Chapter 43 Flashcards
(276 cards)
1
Q
What do sensory receptors do?
A
detect stimuli
2
Q
What do motor effectors do?
A
respond to stimuli
3
Q
What is another name for sensory neurons?
A
afferent neurons
4
Q
What do sensory neurons do?
A
carry impulses from sensory receptors to the CNS
5
Q
What is another name for motor neurons?
A
efferent neurons
6
Q
What do motor neurons do?
A
carry impulses from the CNS to effectors (muscles and glands)
7
Q
What is another name for interneurons?
A
association neurons
8
Q
Where are interneurons located?
A
in the brain and spinal cord (of vertebrates)
9
Q
What do interneurons do?
A
help provide more complex reflexes and higher associative functions, including learning and memory
10
Q
Sensory and motor neurons constitute
A
the PNS in vertebrates
11
Q
Motor neurons that stimulate skeletal muscles make up the
A
somatic nervous system
12
Q
Motor neurons that stimulate smooth/cardiac muscles and glands make up
A
the autonomic nervous system
13
Q
What are the two further divisions of the autonomic nervous system?
A
sympathetic and parasympathetic divisions
14
Q
What is the neuron cell body?
A
enlarged region containing the nucleus
15
Q
What are dendrites?
A
cytoplasmic extensions of a neuron
16
Q
What are dendritic spines?
A
branches of dendrites that further increase the surface area available to receive stimuli
17
Q
Each neuron has how many axons?
A
just one
18
Q
The supporting cells of neurons are collectively called
A
neuroglia
19
Q
How big are neuroglia compared to neurons?
A
1/10th the size of neurons
20
Q
How numerous are neuroglia compared to neurons?
A
10 times more numerous than neurons
21
Q
What are the two most important kinds of neuroglia?
A
Schwann cells and oligodendrocytes
22
Q
Schwann cells and oligodendrocytes both produce
A
myelin sheaths
23
Q
Which neuroglium produces myelin sheaths in the PNS?
A
Schwann cells
24
Q
Which neuroglium produces myelin sheaths in the CNS?
A
oligodendrocytes
25
What is white matter?
In the CNS, myelinated axons form white matter
26
What is gray matter?
unmyelinated dendrites and cell bodies form gray matter
27
How are myelinated axons organized in the PNS?
arranged in bundles
28
What are the intervals for nodes of Ranvier?
1 to 2 micrometers
29
The resting membrane potential of many vertebrate neurons ranges from
-40 to -90 millivolts, or 0.04 V to 0.09 V
30
The inside of the cell is (+/-) charged whereas the outside is (+/-) charged.
The inside of the cell is negatively charged and the outside is positively charged.
31
What are the two contributors to the membrane potential?
sodium/potassium pump; ion channels
32
How many of each ion does the sodium/potassium pump exchange?
The sodium potassium pump brings in 2 potassium ions for every 3 sodium ions it pumps out
33
Describe the relative amounts of Na+ and K+ inside and outside the cell in a resting potential.
The inside has high K+ and low Na+ concentrations, whereas the outside has high Na+ and low K+ concentrations.
34
Refer to Figure 43.5 on page 890. Describe how the sodium/potassium pump works. (6)
carrier in membrane binds to intracellular sodium; ATP phosphorylates protein with bound sodium; phosphorylation causes conformational change in protein, which reduces affinity for Na+ and releases Na+ out of the cell; this conformation has affinity for K+ so 2 K+ ions bind; binding of K+ causes dephospho rylation of protein; dephosphorylation of protein triggers back to original conformation with low affinity for K+ so K+ diffuses into cell
35
Are there more K+ or Na+ ion channels in the cell membrane?
there are more K+ ion channels in the membrane
36
What are ion channels?
membrane proteins that form pores through the membrane, allowing diffusion of specific ions across the membrane
37
What is the equilibrium potential?
the balance between the diffusional force and the electrical force
38
Write out the Nernst equation (pg. 890)
*write out*
39
What are the two types of disruptions to the resting membrane potential?
