Exam 1 Flashcards
1
Q
Membrane Permeability
A
How easily a substance can move through a membrane
2
Q
Membrane Conductance
A
How easily electric current flows through a cell membrane. Quantified in units of siemens (S).
Electrical equivalent of permeability
3
Q
Membrane Resistance (Rm)
A
The logical and mathematical inverse of conductance. Quantified in ohms
4
Q
Quantifiable unit of conductance
A
Siemens
5
Q
Rate of charge (ion) flow across a cell membrane. Quantified in amperes.
A
Membrane current
6
Q
Net electrochemical force acting on an ion.
A
Driving force
7
Q
The net effect of the total electrical charge distribution across the cell membrane and the ion concentration difference across the cell membrane.
A
Driving Force
8
Q
Membrane excitability
A
Ability of a cell to generate action potentials (brief, large changes in the electrical potential across the cell membrane)
9
Q
Channelopathies
A
Diseases caused by improper function of ion channels
10
Q
Membrane surface charge screening
A
EC cell surface has fixed negative (net) charge. Divalent cations bind to these, neutralizing them. Changes in levels of extracellular divalent cations can cause a change in membrane potential.
11
Q
Gives a value in mV at which the electrical potential across a cell membrane is exactly equal and opposite to the chemical potential of the concentration gradient.
A
Nernst Equation (equilibrium potential and Nernst Potential are synonymous)
12
Q
Describes an equilibrium state where net ion flux across the cell membrane is zero. The net ion flux of ALL ions is zero.
A
G-H-K equation
13
Q
to move a substance over a distance, you must have a pressure or force applied. The rate of movement depends on the amount of force and the ease at which the force can move thru a substance
A
Ohm’s law
14
Q
Ohm’s law applied to cell membrane
A
Flow of ions across membrane depends directly on the magnitude of the driving force for that ion AND the conductance of the membrane to that ion
15
Q
Inward current
A
Makes the interior of the cell more positive
16
Q
Outward current
A
Makes the interior of the cell less positive
17
Q
The cell membrane’s capability to store electrical charge
A
Capacitance
18
Q
Capacitance is directly proportional to ___
A
Membrane surface area
19
Q
Capacitance is inversely proportional to __________
A
Membrane thickness
20
Q
What does Ra (axon resistance) depend on?
A
Concentration of dissolved electrolytes, and the quantity of intracellular fluid available (which is determined by cross-sectional area of the axon which is determined by the diameter of the axon). Concentration of electrolytes is relatively constant, so diameter is principle determinant of Ra.
21
Q
Type of glial cells that produce myelin in the CNS
A
Oligodendrocytes
22
Q
Type of glial cells that are derived from monocytes and have similar phagocytic function as macrophages
A
Microglia.
23
Q
4 types of glial cells
A
Oligodendrocytes, astrocytes, ependymal cells, microglia
24
Q
Membrane current begins and ends
A
Instantaneously
25
Capacitance is _____ by myelination
Decrease
26
The distance at which DeltaVm declines by approximately 63%
Length constant (gamma)
27
How do Delayed rectifier K channels differ from Voltage-gated Na channels?
```
Ion permeability (K rather than Na)
Activation rate (slow compared to the voltage gated Na channels)
No fast inactivation (DRK channels do not have 'ball and chain' structure)
```
28
Tetrodotoxin (TTX)
Virulent poison from puffer fish which blocks voltage-gated Na channels and is fatal at very low doses
29
Produced by marine dinoflagellates responisble for red tide.
Blocks voltage-gated Na channels.
Shellfish can be contaminated w/ this and it can lead to paralytic shellfish poisoning.
Can be lethal
Saxitoxin (STX)
30
Derivates from cocaine which act by blocking voltage gated Na Channels.
Some have a 'use dependence' property meaning they bind to voltage gated Na channels in the 'open' state.
Local anesthetics, procaine, lidocaine
31
Partially block cardiac voltage gated Na channels to help control arrhythmias of the heart.
Mexilletine, procainamide. (Antia-arrhythmytics [some])
32
Drugs used to control seizures by acting on the voltage-gated Na channels.
Principle effect of these is to promote inactivate state of channel reducing ability of neurons to fire at a high rate.
Phenytoin, lamotrigine, carbamazepine
33
Tetraetylammonium, 4-aminopyridine and some ions (barium and cesium). Increase duration of the action potential and shorten the refractory period.
