Post on 13-Jan-2016
NERVE TISSUEPart 2
NERVE TISSUEPart 2
Instructor Terry Instructor Terry WisethWiseth
ANATOMY & PHYSIOLOGYANATOMY & PHYSIOLOGY
2
MEMBRANE POTENTIAL AND MEMBRANE POTENTIAL AND NERVE IMPULSE NERVE IMPULSE TRANSMISSIONTRANSMISSION
Resting neurons maintain a difference in electrical charge across their cell membranes
+ + + + + + + + + + + + + + + + +
+++++++++++++++++- - - - - - - - - - - - - - - - -
-----------------
3
MEMBRANE POTENTIAL AND MEMBRANE POTENTIAL AND NERVE IMPULSE NERVE IMPULSE TRANSMISSIONTRANSMISSION
The inside of the resting neuron is negatively charged, the outside is positively charged
+ + + + + + + + + + + + + + + + +
+++++++++++++++++- - - - - - - - - - - - - - - - -
-----------------
4
MEMBRANE POTENTIAL AND MEMBRANE POTENTIAL AND NERVE IMPULSE NERVE IMPULSE TRANSMISSIONTRANSMISSION
When a neuron is stimulated this polarity is reversed, these reversals are called action potentials
+ + + + + - - - + + + + + + + + +
+++++++++---+++++- - - - - + + + - - - - - - - - -
---------+++-----
5
ACTION ACTION POTENTIALPOTENTIAL
Nerve impulses are conducted along the neuron by a wave of membrane polarity reversals (action potentials)
6
ACTION ACTION POTENTIALPOTENTIAL
Chemical messengers (neurotransmitters) carry nervous impulses from one neuron to another across the synapse
7
THE NEURON MEMBRANE AT THE NEURON MEMBRANE AT RESTREST
Neuron maintains a resting membrane potential of about -70 millivolts across the cell membrane
Sodium (NaNa++) and potassium (KK++) are the main ions involved
8
THE NEURON MEMBRANE AT THE NEURON MEMBRANE AT RESTREST
NaNa++ and KK++ cannot pass through the lipid bilayer membraneMove through the membrane by
using membrane proteins (pumps)
9
MEMBRANE PROTEINSMEMBRANE PROTEINS
Membrane proteins do several things: Some "leak" ions all the timeSome "leak" ions only when the cell
has been stimulated (ion "gates")Some "pump" ions by active
transport
10
NaNa++ / K / K++ PUMP PUMP
Membrane proteins actively transport Sodium out of the cellPotassium into the cell
Click Here to See Next Image
Click Here to See Next Image
Click Here to See Next Image
Click Here to See Next Image
11
NaNa++ / K / K++ PUMP PUMP
Three Na+ are pumped out for every two K+ pumped in
Result is the cell has more Na+ on the outside and more K+ on the inside
Na+ Na+Na+
Na+ Na+ Na+ Na+
Na+
Na+
Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+
K+ K+ K+ K+ K+K+
K+ K+ K+ K+ K+ K+ K+ K+ K+ K+
K+K+ 18+
18+17+
19+
Cell MembraneNa+ / K+ Pump
12
Na+ / K+ PUMPNa+ / K+ PUMP
The pumping of Na+ out makes the outside moremore positive and the inside of the cell moremore negative
13
STIMULATED NEURONSTIMULATED NEURON
Nerve cells are unique in their ability to carry a signal using membrane potential changes
14
STIMULATED NEURONSTIMULATED NEURON
Stimulation of a neuron opens some of the membrane proteins(a.k.a. Na+ gates)Allows Na+ to pass freely into
the cells
15
STIMULATED NEURONSTIMULATED NEURON
Free flow of Na+ into the cell causes a reversal of membrane polarity
Polarity reversal is called the action potential
16
ACTION POTENTIALACTION POTENTIAL
Reversal of polarity (action potential) moves along the cell like a wave
The membrane restores the resting potential very quicklyIn less than 7 milliseconds the cell
can be stimulated again
17
ALL-OR-NONE ALL-OR-NONE RESPONSERESPONSE
Once a threshold limit is reached any stronger stimulus will not increase the cell's response
A stimulus below the threshold also will not stimulate the neuron
