Test 3 Nervous System Flashcards
1
Q
What are the initial conditions for an action potential and who sets them up? (two conditions)
A
Na+/K+ ATPase creates two gradients
- chemical; Na+ on outside and K+ on inside
- electrical; 3 cations are pumped out and only 2 cations are pumped in, making cell negative (around -70 mV)
2
Q
What are two ways that ions move?
A
- chemical gradient; Na+ wants to move in and K+ wants to move out
- electrical gradient; both cations want to move inside HOWEVER chemical»_space;> electrical, so K+ will still move out but electrical gradient will slow rate of exit
3
Q
What are four (4) types of ion channels?
A
voltage-gated: opens in response to the cells Vm
ligand-gated: the gate opens when a chemical binds
mechanogated: force, like a sound wave, opens gate
leak: small channels open all of the time
4
Q
What happens to a cell when ions do move?
A
Vm of cell changes.
When Na+ enters, Vm moves positively
When K+ leaves, Vm moves negatively
5
Q
How does fast signaling occur between cells?
A
Voltage of the membrane is changed back and forth (+ and -) rapidly by alternatingly letting Na+ enter and K+ leave. The alternating positive and negative current is called an action potential.
6
Q
(3 factors) How do you get various strength of input?
A
to get a stronger synapse:
- increase proximity of synapse to axon hillock
- increase width of dendrite
- increase amount of neurotransmitter
7
Q
How do you get “pros” and “cons”
A
Pros: make Vm positive by letting Na+ in
Cons: make Vm negative by letting K+ out or Cl- in
8
Q
(3 ways) Reuptake of neurotransmitters
A
Enough nt is released to stimulate every receptor once and only once
- reuptake (SSRI)
- enzymatic breakdown
- diffusion
9
Q
What are two types of synaptic transmission?
A
- inhibitory post-synaptic potential - Cl- is let in or K+ let out
- excitatory post-synaptic potential - Na+ is let in
9
Q
Organization of Nervous System
A
I. Central Nervous System
a. Brain and spinal cord
b. integration and command center
II. Peripheral nervous system
a. Sensory (afferent) division
- sensory afferent fibers (skin, muscles, joints)
- visceral afferent fibers (visceral organs to brain)
b. Motor (efferent) division
i. Somatic nervous system
- conscious control of skeletal muscles
ii. Autonomic
- sympathetic (fight or flight)
- parasympathetic (rest & digest)
10
Q
Three basic functions of brain
A
- sensory input
- integration
- motor output
11
Q
Two principal cell types of nervous system
A
- Neurons - excitable cells that transmit electrical signals
- Glia - supporting cells that surround and wrap neurons
12
Q
6 types of Glia
A
CNS
- astrocytes
- microglia
- ependymal cells
- oligodendrocytes
PNS
- Schwann Cells
- Satellite cells
13
Q
What is most abundant glial cell?
A
Astrocytes
14
Q
Four Astrocyte functions
A
- Support neurons like scaffold (they are highly branches)
- Control chemical environment (clean up ions and neurotransmitters)
- Bridge between neurons and blood vessels
- Guide migration of young neurons
16
Q
What is the function of microglia?
A
Brain’s immune system - small, ovoid phagocytes with spiny processes
17
Q
What is the function of Ependymal cells?
A
Line ventricles of brain and spinal column
18
Q
What is the function of Oligodendrocytes?
A
branched cells that wrap CNS nerve fibers
19
Q
What is the function of Schwann cells?
A
surround fibers of PNS
20
Q
What is the function of satellite cells?
A
surround neuron cell bodies forming ganglion, clusters of nerve cells
21
Q
Four (4) characteristics of Neurons
A
- Long-lived
- Amitotic
- High metabolic rate
- intercellular communication
21
Q
What makes neurons amitotic?
A
Contain no centrioles
22
Q
Four (4) structural parts of Neuron
A
- Soma (axon hillock)
- Dendrite
- Axon
- Synapse
23
Q
How are electrical signals conveyed in dendrites of motor neurons?
A
Graded potentials
25
What are four (4) characteristics of the structure of axons?
1. slender, uniform diameter arising from hillock
2. long axons are called nerve fibers
3. rare branches, if present, called collaterals.