graded potentials and action potentials
40
What are graded potentials?
small continuous changes to membrane potentials
41
What are action potentials?
transient disruptions of the potential triggered by a threshold change in potential
42
Why does the resting potential arise?
because of the permeability of the membrane to K+ through leakage channels
43
What are the two types of gated channels?
ligand-gated (chemically gated) OR voltage-gated channels (respond to changes in membrane potential)
44
Ligand-gated channels lead to what type of potential?
graded potentials that determine whether an axon will fire
45
Voltage-gated channels lead to what type of potential?
action potential
46
Gated ion channels in dendrites respond to
the binding of signaling molecules
47
Which molecules act as ligands and induce the opening of ligand-gated channels?
hormones and neurotransmitters
48
Permeability changes are measurable as
depolarizations or hyperpolarizations of the membrane potential
49
What do depolarizations do?
makes the membrane potential less negative (more positive)
50
What do hyperpolarizations do?
makes the membrane more negative
51
What are the two classifications of graded potentials?
depolarizing or hyperpolarizing
52
What is summation?
the ability of graded potentials to combine
53
Action potentials result when
depolarization reaches a threshold
54
What is the threshold potential?
level of depolarization needed to produce an action potential
55
The action potential is caused by what class of ion channel?
voltage-gated ion channels
56
Voltage-gated ion channels open and close in response to
changes in the membrane potential
57
Voltage-gated channels are found in what two cell types of the body?
neurons and muscle cells
58
What are the two different channels used to create an action potential in neurons?
voltage-gated Na+ channels and voltage-gated K+ channels
59
Which voltage-gated ion channel (Na+ or K+) has more complex behavior?
the voltage-gated Na+ channel
60
The voltage-gated Na+ channel has what two gates?
an activation gate and an inactivation gate
61
In the resting state of the voltage-gated Na+ channel, which gates are opened and closed?
the activation gate is closed and the inactivation gate is open
62
What happens to the gates of the voltage-gated Na+ channel when the threshold voltage is reached?
the activation gate opens rapidly, which leads to an influx of Na+ ions
63
What happens after the influx of Na+ ions after the threshold voltage is reached?
the inactivation gate closes, which stops the influx of Na+ ions and leaves the channel in a temporarily inactivated state
64
How is the channel returned to its resting state following the influx of Na+ ions?
the activation gate closes and the inactivation gate opens, which leads to a transient influx of Na+ that depolarizes the membrane in response to a threshold voltage
65
How many gates does the voltage-gated K+ channel have? (2)
a single activation gate that is closed in the resting state; in response to a threshold voltage, it opens slowly
66
When the voltage-gated K+ channel activation gate, what happens?
an efflux of K+ begins, which contracts the effect of the Na+ channel and repolarizes the membrane
67
What are the three phases of the action potential?
rising phase, falling phase, undershoot phase
68
What happens in the rising phase?
equilibrium between the diffusion of K+ out of the cell and voltage pulling K+ into the cell
69
What happens in the rising phase? (2)
stimulus causes above-threshold voltage; sodium channel activation gate opens
70
What happens in the top of the curve? (3)
maximum voltage reached; sodium channel inactivation gate closes; potassium gate opens
71
What happens in the falling phase?
undershoot occurs as excess potassium diffuses out before potassium channel closes
72
What happens as equilibrium is restored?
potassium channel gate closes; Na+ channel activation gate closes and inactivation gate opens
73
Why does the membrane potential never quite reach +60 mV?
because the inactivation gate of the Na+ channel closes, terminating the rising phase
74
What is the nature of action potentials?
action potentials are separate, all-or-none events
75
Do action potentials interfere with each other?
no, but graded potentials can
76
Why don't action potentials interfere with each other?