18
SYNAPSESYNAPSE
Neurons communicate across the synapse by using chemical messengers called neurotransmitters
19
SYNAPSESYNAPSE
Neurotransmitters may act to inhibit neurons or to excite neurons
20
SYNAPSESYNAPSE
Attachment of the neurotransmitters to presynaptic membrane receptors causes ion channels to open Generate an action potential
21
MEMBRANE POTENTIALMEMBRANE POTENTIAL
Plasma membrane exhibits membrane potentialResting potential
Electrical voltage difference across the membrane
22
ACTION POTENTIALACTION POTENTIAL
With stimulation resting potential can produce responses called action potentials
23
ACTION POTENTIALACTION POTENTIAL
Resting potential is like voltage stored in a battery
Electric current produced by flow of electrons from negative to positive current
24
ACTION POTENTIALACTION POTENTIAL
Action potentials occur because plasma membrane contains ion channels that open or close in response to stimuli
25
ION CHANNELSION CHANNELS
Non-gated channelsAlways open
Gated channels Open or close in response to
stimuli
26
ION CHANNELSION CHANNELS
Plasma membrane has many more K+ non-gated channels than Na+ non-gated channelsThus membrane permeability
to K+ is higher
27
GATED CHANNELSGATED CHANNELS
Gated channels are stimulated by:VoltageChemicalsMechanical pressureLight
28
RESTING MEMBRANE RESTING MEMBRANE POTENTIALPOTENTIAL
Occurs because of the build-up of negative charges in the cytosol (intracellular fluid)
Equal build-up of positive charges in the extracellular fluid just outside the membrane
29
RESTING MEMBRANE RESTING MEMBRANE POTENTIALPOTENTIAL
Separation of charges represents potential energy measured in millivolts
Large +/- difference = large potential
30
RESTING MEMBRANE RESTING MEMBRANE POTENTIALPOTENTIAL
Potential exists only at membrane surfaces
Resting membrane potential in the neurons is -70mV
Cells with membrane potential are polarized
31
RESTING MEMBRANE RESTING MEMBRANE POTENTIALPOTENTIAL
Factors contributing to resting membrane potential1) Unequal distribution of ions2) Relative permeability of the
cell membrane
32
RESTING MEMBRANE RESTING MEMBRANE POTENTIALPOTENTIAL
1)1) Unequal distribution of ions across the plasma membraneExtracellular fluid
Rich in Na+ and Cl-
Intracellular fluidK+ and PO4
-, amino acids -
Na+ Cl-
K+PO4
- AA-
AA-AA-
AA- K+
K+K+
K+
K+
PO4-
PO4-
PO4-
PO4-
Na+ Na+
Na+Na+
Na+Cl- Cl-Cl-
Cl-
Cl-Cl-
33
RESTING MEMBRANE RESTING MEMBRANE POTENTIALPOTENTIAL
2) Relative permeability of the cell membrane to Na+ and K+
Resting neuron permeability 50 to 100 times greater to K+ than to Na+
34
MEMBRANE MEMBRANE PERMEABILITYPERMEABILITY
Cell membrane has a low permeability for Na+ from outside of cell and Pr- inside cells
Membrane has high permeability to K+ to move out of cell
Na+ Cl-
K+PO4
- AA-
AA-AA-
AA- K+
K+K+
K+
K+
PO4-
PO4-
PO4-
PO4-
Na+ Na+
Na+Na+
Na+Cl- Cl-Cl-
Cl-
Cl-Cl-
Click to see theanimation again
35
MEMBRANE MEMBRANE PERMEABILITYPERMEABILITY
Cell membrane has a low permeability for Na+ from outside of cell and Pr- inside cells
Membrane has high permeability to K+ to move out of cell
Na+ Cl-
K+PO4
- AA-
AA-AA-
AA- K+
K+K+
K+
K+
PO4-
PO4-
PO4-
PO4-
Na+ Na+
Na+Na+
Na+Cl- Cl-Cl-
Cl-
Cl-Cl-
Click to see theanimation again
36
MEMBRANE MEMBRANE PERMEABILITYPERMEABILITY
Tendency for K+ to move from inside the cell to outside down the concentration gradient
As K+ move out Na+ move down its concentration gradient into the cell
Na+ Cl-
K+PO4