Delay rectifier K channel blockers
34
Current flowing down the axon ahead of the action potential
Capacitive current
35
Action potentials propagating in the normal, single, direction
Orthodromic
36
Action potentials propagating in the backwards directions
Antidromic
37
The principle determinant of the conduction velocity is the length constant of the axon in _____ axons
Unmyelinated
38
For unmyelinated axons, what can you increase to increase conduction velocity.
Diameter.
Increased diameter -> decreased axial resistance -> increased length constant -> further flow of capacitance current -> faster flow
39
Two major ways that myelination affects action potential propagation
1. Altering the distribution of ion channels in the axon membrane
2. Altering the length and time constants of the axon membrane.
40
Area with high density of Voltage dependent Na channels?
Stretch of axon membrane in the nodes of ranvier
41
Part of myelinated axons w/ high density of K channels
Nodes and juxtaparanodes
42
What section of myelinated axons have more K channel sensitivity to 4-aminopyridine?
Juxtaparanodal region
43
Do capacitive currents flow further along myelinated or unmyelinated axons and why?
Myelinated. Higher membrane resistance -> higher length constant.
44
Which type of cell is responsible for myelination in CNS
Oligodendrocytes
45
Which type of cell is responsible for myelination in PNS
Schwann Cells
46
Multiple Sclerosis is caused by defect in ?
CNS myelin
47
Guillain-Barre syndrome is caused by a defect in ?
Peripheral myelin
48
What is believed to be the method of improving MS w/ 4 aminopyridine?
Drug blocking voltage dependent K channels in the juxtaparanodal region (which are exposed by demyelination)
49
What motor protein is used to carry things down an axon?
Kinesin
50
Anchoring of vesicles in a presynaptic terminal to cytoskeletal filaments
Tethering
51
Interactions between this vesicle membrane protein and filaments leads to tethering
Synapsin
52
When phosphorylated, synapsin affinity for actin is ___
Reduced
53
Phosphorylating synapsin causes what?
Reduced affinity so vesicles become freed from the cytoskeleton where they are then transported to the active zone.
54
Vesicles which remain anchored to the cytoskeleton
Reserve pool
55
Vesicles that have been freed from the cytoskeleton and transported to the active zone
Releasable pool
56
Increasing free calcium in the axon terminal does what to synapsin?
Leads to the phosphorylation of synapsin which then releases vesicles.
57
Two proteins that act as target SNARE"s
SNAP-25
| Syntaxin
58
V-SNARE protein
Synaptobrevin
59
Calcium sensor which signals neurotransmitter release
Synaptotagmin
60
This connects the vesicle lumen w/ the extracellular space in the synaptic cleft, forming a pathway for the neurotransmitter to diffuse through
Fusion pore
61
These toxins enter the axon terminals and destroy SNARE proteins by cleaving one or more of the proteins involved in the v-SNARES and t-SNARES
Clostridium tetani
| Clostridium botulinum
62
Characterized by spinal inhibition resulting in unbalanced, excessive excitation of spinal motor neurons. This leads to uncontrolled muscle contraction and spasms often beginning in the jaw and then spreading.
Tetanus toxin
63
Characterized by decrease in ACh release (due to cleavage of SNARE proteins) in the neuromuscular junction. Leads to paralysis up to and including losing the ability to breath.
Botulsim toxin
64
Toxin which causes a massive release of neurotransmitter leading to release of ACh at the neuromuscular junction causing constant, painful muscle contractions and cramping. Requirement for Ca influx into synaptic terminal is bypassed.
Larotoxin poisoning - latrodectus spider - black widow spider
65
Toxin which prevents the activation of the voltage-gated calcium channels in presynaptic axon terminal which causes failure of transmitter release. This can lead to problems in neuromuscular junctions w/ potential respiratory failure
Conotoxin - cone snails
66
Two processes used in neurotransmitter termination for rapid removal of neurotransmitter from the synaptic cell
Reuptake
Enzymatic degradation
67
Transporters involved in neurotransmitter reuptake use what type of transport?
