Neurotransmission Flashcards
(167 cards)
1
Q
Resting membrane potential voltage
A
-80 mv
2
Q
Threshold voltage
A
-55 mv
3
Q
Which communicates faster?
Chemical or electrical synapse
A
electrical
4
Q
Slower, more controlled communication
A
chemical synapse
5
Q
Primary cellular communication forms
A
Chemical (NTs)
Electrical (passive/active conduction)
6
Q
Chemical communication uses
A
NTs
7
Q
Synapse/synaptic cleft is located between…
A
the nerve terminal
&
post synaptic membrane
8
Q
If we open Na channels on the post synaptic membrane, what happens?
A
depolarization
9
Q
T/F
Normally, ICF is polarized.
A
True
10
Q
When negative voltage becomes more positive, it is called
A
depolarization
more positive/closer to 0
11
Q
Allows nearly instant binding of NT to post-synaptic membrane
A
synapse is very small
pre & post synaptic membranes very close together
12
Q
Neurons act as _____. They take info coming in and will fire/not fire, depending on ____ & ____.
A
integrating engines
timing
sequence
13
Q
Synapse locations
A
can synapse on:
dendrite
body
axon
terminal
14
Q
only thing neurons can do
A
decide whether to fire or not fire
15
Q
electrical communication
A
Passive Conduction
Active Conduction
16
Q
T/F
Very few places in the brain have true electrical conduction.
A
True
17
Q
T/F
Changes in voltage when ions enter the dendrite = change sensed at the cell body.
A
False
cell body senses only fraction of change that happens at dendrite d/t ion diffusion
(passive conduction)
18
Q
(Active/passive) conduction utilizes brownian motion.
A
passive
19
Q
disruption of charge
A
as ions diffuse, some of charge is lost
[ ] drops
20
Q
what increases disruption of charge?
A
more fluid
longer distance to travel
21
Q
disruption of charge occurs in (passive/active) conduction
A
passive
22
Q
Cl- influx can bring the potential to
A
-90
23
Q
active conduction
A
pass signal down the axon itself
constantly regenerated
voltage DOES NOT DIMINISH (like passive)
24
Q
(active conduction)
as charge passes along, triggers ______ channels to open.
A
voltage-gated Na
25
Wavelike, marching of charge down axon
active conduction
26
normal resting state (negative charge) is restored by
opening of K channels
K exits
27
T/F
A wave of depolarization travels down the axon, opening Na channels on one side of the axon, followed by K channels on the other side.
False
Na and K channels are intermixed on the axon
28
T/F
Na channels on the post-synaptic membrane are voltage gated.
False
Na channels on axon are
29
restores particular ion [ ]
Na/KATPase
3 Na out
2 K in
30
Na/KATPase
what comes in?
what goes out?
3 Na out
2 K in
31
Na/KATPase makes ICF more (-/+)
-
32
T/F
the neuron requires a separate signal to trigger repolarization
False
occurs automatically in response to voltage changes
33
Influx of Na+ changes voltage to
-40
34
boutons
nerve terminals
35
Dendrites (actively/passively) transmits info to cell body.
passively
36
A neuron's ribosomes are located in the
cell body/soma
37
To fire an axon, we stimulate the ___
axon hillock
38
axon hillock attaches....
axon and cell body
39
Neuron
ligand channels/receptors
(axon hillock)
receptor zones inside cell
react to particular substance
produces it in nucleus
releases via ribosome/biochem mechanism
40
T/F
The axon hillock features voltage gated Na channels
false
ligand gated
axon = voltage gated
41
Intracellular ligand channels in the axon hillock are associated with ___ channels.
Na
42
How do Na ions enter the axon hillock?
