Exam 3 Flashcards
(264 cards)
1
Q
What do neurons do?
A
- sensory perception of stimuli integration
- integration
- motor output (muscles and glands)
2
Q
How is it organized?
A
- Central nervous system (CNS)
* peripheral nervous system (PNS)
3
Q
What system contains the brain and spinal cord?
A
*CNS
4
Q
What system is the command center/integrating?
A
*CNS
5
Q
What system includes nerves from the brain and spinal cord?
A
*PNS
6
Q
What links body parts to the CNS?
A
- spinal nerves
- cranial nerves (leaves the brain, outside CNS)
- split into subdivisions
7
Q
What are the PNS subdivisions?
A
- sensory division
* motor division
8
Q
What is another name for the sensory division?
A
*afferent
9
Q
What is another name for the motor division?
A
*efferent
10
Q
What division is info from sensory receptors to CNS?
A
*sensory (afferent)
11
Q
What division has somatic afferent fibers?
A
*sensory (afferent)
12
Q
What division has visceral afferent fibers?
A
*sensory (afferent)
13
Q
Where do somatic afferent fibers come from?
A
*skin, joints
14
Q
Where do visceral afferent fibers come from?
A
*visceral or abdominal inner cavities
15
Q
What division comes from the CNS to effector organ gland/muscle?
A
*motor (efferent)
16
Q
What are the main parts of the PNS motor division?
A
- somatic nervous system
* autonomic nervous system (visceral)
17
Q
What system of the motor subdivision is for voluntary control?
A
*somatic nervous system
18
Q
What is the autonomic nervous system (visceral)?
A
*involuntary control (ex. cardiac muscle)
19
Q
What is biofeedback?
A
When you override your involuntary controls or autonomic nervous system
20
Q
What are the two subdivisions of the autonomic nervous system?
A
- sympathetic
* parasympathetic
21
Q
Which subdivision of the autonomic nervous system speed things up and is for flight or fight?
A
*sympathetic
22
Q
What is the parasympathetic subdivision?
A
- slows things down
- rest and digest activities
- lower heart rate
23
Q
What types of cells are found in the nervous system?
A
- neurons
* neuroglia
24
Q
What are neurons for?
A
- excitable cells
* can create an electrical potential, carry a charge
25
What are neuroglia cells for?
* supporting cells (glial cells)
* provide nutrition
* get rid of waste products
* 9-10 times more common than neurons
26
How many types of neuroglia cells are found in the CNS and PNS?
* CNS:4
| * PNS: 2
27
What glial cells are in the CNS?
* astrocytes
* ependymal cells
* microglia
* Oligodendrocytes
28
What do astrocytes do?
* serve nutritional flow to neuron
* guide neurons
* clean up waste products
29
What are the most abundant glial cells in the CNS?
*astrocytes
30
What do ependymal cells produce?
* CSF
| * form barrier for CNS
31
What do microglia do?
* functions as clean up
* small macrophages
* phagocytosis
32
What do oligodendrocytes form?
* myelin sheaths
| * speed up action potential
33
What glial cells are in the PNS?
* satellite cells
| * schwann cells
34
What are satellite cells?
* surround soma (cell body)
| * facilitate chemical balance
35
What are schwann cells?
* faster action potential
| * insulate around neurons
36
What is myelin sheath?
* protein-lipid filled cytoplasm of schwann cells
* protects/insulates axon
* nodes of ranvier
* oligodendrocytes serve same purpose in CNS
37
What are some examples of the protein-lipid filled cytoplasm of schwann cells?
* neurilemma (outermost role)
| * myelin sheath (inner insulation)
38
What is the nodes of ranvier?
* in gaps
| * on either side
39
What are some examples of oligodendrocytes?
* White matter
| * gray matter
40
What matter is the fatty protein layer?
*white matter
41
What matter is the axons that are bare?
*gray matter
42
Why do PNS neurons regenerate?
* myelin sheaths form regeneration tube
| * only neurons with myelin sheath can regenerate
43
Can CNS neurons regenerate?
*NO
44
What are neurons?
* long living
* amitotic (don't divide)
* metabolic rate (high rate, need constant nutrition)
* bundles of arm-like processes
45
What are the neurons that do divide?
* olfactory (closely tied to memory)
| * hippocampus nerves (memory)
46
Examples of bundles of arm-like processes?