After Na+ channels fire, they remain in an inactivated state until the inactivation gate reopens, preventing any summing of effects
77
What is the absolute refractory period? (2)
when the Na+ channels remain in an inactivated state after they fire but before the inactivation gate reopens; membrane cannot be stimulated
78
What is the relative refractory period?
stimulation produces action potentials of reduced amplitude
79
The production of an action potential results entirely from
the passive diffusion of ions
80
At the end of an action potential, what is the ion composition like?
cytoplasm contains a little more Na+ and a little less K+ than it did at rest, but the Na/K pump compensates for this change
81
The sodium/potassium pump operates using what kind of transport?
active transport
82
What is the relationship between velocity of conduction and the diameter of the axon?
the velocity of conduction is greater if the diameter of the axon is large
83
What is the relationship between myelination and velocity of conduction?
the velocity of conduction is greater if the axon is myelinated
84
Why does velocity increase as diameter increase?
because electrical resistance is inversely proportional to cross-sectional area
85
Are large diameter axons found in vertebrates or invertebrates?
found primarily in invertebrates
86
What is saltatory conduction?
when depolarizations spread quickly beneath insulating myelin to trigger the opening of voltage-gated channels at the next node
87
Action potentials in myelinated axons are only produced at
the nodes of Ranvier
88
What are synapses?
specialized intercellular junctions that are found at the end of an axon
89
What is the presynaptic cell?
the neuron that is sending the action potential
90
What is the postsynaptic cell?
the neuron that is receiving the action potential
91
What are the two basic types of synapses?
electrical and chemical synapses
92
What are electrical synapses?
electrical synapses involve direct cytoplasmic connections formed by gap junctions between the pre and post synaptic neurons
93
Electrical synapses are common in what types of organisms?
common in invertebrate nervous systems, but are rare in vertebrates
94
The vast majority of vertebrate synapses are what type of synapse?
chemical synapses
95
What is the synaptic cleft?
a narrow space that separates these two cells
96
The end of a presynaptic axon is swollen and contains
numerous synaptic vesicles
97
Each synaptic vesicle is packed with chemicals called
neurotransmitters
98
When action potentials arrive at the end of the axon?
they stimulate the opening of voltage-gated calcium channels, causing a rapid inward diffusion of Ca2+
99
The rapid inward diffusion of Ca2+ triggers
a complex series of events that leads to the fusion of synaptic vesicles with the plasma membrane and the release of the neurotransmitter by exocytosis
100
What is the relationship between the frequency of action potentials and the number of vesicles that release neurotransmitters?
The higher the frequency of action potentials, the greater the number of vesicles that release neurotransmittesr
101
What happens after the neurotransmitters are released?
The neurotransmitters are released to the other side of the cleft and bind to the chemical or ligand-gated receptor proteins in the membrane of the post synaptic cell
102
Why is the presence of neurotransmitters in the synaptic cleft tightly controlled?
they must be removed rapidly to allow new signals to be transmitted
103
What are three ways in which neurotransmitters are removed from the synaptic cleft?
enzymatic digestion, reuptake of neurotransmitters by the original neuron, uptake by glial cells
104
What is acetylcholine?
a neurotransmitter that crosses the synapse between a motor neuron and a muscle fiber
105
The synapse in which acetylcholine is found is called
a neuromuscular junction
106
How does acetylcholine work?
binds to its receptor proteins in the post-synaptic membrane and causes ligand-gated ion channels within these proteins to open
107
What is the result of acetylcholine opening ligand-gated ion channels?
that site on the post synaptic membrane produces a depolarization called an excitatory postsynaptic potential (EPSP)
108
What are the consequences for the production of an EPSP?
The EPSP, if strong enough, can open the voltage-gated channels for Na+ and K+ that are responsible for action potentials
109
How is acetylcholine removed?