- AA-
AA-AA-
AA- K+
K+K+
K+
K+
PO4-
PO4-
PO4-
PO4-
Na+ Na+
Na+Na+
Na+Cl- Cl-Cl-
Cl-
Cl-Cl-
37
MEMBRANE MEMBRANE PERMEABILITYPERMEABILITY
This has the effect of balancing electrical effect of K+ outflow
Na+
K+ K+ K+ K+ K+
Na+ Na+ Na+ Na+Na+
K+
Na+
K+
Na+
K+
38
MEMBRANE MEMBRANE PERMEABILITYPERMEABILITY
But Na+ inward flow is too slow to keep up with K+ outflow
Net effect of K+ outflow is that the inner cell membrane surface becomes more negative
Na+ Cl-
K+PO4
- AA-
AA-AA-
AA- K+
K+K+
K+
K+
PO4-
PO4-
PO4-
PO4-
Na+ Na+
Na+Na+
Na+Cl- Cl-Cl-
Cl-
Cl-Cl-
39
NaNa++ /K /K++ PUMPS PUMPS
Both electrical and concentration gradients promote Na+ inflow
Na+ Cl-
K+PO4
- AA-
AA-AA-
AA- K+
K+K+
K+
K+
PO4-
PO4-
PO4-
PO4-
Na+ Na+
Na+Na+
Na+Cl- Cl-Cl-
Cl-
Cl-Cl-
40
NaNa++ /K /K++ PUMPS PUMPS
Small inward Na+ leak is taken care of by Na+ / K+ pumps
Maintain resting membrane potential by pumping out Na+ as fast as it leaks in
NaNa++ / K / K++ PUMPSPUMPS K+
Cell exterior
Cell interior
Na+
Na+ K+
Pump
Axon interior
Na+
150 mMK+
5 mM
K+
150 mM
Na+
15 mM++
+ ++ +
++
+ ++ +
++
+ ++ +
++
+ ++ +
++
+ ++
++
++ +
+ ++
++ +
+ ++
++ +
+ ++
++ +
+ ++
++ +
+
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-70mV (across membrane
Axon exterior
Na+ / K+ pumps bring in K+ K+ redistributes immediately
because it is permeable to the membrane
Click toClick toView ImageView Image
42
NaNa++ /K /K++ PUMPS PUMPS
Thus the critical job of the Na+ / K+ pumps is to expel Na+
Total effect is -70 mV resting membrane potential
43
ACTION POTENTIALSACTION POTENTIALS
"impulse"Occurs when depolarization is
large enough at a trigger zone
44
ACTION POTENTIALSACTION POTENTIALSDepolarization
Membrane becomes less negative (more positive) than the resting level
45
IMPULSEIMPULSE
Sequence of rapidly occurring events that decrease and reverse the membrane potential (depolarization)and then restore it to the resting state (repolarization)
46
Impulse Impulse SummarySummary
1)1) Resting Potential2)2) NaNa++ gates open 3)3) NaNa++ enters axon4)4) NaNa++ gates close 5)5) KK++ gates open6)6) KK++ flows out of axon7)7) KK++ gates close
47
IMPULSEIMPULSE
Two types of voltage gated ion channels open and close
Na+
K+
Na+
Na+
Na+
Na+
Na+
Na+Na+Na+ Na+
Na+
Na+Na+Na+
Na+Na+
Na+
Na+Na+
Na+
Na+
K+K+
K+
K+
K+
K+
K+
K+K+
K+
K+
K+
K+
K+
K+ K+ K+
K+
K+
K+
K+K+
30
0
-70
mV
Click to Click to View View
AnimationAnimation
Click to Click to View View
AnimationAnimation
48
IMPULSEIMPULSE
1)1) First channels to open allow Na+ to rush into the cell causing depolarization
49
IMPULSEIMPULSE
2)2) Second channels open allowing K+ to flow out producing repolarizationLasts about 1 millisecond
(1/1000 sec)
50
DEPOLARIZATIONDEPOLARIZATION
Stimulus causes inflow of Na+ bringing membrane potential from -70 mV to +30 mV
51
DEPOLARIZATIONDEPOLARIZATION
Voltage gated Na+ channels open just long enough for about 20,000 Na+ ions to flow in
Na+ pumps bail the Na+ back out to the extracellular fluid
52
REPOLARIZATIONREPOLARIZATION
Voltage gated K+ channels opened by depolarization Results in out flow of K+ ionsCausing recovery of resting
membrane potential
53
REPOLARIZATIONREPOLARIZATION
Na+ ion channels closeK+ channels openMembrane potential changes
from +30 mV to 0 mV to -70 mV
54
REFRACTORY PERIODREFRACTORY PERIODTime where excitable cell cannot
generate another action potential
Click the image to slow the impulse down
55
PROPAGATION OF PROPAGATION OF NERVE IMPULSESNERVE IMPULSES