* tracts in CNS
| * nerves in PNS
47
What are the parts of a neuron?
* cell parts
- soma
- dendrites
- axon
48
What is the soma?
* all organelles but centrioles (they don't divide)
* nissl bodies (equivalent to ER)
* nuclei
* ganglia
49
What is a cluster of cell bodies in CNS called?
*nuclei
50
What is a cluster of cell bodies in PNS called?
*ganglia
51
What brings in signals?
*dendrites
52
What is an axon?
* axon hillock
* axon collaterals
* terminal branches
* synaptic knob (axonal terminals)
* axoplasm
* axolemma
53
What is the axon hillock?
* part of the trigger zone
| * decides whether a signal is sent
54
What is an axon collaterals?
*side branch that goes over to another area
55
What travels down an axon via axoplasmic flow "cytoplasm"?
*axoplasm
56
What is the covering or membrane of the axons cell layer?
*axolemma
57
Plasticity of the nervous system is our substitute for our nervous system to mitotically divide.
*the older we get the less plasticity we have
58
How are neurons classified?
* structure
| * function
59
Examples of neurons classified based on structure?
* multipolar neurons
* bipolar neurons
* unipolar neurons
60
What is the most common neurons that does 3 or more processes?
*multipolar neurons
61
What neuron is not as common, and is found in olfactory mucosa?
*bipolar neurons
62
What neuron does one process, is found in specialized structures for transducing physical stimulus?
*unipolar
63
Examples of neurons that are classified based on function?
* sensory (afferent)
* motor (efferent)
* interneurons (association neurons)
64
Interneurons are confined to the?
*CNS
65
What neurons conduct signals from receptors to the CNS?
*sensory (afferent)
66
What neurons conduct signals from the CNS to effectors such as muscles and glands?
*motor (efferent)
67
What does it mean when a neuron fires?
* sends a signal for your body to do something
| * firing= excitability = action potential= nerve impulse
68
Resting potential of cells?
* potential = difference in electrical charge
| * slightly negative compared to outside because more Na is being sent out
69
What lets ions move across the PM?
* membrane ion channels
- passive (leakage)
- active (gated)
70
Example of passive leakage channel?
* potassium leak channel
71
Example of active (gated) channels?
* actually open and close
* ligand gated
* voltage gated (use electricity)
72
What is the resting potential?
* measure by inserting one electrode inside cell, other outside
* charges only occur at PM surface (away from PM, charge is mostly neutral)
73
Neurons=
*-70mV inside
74
What causes resting potential?
* negatively charged anions inside cell like RNA, ATP pump maintain it
* membrane permeability
75
Membrane permeability?
* K permeable, but not Na permeable
| * Na/K pump maintain but does not create resting potential
76
What is high outside and inside of the cell?
* Na high outside
* k high inside
* slightly negative inside cell, middle not effected
77
What percent of ATP in your body is used for the sodium potassium exchange pump?
*20%
78
What causes changes in membrane potential?
* change in membrane permeability
* change in ion concentration
* may cause graded potentials or action potentials
79
What is depolarization?
* made inside more similar to outside of cell (inside becomes more positive)
* reduction in membrane potential
* hyperpolarization (opposite to depolarization)
80
What is hyperpolarization?
* overshoots, becomes more negative
| * inhibitory event
81
What is threshold a bout?
*-55mV
82
What are local potentials?
* short lived, local (doesn't hit threshold so you don't reach an action potential)
* depolarize or hyperpolarize cell
* ligand regulated
* graded
83
What is a depolarized local potential?
*more likely to fire
84
What is a hyperpolarized cell in local potential?
*less likely to fire
85
What is a ligand regulated local potential?
*certain chemicals can bind and cause a local potential to take place
86
What is a graded local potential?
* different levels
* can summate and trigger action potential to take place
* magnitude varies with strength of stimulus
87
What is an initiator of local potentials?
* energy (heat, light)
| * neurotransmitter
88
What are the characteristics of local potentials?
* decremental
* reversible (if doesn't reach action potential)
* hyper of de-polarizing
89
What is decremental?
* dissipate rapidly
| * comes on and if not used if fades away
90
What is not part of the CNS?
* Schwann cell
| * in PNS, counter part is oligodendrocytes
91
Na/K pumps in neurons consume an estimated 20% of all energy in your body. Why?