Acetylcholinase is an enzyme found in the postsynaptic membrane that eliminates acetylcholine by cleaving it into inactive fragments
110
What are 2 potent inhibitors of acetylcholinase?
nerve gas; parathion (an agricultural insecticide)
111
How can acetylcholinase inhibitors harm humans? (2)
can cause severe spastic paralysis; death if paralysis affects respiratory system
112
Is acetylcholine restricted to use for skeletal muscle cells?
no
113
What is the function of glutamate as a neurotransmitter?
major excitatory neurotransmitter for the vertebrate CNS
114
Excitatory neurotransmitters act to
stimulate action potentials by producing EPSPs
115
What is the consequence of hypersensitivity to glutamate?
causes someone to suffer from Huntington disease which leads to neurodegeneration
116
Give two examples of inhibitory neurotransmitters.
glycine, GABA
117
What do glycine and GABA do?
cause the opening of ligand-gated channels for the chloride ion, which has a concentration gradient favoring its diffusion into the neuron
118
What is the effect of glycine and GABA diffusing Cl- into the neuron? (2)
the inside of the membrane is even more negative than it usually is at rest; is an example of hyper polarization called inhibitory post synaptic potential (IPSP)
119
What does EPSP stand for?
excitatory post synaptic potential
120
What does IPSP stand for?
inhibitory post synaptic potential
121
How does the drug diazepam (Valium) work?
causes sedation by enhancing the binding of GABA to its receptors, increasing the effectiveness of GABA at the synapse
122
What are the four biogenic amines?
epinephrine/adrenaline, dopamine, norepinephrine, serotonin
123
Epinephrine, norepinephrine, and dopamine are derived from
tyrosine
124
Epinephrine, norepinephrine, and dopamine are included in the category called
catecholamines
125
Serotonin Is derived from
tryptophan
126
Epinephrine is released into
the blood as a hormonal secretion
127
Norepinephrine is released at
the synapses of neurons in the sympathetic nervous system
128
What is dopamine?
very important neurotransmitter used in some areas of the brain controlling body movement
129
Degeneration of particular dopamine-releasing neurons results in
resting muscle tremors in Parkinson disease
130
How are people with Parkinson disease treated?
with L-dopa
131
Schizophrenia is associated with
excessive activity of dopamine-releasing neurons
132
How are people with schizophrenia treated?
chlorpromazine (Thorazine), which blocks the production of dopamine
133
What is serotonin? (2)
neurotransmitter involved in the regulation of sleep; implicated in various emotional states
134
What might be one possible cause of depression?
insufficient activity of neurons that release serotonin
135
How are people with clinical depression treated?
Fluoxetine (prozac), which blocks the elimination of serotonin in the synaptic cleft
136
Drugs like prozac are termed
selective serotonin reuptake inhibitors (SSRIs)
137
What are neuropeptides?
a type of polypeptide released at the synapse that may have a typical neurotransmitter function or may have a subtle long-term effect on the postsynaptic neuron
138
Neuropeptides that have a subtle long-term effect on the post synaptic neuron are called
neuromodulators
139
How many kinds of neurotransmitters can an axon release?
generally only one
140
What is substance P?
an important neuropeptide released at synapses in the CNS by sensory neurons activated by painful stimuli
141
The intensity with which pain is perceived partly depends on what two neuropeptides?
enkephalins and endorphins
142
What are enkephalins? (2)
inhibit the passage of pain information back up to the brain; released by axons descending from the brain into the spinal cord
143
What are endorphins? (2)
released by neurons in the brain stem; block the perception of pain
144
What are two derivatives of opium?
morphine and heroin
145
Why are opium and its derivatives used as analgesic drugs?
they have a similar enough chemical structure to bind to the receptors normally used by enkephalins/endorphins.
146
What is the first gas known to act as a regulatory molecule in the body?
nitric oxide
147
How is NO transferred?
diffuses through membranes
148
How is NO produced?
produced as needed from arginine
149
What does NO do?
diffuses out of the presynaptic axon and into the neighboring cells by simply passing through the lipid portions of the plasma membranes
150
What is the role of NO in the PNS? (4)
innervates the gastrointestinal tract, penis, respiratory passages, cerebral blood vessels
151
How does sildenafil/Viagra work?
increases the release of NO in the penis, enabling and prolonging an erection
152
How does the brain use NO?