4. branches at end called axonal terminal
26
What are three (3) functions of the myelin sheath?
whitish, fatty (protein-lipoid)
1. protect axon
2. insulate fibers from one another
3. increase speed of transmission
27
Describe the composition of gray matter and where is it located?
mostly soma and unmyelinated fibers
brain- outside
spinal cord - inside
28
Describe the composition of white matter and where is it located?
dense collections of myelinated fibers (axons)
brain - inside
spinal cord - outside
29
What are three (3) classifications of neuron by structure?
1. multipolar - three or more processes
2. unipolar - single, short process
3. bipolar - two processes (axon and dendrite)
30
What are three (3) classifications of neuron by function?
1. motor (efferent) carry impulses away from CNS
2. interneurons (association) shuttle signals through CNS pathways
3. sensory (afferent) transmit impulses toward CNS. smell and sight use bipolar
31
What are four (4) chemical species that generate potential difference (voltage)?
Na+, K+, Cl-, protein anions
32
What are two (2) causes ionic differences in membrane?
1. differential permability of the neurilemma (neuron membrane) to Na+ and K+
2. operation of sodium-potassium pump
33
What are four (4) key membrane potentials for an action potential?
1. -70 mV - resting membrane potetial
2. -55 mV - Na+ channel open
3. +30 mV - K+ channels open
4. -90 mV - hyperpolarization
33
When does relative refractory period occur? (3 associated events)
Interval following absolute refractory period when
1. sodium gates closed
2. potassium gates open
3. repolarization is occurring
34
What is the Absolute refractory period description and what are three (3) consequences?
Time from opening of Na+ to closing
1. prevents neuron from generating action potential
2. ensures that each action potential is separate
3. enforces one-way transmission of nerve impulses
35
Why can action potential be generated during relative refractory period?
Even though potassium channels are open, a strong stimuli will let in enough sodium to generate action potential.
37
What is saltatory conduction?
Comes from latin saltare "to hop"
Current passes through myelinated axon only at nodes of Ranvier.
38
What are three (3) characteristics of saltatory conduction
1. voltage gated Na+ channels are concentrated at anodes
2. action potentials are triggered only at nodes
3. action potentials jump from node to node, making conduction faster
39
What are four (4) characteristics of graded potentials
1. short-lived local changes jn membrane potential
2. decrease in intensity with distance
3. magnitude varies directly with strength of stimulus
4. sufficiently strong graded potentials can initiate action potentialsp
39
Two characteristics of electrical synapses
1. less common than chemical synapses
| 2. correspond to gap junctions found in other cell types
40
Two types of synaptic neurons
1. Presynaptic neuron - conducts impulses toward the synapse
| 2. postsynaptic neuron - transmits impulses away from the synapse
41
Two components of chemical synapse
1. axonal terminal of presynaptic neuron - contains synaptic vesicles
2. receptor regions on dendrite/soma of postsynaptic neuron
42
Four areas of CNS electrical synapses are important
SHAME
1. arousal from Sleep
2. ion and water Homeostasis
3. mental Attention
4. Memory
5. Emotions
43
Four steps of information transfer in synaptic cleft
1. Axon terminal reaches +30 mV
2. Voltage-dependent Ca2+ channels open
3. Ca2+ enters and binds to neurotransmitter vesicles.
4. Neurotransmitter released and interacts with postsynaptic receptors.
44
3 effects of neurotransmitter on receptor
1. produces a continuous postsynaptic effect
2. blocks reception of additional "messages"
3. must be removed from receptor by RED (reuptake, enzyme, diffusion)
45
What are neurotransmitters?
chemicals used for neuronal communication with the body and the brain
46
how many neurotransmitters have been identified and how are they classified?
50 different neurotransmitters.
Classified chemically and functionally
47
5 examples of Neurotransmitters
1. Acetylcholine (ACh)
2. Biogenic amines
3. Amino acids
4. Peptides
5. Novel messengers: ATP and dissolved NO and CO
48
Where is Acetylcholine found? (CNS and PNS)
CNS: motor cortex
PNS: neuromuscular junctions @ skeletal muscle
49
Three examples of Catecholamines
1. dopamine
2. norepinephrine (NE)
3. epinephrine
50
Is acetylcholine excitatory or inhibitory?
Both
51
Two examples of Indolamines
1. serotonin
| 2. histamine
52
Catecholamines and Indolamines belong to what chemical classification?