*they are required to maintain resting membrane potential
92
Where is Na, K and Cl highest in a cell?
* Na=outside
* K=inside
* Cl=outside
93
Examples of voltage gates?
* sodium voltage gate
| * calcium voltage gate (helps muscles contract)
94
Examples of ligand gates?
*neurotransmitters (acetocolene)
95
Examples of channels?
*potassium leak channel, K leaks out
96
Examples of mechanical gates?
* open and close to interaction
| * respond to touch, pressure, or vibration
97
What causes a cell to be negative?
* presence of nucleic acids inside the cell
| * presence of proteins inside the cell
98
Resting membrane potential of a cell is due mainly to?
*open K channels
99
Na diffusional and electrical force?
* diffusional: into
| * electrical: into
100
K diffusional and electrical force?
* diffusional: out
| * electrical: into
101
What are action potentials?
* only occur where high concentration of voltage regulated gates (Na and K regulated gates)
* local potential can cause one (graded can cause one due to summation)
102
What is EPSP?
* excitatory post synaptic potentials
| * local potentials
103
What is an axon hillock also known as?
*trigger zone
104
What happens during an action potential?
1. sodium ions arrive at axon hillock, and depolarize the membrane
2. threshold reached (`-55mV)
3. voltage regulated Na gates open (fast)
4. propagation of signals
5. Na gates are inactive at this point. slow K gates are open, K outflow repolarizes the membrane
6. slow k gates stay open longer so slightly more K leaves the cell than the amount of Na that entered
7. re-establishment of RMP
105
What happens when the voltage regulated Na gates open?
* action potential
* not reversible
* Na floods in cell
* slow voltage K gates also open
106
What is a propagation of signal?
* reverses its direction due to closed Na channels
| * Na channels begin to close and are inactivated
107
What is overshoot?
* hyperpolarization
| * makes it more negative
108
Characteristics of an action potential?
* all or none response (once reaches threshold can't reverse)
* nondecremental
* irreversible
109
What is nondecremental?
* do not dissipate
| * doesn't fade, you turn it off
110
What happens after an action potential?
* refractory period
| * two stages
111
What are the two refractory periods?
* absolute refractory period
| * relative refractory period
112
What is an absolute refractory period?
*no new action potentials are possible
113
What is a relative refractory period?
*can trigger action potential if the stimulus is strong enough
114
How do action potentials travel?
* nerve signal
* unmyelinated sheaths
* myelinated sheaths
115
What is continuous conduction?
*unmyelinated sheaths
116
What is salutatory conduction?
*myelinated sheaths
117
What two things influence conduction speed?
1. diameter of the fiber (larger diameter, the faster the flow of electricity)
2. myelination
118
What is myelin for?
* insulation
| * reduces resistance
119
Why does myelin increase transmission speed?
* causes salutary (jumping)
| * salutatory conduction is faster than smooth conduction
120
Why do action potentials only travel one direction?
* happens many times (opening and closing of gates)
| * only Na gates at nodes of ranvier
121
What happens if myelination is lost?
*multiple sclerosis
122
What is multiple sclerosis?
* autoimmune disease
* blindness
* problems controlling muscles
* immune system attacks myelin sheath
123
Why do we have the gap?
* so you can have more responses not just one
| * you can also block things from happening
124
Types of synapse?
* electrical synapse
| * chemical synapse
125
What are neurotransmitters?
* chemicals which cross the synaptic cleft
* over 100
* excitatory or inhibitory
126
How do neurotransmitters work?
* ACh and some others are ionotropic
| * rest are metabotropic
127
What is ionotropic?
* will bind to its receptor and cause a change in membrane potential
* quicker to respond
128
What is metabotropic?
* stimulates a secondary messenger (ex. cyclic AMP) and eventually changes membrane potential
* slower acting
129
During salutatory conduction, action potentials jump from?
*one node of Ranvier to another
130
After being released, neurotransmitters bind to receptors on the?
* postsynaptic membrane
| * presynaptic membrane is where they are released
131
A neurotransmitter attaches to its post-synaptic receptor and this eventually induces the production of cAMP. This neurotransmitter is?
*metabotropic (eventually, and cAMP is the keywords)
132
Inducing a change in charge across the membrane?
*ionotropic
133
What stage is where almost all voltage-sensitive K gates are now closed?
*6ish
134
What stage is where voltage-sensitive Na gates are closed and inactive?