1. particular substance binds to **intracellular** receptor zone (ligand gated)
2. substance released intracellularly
3. interacts with receptor zone
4. opens Na channel
43
At the **axon hillock**, a substance binds to & interacts with an intracellular receptor, opening its associated Na channel. This is an example of a ______ gated channel.
ligand
not voltage
axon = voltage gated
44
ligand gated vs voltage gated channels
-what opens them
-location
45
Initiation of a signal occurs by activating (ligand/voltage) gated Na channels at the axon hillock.
ligand
1. stimulate ligand-gated Na channels (hillock)
2. Na enters, increasing voltage
3. stimulates the adjacent voltage-gated channels (axon)
46
_____ gated Na channels initiate positive depolarization at the ____ ____ that is sensed by the ____ gated Na channels adjacent to them.
ligand
axon hillock
voltage
47
T/F
Ca channels can be voltage gated
True
present esp at nerve terminal
48
triggers fusion of vesicles with terminal membrane
Ca influx
49
T/F
vesicle membranes are made of the same material as the membrane on the outside of the nerve terminal
True
fusion creates weak point
terminal absorbs vesicle membrane
pulls open
forces contents into synapse
50
Mechanism
Fusion of vesicle and terminal
(made of same material)
1. fusion creates weak point
2. terminal absorbs vesc. memb.
3. pulls vesc. open
4. contents into synapse
5. vesicle memb incorporated into nerve terminal
6. terminal constantly being pinched off to make more vesicles
51
2 types of axons
myelinated
nonmyelinated
52
myelinated sheaths of PNS
schwann cells
wrap their membrane around axon
53
Schwann cells ___ the axon, bc cell membrane is made of ___ material
insulate
lipid
54
Schwann cells/myelin sheaths, prevent penetration of ___.
ions
55
(myelinated axon)
the only place ions can enter
nodes of Ranvier
(gaps between myelin sheaths)
56
myelin is made up of ....
EC membrane
57
myelinated axon benefits
-less energy required
-faster conduction
"saltatory conduction"
jumps current between nodes
58
(myelinated axon)
Na channels are only located...
in the nodes of Ranvier
(gaps between myelin sheaths)
59
T/F
Most nerves are myelinated.
True
60
T/F
Most nerves in the periphery are myelinated.
True
61
T/F
All motor nerves are myelinated
True
62
Motor neurons only synapse in the periphery at...
their final point of contact (the muscle)
63
(myelinated/non-myelinated) nerves are more likely to be disrupted by ion channels/current in ECF.
non-myelinated
64
(myelinated/non-myelinated) have less ion channels, so there is less transport of ions, and thus requires (more/less) energy for Na/KaTPase
myelinated
less energy
65
T/F
all nerves have the same resting potential
False
but
all within same range -60 to -90
66
⭐️
normal ion [ ]
67
When Na enters cell, voltage becomes
-40 to -30
depends on how much enters
68
⭐️
Primary contributor to resting charge is
K+ channels
69
Which ion is a secondary messenger?
Ca
70
only channel open at rest (-70 mv)
K+ channels
-70 is negative enough to where we can keep K in the cell
electromotive forces = diffusional forces
71
electromotive force
charges of ECF/ICF and charge of ion interact to either facilitate or inhibit movement across membrane
72
entrance is opposed by electromotive force but aided by diffusional force
Cl-
- charge & - ICF = repels
[ ] gradient: High ECF, low ICF = facilitates
73
entrance is aided by electromotive force and diffusional force
Na+
+ charge & - ICF = facilitates
[ ] gradient: High ECF, low ICF = facilitates
74
Why does Na enter so rapidly?
electromotive force & diffusional force favors its entrance into cell
75
exit is inhibited by electromotive force but aided by diffusional force
(as K is leaving the cell)
K+
+ charge & - ICF = holds it inside cell
[ ] gradient: high ICF, low ECF = facilitates exit
76
Why does more Na enter cell than K exiting?
Na entrance aided by electromotive & diffusional forces
K exiting only favored by diffusional forces
77
T/F
All K and Na channels open at the same voltage.
False
but they work the same way
78
How can K gradients be kept in balance if the channel is open at rest?
at rest = -70
-70 is negative enough to where we can keep K in the cell
electromotive forces = diffusional forces
79
At ___ mv, there is no *net* movement of K b/c...
-70 mv
electromotive forces = diffusional forces
80
Dendritic Conduction is an example of (passive/active) conduction.
passive
81
Axonal Conduction is an example of (passive/active) conduction.
active
Axonal = active
82
restores chemical equilibrium
Na/K/ATPase
83
Signal initiated at ____ by ....
axon hillock
internally ligand-gated Na+ channels
84
T/F
In order for the action potential to travel across the axon, there must be a fully positive charge.