Biogenic Amines
53
temporal summation
presynaptic neurons transmit impulses transmit in rapidly to build EPSP up to threshold
54
spatial summation
postsynaptic neuron is stimulated by a large number of neurons at the same time
55
Two types of circuits in neuronal pools
divergent - one incoming fiber stimulates ever increasing number of fibers, amplifying circuits
convergent - many incoming fibers stimulate one fiber, resulting in strong stimulation or strong inhibition
56
Symptoms of multiple sclerosis
visual disturbances, weakness, loss of muscular control, urinary incontinence
57
cause of multiple sclerosis
autoimmune attack on myelin sheaths and nerve fibers are severed
58
Five drugs used to treat MS and three things they do
1. interferon beta-1a
2. interferon beta-1b
3. Avonex
4. Betaseran
5. Copazone
Hold symptoms at bay, reduce
complications, reduce disability
59
Two structures of Forebrain
Cerebrum and Diencephalon
60
4 parts of Cerebrum
1. Cerebral hemispheres
2. cerebral cortex
3. white matter
4. basal nuclei
61
when does nervous system start developing?
3 weeks, finishes first stage at 5 weeks
62
Four ventricles and where they are found
1&2. paired C shaped lateral ventricles
3. third ventricle in Diencephalon
4. fourth ventricle in hind brain dorsal to pons
63
gyri
ridges in cerebral hemisphere
64
sulci
shallow grooves in cerebral hemispheres
65
fissures
deep grooves in cerebral hemisphere
66
separates cerebral hemispheres
longitudinal fissure
67
five major lobes of cerebral hemisphere
1. frontal
2. parietal
3. temporal
4. occipital
5. insula (deep under temporal)
68
separates parietal and occipital lobes
parieto-occipital sulcus
69
separates parietal and temporal lobes
lateral sulcus
70
regions that border central sulcus
precentral gyrus and postcentral gyrus
71
three basic regions of cerebral hemispheres
cortex (gray matter), white matter, basal nuclei
72
Five things cerebral cortex enables you to do
1. sensation
2. communication
3. memory
4. understanding
5. voluntary movements
73
contralateral (in brain)
left hemisphere controls right side of body
74
do any functional areas act alone?
no. conscious behavior involves entire cortex
75
three functional areas of cerebral cortex
1. sensory - conscious awarenesss of sensation
2. association areas - integrate diverse information
3. motor areas - control voluntary movement
76
Four motor areas of cerebral cortex
1. primary (somatic) motor cortex
2. premotor cortex
3. Broca's area
4. Frontal eye field
77
location of primary motor cortex
in the precentral gyrus
78
two functions of primary motor cortex
allows conscious control of precise, skilled, voluntary movements.
actually signals muscles
79
premotor cortex location
anterior to precentral gyrus
80
two functions of premotor cortex
controls learned, repetitious, or patterned motor skills
involved in the planning of movements
81
Broca's area location
located anterior to he inferior region of premotor area
82
Two functions of Broca's area
directs muscles of tongue (motor speech)
allows you to actually say words
83
Frontal Eye field location
anterior to premotor cortex and superior to Broca's area
84
Frontal Eye Field function
controls voluntary eye movement
85
Four sensory areas of cerebral cortex
1. primary somatosensory cortex
2. somatosensory association cortex
3. visual and auditory areas
4. olfactory, gustatory, and vestibular cortices
86
primary somatosensory cortex location
located in postcentral gyrus
87
two functions of primary somatosensory cortex
receives information from the skin and skeletal muscles
exhibits spatial discrimination
88
somatosensory association cortex location
posterior to the primary somatosensory cortex
89
three functions of somatosensory association cortex
1. integrates sensory information
2. forms comprehensive understanding of the stimulus
3. determines size, texture and relationship of parts
90
primary visual cortex location
occipital lobe
91
two functions of primary visual cortex
1. receives visual information from the retinas
| 2. simple interpretations
92
visual association area location
surrounds primary visual cortex
93
function of visual association area
interprets visual stimuli (color, form, and movement)
94
primary auditory cortex location
superior edge of temporal lobe
95
function of primary auditory cortex
interprets pitch, rhythm and loudness
96
auditory association area location
posterior to primary auditory cortex
97
function of auditory association area
stores memories of sounds and permits perception of sounds
98
Four association areas of cerebral cortex
1. prefrontal cortex
2. language areas
3. general (common) interpretation area
4. visceral association area
99
prefrontal cortex location
anterior to premotor cortex (anteriormost portion of brain)
100
9 functions of prefrontal cortex
1. intellect
2. cognition
3. recall
4. personality
5. planning
6. complex ideas
7. behaviors
8. concentration/focus
9. emotions/judgment
101
Two Major language areas and their function
1. Wernicke's area - involved in sounding out unfamiliar words
2. Broca's area - speech preparation and production
102
What is General (Common) Interpretation Area?