* 4 shut fast
* open at 2
* closed at 5,6, &7
135
What stage is where all voltage-sensitive K gates are finally open?
*start opening at 4
136
What stage is where voltage-sensitive Na gates are open and voltage-sensitive K gates are nearly open?
*3
137
What stage is the point at which the process is still reversible?
*1 (hasn't hit threshold)
138
What stage is where the cell is at resting membrane potential but ions may not be yet in their proper location; firing may not be possible?
* 6
| * in hyperpolarization or relative refractory period
139
How does a nerve signal stop?
* neurotransmitters usually bind for only about 1 msec
| * if no new neurotransmitter available, stimulus stops
140
What are the three ways stimulus can stop?
* diffusion
* reuptake
* destruction
* blocking re-uptake (cocaine)
141
What is diffusion?
*escapes from synapse and dilutes out
142
What is reuptake?
*reabsorption and repackages it to be used again
143
What is destruction?
* recycle
| * breakdown with AchE and synaptic knob reabsorbed it
144
What is BOTOX?
* a neurotoxin
* decreases overactive muscle activity (causes muscle paralysis)
* prevents the release of acetylcholine (Ach) at the neuromuscular junction
* temporary
145
What does BOTOX cleave?
*SNAP 25
146
Why is BOTOX temporary?
*SNAP 25 regenerates by translation
147
How do neurons integrate multiple signals?
* postsynaptic potentials
- Excitatory postsynaptic potentials (EPSP)
- Inhibitory postsynaptic potentials (IPSP)
148
What is EPSP and what is an example of it?
* Na flows in
| * Glutamate, aspartate
149
What is IPSP and what is an example of it?
* increases negative charge (less likely to get an action potential)
* Glycine, GABA
150
Graded potentials can be either?
* EPSP
* IPSP
* spatial and temporal summation
151
What is spatial summation?
* they are in different locations
| * 2 different presynaptic nerves
152
What is temporal summation?
* added it together in an amount of time
| * same nerve firing at the same time
153
How do neurons integrate multiple signal?
* summation
* temporal summation (one neuron firing enough to reach threshold)
* spatial summation
154
How many EPSP's are needed to summate and reach threshold?
*30
155
What are neuronal circuits?
*pathways among neurons (ex. diverging, converging, reverberating, and parallel after discharge)
156
What is diverging?
*multiple muscle fibers being fired
157
What is converging?
*ex. is for sensory input
158
What is reverberating?
* causes constant input signals
| * ex inhalation
159
What is parallel after discharge?
*ex. sensory input for eye
160
Some general features of the brain?
* Hemispheres
* gryi
* sulci
* corpus callosum
* gray matter
* white matter
* frontal cortex
161
What is Gyri for?
* increases SA
| * bumps
162
What is sulci?
* folds or depressions
| * increases SA
163
What is the corpus callosum?
*major tract that connects the right side to the left side of the brain
164
What is gray matter?
*unmyelinated
165
What is white matter?
* myelinated
| * fatty protein shealth
166
What is the frontal cortex?
* Where personality sits
| * we have one of the largest ones
167
What is the longitudinal fissure?
* separates the two cerebral hemispheres
* extensive fold (increase the surface area
* Convolutions (Gyri, Sulci)
168
How is the brain protected?
* meninges (covering)
- dura
- arachnoid mater
- pia matter
169
What is the most superficial meninge?
*dura matter
170
What meninge is in direct contact with the brain?
*pia matter
171
What is in the arachnoid mater?
*subarachnoid space and CSF
172
Where does CSF come from and drains back into?
*blood
173
What are the ventricles of the brain?
1. right lateral ventricle
2. left lateral ventricle
3. third ventricle
4. fourth ventricle
174
Where are choroid plexus located and what does it produce?
*located in ventricles and produces CSF
175
What is CSF?
* a clear liquid that fills the ventricles/canals and bathes the external surface of the brain
* approximately 150mL of CSF in the CNS
176
What if the function of CSF?
* buoyancy
* protection
* chemical stability
177
What is buoyancy for?
*floats brain
178
What does protection do>
*cushions the brain
179
What does chemical stability do?
*rinses the brain of wasts
180
What is a hangover?
*low amounts of CSF causes the brain to rest directly on the skull
(dehydration causes low CSF production)
181
Describe the flow of cerebrospinal fluid?