False
does not need to be positive
it just becomes *less negative*
85
Channel plugs exist in...
a tri-state
86
hysteresis
oscillation occurring in a physical process
(structure goes back and forth between 2 forms)
Also:
Lag between plasma [ ] & drug rcptr [ ]
87
Tri-state allows the system to ___ itself.
reset
88
Existing in a tri-state prevents ____
hysteresis
89
Increases conduction rates
1. Myelination
-**Decreased Capacitance**
-Saltatory Conduction
2. Higher resting potential (less - = closer to having Na ch open)
3. Increasing Na+ channel density
4. **Increasing Axonal diameter (less resistance to impulse's flow**; fit more ions)
90
Capacitance
movement of ions across a membrane
91
Myelination (decreases/increases) capacitance
decreases
(can only move ions at nodes of ranvier)
92
Ions in smaller diameters have less movement/slow down d/t...
interact with membrane and other charges
93
T/F
Small diameter increases conduction rate.
False
decreases conduction rate
94
Synaptic Transmission occurs at
bouton/nerve terminal
95
Terminal membrane is gradually lost and is replenished by...
synthesized in cell body
transported down axon to terminal
96
T/F
Vesicles are usually composed completely of NTs
False
NT maybe primary substance
other components present (ie: proteins)
97
Vesicles contain ____ neurotransmitter
1 quanta of
98
1 quanta = ___ NTs
5,000-10,000
99
Vesicles are reformed by an (endo/exocytotic) process, and can then be refilled
endocytotic
(pinching off)
100
When wave of depolarization reaches nerve terminal, what happens?
-Ca channels open
-Ca influx (down its gradient)
-triggers S.R. to dump its Ca into ICF
-S.R.'s ion pump dumps into ECF
-very quickly taken back up w/ extra Ca that came in
101
Most ICF Ca is located in...
sarcoplasmic reticulum
102
multifolded tissues that store lots of Ca inside
sarcoplasmic reticulum
103
The surface of the sarcoplasmic reticulum has many _____
Ca ion pumps
104
What causes the large increase in Ca [ ] at the nerve terminal?
SR dumps its Ca into ICF
(not the Ca channels that are triggered when depolarization reaches terminal)
105
When Ca pumps complete their fxn at nerve terminal, the ICF has ____ Ca.
nearly net 0
106
Axon fibrils
rotating fibers
transport mechanism
ie: vesicles from soma --> terminal
107
How to make vesicles
1. vesicles produced in cell body
2. transported down axon
3. filled & used at terminal
-OR-
endocytotic process (pinching off membrane)
108
T/F
Vesicles hold a consistent # of NTs
False
109
Primary Excitatory NTs (7)
Acetylcholine
Norepinephrine, Epinephrine
Dopamine
Serotonin (at ionophoric 5-HT3)
Glutamic Acid
Aspartic Acid
110
Most numerous primary excitatory NTs
Glutamic Acid, Aspartic Acid
111
Serotonin is excitatory at ____ but inhibitory at _____
excite: ionophoric 5-HT3
inhibit: G-protein type receptors
"excite my ions!"
112
Primary Inhibitory
Gamma Amino Butyric Acid (GABA)
Glycine
Serotonin (at G-protein type receptors)
113
resting state/region of next AP
Na+ channel is closed
membrane potential -
114
refractory
Na+ channel inactive
membrane potential -
115
depolarized
Na+ channel open
membrane potential +
116
Na+ enters the channels when the region is ____
depolarized
117
Na+ channels are open when...
the region is depolarized
118
Na+ channels are inactive when...
refractory
(the AP just passed over this region)
119
Na+ channels are closed in the resting state and when...
its the next region the AP will trigger
120
When is membrane potential +?
depolarization
121
When _____, the Na+ channel plug goes into the lumen d/t ...
refractory/inactive
adjacent Na ions change channel shape
122
T/F
ACh is inhibitory
False
123
All volatile agents are highly potent inhibitors of _____ receptors
nicotinic acetylcholine (nAChr)
124
T/F
NTs are voltage dependent
True
requires influx of Ca++ into the presynaptic terminals
125
T/F
Myelination increases capacitance, leading to faster conduction.
