked in active zone will fuse to PM and open and dump contents (neurotransmitter) into cleft

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

describe step 2 of chemical synaptic transmission

A

neurotransmitter in cleft
binds to ligand gated ionotropic neurotransmitter receptors and causes ion channels to open and changes electrical properties of postsynaptic cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the fusion of a synaptic vesicle at an active zone dependent on

A

calcium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

the postsynaptic response to neurotransmitter is either what (name and describe - 2)

A

EPSP = excitatory postsynaptic potential, depolarizes postsynaptic membrane
IPSP = inhibitory postsynaptic potential, hyperpolarizes postsynaptic membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

describe excitatory synapses (EPSP)

A

on spines
makes postsynaptic cell more likely to fire an ap
closer to ap threshold, depolarizes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

describe inhibitory synapses (IPSP)

A

on dendritic shaft
makes postsynaptic cell less likely to fire an ap, hyperpolarizes postsynaptic cell and pushes away from ap threshold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is the main excitatory neurotransmisster in brain

A

glutmate (an amino acid)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is monosodium glutmate

A

MSG
can have effects if too much since glutamate is a biologically active neurotransmitter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is rapid excitatory transmission at synapses due to

A

actions of glutamate on 2 types of ionotropic glutamate receptors = AMPA and NMDA receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