Secondary active transport
Na-dependent co-transport
68
Form joints between adjacent vertebrae, orientation of these determines the types of movement that occur between that vertebrae
Superior and inferior articular processes
Facets
69
How many cervical vertebrae are there
7
70
How many thoracic vertebrae are there
12
71
Number of lumbar vertebra
5
72
Number of sacral vertebrae
5, they are fused
73
of coccygeal vertebrae
3-5
74
Hole in the transverse process for vertebral artery and veins (c1-c7)
Foramen transversarium
75
Two key identifiers for cervical vertebrae
Bifid spinous process and foramen transversarium
76
No movement joint
Second cervical vertebra
77
Yes movement joint
First cervical vertebra
78
This cervical vertebra is the first palpable vertebra
Vertebra prominens (C7)
79
Inner gelatinous core of the intervertebral disk
Nucleus pulposus
80
Collagen fibers and fibrocartilage which makes up the ring of the intervertebral disk
Anulus fibrosus
81
Most common direction of herniation of nucleus pulposus through the anulus fibrosus
Postero-lateral
82
Permits considerable flexion-extension, lateral flexion, rotation
Cervical (c3-c7
83
Permit some rotation - little or no flex/extend
Thoracic
84
Permit flex-extend, little or no rotation, helps increase abd prssure.
Lumbar
85
Exaggerated lumbar curvature, common in pregnancy
Lordosis
86
Irreversible cessation of the function of nervous system
Legal definition of death
87
Neurons that conduct towards the CNS
Afferent
88
Axons that conduct away from the CNS (motor axons)
Efferent
89
Voluntary, conscious part of nervous system
Somatic nervous system.
90
Conntrol smooth and cardiac muscle, glands, and internal organs, largely unconscious actions
Visceral efferents. (Autonomic nervous system)
91
Area of skin innervated by a single spinal nerve
Dermatome
92
What spinal nerve is pinched if you have paresthesia in the thumb
C6
93
What level of herniation do you have if you have little finger paresthesia
C8 (disk between c7 -t1)
94
Contains sensory and motor axons to region of back; sensory to skin of back and posterior neck, motor axons t deep muscles of back and neck
Dorsal ramus
95
Inferior end of spinal cord. L1 in adults, L3 in newborns
Conus medullaris
96
Where does dural sac end
Inferiorly at level S2
97
3 categories on low molecular weight neurotransmitters
Acetylcholine, biogenic amines, and amino acids
98
Locations that acetylcholine is used at
Neuromuscular junction
Autonomic nervous system (parasympathetic postganglion neurons and preganglionic neurons)
Some neurons in the brain
99
Acetylcholine is synthesized by what?
Choline + acetyl CoA (and enzyme choline acetyltransferase)
100
Catecholaminens, dopamine, norepinephrine, epinephrine, serotonin, histamine
Biogenic amines
101
The principle inhibitory neurotransmitter in the spinal cord
Glycine
102
The principle excitatory neurotransmitter in the central nervous system
Glutamate
103
The principle inhibitory neurotransmitter in the brain. Synthesized from glutamate by glutamic acid decarboxylase
Gamma amino butyric acid (GABA)
104
One of two general types of neurotransmitter receptros where the receptor directly gates an ion channel
Direct / ionotropic receptors
105
One of two general types of membrane receptors where the receptor indirectly regulates an effector molecule, which may be an ion channel, enzyme, or other..
Indirect / metabotropic receptors
106
What is MoA of benzodiazepines on GABAa receptors
GABAa receptors have benzo modulatory sites. Benzos bind, increase length of time channel stays open, thereby increase total Cl flux and enhancing effect of GABA
107
Difference in GABAa and GABAb
GABAa ionotropic
| GABAb metabotropic
108
Nicotinic ACh receptor toxins
Nicotine
Curare (south american plants)
Some snake venoms (cobras, mambas, kraits,...)
109
Plate or layer
Lamina
110
An opening, hole, or passage. Especially in bone
Foramen
111
A small smooth area on a bone or other firm structure, usually an articular surface covered in life w/ articular cartilage
Facet
112
A change in postsynaptic ion permeability that increases probability of action potential firing in post-synaptic cell. Typically results from synaptic current flow that depolarizes the postsynaptic cell membrane
Excitatory postysnaptic potential (EPSP)
113
A change in postsynaptic ion permeability that decreases the probability of the postsynaptic cell firing action potential. May result from hyperpolarization of the postsynaptic membrane
Inhibitory postsynaptic potential (IPSP)
114
These open cation channels and use the higher resting membrane driving force of sodium over potassium to depolarize the postsynaptic cell
Conductance increase EPSP
115
Addition of Cl permeability to the membrane (by GABAb and Glycine) does what ?
Stabilizes the membrane potential, reducing the cells ability to depolarize in response to excitation.