False
**decreases** capacitance
(Capacitance: movement of ions across membranes)
126
Myelination requires less energy b/c...
conserves membrane potential with less ion transfer
less energy needed to reestablish Na+/K+ concentration gradients
127
Ca Channels on the bouton are ___ gated
voltage
128
Afferent nerve fibers
Type A fibers: largest diameters, fastest; myelinated; divided into alpha, beta, gamma, delta
Type B fibers: smaller diameter; myelinated
Type C fibers: smallest diameter; unmyelinated; slow pain, pruritis, temperature sensation
129
transmission (impulses btwn neurons) is mediated by ___ while transduction (AP) is conducted by ___.
Transmission = Neuro**transmitters**
Transdxn = channels w/in membrane
130
Norepinephrine receptor activity
excitatory at A1 receptors
inhibitory at A2 receptors
131
Inhibited by antiemetic
Serotonin
132
T/F
etomidate acts on GABAr
True
133
Coagonist at the N-methyl-D aspartate (NMDA) receptor
glycine
134
Principle inhibitor neurotransmitter in spinal cord
glycine
increases Cl- into the cell, causing hyperpolarization
135
T/F
The PNS and SNS are part of the motor aspect of the nervous system.
True
motor portion of ANS:
SNS and PNS
136
Neurons are surrounded and protected by
glial cells
137
Types of Glial cells in CNS
Astrocytes: anchor to blood supply; exchange between neurons and capillaries
**Microglial cells: immune defense**
Ependymal cells: create, secrete, and circulate CSF
Oligodendrocytes: myelin sheath
(CNS glials: "C.A.M.E.O.")
138
Types of Glial cells in PNS
Satellite cells: surround & support (like astrocytes)
Schwann cells: myelin sheath
"P.S.S."
139
Multipolar neuron
one cell body, one axon, and a bunch of dendrites
Most of our neurons are multipolar neurons, especially motor neurons and interneurons
140
Bipolar neuron
**two processes** (“bi-“) with an axon and a single dendrite extending from opposite sides of the cell body
141
just one process; usually found on sensory receptors
unipolar neuron
142
How we respond to threats/pain
SENSORY receptors detect stimulus
⬇️
interneuron (CNS; process info (integration)
⬇️
motor neuron
⬇️
sends response to skeletal muscles to contract and pull away
⬇️
React
motor effectors = MOTOR response
143
determines movement of the ions in/out of the cell
Electrochemical gradient
144
open in response to physical stretching of the membrane
Mechanically-gated channels
145
summation
electrical potentials combine at the axon hillock
(process that determines whether or not an AP will be generated by the combined effects of excitatory and inhibitory signals)
146
T/F
multiple APs can be generated at once
False
one at a time
uniform strength and speed
147
Restores RMP from hyperpolarized state
NaKATPase
148
Graded potential
only a few channels open
a little bit of sodium enters the cell
localized slight change in the membrane potential
149
Action potentials vary in
Frequency
(Less frequent = weak stimulus; more frequent = stronger)
Conduction velocity (speed)
(Myelinated = faster; unmyelinated = slower)
150
Action potentials don’t vary in
intensity through amount of **voltage**
151
T/F
signals can be modified, amplified, inhibited, or split
True
At a synapse this is possible
152
T/F
Electrical synapses offer immediate communication.
True
153
Brain outer layer vs inner layer
Outer layer = gray matter
inner layer = white matter
154
Broca’s area location
left side of frontal lobe
155
contains Wernicke’s area for written/spoken language
temporal
156
contains hippocampus and amygdala of limbic system
temporal
157
The Brainstem connects which two structures?
cerebral cortex to the spinal cord
158
determines overall level of CNS activity
RAS
159
sends out reflexive motor signals
midbrain
“Those reflexes are mid, B.”
160
Limbic system & hypothalamus:
emotions
core temp
___
___
thirst
appetite
161
short term memory
Hippocampus
162
sexual and social behavior
Amygdala
163
Basal ganglia
Inhibitory process is mediated by
dopamine and GABA for skeletal muscle contraction
164
Ascending/descending tracts in ___ matter
white
165
Sensory info flows into ___ portion of gray matter; motor info outflow exits from ___ portion
dorsal (posterior)
ventral (anterior)
(S.A.G.'D. : sensory afferent grey dorsal)
166
T/F
The peripheral nervous system is responsible for integrating sensory information and coordinating both conscious and unconscious activity
False
CNS does this
167
Meningeal layers
bone
dura matter
arachnoid matter
pia matter