ill-defined region including parts of temporal, parietal and occipital lobes. found in one hemisphere, usually left
103
what does general (common) interpretation area do? (two things)
1. integrates incoming signals into a single thought
| 2. processing spatial relationships (outside world, one's body, sentence structure)
104
location of visceral association area
located in the cortex of insula
105
two functions of visceral association area
1. involved in conscious perception of visceral sensations
| 2. habits
106
which lobe is associated with habits?
insula
107
what does lateralization refer to in the brain?
each hemisphere has abilities not shared with its partner
108
three abilities of left hemisphere
controls language, math and logic
109
three abilities of right hemisphere
controls visual-spacial skills, emotion and artistic skills
110
what is cerebral white matter responsible for?
communication between cerebral cortex, the lower CNS center and areas of cerebrum
111
what are basal nuclei composed of?
gray matter composed of several different groups of cells; substantia nigra and the amygdala.
112
what is considered the master of the motor system?
basal ganglia (basal nuclei)
113
what is the brake hypothesis
to sit still, the basal ganglia must put the breaks on all movements except those reflexes that maintain an upright posture
114
two categories of deficits of BG
1. presence of extraneous unwanted movements
| 2. absence or difficulty with intended movements
115
Where is diencephalon located?
Central core of the forebrain
116
3 structures of diencephalon
All three are paired.
1. thalamus
2. hypothalamus
3. epithalamus
117
Structure of thalamus
paired, egg-shaped masses connected at the midline by the intermediate mass
contains many nuclei
118
What is considered the grand central station for sensory information?
Thalamus (except smell)
119
Three functions of Thalamus
1. afferent impulses from all senses except olfaction converge and synapse in thalamus
2. impulses sorted out, edited and relayed as a group
3. some motor information
120
5 activities thalamus plays a key role in
1. mediating sensation
2. motor activities
3. cortical arousal
4. learning
5. memory
121
What structure helps you hear your name in a crowd?
Thalamus (picks out important sensory information)
122
3 components of hypothalamus
1. hypothalamic nuclei
2. mammillary bodies
3. infundibulum
123
structure of mammillary bodies
small, paired nuclei bulging anteriorly from hypothalamus
124
function of mammillary bodies
relay station for olfactory pathways
125
structure of infundibulum
stalk of hypothalamus; connects to pituitary gland
126
function of infundibulum
main visceral control center of the body
127
8 hypothalamic functions
1. regulates blood pressure
2. rate and force of heartbeat
3. digestive tract motility
4. rate and depth of breathing
5. perception of pleasure, fear and rage.
6. controls mechanisms that maintain body temperature
7. regulate feelings of hunger and satiety
8. regulate sleep and sleep cycle.
128
Two endocrine functions of Hypothalamus
1. releases hormones that control secretion by anterior pituitary
2. posterior pituitary releases ADH and oxytocin
129
Two structures of Epithalamus
1. pineal gland - secretes melatonin
| 2. choroid plexus - secretes cerebral spinal fluid
130
three regions of brain stem
1. midbrain
2. pons
3. medulla oblongata
131
how does brain stem differ from spinal cord
brain stem contains embedded nuclei
132
two functions of brain stem
1. controls automatic behaviors necessary for survival (respiration, heart rate, etc.)
2. provides pathway for tracts between higher and lower brain centers
133
how many cranial nerves is brain stem associated with?
10 of the 12 pairs of cranial nerves
134
Where is midbrain located?
Between diencephalon (thalamus) and pons.
135
Two structures of midbrain
1. cerebral peduncles
| 2. cerebral aqueduct
136
function of cerebral aqueduct
hollow tube that connects third and fourth ventricles - circulates cerebral spinal fluid
137
What is the corpora quadrigemina?
four dome like protrusions of dorsal midbrain (2 paired colliculi)
called midbrain nuclei
138
function of superior colliculi
visual reflex centers
139
function of inferior colliculi
auditory reflex centers
140
location of pons
bulging brainstem region between the midbrain and the medulla oblongata
141
Two functions of the fibers of the Pons
1. connect higher brain centers and the spinal cord
| 2. relay impulses between the motor cortex and the cerebellum
142
where is the Reticular Formation located?
the Pons
143
Where is the Medulla Oblongata located?
most inferior part of the brain stem?