Nerve impulses occur in two different ways1) Continuous conduction2) Saltatory conduction
56
CONTINUOUS CONTINUOUS CONDUCTIONCONDUCTION
Unmyelinated axonsMuscle cells
57
CONTINUOUS CONTINUOUS CONDUCTIONCONDUCTION
Dominoes (self-propagation)Normally moves only one
direction from where it arises
Click toView Animation
58
CONTINUOUS CONTINUOUS CONDUCTIONCONDUCTION
Dominoes (self-propagation)Setting the dominoes back up
simulates repolarization
Click toView Animation
59
LOCAL ANESTHETICSLOCAL ANESTHETICSNovocaine / lidocaine used to block pain
Block opening of voltage gated Na+ channels
Na+
K+
Na+
Na+
Na+
Na+Na+
Na+Na+Na+ Na+
Na+
Na+Na+Na+
Na+Na+
Na+
Na+Na+
Na+
Na+
K+K+
K+
K+
K+
K+
K+
K+K+
K+
K+
K+
K+
K+
K+ K+ K+
K+
K+
K+
K+K+
Click toView Animation
60
SALTATORY SALTATORY CONDUCTIONCONDUCTION
Myelinated axonsMyelin sheath acts as an insulatorBlocks ionic currents across the
membrane
61
SALTATORY SALTATORY CONDUCTIONCONDUCTION
Nodes of RanvierInterrupt
myelin sheathHigh density of
voltage-gated Na+ channels
Membrane depolarization can occur
62
SALTATORY SALTATORY CONDUCTIONCONDUCTION
Currents carried by Na+ and K+ can flow across the plasma membrane
63
SALTATORY SALTATORY CONDUCTIONCONDUCTION
Currents carried by ions through extracellular fluid around myelin sheath
Current flows across membrane only at nodes
64
SALTATORY SALTATORY CONDUCTIONCONDUCTION
Impulse appears to leap from node to node
65
SALTATORY SALTATORY CONDUCTIONCONDUCTION
Current travels faster than in continuous conduction in fibers of equal diameter
66
SPEED OF IMPULSESPEED OF IMPULSE
1)1) Diameter of fibers2)2) Presence or absence of myelin
sheath3)3) Temperature
ex. Pain reduced by localized cooling of nerve
67
FIBER DIAMETERFIBER DIAMETER
Largest diameter called A fibersAll myelinatedSpeed 12-130 m/sec (27-280
mph)Touch, pressure, propriception,
heat, cold, skeletal musclemotor nerves
Exist where quickreactions are critical
68
FIBER DIAMETERFIBER DIAMETER
B fibers Myelinated15 m/sec (32
mph)Sensory
viscera nerves
69
FIBER DIAMETERFIBER DIAMETER
C fibers (smallest) Unmyelinated2m/sec (1-4 mph)Pain from viscera
70
IMPULSE SPEEDIMPULSE SPEED
Large diameter axons can transmit up to 2500 impulses/sec
Small diameter axons can transmit only 250 impulses/sec
Normal rate is10-1000 impulses/sec
71
NEUROTRANSMITTERSNEUROTRANSMITTERS
Neurotransmitters are released during a synapseNeurotransmitters are chemicals
which are able to stimulate an action potential on another neuron
72
NEUROTRANSMITTERSNEUROTRANSMITTERS
Neurotransmitters cause either 1) Excitatory potentials2) Inhibitory potentials
73
REMOVAL OF REMOVAL OF NEUROTRANSMITTERNEUROTRANSMITTER
Neurotransmitters must be removed from the synaptic cleft or there would be a constant stimulus for an action potential1)1) Diffusion2)2) Enzymatic degradation
ex. acetylcholinesterase3)3) Cellular reuptake
74
DIFFUSIONDIFFUSION
The neurotransmitter drifts away, out of the synaptic cleft where it can no longer act on a receptor
75
ENZYMATIC ENZYMATIC DEGRADATIONDEGRADATION
Neurotransmitters are broken down by enzymes into non-initiating by products
76
ENZYMATIC ENZYMATIC DEGRADATIONDEGRADATION
Nerve gas and some insecticides work by interfering with acetylcoholinesterase and thus a build up of the neurotransmitter aceylcholine in the synaptic cleft
Normal ACh
action
Interference of Nerve gas
on AChE
77
ENZYMATIC ENZYMATIC DEGRADATIONDEGRADATION
Causes a continuous initiation of the nerve impulse with no relaxation
Atropine is an antidote for nerve gas