1. choroid plexus of lateral ventricles produce CSF
2. CSF flows through the interventricular foramina
3. into the third ventricle
4. through the mesencephalic aqueduct (or cerebral aqueduct)
5. into the fourth ventricle
6. and into the subarchnoid space between the arachnoid and pia matter
182
All ventricles contain what and produce what?
*choroid plexus and produce CSF
183
What is hydrocephaly?
* a ventricular disease
* swelling of the head caused by overproduction or blockage of CSF (accumulates in the ventricles)
* causes pressure on the brain
* about 1/3 have normal intellectual function
* 50-60% mortality rate if untreated
184
What is meningitis?
*infection of meningeal layer
185
What are the symptoms of meningitis?
*rigidity of neck, sudden high fever, and altered mental status (flu like symptoms)
186
What are the causes of meningitis?
* bacteria N. meningitides (more common in college aged students)
* S. pneumonia (young and old more common)
* these enter the bloodstream or come into contact with meninges, nasal cavity or skin
* occurs in overcrowded living quarters
187
What are the effects of meningitis?
*swelling of the brain
188
What is the prognosis of meningitis?
*if untreated, almost always fatal
189
What are the preventions of meningitis?
*some vaccines available
190
What is the gray matter and its regions?
* nuclei
| * three regions (cerebral cortex, basal nuclei, and limbic system)
191
What is the basal nuclei?
* nuclei found in forebrain
| * links cerebral cortex to thalamus
192
What is the limbic system?
* lies on both sides of thalamus
| * support emotional activities, smell, motivation, and memory
193
What is the white matter?
* tracts (myelinated)
| * three types (projection tracts, commissural tracts, and association tracts)
194
What are projection tracts?
* extends vertically between higher and lower brain activities
* have long distance to travel (need myelination)
195
What are commissural tracts?
*goes from right to left side of brain
196
What are association tracts?
*connect different regions of same hemisphere
197
What are the cranial nerves?
* 12 of them
* sensory, motor, and mixed
* outside of brain
198
What are the brains three main regions
* Forebrain
* midbrain
* hindbrain
199
What is the forebrain?
*telencephalon (cerebrum) + diencephalon
200
What is in the forebrain?
* cerebrum
| * diencephalon
201
What is in the cerebrum?
*lobes: frontal, parietal, temporal, occipital
202
What is in the diencephalon?
* thalamus
* hypothalamus
* pituitary gland
* pineal gland
203
What is in the hindbrain?
* pons
* cerebellum
* medulla oblongata
204
What are the cerebral lobes?
*frontal, parietal, occipital, temporal
205
What is the function of the frontal lobe?
*involved in higher though
206
What is in the frontal lobe?
* central sulcus
* primary motor cotex/ precentral gyrus
* broca area
207
What is the central sulcus?
*posterior border of the frontal lobe
208
What is broca area?
*controls the formation of speech
209
What is aphasia?
*language disorder
210
What is broca's aphasia and causes?
* allows for word comprehension but does not allow for word production
* causes: stroke, head injury, brain tumor, or brain infections
211
What is the function of the parietal lobe?
*integrates sensory information
212
What is in the parietal lobe?
* primary somatic sensory cotex/ postcentral gyrus
| * Wernicke area
213
What is the primary somatic sensory cotes/ postcentral gyrus for?
*receives sensory information such as touch
214
What is wenicke ares?
*controls the understanding of spoken and written words
215
What is wenicke's apahsia and causes?
* allows for word production but word comprehension is damaged
* causes stroke, head injury, brain tumor, or infections
216
What is the function of the temporal lobe?
*allows for auditory, olfactory, and gustatory interpretation
217
What is in the temporal lobe?
*lateral sulcus?
218
What is lateral sulcus for?
*separates the frontal and parietal lobes from the temporal lobes
219
What is the function of the occipital lobe and what is in it?
* allows for visual acuity
| * transverse sulcus
220
What is transverse sulcus?
*separates occipital lobe from the cerebellum
221
What does it mean to see stars?
* disrupts neuro pathways by mechanical gates
| * mechanically stimulates a nerve
222
What is in the cerebrum?
*pre and post-central gyrus
223
What is in the limbic system?
* cingulate gyrus
* hippocampus
* amygdala
224
What is the cingulate gyrus?