144
What occurs at the decussation of the pyramids of medulla oblongata?
Contralateral crossover occurs
145
Two Medulla nuclei
1. cardiovascular control center - force and heart rate
| 2. respiratory centers - control rate and depth of breathing
146
What is the most primitive part of brain ("reptiliam brain")?
the brainstem
147
location of cerebellum
located dorsal to the pons and medulla. posteriormost part of brain
148
what percent of brains mass does cerebellum account for?
11%
149
function of cerebellum
coordination - precise timing and appropriate patterns of skeletal muscle contraction
150
Four steps of Cerebellar Processing
1. Cerebellum receives impulses of intent to initiate voluntary muscle contraction
2. proprioceptors and visual signals "inform" cerebellum of the body's conditions
3. cerebellar cortex calculate best way to perform a movement
4. a "blueprint" of coordinated movement is sent to cerebral motor cortex
151
What cognitive functions does cerebellum play a role in?
any activity that requires sequential planning:
problem solving, language, chess etc.
recognized and predicts sequences of events
152
Why do you become ataxic from alcohol?
Cerebellum is not well protected so coordination is easily affected
153
Three main parts of limbic system
1. amygdala
2. cingulate gyrus
3. hippocampus
154
function of amygdala
deals with anger, danger and fear responses. also plays role in memory
155
In the first moments of pain or trauma, what assessments can amygdala make?
1. This is real. I must take action.
| 2. This is a false alarm. Laughter can defuse situation.
156
7 functions of cingulate gyrus
1. shifting of attention
2. cognitive flexibility
3. adaptability
4. helps mind move between ideas
5. gives ability to see options
6. helps you go with the flow
7. cooperation
157
What does Reticular Formation do?
controls brain arousal by sending out repeated electrical "jolts"
158
Retiular Formation makes axonal connections with what 4 structures?
1. hypothalamus
2. thalamus
3. cerebellum
4. spinal cord
159
What are brain waves?
Unique pattern of neuronal electrical activity recorded by Electroencephalogram (EEG)
160
6 conditions an EEG can be used to diagnose
1. brain lesions
2. tumors
3. infarcts (clot)
4. infections
5. abscesses
6. epileptic lesions
161
In what percentage of population does epilepsy occur?
1%
162
Two main classifications of seizures
1. partial, involved in only a part of the brain
| 2. generalized, where the seizure spreads to entire brain
163
Three layers of protection of brain
1. skull (bone)
2. three layers of meninges
3. cerebrospinal fluid
164
what protects brain from harmful chemical substances?
blood-brain barrier
165
3 connective tissue meninges
1. dura mater
2. arachnoid mater
3. pia mater
166
Four functions of meninges
1. cover and protect CNS
2. protect blood vessels and enclose venous sinuses
3. contain cerebrospinal fluid (CSF)
4. form partitions within the skull
167
description of dura mater
leathery, strong meninx composed of two fibrous connective tissue layers
168
what separates dura mater and arachnoid mater?
subdural space
169
what lies beneath arachnoid mater?
subarachnoid space filled with CSF and large blood vessels
170
What do arachnoid villi do?
Protrude superiorly and permit CSF to be absorbed into venous blood
171
description of pia mater
deep meninx composed of delicate connective tissue that clings tightly to the brain
172
4 functions of cerebrospinal fluid
1. forms liquid cushion that gives buoyancy to CSF organs
2. prevents brain from crushing under its own weight
3. protects the CNS from blows and other trauma
4. nourishes brain and carries chemical signals throughout it
173
cerebrospinal fluid composition
watery solution similar to plasma but contains less protein and different ion concentrations
174
structure of choroid plexus
clusters of capillaries that form tissue fluid filters and hang from roof of each ventricle
175
Two functions of choroid plexuses
1. ion pumps allow them to alter ion concentrations of CSF
| 2. remove waste from CSF
176
Three components of blood brain barrier
1. continuous endothelium of capillary walls
2. relatively thick basal lamina
3. bulbous feet of astrocytes
177
Where is blood brain barrier absent?
