Test 2 Material Flashcards
(185 cards)
1
Q
Bone (Functions)
A
-Support
-Protection
-Movement
-Mineral Homeostasis
-Blood Cell Production (hemapoiesis/hematopoiesis)
-Storage
2
Q
Structures in Bone
A
-Diaphysis
-Epiphyses
-Metaphyses
3
Q
Diaphysis
A
-Long main portion of the bone
-a.k.a body, shaft
4
Q
Epiphyses
A
-Ends of the bone
5
Q
Metaphyses
A
-Regions between the diaphysis and the epiphyses
-Contains the epiphyseal growth plate/epiphyseal line
6
Q
Epiphyseal Growth Plate
A
-Cartilagenous area within the metaphysis of a growing bone
-once growth stops, what remains is the epiphyseal line
7
Q
Articular Cartilage
A
-Thin layer of hyaline cartilage covering the epiphyses
8
Q
Perosteum
A
-Tough CT covering that surrounds bone
-Protects, nourishes, and heals bone
-Is an attachment for tendons & ligaments
-Outer layer is tough and supportive/protective
-Inner layer has bone forming cells
-Well vascularized and innervated *(Especially innervated for pain)
9
Q
Medullary Cavity
A
-a.k.a marrow cavity
-Space within the diaphysis that contains:
1. Red Marrow (for blood cell formation)
2. Yellow Marrow (for fat storage)
10
Q
Red Marrow
A
For blood cell formation
*(Pelvis, spine, ribs, sternum, scull, proximal ends of upper arm bone and thigh bones humorous & femur)
11
Q
Yellow Marrow
A
For fat storage
*(everything else)
12
Q
Bone is ______________.
A
CT
13
Q
Bone Matrix
A
25% water, 25% collagen, 50% mineral salts
14
Q
Bone Cells (In order)
A
- Osteoprogenitor Cells
- Osteoblasts
3.Osteocytes - Osteoclasts
15
Q
Osteoprogenitor Cells
A
Active during normal growth, healing and cyclical bone replacement
16
Q
Osteoblasts
A
Bone building cells
17
Q
Osteocytes
A
Mature bone cells
18
Q
Osteoclasts
A
Bone ‘eating’ cells
*Breaks down bone
19
Q
Types of bone
A
- Compact
- Spongy
20
Q
Compact
A
-a.k.a. cortical, dense
-external layer of all bones
-provides protection and support
21
Q
Cortex is the __________ layer.
A
Outer Layer
22
Q
Structures of Compact Bone
A
-Osteon
-Central Canal
-Concentric Lamellae
-Lacunae
-Canaliculi
-Volkmann’s Canals
23
Q
Osteon is also known as _______________.
A
-a.k.a Haversian Systems
24
Q
Central (a.k.a Haversian) Canal
A
-A hole through the centre of the osteon through which blood and lymphatic vessels run
25
Concentric Lamellae
-Rings of hard, calcified bone matrix around the central canal
26
Lacunae
-Spaces between the rings
-In the lacunae are osteocytes
27
Canaliculi
-Small channels sticking out (in all directions) from the lacunae
-Filled with extracellular fluid
-Allows osteocytes to communicate
28
Volkmann's Canals
-a.k.a transverse perforating canals
-holes which run transversely to connect the inner and outer portions of the bone
29
Spongy Bone
-Trabeculae
-Trabeculae contain osteocytes in lacunae connected by canaliculi
-Lighter
-Spaces can contain red bone marrow
-Designed for lower stresses or stresses from different directions
30
Bone Blood Supply
-Well Vascularized
-Periosteal arteries enter the diaphysis at multiple points (Volkmann's canals) to supply the periosteum and outer compact bone
-Nutrient arteries enter the diaphysis via the nutrient foramen to supply the inner compact bone, spongy bone & red bone marrow
-Metaphyseal arteries - supply the metaphysis
-Epiphyseal Arteries - supply the epiphysis
31
Metaphyseal arteries
Supply the metaphysis
32
Epiphyseal Arteries
Supply the epiphysis
33
Bone Growth/Aging
-Bone is in a constant state of remodelling
-From birth to adolescence, bone growth is greater than bone loss
-Long bones lengthen through growth at the epiphyseal growth plates and they get thicker by osteoblasts in the periosteum laying new bone at the periphery
-In young adults - bone growth is about equal to bone loss
-From middle ages - bone loss exceeds bone growth
34
From middle ages bone loss _____________ bone growth.
Exceeds
35
In young adults bone growth _______________ to bone loss.
Is about equal
36
From birth to adolescence, bone growth is _____________ than bone loss.
Greater
37
Long bones lengthen through growth at the ___________________ and they get thicker by ___________ in the _______________ laying new bone at the ________________.