78
CELLULAR REUPTAKECELLULAR REUPTAKE
Active transport of neurotransmitter back into the neuron that released them (recycling)
79
CELLULAR REUPTAKECELLULAR REUPTAKE
Cocaine produces intense pleasurable euphoria because it blocks transporters for the reuptake of dopamine
80
REMOVAL OF REMOVAL OF NEUROTRANSMITTERNEUROTRANSMITTER
Allows dopamine to linger in synthetic cleft
Excessively stimulating certain brain regions
81
NEUROTRANSMITTERSNEUROTRANSMITTERS
Excitatory and inhibitory neurotransmitters found in both PNS and CNS
82
NEUROTRANSMITTERSNEUROTRANSMITTERSSame
neurotransmitter may be inhibitory in one location but excitatory in anotherEx: ACh
Type of receptors determines which response occurs
83
ACETYLCHOLINEACETYLCHOLINEExcitatory at neuromuscular junctionActs to open chemically gated ion
channels
84
ACETYLCHOLINEACETYLCHOLINE
Inhibitory in parasympathetic fibers of Vagus nerve (cranial nerve X)Innervates the heartSlows the heart rate down
85
KNOWN KNOWN NEUROTRANSMITTERSNEUROTRANSMITTERS
60 known neurotransmittersParkinson's Disease, Alzheimer's
Disease, depression, anxiety and schizophrenia are caused by neurotransmitter problems
86
KNOWN KNOWN NEUROTRANSMITTERSNEUROTRANSMITTERS
Neurotransmitters are grouped by chemical similarities1) Small molecule
neurotransmittersubstances
2) Amino acids3) Neuropeptides4) Soluble gases
KNOWN KNOWN NEUROTRANSMITTERSNEUROTRANSMITTERS
Small Molecule Neurotransmitter SubstancesAcetylcholine (ACh) Dopamine (DA) Norepinephrine (NE)
Serotonin (5-HT) Histamine Epinephrine
Amino AcidsGamma-aminobutyric
acid (GABA)Aspartate Glycine Glutamate
Soluble Gases
Nitric Oxide (NO) Carbon Monoxide
NeuropeptidesBradykinin Endorphin Bombesin Calcitonin
Cholecystokinin Enkephalin Dynorphin Insulin
Gastrin Substance P Neurotensin Glucagon
Secretin Somatostatin Motilin Vasopressin (ADH)
Oxytocin Prolactin Thyrotropin Angiotensin II
Sleep peptides Galanin Neuropeptide Y Vasoactive intestinal peptide
Gonadotropnin-releasing hormone
Growth hormone-releasing hormone
Luteinizing hormone Thyrotropin-releasing hormone
88
ACETYLCHOLINEACETYLCHOLINE
Released at neuromuscular junction
89
ACETYLCHOLINEACETYLCHOLINE
Released by axons of limbic system in brainDestruction of these neurons is a
hallmark of Alzheimer's Disease
90
AMINO ACIDSAMINO ACIDS
Glutamate and aspartate are excitatory in the brain
GABA and glycine are inhibitory
91
AMINO ACIDSAMINO ACIDS
GABA found primarily in the brainAntianxiety drugs (valium)
enhance the action of GABAGlycine found primarily in the
spinal cord
92
STRYCHNINE STRYCHNINE POISONINGPOISONING
Normally neurons release inhibitory glycine in spinal cord to motor neurons to prevent excessive muscular contraction
93
STRYCHNINE STRYCHNINE POISONINGPOISONING
Strychnine binds and blocks glycine receptors
Result is massive tetanic contractions
94
NOREPINEPHRINE (NE) NOREPINEPHRINE (NE) & EPINEPHRINE& EPINEPHRINE
May act as inhibitory or excitatoryImplicated in maintaining arousal,
dreaming and mood regulation
95
DOPAMINE (DA)DOPAMINE (DA)
Involved in emotional responsesRegulate gross automatic
movements of skeletal muscles
96
DOPAMINE (DA)DOPAMINE (DA)Degeneration of neurons producing
dopamine causes Parkinson's Disease
97
SEROTONIN (5-HT)SEROTONIN (5-HT)
Induce sleep, sensory perception, temperature regulation and control of mood
98
SEROTONIN (5-HT)SEROTONIN (5-HT)
Anti-depressant (Prozac) is a serotonin inhibitor of serotonin reuptakeThus more serotonin available in