116
Change in postsynaptic ion permeability caused by released neurotransmitter
Postsynaptic potential
117
Postsynaptic response which increases the probability that postsynaptic neuron will fire and action potential
EPSP
118
Postsynaptic response which decreases the probability that postsynaptic neuron will fire an action potential
IPSP
119
All conductance increase EPSP are permeable to at least
Sodium and potassium
120
In general, the ____ a synapse is to the site of action potential initiation (the axon), the more influence that synapse has over the generation of action potentials.
Closer
121
Two or more synapses are simultaneously activated and elicit an action potential. Amount that the synapses combine depends on their length constants.
Spatial summation
122
The same synapse is activated more than once in a short time period and the combinatory effect is what determines the time constant of the postsynaptic neuron.
Temporal summation
123
GABA receptors are located where and why
GABA are inhibitory. The receptors are located at cell body near axon (rather than out in the dendrites like glutamate). For this reason, it takes much less of a synaptic potential to elicit an action potential (less distance, less attenuation, more umph.)
124
Decreases the amount of neurotransmitter released by a synapse
Presynaptic inhibition
125
Two most common types of presynaptic inhibition
1. Open K channels in the presynaptic terminal (causes hyperpolarization and less Ca channel opening)
2. Inhibition of voltage-gated Ca channels from opening
126
Receptors located in the presynaptic terminal and activated by the neurotransmitter that THAT synapse releases.
Autoreceptors
127
Second messenger pathways that change the electrical properties of the postsynaptic cell and can alter cell function w/o changing membrane potential
Neuromodulation
128
having so much of the neurotransmitter that it escapes and causes an effect on cells outside of the synapse (example: NO)
Volume transmiission
129
The lag between flow of membrane current and change in membrane potential
Time constant
130
Short time constant has ____ temporal resolving power
High (will not do as much temporal summation)
131
Small SA - _____ time constant
Short
132
This structure enters into the membrane, bends and returns back to EC side w/o passing all the way through
P loop
133
This transmembrane segment of ion channels contains the voltage sensor
S4 (transmembrane)
134
This segment lines the outer mouth of the pore of the ion channel and forms selectivity filter
P-loop.
135
Where are amino acid neurotransmitters packaged and synthesized?
Nerve terminal
136
Where is norepinephrine packaged and synthesized?
Nerve terminal
137
Where is ACh packed and synth'd?
Nerve terminal
138
Where are neuroactive peptides packed and synth'd?
Within the cell body and then transported own anterograde
139
What is the most common (not exclusive, though) type of co-expression in neurotransmitters?
One low molecular weight neurotransmitter and one neuropeptide
140
Why is acetylcholine not synthesized within nervous tissue?
Choline is supplied through the blood
141
Conductance increase Excitatory EPSP's are typically generated by __
Gating of ion channels which are equally permeable to both Na and K
142
At resting membrane potential, is driving for higher for sodium or potassium?
Sodium
143
How many alpha subunits must be bound bind ACh to gate the channel of the nicotinic ACh receptor?
There must be 2 ACh bound. 1 to each of the two alpha subunit.
144
Where are nicotinic ACh receptors primarily located?
Neuromuscular junctions
Autonomic nervous system
Central nervous system
145
What are three types of ionotropic glutamate receptors and what are they named for?
Kainate
AMPA
NMDA
These are all agonists of the receptors.
146
What is the NMDA receptor permeable to that other glutamate receptors are not?
Calcium (along with Na and K) [kainate and AMPA are only permeable to Na and ]
147
The lag between the peak in synaptic current and the peak in synaptic potential is due to?
The membrane time constant
148
What is a way that you can create a conduction decrease EPSP?
Decreasing the resting leak potassium permeability.
| This removes a hyperpolarizing element, allow some depolarization
149
Are conductance decrease EPSP's ionotropic or metabotropic?
Metaboptropic. (Or G protein coupled)
150
In this summation, the same synapse is activated more than once w/in a short period of time and the multiple synaptic potentials are summed
Temporal summation
151
The strongest inhibitory synapses are found where??
Directly on the axon initial segment
152
When a transmitter acts in a feedback manner binding to receptors on the cell from which it was released, it is called
Autocoid (autoreceptors)
153
Autoreceptors provide ____ to the terminal from which they were released
Negative feedback
154
Two ways of presynaptic inhibition that both axo-axonic synapses and autoreceptors use.