uses NO as a neurotransmitter, where it appears to participate in the processes of learning and memory
153
What is synaptic integration?
when EPSPs and IPSPs add up amongst each other
154
A post synaptic neuron is like a (analogy)
switch that is either turned on or remains off
155
What are the two ways that a membrane can reach the threshold voltage?
by many different dendrites producing EPSPs that sum to the threshold voltage OR by one dendrite producing repeated EPSPs that sum to the threshold voltage
156
What is spatial summation?
when many different dendrites produce EPSPs that sum to the threshold voltage
157
What is temporal summation?
when one dendrite produces repeated EPSPs that sum to the threshold voltage
158
What happens in spatial summation?
graded potentials due to dendrites from different presynaptic neurons that occur at the same time add together to produce an above-threshold voltage
159
What happens in temporal summation?
a single dendrite produces a sufficient depolarization to produce an action potential if it produces EPSPs that are close enough in time to sum to a depolarization greater than the threshold
160
How long does a typical EPSP last for?
15 milliseconds
161
What is habituation?
when certain cells of the nervous system are exposed to a constant stimulus and cells lose their ability to respond to that stimulus
162
How are synapses affected by habituation?
If receptor proteins within synapses are exposed to high levels of neurotransmitter molecules for prolonged periods, the postsynaptic cell responds by decreasing the number of receptor proteins in its membrane
163
What is the only major phylum to lack nerves?
sponges
164
The simplest nervous system occurs in
cnidarians, in which all the neurons are similar and linked together in a nerve net
165
What are the simplest animals with associative activity?
free-living flatworms (phylum Platyhelminthes)
166
How many nerve cords do flatworms have?
2
167
What are the three divisions of contemporary vertebrate brains?
hindbrain, midbrain, forebrain
168
What is another name for the hindbrain?
rhombencephalon
169
What is another name for the midbrain?
mesencephalon
170
What is another name for the forebrain?
prosencephalon
171
What are the three components of the hindbrain in fishes?
cerebellum; pons; medulla oblongata
172
The hindbrain in fishes may be considered
an extension of the spinal cord responsible for coordinating motor reflexes
173
The hindbrain in fishes ntegrates
sensory signals coming from muscles and coordinates the pattern of motor responses
174
What is the function of the cerebellum? (2)
coordination of movements; balance
175
What is the function of the pons? (2)
reticular-activating system; autonomic functions
176
What is the function of the medulla oblongata? (3)
sensory nuclei; reticular-activating system; autonomic functions
177
The midbrain in fishes is primarily composed of
the optic tectum
178
What does the optic tectum do in fishes?
receives and processes visual information
179
What does the forebrain in fishes do?
processing olfactory information
180
How is brain development different in fishes compared to other vertebrates?
brains of fishes continue growing throughout lifetime; in other vertebrates, brain development is usually done in infancy
181
What is neurogenesis?
production of new neurons
182
Starting with amphibians and continuing with reptiles, the processing of sensory information is increasing
centered in the forebrain
183
The forebrain in reptiles/amphibians/birds/mammals is composed of what two elements?
diencephalon; telencephalon
184
What does the diencephalon consist of? (2)
thalamus and hypothalamus
185
What is the thalamus?
integration and relay center between incoming sensory information and the cerebrum
186
What is the hypothalamus?
participates in basic drives and emotions and controls the secretions of the pituitary gland
187
What controls the secretions of the pituitary gland?
the hypothalamus
188
Where the telencephalon located?
front of the forebrain
189
What does the telencephalon do?
devoted to associative activity
190
What is the cerebrum? (2)
center for correlation, association, and learning in the mammalian brain; receives sensory data from the thalamus and issues motor commands to the spinal cord via axons
191
In vertebrates, the CNS is composed of
the brain and the spinal cord
192
The human cerebrum is split into
right and left cerebral hemispheres
193
What connects the right and left cerebral hemispheres?