synaptic cleftAllowing signals to pass from
neuron to neuron more easily
99
NEUROPEPTIDESNEUROPEPTIDES
May also act as hormonesLargest class of neurotransmitters
NeuropeptidesBradykinin Endorphin Bombesin Calcitonin
Cholecystokinin Enkephalin Dynorphin Insulin
Gastrin Substance P Neurotensin Glucagon
Secretin Somatostatin Motilin Vasopressin (ADH)
Oxytocin Prolactin Thyrotropin Angiotensin II
Sleep peptides Galanin Neuropeptide Y Vasoactive intestinal peptide
Gonadotropnin-releasing hormone
Growth hormone-releasing hormone
Luteinizing hormone Thyrotropin-releasing hormone
100
NEUROPEPTIDESNEUROPEPTIDES
Angiotensin IIStimulates thirst
OxytocinImproves memory
101
NEUROPEPTIDESNEUROPEPTIDESAntidiuretic hormone (ADH)
Also called vasopressinRegulates water reabsorption
Enkaphalins and endorphinsAnalgesic effects
102
ENKAPHALLINS AND ENKAPHALLINS AND ENDORPHINSENDORPHINS
Linked to improved memory, learning, feelings of pleasure and euphoria200 X stronger than morphine
103
ENKAPHALLINS AND ENKAPHALLINS AND ENDORPHINSENDORPHINS
Acupuncture may increase release of enkaphalins and endorphins (opioids)
104
GASESGASES
Nitric oxide (NO)Released by endothelial cells
lining blood vesselsCauses relaxation
and vasodilationEffect is tolower BP
105
NITRIC OXIDENITRIC OXIDE
Phagocytic cells produce NO to kill microbes and tumor cells
In large quantities NO is toxic
106
ALTERATION OF ALTERATION OF IMPULSES AND IMPULSES AND
SYNAPSESSYNAPSESAlkalosisAcidosisHypnoticsCaffeine
107
ALKALOSISALKALOSIS
Increase in the pH above 7.45Increases the excitability of neuronsImpulses arise inappropriatelyLight headedness, numbness,
tingling, nervousness, muscle spasms
108
ACIDOSISACIDOSIS
Decrease in pH below 7.35Progressive depression of neuron
activityProduces apathy and muscle
weakness
109
EXCESSIVE PRESSUREEXCESSIVE PRESSURECauses blockage of nerve impulseCan cause appendages to "go to sleep"
110
HYPNOTICS, HYPNOTICS, TRANQUILIZERS, TRANQUILIZERS,
ANESTHETICSANESTHETICSIncrease the threshold for excitation
111
CAFFEINE, CAFFEINE, BENZEDRINE, BENZEDRINE,
NICOTINENICOTINEReduce threshold for excitation
112
CHEMICAL SYNAPSE CHEMICAL SYNAPSE MODIFICATIONMODIFICATION
Clostridium botulinum bacteria in some canned foods produce a toxin
Small amounts are very poisonous
113
CHEMICAL SYNAPSE CHEMICAL SYNAPSE MODIFICATIONMODIFICATION
Toxin inhibits the release of ACh if ingestedWeakens muscle contractions
114
CHEMICAL SYNAPSE CHEMICAL SYNAPSE MODIFICATIONMODIFICATION
Basis for Botox treatments
115
CHEMICAL SYNAPSE CHEMICAL SYNAPSE MODIFICATIONMODIFICATION
Strabismus, uncontrolled winking, stuttering are uncontrollable muscle contraction
Can be helped by injections of botulinum toxin
116
MYASTHENEA GRAVISMYASTHENEA GRAVIS
Weakened muscle condition brought on by antibodies blocking acetylcholine receptors
117
MYASTHENEA GRAVISMYASTHENEA GRAVIS
Neostigmine and phystigmineAnticholinesterase agents that
inactivate acetylcholinesteraseResults in slow removal of
acetylcholineUsed to treat myasthenia gravis
118
DIISOPROPYL DIISOPROPYL FLUOROPHOSPHATEFLUOROPHOSPHATE
Powerful nerve gasAnticholinesterase agent active
in many insecticides
119
CURAECURAE
Plant derivativeSouth American Indians poisoned
arrows and darts
120
CURAECURAE
Blocks acetylcholine receptors causing muscular paralysis
May be used during surgery to relax muscles
Neostigmine is antidote for curare
EndEndNerve TissueNerve Tissue
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