1. Open K channels to hyperpolarize.
| 2. Directly inhibit voltage gated calcium ion channels
155
Region of the presynaptic membrane where synaptic vesicles fuse and release ACh
Active zone
156
Protein released from motor nerve that aggregates pre-existing AChR's on the muscle membrane at the neuromuscular junction
Agrin
157
Muscle specific activator of MuSK required for NMJ formation
Dok7
158
Flow of sodium ions thru AChR that occurs when ACh binds
End plate current
159
Change in potential at the NMJ to more positive due to the end plate current
End plat potential
160
Small changes in muscle membrane potential caused by spontaneous release of quanta of ACh
Miniature end plate potentials
161
Low density lipoprotein receptor related protein 4; binds to agrin and MuSK; required for NMJ formation
LRP4
162
Muscle specific kinase;when activated by agrin, induces the clustering of AChR's @ NMJ by rapsyn
MuSK
163
Invagination of muscle membrane at the NMJ
Postjunctional fold
164
Vesicles containing ACh that are released and bind to AChRs even in the absence of nerve stimulation
Quanta
165
Protein in muscle that binds to AChRs and clusters them at the NMJ
Area between motor nerve and muscle that contains proteins involved in development and regulation of the NMJ
166
Differencee between actual EPP and threshold potential required to generate muscle action potential
Safety factor
167
Do adult or embryonic AChR's have longer mean open time??
Embryonic
168
```
Characterized by;
Making antibodies against presynaptic Ca channels
Reduced neurotransmitter release
Affects primarily limb muscles
Symptoms; skeletal muscle weakness
Improved w/ exercise
```
Lambert-Eaton Syndrome
169
Test used to determine if decreased muscle function is due to motor nerve or muscle. Measures a current which is generated at the NMJ
Electromyography (EMG)
170
Layout of the articular facets of the cervical vertebrae
Angled superiorly and medially : gives considerable freedom of movement.
171
Atlas
C1
172
Axis
C2
173
Dens is on
C2, axis
174
C7
Vertebra prominens
175
First spinous process that is not bifid?
C7
176
What makes the thorax the least mobile part of the vertebral body?
The spinous processes of the thorax are long and inclined posteriorly and inferiorly
177
Most chunky vertebral section
Lumbar
178
Articular process of the lumbar vertebra are in what plane?
Sagittal - allows for flexion / extension movement
179
What two ligaments are in the vertebral foramen?
Posterior Longitudinal column
Ligamenta flava
180
Which ligament is elastin containing
Ligamenta flava
181
Ligamentum nuchae is what ?
Greatly thickened interspinous and supraspinous ligaments in cervical region
182
Synovial plane joints that permit sliding movements that are immobilized in facet fusion surgery
Joints between articular processes (facets)
183
Made of collagen fibers and fibrocartilage
Anulus fibrosus
184
Gelatinous core
Nucleus pulposus
185
Degenerative changes + back strain can cause
Herniation of nucleus pulposus (most common in postero-lateral direction) (ofter l4l5 or l5s1)
186
Hump back, exaggerated curvature, concave anteriorly. Normally in thorax
Kyphosis
187
Can be caused by the presence of a hemivertebra
Scoliosis
188
Exaggerated lumber curvature, concave posteriorly
Lordosis
189
Groups of nerve cell bodies in central nervous system
Nuclei
190
Groups of nerve cell bodies in peripheral nervous system
Ganglia
191
Groups of axons in CNS
Tract
192
Groups of axons in the PNS
Nerves
193
Stimulus goes through sensory neuron -> interneuron(s) -> motor neuron -> flexor muscle
Reflex
194
Control skeletal muscle, voluntary activities
Somatic efferents
195
Sensory neurons that innervate skin, joints; provide precise conscious sensation of touch pressure pain to skin, also provide sense of body position
Somatic afferents
196
Control smooth muscle and cardiac muscle, glands, internal organs, largely unconscious
Visceral efferents
197
Sensory neurons that innervate the internal organs, blood vessels, only provide imprecise localization of sensation and dull sense of pressure, pain
Visceral afferents
198
.
.
199
Cell bodies of all sensory. Neurons are located at the dorsal root ganglia - look like swellings attached to dorsal root
Dorsal root ganglia
200
Are there any synapses in the dorsal root ganglia?
No, dorsal root ganglia is only the collection of cell bodies of all sensory neurons.