corpus callosum
194
The cerebral hemispheres are further divided into (4)
frontal, parietal, temporal, and occipital lobes
195
Each cerebral hemisphere receives sensory input from
the opposite (contralateral) side of the body
196
Much of the neural activity of the cerebrum occurs in
the cerebral cortex
197
Describe the physical appearance of the cerebral cortex.
layer of gray matter only a few millimeters thick
198
How many nerve cells are in the cerebral cortex?
over 10 billion
199
Why are convolutions in the cerebral cortex important?
increase surface area
200
What are the three activities of the cerebral cortex?
motor, sensory, associative
201
Where is the primary motor cortex located?
along the gyrus on the posterior border of the front lobe, just in front of the central sulcus
202
A gyrus is a
convolution
203
A sulcus is a
crease
204
Where is the primary somatosensory complex located?
just behind the central sulcus, on the anterior edge of the parietal lobe
205
Each point in the area of the primary somatosensory complex receives input from
sensory neurons serving skin and muscle senses
206
Large areas of the primary motor/primary somatosensory cortexes are devoted to
fingers/lips/tongue because of the need for manual dexterity and speech
207
Where is the auditory cortex located?
within the temporal lobe
208
Where is the visual cortex located?
on the occipital lobe
209
What is the association cortex? (2)
the portion of the cerebral cortex that is not occupied by these motor and sensory cortices; location of higher mental activities
210
The association cortex makes up what percent of the surface of the cerebral cortex in humans?
95%
211
What are basal ganglia?
aggregates of neuron cell bodies located deep within white matter of cerebrum that produce islands of gray matter
212
Damage to specific regions of the basal ganglia can result in what?
can result in resting tremor of muscles that is characteristic of Parkinson's disease
213
Somatosensory information is handled by which lobe?
the parietal lobe
214
What brain structure is responsible for body temperature/hunger/thirst/various emotional states?
hypothalamus
215
What is the brainstem?
term that collectively refers to midbrain/pons/medulla oblongata
216
What are the three major components of the limbic system?
hippocampus, amygdala, hypothalamus
217
The limbic system is responsible for
emotional responses
218
The hippocampus is believed to be important in
the formation and recall of memories
219
What is the reticular formation?
diffuse collection of neurons in the brainstem
220
What does the reticular activating system do?
controls consciousness and alertness
221
All sensory pathways feed into what system?
the reticular activating system
222
Drugs like anesthetics and barbiturates can depress
neural pathways from the reticular formation to the cortex
223
What controls both sleep and the waking state?
reticular-activating system
224
What does EEG stand for?
electroencephalogram
225
What is an EEG?
a recording of electrical activity that is used to monitor brain state
226
What are alpha waves?
large, slow waves found in awake, relaxed individuals with closed eyes
227
What are beta waves?
rapid waves found in alert individuals with opened eyes
228
What kind of brain waves are observed in sleep?
theta and delta waves, which are very slow waves
229
When an individual is in REM sleep, what are the brain waves like?
alpha waves
230
Which hemisphere is the dominant hemisphere for language in most right-handed people?
left hemisphere
231
Where is Wernicke's area located?
in the parietal lobe between the primary auditory and visual areas
232
What is the function of Wernicke's area? (2)
important for language comprehension and the formulation of thoughts into speech
233
Where is Broca's area located?
found near the part of the motor cortex controlling the face
234
What is the function of Broca's area?
responsible for generation of motor output needed for language communication
235
What are aphasias?
language disorders caused by damage to the relevant brain areas
236
If Wernicke's area is damaged, what happens?
person's speech is rapid and fluid but lacks meaning
237
What hemisphere is used for spatial reasoning in most right handed people?
the right hemisphere
238
Which hemisphere is involved in musical ability?
right hemisphere
239
Damage to the inferior temporal cortex results in
the loss of the ability to recognize faces, a condition called prosopagnosia
240
Which hemisphere is important for the consolidation of memories of nonverbal experiences?
the right hemisphere
241
What are two examples of synaptic plasticity?
long-term potentiation (LTP) and long-term depression (LTD)
242
What are the effects of Alzheimer disease?
memory and thought processes of the brain become dysfunctional
243
What are the two hypotheses about the origin of Alzheimer disease?
nerve cells in the brain are killed from the outside in; nerve cells in the brain are killed on the inside out
244
What happens in the first hypothesis about Alzheimer disease?
proteins called beta-amyloid form aggregates and fill the brain and kill nerve cells
245
What happens in the second hypothesis about Alzheimer disease?
nerve cells are killed by an abnormal form of tau protein, which tangle up and interfere with the normal function of nerve cells
246
What are meninges?
layers of membrane that protect the spinal cord
247
What are the two zones in the spinal cord?
inner zone of grey matter; outer zone of white matter
248
Describe the inner zone of the spinal cord. (2)
gray matter; consists of cell bodies of interneurons/motor neurons/neuroglia
249
Describe the outer zone of the spinal cord. (2)
white matter; contains cables of sensory axons in the dorsal columns and motor axons in the ventral columns
250
What are reflexes?
sudden, involuntary movement of muscles
251
Which structure is responsible for reflexes?
spinal cord
252
What happens in monosynaptic reflex arcs?
sensory nerve cell makes synaptic contact directly with a motor neuron in the spinal cord whose axon travels directly back to the muscle
253
Most reflexes in vertebrates, however, involve what?
a single connecting interneuron between the sensory neuron and a motor neuron
254
What does the PNS consist of?
nerves (collections of axons) and ganglia
255
What are ganglia?
aggregations of neuron cell bodies located outside the CNS
256
What is the dorsal root?
the point where the axons of sensory neurons enter the dorsal surface of the spinal cord
257
What is the ventral root?
the point where motor axons leave from the ventral surface of the spinal cord
258
What is the dorsal root ganglia?
where the cell bodies of sensory neurons are grouped together
259
Where are the cell bodies of somatic motor neurons located?
within the spinal cord, NOT in ganglia
260
What are the two divisions of the autonomic nervous system?
sympathetic and parasympathetic divisions
261
The autonomic nervous system is composed of (3)
the sympathetic division, parasympathetic division, medulla oblongata
262
How are the sympathetic and parasympathetic divisions similar?
both have efferent motor pathway involving two neurons
263
The first neuron of the efferent motor pathway in the sympathetic and para sympathetic divisions is located in / its name (2)
the CNS and sends an axon to an autonomic ganglion; called the preganglionic neuron
264
The preganglionic neuron uses what neurotransmitter?
acetylcholine
265
The second neuron of the efferent motor pathway in the sympathetic and para sympathetic divisions is located in / its name (2)
autonomic ganglion and sends it axon to synapse with a smooth muscle/cardiac muscle/gland cell; called the postganglionic neuron
266
The postganglionic neuron uses what neurotransmitter?
In the parasympathetic division, acetylcholine; in the sympathetic division, norepinephrine
267
The preganglionic neurons of the sympathetic nervous system originate in what part of the spinal cord?
thoracic and lumbar regions of the spinal cord
268
What is the sympathetic chain of ganglia?
the two parallel chains of ganglia immediately outside the spinal cord
269
The sympathetic chain of ganglia contains what?
the cell bodies of postganglionic cells
270
Where do preganglionic parasympathetic neurons originate in?
brain and sacral regions of the spinal cord
271
Where do preganglionic parasympathetic axons terminate?
near or within internal organs
272
How do preganglionic parasympathetic neurons regulate internal organs?
by releasing acetylcholine at their synapses
273
Which system (sympathetic/parasympathetic) is the one used for fight/flight?
sympathetic - fight/flight; parasympathetic - resting
274
What effect does acetylcholine have on heart rate?
slows heart rate
275
The acetylcholine receptor in the heart is a member of a class of receptors called
G protein-coupled receptors
276
How do G proteins mediate sympathetic nerve effects?
stimulation by norepinephrine from sympathetic nerve endings and epinephrine from eh adrenal medulla require G proteins to activate the target cells