*involved with emotional formation and processing, learning, memory, and respiratory control
225
What is the hippocampus for?
*plays a role in the conversion of short term memory to long term memory
226
What is the amygdala for?
*plays a role in processing memory as well as emotional reactions
227
What is the left hemisphere for?
*language and reasoning
228
What is the right hemisphere for?
* space/pattern perception
* artistic awareness
* imagination
* music comprehension
229
What are the right and left hemispheres connected by?
*corpus calosum (helps us coordinate activity from one side to another)
230
What is left handed lateralization?
* usually categorical or spatial
* 96 vs 70%
* 85% left brain dominant
231
What is right handed lateralization?
*usually representational or coordinate
232
What is the thalamus?
* surrounds the third ventricle
* relay center that receives almost all the sensory info from the body on its way to the cerebral cortex
* connects to hypothalamus
233
What is the hypothalamus a center for?
* thirst
* water balance
* pleasure
* rage
* sexual desire
* hunger
* sleep patterns
* temperature
* aggression
234
What is the pituitary gland for?
* sits in the hypophyseal fossa of the skull
| * contains hormones for growth, blood pressure, pregnancy, and sex organ development
235
What is the pineal gland for?
* secrets melatonin
| * allows for circadian rhythm
236
Hindbrain =
*metencephalon + myelencephalon
237
What is in the metencephalon?
* pons
| * cerebellum
238
What is in the myelencephalon?
*medulla oblongata
239
What is the cerebellum?
* little brain
| * functions for muscle coordination, maintains posture, and conceptualizes the passage of time
240
What is in the cerebellum?
* arbor vitae
| * folia
241
What is the arbor vitae?
* branched pattern of white matter
| * tree of life
242
What is the folia
*thin ridges that increase surface area of cerebellum
243
What is the medulla oblongata?
* forms a portion of the brain stem
* involved in autonomic functions (cardiac and respiratory centers)
* reflex centers for coughing, sneezing, gaging, swallowing, vomiting and salivation and sweating
244
How is the brain organized?
* motor in front, sensory in back
| * top for higher level thought processes, inferior is involuntary (autonomic functions)
245
What are the pons for?
* relays signals from the cerebrum to the cerebellum
* associated with sleep, hearing, equilibrium, taste, eye movement, facial expression/sensation, respiration, swallowing and bladder control
246
What is the mesencephalon?
* midbrain
| * contains four hemispheric processes known as corpora quadrigemina (superior colliculi, inferior colliculi)
247
What is the superior colliculi?
* allows for the tracking of moving objects
| * receives input from the eyes
248
What is the inferior colliculi?
*allows for auditory reflex
249
The precentral gyrus is responsible for what?
*directing motor movements
250
WHat is the medulla oblongata for?
*coordinating the rate and timing of breathing
251
A 67-year-old woman experiences a stroke to her right temporal lobe. Which of the following will most likely result from this permanent damage?
*Loss of gustation on the left side and loss of hearing in the left ear
252
Because of a brain lesion, a patient never feels full, but eats so much that she now
weighs nearly 600 pounds. The lesions is most likely in her?
*hypothalamus
253
What does the spinal cord do?
* coordinates reflexes
* locomotion (central pattern generator)
* passes info between PNS and brain
254
What are the major parts of the spinal cord?
* dura mater
* arachnoid mater
* pia mater
255
What matter has epidural space
*dura
256
What matter has subarchnoid space?
*arachnoid
257
What is the cervical spine?
*supports the head and provides attachment for muscles of the neck and upper extremities (protects spinal cord)
258
What is the atlas?
* c1
* supports the skull
* concave superior articular facet
* movement of head in the sagittal plane (nodding yes)
* articulates with occipital condyles
259
What is the axis?
* C2
* dens is hold in place inside the vertebral foramen of the atlas by ligaments
* movement of head in the transverse plane(shaking no)
260
What is the thoracic spine?
*the transition between cervical and lumbar regions and is an integral part of the thoracic cage (;not much movement)
261
What is the lumbar spine?
* sustains enormous loads
| * allows for mobility needed for daily activity and exercise
262
What is a herniated disc?
* Damage to discs
* they can bulge or break open
* also called slipped disc
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What discs are most prone to wear and tear?
*L4 and L5
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What is spondylolisthesis?
* the forward displacement of a vertebra, especially the fifth lumbar vertebra
* most commonly occurring in a break