201
Contains sensory and motor axons to regions of back; sensory to skin of back and posterior neck, motor axons to deep muscles of back and neck
Dorsal ramus
202
Sensory to skin of extremities, anterior and lateral trunk, motor to muscles of extremities & anterior and lateral regions of trunk
Ventral ramus
203
Conus medullaris ends at where in newborn
L3
204
Conus medularis ends at where in adults
L1
205
Where does cauda equina show up?
Below level of conus medullaris
206
Dural sac is separated from inner side of vertebral canal by space containing fat and loose connective tissue, also contains internal vertebral venous plexus
Epidural space
207
Tough outer layer that forms sac that completely surrounds spinal cord in vertebral canal.
Dura mater
208
The middle layer of meninges that is attached to the inner side of dura. Has fine strands that extend to pia mater
Arachnoid
209
Found between arachnoid and pia - CONTAINS cerebrospinal fluid
Subarachnoid space
210
Thin layer, adherent to spinal cord. Contains blood vessels supplying cord
Pia mater
211
Projections of pia on each side of cord. Extend to arachnoid on inner side of dura. Landmarks in neurosx. Dorsal roots are dorsal to these. Ventral roots are ventral to these. (Dorsal roots are sometimes cut for relief of chronic pain)
Denticulate ligaments
212
Thin strand of pia which extends below conus medullaris. Pierces dural sac at S2 and attaches @ first coccygeal vertebra
Filum terminale
213
Where is CSF produced?
W/in choroid plexuses (mostly in brain
214
Type of ACh receptor that directly opens (Na/K) channels
Nicotinic
215
Type of ACh receptor that stimulates PLC and closes K channels
Muscarinic, m1, m3, m5
216
Type of acetylcholine receptor that inhibits adenylyl cyclase, opens K channels, and inhibits Ca channel opening
Muscarinic, m2, m4
217
Mechanism of KA, AMPA, and NMDA receptors
Directly open cation channels ( these are glutamate ionotropic receptors) (NMDA is does Ca, K, Na)[other two do K, Na)
218
Mechanism GABAa
Ionotropic. Directly opens Cl- channels. (Inhibitory)
219
GABAb mechanism
Metabotropic; opens K channels which hyperpolarizes and inhibits Ca channels from opening
220
Glycine MoA
Ionotropic, directly opens Cl channels
221
```
Affects autonomic nervous system and NMJ
Inhibits synaptic vesicle release
Affects SNARE proteins of vesicle fusion
Weakness and paralysis of limbs
Death from resp muscle paralysis
```
Botulism
222
Does myasthenia gravis or lambert-eaton worsen on exertion?
Myasthenia gravis
223
These two toxins interfere with neuronal Na channels
Terodotoxin (pufferfish) and saxitoxin (red sea)
224
This toxin interferes with Ca channels in the terminal
Conotoxin - omega
225
What effect does nicotine have at the neuromuscular junctions?
Activates AChR's
226
What toxins inhibit AChR's
Tubocurarine (curare) and bungarotoxin (king cobras)
227
Type of ACh receptor that directly opens (Na/K) channels
Nicotinic
228
Type of ACh receptor that stimulates PLC and closes K channels
Muscarinic, m1, m3, m5
229
Type of acetylcholine receptor that inhibits adenylyl cyclase, opens K channels, and inhibits Ca channel opening
Muscarinic, m2, m4
230
Mechanism of KA, AMPA, and NMDA receptors
Directly open cation channels ( these are glutamate ionotropic receptors) (NMDA is does Ca, K, Na)[other two do K, Na)
231
Mechanism GABAa
Ionotropic. Directly opens Cl- channels. (Inhibitory)
232
GABAb mechanism
Metabotropic; opens K channels which hyperpolarizes and inhibits Ca channels from opening
233
Glycine MoA
Ionotropic, directly opens Cl channels
234
```
Affects autonomic nervous system and NMJ
Inhibits synaptic vesicle release
Affects SNARE proteins of vesicle fusion
Weakness and paralysis of limbs
Death from resp muscle paralysis
```
Botulism
235
Does myasthenia gravis or lambert-eaton worsen on exertion?
Myasthenia gravis
236
These two toxins interfere with neuronal Na channels
Terodotoxin (pufferfish) and saxitoxin (red sea)
237
This toxin interferes with Ca channels in the terminal
Conotoxin - omega
238
What effect does nicotine have at the neuromuscular junctions?
Activates AChR's
239
What toxins inhibit AChR's
Tubocurarine (curare) and bungarotoxin (king cobras)