vomiting center and hypothalamus. so they can monitor chemical composition of blood
178
what is stress's affect in blood-brain barrier?
stress increases ability of chemical to permeate
179
what causes a stroke?
blood circulation to brain is blocked and brain tissue dies
180
three common causes of stroke
1. blockage of cerebral artery
2. compression of the brain by hemorrhage of edema
3. atherosclerosis
181
what is a transient ischemic attack (TIA)?
temporary episode of reversible cerebral ischemia
182
what is the only approved treatment for stroke?
tissue plasminogen activator
183
What is Alzheimer's disease?
a progressive degenerative disease that results in dementia
184
what is Parkinson's disease?
degeneration of dopamine-releasing neurons of substantia nigra
185
what is Huntington's disease?
a fatal hereditary disorder caused by accumulation of the protein huntingtin that leads to degeneration of basal nuclei
186
CNS tissue of spinal cord spans what vertabrae?
foramen magnum to L1
187
what protects spinal cord?
vertebral column (bone), meninges and CSF
188
how many pairs of spinal nerves are there?
31
189
What are cervical and lumbar enlargements?
sites of spinal cord where nerves serving upper and lower limbs emerge
190
What is the cauda equina?
collection of nerve roots at the inferior end of the vertebral canal
191
What 3 things does the gray matter of spinal cord consist of?
1. soma
2. unmyelinated processes
3. neuroglia
192
what is contained in posterior (dorsal) horns of spinal cord?
interneurons
193
what is contained in anterior (ventral) horns of spinal cord?
interneurons and somatic motor neurons
194
what is contained in lateral horns of spinal cord?
sympathetic nerve fibers
195
What part of PNS is located in dorsal half of spinal cord?
sensory roots and ganglia
196
what part of PNS is contained in ventral half of spinal cord?
motor roots
197
What four zones are evident within the gray matter of spinal cord?
1. somatic sensory (SS)
2. visceral sensory (VS)
3. visceral motor (VM)
4. somatic motor (SM)
198
Where do dorsal and ventral roots of spinal cord fuse?
Laterally to form spinal nerves
199
Three ascending pathways of spinal cord
1. non-specific
2. specific
3. spinocerebellar
200
function of non-specific ascending pathway
pain, temperature and crude touch
201
function of specific ascending pathway
normal touch
202
function of spinocerebellar tracts (ascending pathway)
send impulses to cerebellum, do not contribute to sensory perception
203
Four steps of Direct (Pyramidal) System
1. originate with pyramidal neurons of precentral gyrus
2. impulses sent through corticospinal tracts to anterior horns
3. stimulation of anterior horn neurons activates skeletal muscles
4. regulates fast and fine (skilled) movements
204
Extrapyramidal system (descending pathway) controls what movements?
1. axial muscles that maintain balance and posture
2. coarse movements of proximal portions of limbs
3. head, neck and eye movement
205
What is paralysis?
loss of motor function
206
what is flaccid paralysis?
severe damage to ventral root or anterior horn cells. results in muscle atrophy
207
what is spastic paralysis?
only upper motor neurons of primary motor cortex are damaged. intact spinal neurons stimulated irregularly. no voluntary movement
208
paraplegia
transection between T1 and L1
209
quadriplegia
transection in cervical region
210
what is poliomyelitis (polio)?
destruction of the anterior horn motor neurons by poliovirus
211
early symptoms of poliomyelitis
fever, headache, muscle pain and weakness, loss of somatic reflexes
212
Whats the scientific name of Lou Gehrig's disease?
Amyotrophic Lateral Sclerosis (ALS)
213
What is ALS?
neuromuscular condition involving destruction of anterior horn motor neurons and fibers of the pyramidal tract
214
Symptoms of Lou Gehrig's disease
loss of the ability to speak, swallow and breathe
215
Define sensory input
monitoring stimuli inside and outside body
216
Define integration [neurology]
interpretation of sensory input
217
Define motor output [neurology]
response to stimuli by activating effector organs
218
How is acetylcholine removed?
degraded by acetylcholinesterase (AChE)
219
How is nerve gas related to neurotransmitters?
prolonged ACh effects
220
How is Alzheimer's related to neurotransmitters?
low levels of Ach
221
How are Botulinum toxins related to neurotransmitters?
prevent Ach release from presynaptic neuron
222
How is snake venom related to neurotransmitters?
blocks Ach receptors