describe NMDA and AMPA receptors

A

both in postsynaptic spine
ion channels that open in response to binding of small molecules (like neurotransmitters) to receptor sites on their external surfaces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
what are AMPA receptors responsible for
fast EPSP at excitatory synapses
26
describe AMPA receptors creating EPSP
calcium flows into presynaptic terminal docked glutamate vesicles will fuse and dump glu into cleft and binds to AMPA receptor in postsynaptic cell and opens ion channel pore is permeable to sodium, so sodium flows in and depolarizes
27
what is EPSP
small transient depolarization of the postsynaptic spine depolarization is super short, a few milivolts and lasts around 20msec (long compared to ap) just brings it a bit closer to threshold
28
in typical brain synapses
depolarization causes by a single EPSP is > (or equal to) a few milivolts and lasts around 20msec
29
is the depolarization caused by a single EPSP large enough to depolarize initial segment to threshold
NOOOO too small need around 50-100 epsps neuron usually has many synapses, most are excitatory EPSP and many of these happen at same time they add to each other and drives postsynaptic cell to ap threshold
30
does ap happen in dendrites
nooo depolarization spreads passively and can add together = depolarizes initial segement
31
how many epsps must sum at initial segment to initiate ap
50 to 100
32
what can the near simultaneous epsps come from
multiple synapses acting in synchrony individual synapses activated at high frequencies
33
what are the 2 key properties of NMDA receptors
at resting membrane potential the pore is blocked by magnesium, depolarization expels magnesium and enables pore to conduct open pore is highly permeable to calcium and monovalent cations
34
describe NMDA receptors at resting potential
pore plugged by mg so will not react when glu arrives also need glycine (along with glu)
35
describe NMDA receptors at threshold potential
if membrane is depolarized = mg comes out since the inside is not as negative, and magnesium is attracted to the negatives, unplugs and allows calcium to flow opens and makes pore for calcium and flows into presynaptic cell and triggers biochemical events in spine
36
what does NMDA receptor act as
Coincidence receptor
37
what is a coincidence receptor
detects 2 things happening at same time detects presynaptic neuron released glutamate and postsynaptic cell is already depolarized if these 2 things happen at same time = NMDA receptor can conduct calcium into cell
38
what happens at -70mv and if postsynaptic membrane is depolarized
at -70mv, almost all synaptic current at an excitatory glutamate synapse is carried by Na+ through AMPA receptors if postsynaptic membrane is depolarized a substantial calcium current flows through NMDA receptors
39
what is synaptic plasticity
high active excitatory synapses become stronger epsps become larger involves NMDA receptors
40
how do you learn things
synapses which get stringer ex = learn a new word, connections between the word and meaning become stronger by specific synapses becoming stronger, pathways become stronger
41
what is LTP (long term potentiation)
Experimental protocol records epsps in postsynaptic neuron and puts electrode to simulate presynaptic neuron send an ap = 1 test pulse and then stimulate presynaptic membrane a bunch
42
what happens when burst of aps (LTP)
high frequency activity depolarizes postsynaptic spine, removes magnesium block of NMDA receptor and enables them to conduct calcium lots of glutamate released, induction phase
43
what happens hours after induction of LTP
epsps are larger send a single test pulse = will be larger than initial synapse will have greater influence on if cell fires ap many effects can happen
44
what are the 3 steps/summary of LTP
control induction LTP
45
what is excitotoxicity
high concentrations of glutamate is toxic to neurons Phenomenon thought to involve calcium influx through NMDA receptors
46
what is glutamate
also a neurotoxin brain must regulate carefully
47
what happens if too much glu
neurons get way too depolarized and lots of calcium flows into and if calcium is super high cell with die
48
describe effect of msg
adults have blood brain barrier so glutamate will not get into brain but in babies = not developed and more susceptible to excitotoxicity (in olden days, msg would be in baby food since moms would taste and be like yum, so good for baby)
49
describe effect of stroke
no oxygen to regions of brain and neurons die (1st phase of neurodegeneration) and release much glu and diffuses to other neurons and diffuses out of localized region where stroke happened into surrounding areas (penumbra) and too much depolarization and cells die too (2nd phase of neurodegeneration)
50
what is excitotoxicity likely to contribute to
neuronal degeneration after stroke and in some neurodegenerative diseases important in epilepsy
51
what is main inhibitory neurotransmitter in brain
gamma-aminobutyric acid (GABA)
52
what receptor is responsible for IPSPS
postsynaptic receptor GABA a receptor
53
describe GABA a receptors
GABA is in vesicles and is released and binds to post synaptic ligand gated ion channels GABA a receptors open and form pore and changes electrical properties of post synaptic cell
54
what is GABA
neurotransmitter derived from amino acid smal molecule
55
what type of receptor is GABA a
ionotropic
56
what does activation of GABA a receptor cause
influx of chlorine and hyperpolarizes postsynaptic membrane inhibits post synaptic cell
57
what can GABA a receptors be acted on by
pharmacological agents
58
describe effects of benzodiazepines on GABA a
xanax and valium mild tranquillizers feel relaxed and sleepy drugs bind to GABA a and potentiate, make receptor more sensitive to GABA enhances transmission to inhibitory synapses and causes more inhibition in brain and increased efficacy of inhibitory synapses
59
describe effects of barbiturates on GABA a
phenobarbital and pentobarbital do same thing and act on GABA and makes inhibitory synapses stronger stronger than benzodiazepines has bigger effect on receptors and will just put you to sleep
60
describe effects of ethanol - alcohol on GABA a
makes you sleepy acts on GABA a receptors partly due to potentiating GABA a
61
do neurons receive both excitatory and inhibitory synapses
yesssss some of each type
62
where are excitatory and inhibitory synapses located
excitatory = located on dendritic spines Inhibitory = clustered on or near the cell soma, where inhibitory effect is maximal
63
whether or not neuron fires ap depends on...
relative balance of EPSPs and IPSPs depends on relative amounts of excitatory vs inhibitory, shapes firing power of neuron and how it communicates
64
what is output of neuron
all or none firing of action potentials down axon
65
can a neuron be both excitatory and inhibitory
NOOO excitatory or inhibitory will only released GABA or glu from terminal, will not switch back and forth
66
give an ex of an inhibitory and excitatory neuron
pyramidal neurons = excitatory, release glu perkinje = inhibitory, release GABA
67
describe how inhibitory neurons are stimulated to release GABA
must fire ap and to fire ap must have excitatory synapses on dendrites drives ap to inhibit other neurons
68
what happens if there is no inhibition and just excitation
excitation takes over and feeds on itself = epileptic seizure, electrical storm in brain inhibitory sculpts activity in nervous system and acts as break to control excitation drugs that block GABA receptors can also cause seizures
69
what are. Metabotropic receptors (G-protein coupled receptors, GPCRs)
different family of neurotransmitter receptors not ion channels
70
what do glutamate synapses have
ionotropic receptors = AMPA and NMDA metabotropic glutamate receptors (mGluRs)
71
describe mGluRs
not ion channels activated by glutamate relays chemical signal to inside of postsynaptic neuron
72
what does activation of mGluRs generate
chemical signal called second messenger inside postsynaptic spine changes conformation and becomes activated and initiates synthesis of 2nd messengers receptor initiates biochemical events on inside of cell
73
what are 2nd messengers
transmit messages, build up in cell and can diffuse concentrations build up and then can activate proteins inside of cell, ex like bind to ion channel and open it up and change electrical properties of post synaptic cell
74
what can 2nd messengers activate
ion channels protein kinases transcription factors
75
are metabotropic receptors fast
nooooooooo slow to turn on and off generation, diffusion and effects of small molecules can last long
76
describe 2nd messengers activating protein kinases
activate proteins attaches phosphate groups to proteins stick proteins to enzymes changes biochemistry of cells
77
describe 2nd messengers activating transcription factor
activated transcription factor migrates into nucleus and regulates transcription/expression of new genes (regulation of genes)
78
what do glutamate and GABA activate
both ionotropoic and metabotropic receptors glu = NMDA, AMPA and mGluRs GABA = GABA b and GABA b
79
what is difference between GABA a and GABA b
a = ionotropic b = metabotropic both activated by GABA
80
what are neuromodulators
dopamine serotonin Norepinephrine neuropeptides like endorphins interact mainly or entirely with metabotropic receptors
81
describe purpose of neuromodulators
not directly involved in fast flow of info, modulate global neural states like attention, mood, alertness shapes overall properties (global) of neuron systems overall functional states of nervous system
82
describe effects of norepinephrine
involves in sleep wake cycles and attention when asleep = neurons that release norepi are off when awake = neurons that release norepi fire at steady rate if suddenly pay attention = fires bursts of ap and release more norepi
83
describe effects of serotonin
given for depression specific serotonin reuptake inhibitors = increases amount of serotonin in brain correlation between serotonin and mood more serotonin is better than not enough
84
describe effects of dopamine
involved in behaviour associated with reward like casino and gambling, win = brain releases dopamine then neurons will release dopamine when gamble and you become a gambler also cigarettes = cause increase in dopamine and indirectly affects other receptors, if an addict went into a room with people smoking = neuron will release dopamine
85
where do neurons that release neuromodulators originate
small brainstem or mid brain nuclei axons project diffusely throughout the brain
86
describe neurons that release neuromodulators
small amount of neurons small clusters of them axons spread and branch all over brain and cerebral cortex
87
neurons that release neuromodulators are usually...
targets for pharmacological agents = treat psychological disorders main targets for substance abuse
88
describe effect of cocaine
cocaine up nose = face turns numb cocaine = local anesthetic like lidocaine and benzocaine inhibits voltage gated sodium channels but people still use it since it increases amount of dopamine and has stimulant and reinforcing effects, makes ppl wanna do it again
89
name the 2 specific areas where neurons that release neuromodulators are
SN = substantial nigra VTA = ventral tegmental area
90
describe effects of antidepressants
affect serotonin transmission
91
describe effects of amphetamines and cocaine and other stimulants
affect dopamine and norepinephrine (speeds you up, causes norepi neurons to release a lot of it) transmission

PHGY 209 (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions