Chapter 6 Flashcards
(264 cards)
1
Q
brain and spinal cord
A
central nervous system
2
Q
nerves that connect the brain or spinal cord with the body’s muscles, glands, sense organs, and other tissues
A
peripheral nervous system
3
Q
functional unit, generates electrical signals called action potentials or nerve impulses
A
neuron
4
Q
supporting cells, do not generate nerve impulses
A
glial cells
5
Q
highly branched extensions of neuron cell body; receive synaptic input from other neurons
A
dendrites
6
Q
in cells with long extensions, the part that contains the nucleus
A
cell body
7
Q
in cells with long extensions, the part that contains the nucleus
A
axon hillock
8
Q
in cells with long extensions, the part that contains the nucleus
A
axon
9
Q
in cells with long extensions, the part that contains the nucleus
A
axon terminals
10
Q
Kinesin transport mainly occurs from the cell body toward the axon terminals (anterograde) and is important in moving nutrient molecules, enzymes, mitochondria, neurotransmitter-filled vesicles, and other organelles
A
anterograde transport
11
Q
Dynein movement is in the other direction (retrograde), carrying recycled membrane vesicles, growth factors, and other chemical signals that can affect the neuron’s morphology, biochemistry, and connectivity
- route by which some harmful agents invade the CNS, including tetanus toxin and the herpes simplex, rabies, and polio viruses
A
retrograde transport
12
Q
neurons whose cell bodies and axons lie entirely in CNS
A
interneurons
13
Q
neurons that carry information from sensory receptors at their peripheral endings to CNS; cell body lies outside CNS
A
afferent neuron
14
Q
neurons that carry information away from CNS
A
efferent neuron
15
Q
- chemical and electrical stimuli to pass information.
- inhibitory or excitatory depending on the signal/ neurotransmitter being transmitted
A
Neuron Postsynaptic to One Cell Can be Presynaptic to Another
16
Q
regulate the composition of the extracellular fluid by removing potassium ions and neurotransmitters around synapses, stimulate the formation of tight junctions, and sustain neurons metabolically
A
astrocytes
17
Q
perform immune functions and may also contribute to synapse remodeling and plasticity
A
microglia
18
Q
line the fluid-filled cavities and regulate the production and flow of cerebrospinal fluid (CSF)
A
ependymal cells
19
Q
form the myelin sheath
A
oligodendrocytes
20
Q
insulating material covering axons of many neurons; consists of layers of myelin-forming cell plasma membrane wrapped around axon
A
myelin
21
Q
growth and development of neurons in the embryo begins with
A
stem cells
22
Q
after the last cell division, differentiates, migrates to its final location, and sends out processes that will become its axon and dendrites
A
neuron cells
23
Q
axon terminal, in the ___ ___ finds the correct route and final target for the process guided by glial cells neurotrophic factors, form synapses when reach the target
A
growth cone
24
Q
during early stages of ____ _____, which occur during fetal life and infancy, alcohol and other drugs, radiation, malnutrition, and viruses can cause permanent damage to the developing nervous system
A
neural development
25
the basic shapes and locations of ___ ___ ___ in the mature nervous system do not change once formed
major neural circuits
26
the degree of neural ____ varies with age
plasticity
27
the creation and removal of ____ ____ begun during fetal development continue throughout life as part of normal growth, learning, and aging
synaptic contacts
28
severed axons
can repair and restore significant function at a slow spee
Outside the CNS and neuron’ cell body not affeered
29
crush not cut the tissue, leaving the axons intact, apoptosis of the nearby oligodendrocytes results in loss of the myelin sheath and the axons transmit information ineffectively
spinal injuries
30
severed axons may grow small new extensions, but no significant regeneration of axon occurs across the damaged site, and no significant return of function
within the CNS
31
Relationships between type and amount of charge and distance
- force increases with the quantity of change
- force increases as distance of separation between charges decreases
32
the potential difference across the plasma membrane of a neuron when it is at rest
resting membrane potential
33
inside the neurons is ____ _____ with respect to outside, typically -40 to -90 millivolts
negatively charged
34
changes in potential are due to
movement of ions
35
establishes the concentration gradients and generates a small negative potential, that keep the resting potential at -70 mV
sodium potassium ATPase Pump
36
makes the resting membrane potential more negative on inside of cell
greater net movement of K+ that Na+
37
any small influx of Na+ ions is balanced by an efflux of K+ ions through
- Then the Na+/K+ ATPase Pump transports both types of ions back to their original locations and concentration
K+ leak channels
38
when the ____ ____ occurs, the pump returns Na+/K+ ions to their original locations after depolarization and depolarization
action potential
39
a. establishment of a concentration gradient by ion pump
b. greater efflux of K+ creates charge difference
c. stable negative resting potential achieved
Steps Explaining the Resting Membrane Potential
40
membrane potential value changed toward zero so that cell interior becomes less negative than resting level
depolarizing
41
part of the action potential in which the membrane potential goes above zero
overshoot
42
transmembrane potential returned to its resting level after a depolarization
repolarizing
43
membrane potential changed so cell interior becomes more negative than its resting state
hyperpolarizing
44
changes in membrane potential that are confined to a small region of the plasma membrane, magnitude of the potential change can vary
graded potentials
45
potential change decreases as the distance from the site of the original even increases
decremental
46
addition of graded potentials from several stimuli, occur in rapid succession and before each graded potential has died out
summation
47
if summation of several small potentials reached the ___ ___, so an action potential will occur
threshold potential
48
Leakage of Charge (Predominately K+) Across the
Plasma Membrane Reduces the Local Current at Sites Farther Along the Membrane From the Site of
Initial Depolarization
49
large alterations in membrane, generally very rapid, may repeat at frequencies of several hundred per second
action potentials
50
ability to generate action potentials
- possessed by neurons, muscle cells, and some other types of cells
excitability
51
the mechanism the nervous system uses to communicate from cell to cell over long distances
propagation of action potentials down the axon
52
Graded potentials produced from ligand-gated and mechanically gated ion channels often serve as the
initiating stimulus for an action potential
53
give a membrane the ability to undergo action potentials
voltage-gated ion channels
54
block voltage-gates Na+ channels from the opening in response to depolarization to prevent the generation of action potential
procaine and lidocaine
55
without ____, graded signals generated in sensory neurons -- in response to injury, for example -- cannot reach the brain and give rise to the sensation of pain
action potentials
56
during the action potential, a second stimulus will not produce a second action potential
- as the voltage-gated Na+ channels either open or have proceeded to the inactivated state
absolute refractory period
57
58
follows absolute refractory period, if the stimulus strength is much greater than usual a second potential might be produced
- coincides roughly with the period of afterhyperpolarization
relative refractory period
59
limit the number of action potentials an
excitable membrane can produce in a given period of time
- contribute to the separation of action potentials so
that individual electrical signals pass down the axon
- determine the direction of action potential
propagation
refractory periods
60
action potentials initiated at one end of the cell and
propagate towards the other end, only forward down the axon, since
the space behind is in its refractory period
In most neurons
61
action potentials initiated near the middle of the cells and propagate toward the two ends
in skeletal muscle cells
62
The velocity with which an action potential propagates along a membrane depends upon ___ ____ and whether or not the fiber is _____
fiber diameter; myelinated
63
electrical insulator
myelin
64
Action potentials occur only at the ___ __ ___, where the myelin coating is interrupted and the concentration of the voltage-gated Na+ channels is high
nodes of Ranvier
65
action potentials appear to jump from one node to the next as they propagate
along a myelinated fiber
saltatory conduction
66
- Amplitude varies with size of the initiating event
- Can be summed
- has no threshold
- Has no refractory period
- Amplitude decreases with distance
- Duration varies with initiating conditions.
- Can be a depolarization or a hyperpolarization
- Initiated by environmental stimulus (receptor),
by neurotransmitter (synapse), or spontaneously.
- Mechanism depends on ligand-gated ion
channels or other chemical or physical
change
graded potential
67
- All-or-none. Once membrane is depolarized to threshold, amplitude is independent of the size of the initiating event.
- Cannot be summed.
- Has a threshold that is usually about 15 millivolts
depolarized relative to the resting potential.
- Has a refractory period.
- Is conducted without decrement; the depolarization is amplified to a constant value at each point along the membrane.
- Duration is constant for a given cell type under constant conditions.
- Is only a depolarization.
- Initiated by a graded potential.
- Mechanism depends on voltage-gated ion channels
action potential
68
an anatomically specialized junction between two neurons
- can be chemical or electrical
synapse
69
where the plasma membranes of the presynaptic and postsynaptic cells joined by gap junctions
- the electrical activity of the presynaptic neuron affects the electrical activity of the postsynaptic neuron
electrical synapses
70
where presynaptic neurons release neurotransmitters from their axon terminals, and the neurotransmitters bind to receptors on post-synaptic neurons
chemical synapses
71
axon terminals of the presynaptic neuron hold the ____ _____ that contain neurotransmitter molecules
synaptic vesicles
72
depolarization during the action potential opens ____ ____ _____ in the plasma membrane of the axon terminal, and Ca2+ flows into the neuron
voltage-gated Ca2+ channels
73
activate processes that lead to the fusion of docked vesicles with the synaptic terminal membrane and their interaction with synaptotagmin and SNARE proteins
calcium ions
74
neurotransmitters are then released via
exocytosis
75
To terminate the signal in a chemical synapse, the unbound neurotransmitters must be removed from the
synaptic cleft
76
active transport back into the presynaptic terminal for reuse
reuptake
77
transport into nearby glial cells
degraded
78
away from the receptor site
diffusion
79
into inactive substances
enzymatic transformation
80
1. action potential reaches terminal
2. voltage-gated Ca2+ channels open
3. calcium enters axon terminal
4. neurotransmitter is released and diffuses into the cleft
5. neurotransmitter binds to postsynaptic receptors
6. neurotransmitter removed from synaptic cleft
signaling at chemical synapse
81
a depolarizing graded potential, to bring the membrane potential of the postsynaptic neuron closer to the threshold potential
- generated by excitatory chemical synapses
excitatory postsynaptic potential (EPSP)
82
a hyperpolarizing graded potential that lessens the likelihood that the postsynaptic cell depolarize to the threshold potential and to generate an action potential
- generated by inhibitory chemical synapses
inhibitory postsynaptic potential (IPSP)
83
- Availability of neurotransmitter
- Axon terminal membrane potential
- Axon terminal Ca2+
- Activation of membrane receptors on presynaptic terminal
- Certain drugs and diseases, which act via the above mechanisms A to D
presynaptic factors that determine synaptic strength
84
- Immediate past history of electrical state of postsynaptic membrane
- Effects of other neurotransmitters or neuromodulators acting on postsynaptic neuron
- Up- or down-regulation and desensitization of receptors
- Certain drugs and diseases
postsynaptic factors that determine synaptic strength
85
- Area of synaptic contact
- Enzymatic destruction of neurotransmitter
- Geometry of diffusion path
- Neurotransmitter reuptake
general factors that determine synaptic strength
86
Drugs act on the ___ ____ by interfering with or stimulating normal processes in the neuron involved in neurotransmitter synthesis, storage, and release, and in receptor activation
nervous system
87
is a protease that destroys SNARE proteins in the presynaptic terminal, preventing vesicle fusion with the membrane, and inhibiting neurotransmitter release. This leads to excess muscle contraction and rigid or spastic paralysis
Toxin (tetanus toxin)
88
toxins cause _____, block neurotransmitter release from synaptic
vesicles by destroying SNARE proteins. They target excitatory synapses
that activate skeletal muscles, leading to reduced muscle contraction or
flaccid paralysis
botulism
89
a drug might
* increase leakage of neurotransmitter from vesicle to cytoplasm, exposing it to enzyme breakdown.
* increase transmitter release into cleft.
* block transmitter release.
* inhibit transmitter synthesis.
* block transmitter reuptake.
* block cleft or intracellular enzymes that metabolize transmitter.
* bind to receptor on postsynaptic membrane to block (antagonist) or mimic (agonist) transmitter action.
* inhibit or stimulate second messenger activity within postsynaptic cell
90
- modify the postsynaptic cell’s response to specific neurotransmitters, amplifying or dampening the effectiveness of ongoing synaptic activity
- may change the presynaptic cell’s synthesis, release, reuptake, or metabolism of a transmitter
neuromodulators
91
influence ion channels that
affect excitation or inhibition of the postsynaptic cell ~milliseconds
Receptors for neurotransmitters
92
bring changes in metabolic processes in neurons ~ minutes, hours, or even days, and include alterations in enzyme activity or protein synthesis
Receptors for neuromodulators
93
are involved in rapid communication
Neurotransmitters
94
associated with slower events such as learning, development, and motivational states
neuromodulators
95
PNS (neuromuscular junctions), CNS (brain.
Release ACh neurons called cholinergic neurons
- binds to muscarinic (G protein-coupled) or nicotinic (ligand-gated ion channel) receptor
acetylcholine (ACh)
96
ACh is synthesized in the ___ ___ ___ ___ and stored in synaptic vesicle
cytoplasm of synaptic terminals
97
Degradation of ACh occurs rapidly via _______ found on the presynaptic and postsynaptic membranes
acetylcholinesterase
98
Nerve gas that inhibits acetylcholinesterase, results in overstimulation of postsynaptic ACh receptors, uncontrolled muscle contractions, and leading to receptor desensitization and paralysis
Sarin ( chemical weapons)
99
Nicotinic receptors in the brain are important in
cognitive functions and behavior
100
Many ____ _____ in the brain degenerate in people with Alzheimer’s disease (AD), a brain disease, age-related
cholinergic neurons
101
related to the declining intellectual function in language and cognitive abilities, confusion, and memory loss in late life
Affected neurotransmitter systems
102
small, charged molecules synthesized from amino acids
Biogenic amines
103
most common biogenic amines are
dopamine, norepinephrine, serotonin, and histamine
104
biogenic amine, is not a common neurotransmitter in the CNS, but it is the major hormone secreted by the adrenal medulla
epinephrine
105
an important neurotransmitter in the CNS and PNS
norepinephrine
106
including dopamine, norepinephrine, and epinephrine, all contain a catechol ring and an amine group
- formed from the amino acid tyrosine
catecholamines
107
binds to norepinephrine (NE) and epinephrine (Epi), use second messengers to transfer a signal from the surface of the cell to the cytoplasm
Adrenergic receptors
108
a neuromodulator involved at virtually every structure in the brain and spinal cord and operates via at least 16 different receptor subtypes
serotonin
109
Serotonin has an excitatory effect on
muscle control pathways
110
Serotonin has an inhibitory effect on pathways that
mediate sensations
111
thought to aid in the treatment of depression by inactivating the presynaptic membrane 5-HT transporter, which mediates serotonin reuptake into the presynaptic cell
Selective serotonin reuptake inhibitors (SSRIs)
112
The most common neurotransmitters in the CNS, affect virtually all neurons there.
- Excitatory synapses include aspartate and glutamate.
- Inhibitory synapses include glycine and GABA
Amino Acid Neurotransmitters
113
The primary neurotransmitter of the excitatory synapses in the CNS
glutamate
114
couples frequent activity across a synapse with lasting changes in the strength of signaling across that synapse, to be a cellular process involved in learning and memory.
long-term potentiation (LTP)
115
a phenomenon in which the injury or death of some brain cells rapidly spreads to adjacent region
- mediated by NMDA
excitotoxicity
116
the major inhibitory neurotransmitter in the brain, not a protein building amino acid, but a glutamate derivative
GABA (gamma-aminobutyric acid)
117
increases Cl- flux into the cell, resulting in hyperpolarization (IPSP) of the postsynaptic membrane
ionotropic receptor
118
stimulates GABA synapses and inhibits excitatory glutamate synapses, resulting in global depression of the electrical activity of the brain
ethanol
119
The major neurotransmitter released from inhibitory interneurons in the spinal cord and brainstem. It binds to ionotropic receptors on postsynaptic cells that allow Cl- ions to enter
glycine
120
Normal function of ___ ____ is essential for maintaining a balance of excitatory and inhibitory activity in spinal cord integrating centers that regulate skeletal muscle contraction
glycinergic neurons
121
two or more amino acids linked by peptide bonds. About 100 have been identified, but their functions are not all known
Neuropeptides
122
In the cell body of a neuron, the precursor protein is packaged into vesicles, which are then moved by axonal transport into the terminals or varicosities, where the protein is cleaved by specific
peptidases
123
produced by enzymes in axon terminals (in response to Ca2+ entry), diffuse origin in one cell into the intracellular fluid of other neurons or effector cells, where they bind to and activate proteins
gases
124
derived from ATP via extracellular enzymatic activity
adenosine
125
a family of molecules derived
from the polyunsaturated fatty acid arachidonic acid
eicosanoids
126
found throughout the CNS and PNS in pathways regulating many physiological functions including appetite, pain sensation, mood, memory, and locomotor activity
Cannabinoid receptors
127
The neurotransmitter is released from the efferent neuron upon arrival of an action potential, diffuses to the surface of the effector cell, and binds to receptors on that cell’s plasma membrane
Neuroeffector Communication
128
develops into the cerebrum and diencephalon
forebrain
129
consists of the right and left cerebral hemispheres and certain structures on the underside of the brain
cerebrum
130
consist of the cerebral cortex, an outer shell of gray matter, and an inner layer of white matter
cerebral hemispheres
131
overlies the subcortical nuclei, cell clusters also composed of gray matter. The tracts consist of the axons of neurons that bring information into the cerebrum, carry information out, and connect different areas within a hemisphere.
- highly folded to containing four time more of neurons yet not increase the volume of the brain
cerebral cortex
132
a massive bundle of axons in a commissure to connect the separated left and right cerebral hemispheres
corpus callosum
133
are the major output cells of the cortex, sending their axons to other parts of the cortex and the CNS
pyramidal cells
134
are involved in receiving inputs into the cerebral cortex and in local processing of information
Nonpyramidal cells
135
basic afferent information is collected and processed into meaningful perceptual images, and control over the movement of the skeletal muscles is refined
cerebral cortex
136
divided in two by the narrow third cerebral ventricle, contains the thalamus, hypothalamus, and epithalamus
diencephalon
137
a collection of several nuclei that serve as synaptic relay stations and integrating centers for most inputs to the cortex, and it also functions in general arousal.
thalamus
138
lies below the thalamus and is on the undersurface of the brain. Its nuclei and their pathways form the master command center for neural and endocrine coordination
hypothalamus
139
an important endocrine gland that the hypothalamus regulates.
pituitary gland
140
a small mass of tissue that includes the pineal gland, which participates in the control of circadian rhythms through release of the hormone melatonin
epithalamus
141
Structures of the ____ ____ are associated with learning, emotional experience and behavior, and a variety of visceral and endocrine functions
limbic system
142
does not initiate voluntary movements, but it coordinates movements and controls posture and balance.
- function is almost exclusively motor
cerebellum
143
144
All the axons of neurons that relay signals between the forebrain, cerebellum, and spinal cord pass through
brainstem
145
runs through the core of the brainstem is the one part of the brain absolutely essential for life, receiving, integrating and processing input from all regions of CNS. It is involved in motor functions, cardiovascular, respiratory, sleep and wakefulness and focus attention
reticular formation
146
the cardiovascular, respiratory, swallowing, and vomiting centers
Integrating centers
147
the peripheral nerves that connect directly with the brain and innervate the muscles, glands, and sensory receptors of the head, and many organs in the thoracic and abdominal cavities
cranial nerves
148
149
an anatomically specialized junction between two neurons.
- can be chemical or electrical
synapse
150
the plasma membranes of the presynaptic and postsynaptic cells joined by gap junctions. Thus, the electrical activity of the presynaptic neuron affects the electrical activity of the postsynaptic neuron
electrical synapse
151
presynaptic neurons release neurotransmitters from their axon terminals, and the neurotransmitters bind to receptors on post-synaptic neurons
chemical synapse
152
Axon terminals of the presynaptic neuron hold the synaptic vesicles that contain ____ _____
neurotransmitter molecules
153
Depolarization during the action potential opens _____ ___ ____ in the plasma membrane of the axon
terminal, and Ca2+ flows into the neuron
voltage-gated Ca2+ channels
154
activate processes that lead to the fusion of docked vesicles with the synaptic terminal membrane, and their interaction with Synaptotagmin and SNARE proteins
Calcium ions
155
To terminate the signal in a chemical synapse, the unbound neurotransmitters must be removed from the ___ ____
synaptic cleft
156
active transport back into the presynaptic terminal for reuse
reuptake
157
transport into nearby glial cells
degraded
158
away from the receptor site
diffusion
159
into inactive substances
enzymatic transformation
160
1. action potential reaches terminal
2. voltage-gated Ca2+ channels open
3. calcium enters axon terminal
4. neurotransmitter is released and diffuses into the cleft
5. neurotransmitter binds to postsynaptic receptors
6. neurotransmitter removed from synaptic cleft
Mechanisms of Signaling at a Chemical Synapse
161
- generated by excitatory chemical synapses
- a depolarizing graded potential, to bring the membrane potential of the postsynaptic neuron closer to the threshold potential
excitatory postsynaptic potential (EPSP)
162
- generated by Inhibitory chemical synapses
- a hyperpolarizing graded potential that lessens the likelihood that the postsynaptic cell depolarize to the threshold potential and to generate an action potential
inhibitory postsynaptic potential (IPSP):
163
- Availability of neurotransmitter
- Axon terminal membrane potential
- Axon terminal Ca2+
- Activation of membrane receptors on presynaptic terminal
- Certain drugs and diseases, which act via the above mechanisms A to D
presynaptic factors that determine synaptic strength
164
- immediate past history of electrical state of postsynaptic membrane
- Effects of other neurotransmitters or neuromodulators acting on postsynaptic neuron
- Up- or down-regulation and desensitization of receptors
- Certain drugs and diseases
postsynaptic factors that determine synaptic strength
165
- Area of synaptic contact
- Enzymatic destruction of neurotransmitter
- Geometry of diffusion path
- Neurotransmitter reuptake
general factors that determine synaptic strength
166
Drugs act on the ____ ____ by interfering with or stimulating normal processes in the neuron involved in neurotransmitter synthesis, storage, and release, and in receptor activation
nervous system
167
is a protease that destroys SNARE proteins in the presynaptic terminal, preventing vesicle fusion with the membrane, and inhibiting neurotransmitter release. This leads to excess muscle contraction and rigid or spastic paralysis
Toxin (tetanus toxin)
168
cause botulism, block neurotransmitter release from synaptic vesicles by destroying SNARE proteins. They target excitatory synapses that activate skeletal muscles, leading to reduced muscle contraction or flaccid paralysis
toxins
169
A drug might:
- increase leakage of neurotransmitter from vesicle to cytoplasm, exposing it to enzyme breakdown.
- increase transmitter release into cleft.
- block transmitter release.
- inhibit transmitter synthesis.
- block transmitter reuptake.
- block cleft or intracellular enzymes that metabolize transmitter.
- bind to receptor on postsynaptic membrane to block (antagonist) or mimic (agonist) transmitter action.
- inhibit or stimulate second-messenger activity within postsynaptic cell
170
- modify the postsynaptic cell’s response to specific neurotransmitters, amplifying or dampening the effectiveness of ongoing synaptic activity.
- may change the presynaptic cell’s synthesis, release, reuptake, or metabolism of a transmitter.
neuromodulators
171
influence ion channels that affect excitation or inhibition of the postsynaptic cell ~milliseconds
Receptors for neurotransmitters
172
bring changes in metabolic processes in neurons ~ minutes, hours, or even days, and include alterations in enzyme activity or protein synthesis
Receptors for neuromodulators
173
involved in rapid communication
neurotransmitters
174
associated with slower events such as learning, development, and motivational states
neuromodulators
175
- PNS (neuromuscular junctions), CNS (brain. Release ACh neurons called cholinergic neurons
- binds to muscarinic (G protein-coupled) or nicotinic (ligand-gated ion channel) receptor
- synthesized in the cytoplasm of synaptic terminals and stored in synaptic vesicle
Acetylcholine (ACh)
176
Degradation of ACh occurs rapidly via _____ found on the presynaptic and postsynaptic membranes
acetylcholinesterase
177
inhibits acetylcholinesterase, results in overstimulation of postsynaptic ACh receptors, uncontrolled muscle contractions, and leading to receptor desensitization and paralysis
Sarin ( chemical weapons)
178
- Many cholinergic neurons in the brain degenerate in people
- a brain disease, age-related
Alzheimer’s disease (AD)
179
Affected neurotransmitter systems are related to the
declining intellectual function in language and cognitive abilities, confusion, and memory loss in late life
180
small, charged molecules synthesized from amino acids
biogenic amines
181
The most common biogenic amines are
dopamine, norepinephrine, serotonin, and histamine
182
biogenic amine, is not a common neurotransmitter in the CNS, but it is the major hormone secreted by the adrenal medulla
Epinephrine
183
an important neurotransmitter in the CNS and PNS
Norepinephrine
184
- including dopamine, norepinephrine, and
epinephrine, all contain a catechol ring and an amine group
- They are formed from the amino
acid tyrosine
Catecholamines
185
binds to norepinephrine (NE) and epinephrine (Epi), use second messengers to transfer a signal from the surface of the cell to the cytoplasm
adrenergic receptors
186
a neuromodulator involved at virtually every structure in the brain and spinal cord and operates via at least 16 different receptor subtypes
serotonin
187
Serotonin has an ____ ____ on muscle control pathways, and an ____ ____ on pathways that mediate sensations
excitatory effect; inhibitory effect
188
such as paroxetine (Paxil) are thought to aid in the treatment of depression by inactivating the presynaptic membrane 5-HT transporter, which mediates serotonin reuptake into the presynaptic cell
Selective serotonin reuptake inhibitors (SSRIs)
189
- The most common neurotransmitters in the CNS, affect virtually all neurons there.
- Excitatory synapses include aspartate and glutamate.
- Inhibitory synapses include glycine and GABA
amino acid neurotransmitters
190
- The primary neurotransmitter of the excitatory synapses in the CNS
- two types of receptors
-- metabotropic receptors
-- i0notropic receptors
glutamate
191
NMDA receptors have been implicated in mediating ______, a phenomenon in which the injury or death of some brain cells rapidly spreads to adjacent regions
excitotoxicity
192
When glutamate-containing cells die and their membranes rupture, the flood of glutamate excessively stimulates
AMPA and NMDA receptors on nearby neurons
193
- The major inhibitory neurotransmitter in the brain, not a protein building amino acid, but a glutamate derivative.
- neurons in the brain are small interneurons that dampen activity within neural circuits. Postsynaptically, may bind to ionotropic or metabotropic receptors.
GABA
194
stimulates GABA synapses and inhibits excitatory glutamate synapses, resulting in global depression of the electrical activity of the brain
Ethanol
195
The major neurotransmitter released from inhibitory interneurons in the spinal cord and brainstem. It binds to ionotropic receptors on postsynaptic cells that allow Cl- ions to enter
glycine
196
Normal function of glycinergic neurons is essential for
maintaining a balance of excitatory and inhibitory activity in spinal cord integrating centers that regulate skeletal muscle contraction
197
two or more amino acids linked by peptide bonds.cAbout 100 have been identified, but their functions are not all know
Neuropeptides
198
In the cell body of a neuron, the precursor protein is packaged into vesicles, which are then moved by axonal transport into the terminals or varicosities, where the protein is cleaved by specific
peptidases
199
Neurons that release one or more of the peptide neurotransmitters are collectively called
peptidergic
200
- serve as neurotransmitters, such as Nitric oxide, Carbon monoxide, Hydrogen sulfide
- Not released by exocytosis of presynaptic vesicles, nor do they bind to postsynaptic plasma membrane receptors.
- produced by enzymes in axon terminals (in response to Ca2+ entry), diffuse origin in one cell into the intracellular fluid of other neurons or effector cells, where they bind to and activate proteins
gases
201
presented in all presynaptic vesicles and coreleased with other neurotransmitters in response to Ca2+ influx into the axon terminal
ATP
202
derived from ATP via extracellular enzymatic activity
Adenosine
203
Several membrane phospholipid-derived substances are used in synaptic signaling, mainly acting as neuromodulators.
lipids
204
found throughout the CNS and PNS in pathways regulating many physiological functions including appetite, pain sensation, mood, memory, and locomotor activity
Cannabinoid receptors
205
- Many neurons of the PNS synapse not on other neurons but at neuroeffector junctions on muscle, gland, and other cells
- neurotransmitter is released from the efferent neuron upon arrival of an action potential, diffuses to the surface of the effector cell, and binds to receptors on that cell’s
plasma membrane
neuroeffector communication
206
develops into cerebrum and diencephalon
forebrain
207
consists of right and left cerebral hemispheres and certain structures on the underside of the brain
cerebrum
208
consist of the cerebral cortex, an outer shell of gray matter, and an inner layer of white matter
cerebral hemisphere
209
overlies the subcortical nuclei, cell clusters also composed of gray matter.
- The tracts consist of the axons of neurons that bring information into the cerebrum, carry information out, and connect different areas within a hemisphere
cerebral cortex
210
a massive bundle of axons in a commissure to connect the separated left and right cerebral hemisphere
corpus callosum
211
- highly folded to containing four times more of neurons yet not increase the volume of the brain
- one of the most complex integrating areas of the nervous system
- basic afferent information is collected and processed into meaningful perceptual images, and control over the movement of the skeletal muscles is refined.
cerebral cortex
212
the major output cells of the cortex, sending their axons to other parts of the cortex and the CNS
pyramidal cells
213
involved in receiving inputs into the cerebral cortex and in local processing of information
nonpyramidal cells
214
-heterogeneous groups of gray matter that lie deep within the cerebral hemispheres.
- Predominant
among them are the basal nuclei (often, but less correctly referred to as basal ganglia), which have an important function in controlling movement and posture and in more complex aspects of behavior.
subcortical nuclei
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divided in two by the narrow third cerebral ventricle, contains the thalamus, hypothalamus, and epithalamus
diencephalon
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a collection of several nuclei that serve as synaptic relay stations and integrating centers for most inputs to the cortex, and it also functions in general arousal
- involved in focusing attention. For example, it filters out extraneous sensory information
thalamus
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lies below the thalamus and is on the undersurface of the brain. Its nuclei and their pathways form the master command center for neural and endocrine coordination
- lies directly above and is connected by a stalk to the pituitary gland, an important endocrine gland that the hypothalamus regulates
hypothalamus
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a small mass of tissue that includes the pineal gland, which participates in the control of circadian rhythms through release of the hormone melatonin
epithalamus
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Some forebrain areas, consisting of both gray and white matter, are also classified together in a functional system called the
- Structures of the ___ ____ are associated with learning, emotional experience and behavior, and a variety of visceral and endocrine functions
limbic system
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- does not initiate voluntary movements, but it coordinates movements and controls posture and balance.
- receives information from the muscles and joints, skin, eyes, vestibular apparatus, viscera, and the parts of the brain involved in control of movement
- function is almost exclusively motor
cerebellum
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All the axons of neurons that relay signals between the forebrain, cerebellum, and spinal cord pass through the
brainstem
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runs through the core of the brainstem is the one part of the brain absolutely essential for life, receiving, integrating and processing input from all regions of CNS. It is involved in motor functions, cardiovascular, respiratory, sleep and wakefulness and focus attention
reticular formation
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the cardiovascular, respiratory, swallowing, and vomiting centers
integrating centers
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peripheral nerves that connect directly with the brain and innervate the muscles, glands, and sensory receptors of the head, and many organs in the thoracic and abdominal cavities
cranial nerves
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lies within the bony vertebral column and is a slender cylinder of soft tissue about as big around as your little finger
spinal cord
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composed of interneurons, the cell bodies and dendrites of efferent neurons, the entering axons of afferent neurons, and glial cells
central butterfly-shaped area of gray matter
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The regions of gray matter projecting toward the back of the body are called the
dorsal horns
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The regions of gray matter projecting toward the front of the body are called the
ventral horns
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Groups of afferent neuron axons that enter the spinal cord from the peripheral nerves enter on the dorsal side of the cord via the
dorsal roots
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Small bumps on the dorsal roots, the ___ ____ ____, contain the cell bodies of these afferent neurons
dorsal root ganglia
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The axons of efferent neurons leave the spinal cord on the ventral side via the
ventral roots
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A short distance from the cord, the dorsal and ventral roots from the same level combine to form a ___ ____, one on each side
spinal nerve
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transmit signals between the CNS and receptors and effectors in all other parts of the body
peripheral nervous system (PNS)
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The eight pairs of ____ ____ innervate the neck, shoulders, arms, and hands
cervical nerves
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The twelve pairs of ____ ____ are associated with the chest and upper abdomen
thoracic nerves
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The five pairs of ____ ____ are associated with the lower abdomen, hips, and legs
lumbar nerves
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The five pairs of ____ ____ are associated with the genitals and lower digestive tract
sacral nerves
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A single pair of ____ ____ are associated with the skin over the region of the tailbone
coccygeal nerves
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carry signals out from the CNS to muscles, glands, and other tissues
efferent neurons
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- Consists of a single neuron between CNS and skeletal muscle cells
- Innervates skeletal muscle cells
- Can lead only to muscle cell excitation
somatic nervous system
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- Has two-neuron chain (connected by a synapse) between CNS and effector organ
- Innervates smooth and cardiac muscle, glands, GI neurons, but not skeletal muscle cells
- Can be either excitatory or inhibitory
- sympathetic, parasympathetic divisions (Anatomical and physiological differences)
autonomic nervous system
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sympathetic fibers from the
thoracic and lumbar regions of the spinal cord
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the parasympathetic fibers from the
brainstem and the sacral portion of the spinal cord
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- also called the thoracolumbar division
- It has short preganglionic and long postganglionic neurons
- The major neurotransmitters are Ach at preganglionic synapses and usually NE and Epi at postganglionic synapses.
- This is the “fight-or-flight” response system
sympathetic division
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- also called the craniosacral division
- It has long preganglionic and short postganglionic neurons
- The major neurotransmitter is ACh at both pre- and postganglionic synapses
- This is the “rest-or-digest” system
parasympathetic division
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These neurons use nitric oxide and other neurotransmitters to mediate blood vessel dilation and to regulate various gastrointestinal, respiratory, urinary, and reproductive functions
nonadrenergic and noncholinergic
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- On postganglionic neurons in the autonomic ganglia
- At neuromuscular junctions of skeletal muscle
- On some CNS neurons
Nicotinic receptors
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- On smooth muscle
- On cardiac muscle
- On gland cells
- On some CNS neurons
- On some neurons of autonomic ganglia (although the great majority of receptors at this site are nicotinic
Muscarinic receptors
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- One set of postganglionic neurons in the sympathetic division never develops axons. Instead, they form the
- Upon activation by preganglionic sympathetic axons, cells of the ____ _____ release a mixture of about 80% epinephrine and 20% norepinephrine into the blood
adrenal medulla
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The heart and most glands and smooth muscles are innervated by both sympathetic and parasympathetic fibers; this is called
dual innervation
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support and protect the structures of the CNS and PNS:
- Skull supports and protects the brain
- Vertebrae support and protect the spinal cord
bone
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the membranes that line the structures and add additional support and protection
meninges
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thick outermost layer, next to the bone
dura mater
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weblike middle layer
arachnoid mater
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thin innermost layer, next to the nervous tissue
pia mater
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protects and cushions the structures
Cerebrospinal fluid (CSF)
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space between the arachnoid mater and the pia mater is filled with cerebrospinal fluid (CSF) and contains the largest blood vessels serving the brain
subarachnoid space
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an infection of the meninges that occurs in the CSF of the subarachnoid space. It can result in increased intracranial pressure, seizures, and loss of consciousness. It can be diagnosed by examining the CSF obtained via a lumbar puncture for microbes or viruses
Meningitis
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make up a specialized epithelial structure called the choroid plexus, which produces CSF
Ependymal cells
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- circulates through the brain’s interconnected ventricular system to the brainstem, where it passes through small openings to the subarachnoid space surrounding the brain and spinal cord
- eventually flows to the top of the outer surface of the brain, where most of it re-enters the bloodstream through one-way valves in large veins
CSF
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- means “water on the brain.”
- It is an accumulation of CSF in the brain that is often caused by tumors.
- In severe, untreated cases, the resulting elevation of pressure in the ventricles causes compression of the brain’s blood vessels, which may lead to inadequate blood flow to the neurons, neuronal damage, and cognitive dysfunction
Hydrocephalus
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- The most common form of brain damage is caused by a decreased blood supply to a region of the brain.
- When neurons in the region are without a blood supply and deprived of glucose and oxygen for even a few minutes, they cease to function and die.
- This neuronal death, when it results from vascular disease
stroke
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A protective mechanism that helps maintain a stable environment for the brain.
blood-brain barrier
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the cells that line the smallest blood vessels in the brain.
astrocytes