Epiphyseal growth plates, osteoblasts, periosteum, periphery
38
Nutrient arteries enter the ____________ via the ________________ to supply the inner compact bone, spongy bone & red bone marrow
Diaphysis, nutrient foramen,
39
Periosteal arteries enter the ______________ at multiple points (Volkmann's canals) to supply the periosteum and outer compact bone
Diaphysis
40
Central Nervous System (CNS)
-Brain
-Spinal cord
41
Peripheral Nervous System (PNS)
-All of the nervous tissue outside of the CNS
42
Functions of the Nervous System
1. Sensory
-detection & input
2. Integrative
-processing/storing/analyzing of sensory info
-decision making
3. Motor
-output
43
Sensory
Detection & input
44
Integrative
-Processing/storing/analyzing of sensory info
-Decision making
45
Motor
Output
46
Nervous Tissue
-Designed for communication
-2 types of cells
1.Neuroglia
2.Neurons
47
Neuroglia
-Support
-Nourish
-Protect
48
Neurons
-Nerve cells
-3 parts: dendrite, cell body, axon
49
Dendrite
Structure: multiple or single extensions off the cell body
Function: the input portion of the neuron
-Contain lots of receptor sites for receiving chemical messages from other cells
50
Dendrite (structure)
Structure: multiple or single extensions off the cell body
51
Dendrite (function)
Function: the input portion of the neuron
52
Cell Body (structure)
Structure: contains the nucleus and other organelles
53
Cell Body (function)
Function: cell processes
54
Axon
-This cylindrical process off the cell body
-Function: The output portion of neuron
-End of an axon divides into many fine processes called axon terminals
-Synaptic end bulb: swollen ends of some axon terminals
-Some axons are myelinated
-Myelin: Multilayered lipid and protein covering that speeds up signal (action potential) conduction (axons coated in myelinare called 'myelinated' axons)
*Conduction of action potential
55
Axon (Function)
Function: The output portion of neuron
56
Synaptic end bulb
Swollen ends of some axon terminals
57
*Myelin
Multilayered lipid and protein covering that speeds up signal (action potential) conduction (axons coated in myelinare called 'myelinated' axons)
*Conduction of action potential
58
Neurons
-Possess electrical excitability
-Can respond to a stimulus and convert it to action potential
-Stimulus: Any change in the environment (internal or external) that is strong enough to stimulate an action potential
-Action Potential: Electrical signal that travels along cell membrane of a neuron
-Can communicate over very small or very great distances
-Action Potentials travel at different speeds
59
Stimulus
Any change in the environment (internal or external) that is strong enough to stimulate an action potential
60
Action Potential
Electrical signal that travels along cell membrane of a neuron
61
Structural Classification of Neurons
-Neurons vary in size and shape
-Structurally, neurons are classified according to the number of processes extending from the cell body
62
What are the 3 Structural Classifications of Neurons?
1.Multipolar
2.Bipolar
3. Unipolar
63
Multipolar
-Several dendrites and one axon
-Most neurons in the brain and spinal cord and all motor neurons
64
Bipolar
-One main dendrite and one axon
*Not very common
65
Unipolar
Peripheral axon - has sensory receptors
Central axon - has axon terminals
Sensory neurons - in the PNS are unipolar
66
Functional Classification of Neurons
-Functionally, they are classified according to the direction in which the action potential is conducted with respect to the CNS
67
What are the 3 Functional Classifications of Neurons?
1. Sensory Neurons
2. Motor Neurons
3. Interneurons
68
Sensory Neurons
-a.k.a Afferent neurons
-Most are unipolar
-Contain either sensory receptors at the dendritic cells or are located just after sensory receptors that are separate cells
-Once activated by a stimulus, action potential forms and propagates along the axon and is conveyed into the CNS (via sensory or afferent neurons)
-Sensory neurons travel together in spinal and cranial nerves
69
Motor Neurons
-a.k.a Efferent neurons
-Multipolar
-Action potential propagates away from the CNS to effectors (via motor or efferent neurons)
-Effectors: cells and organs
70
Effectors
Cells and Organs
71
Interneurons
-a.k.a association neurons
-Most are multipolar
-Primarily in the CNS between sensory and motor neurons
-Interneurons integrate/process info from sensory neurons
-If motor response is required, the specifics of the response are formulated and relevant. motor neurons are activated
72
Synapses
-Site of communication between two neurons or between a neuron and another type of cell
-2 types of synapses: electrical and chemical
73
What are the 2 types of synapses?
1. Electrical
2. Chemical
74
Electrical Synapses
-Action potentials conduct directly between the plasma membranes of adjacent cells through gap junctions
-Faster (than chemical)
-Allow for synchronization of function
75
Pre-Synaptic neuron
Neuron sending the signal
76
Post-Synaptic Neuron
Neuron receiving the signal
77
Synaptic Cleft
Space between the communicating neurons
78
Neurotransmitter
Chemical released by the pre-synaptic neuron to affect (excite or inhibit) the post-synaptic neuron(s) or effector (muscle/gland)
79
Neurotransmitters are specific to the _________________?
Neurotransmitters released (think lock and key)
80
Chemical Synapse Processes
-When action potential reaches the end of the pre-synaptic neuron, it causes release of a neurotransmitter that diffuses across the synaptic cleft, binds to the post-synaptic neuron
-If neurotransmitter is excitatory - continuation of action potential is more likely
-If neurotransmitter is inhibitory - continuation of the action potential is less likely
-Chemical synapses are slower (than electrical)
81
If neurotransmitter is excitatory?
Continuation of action potential is more likely
82
If neurotransmitter is inhibitory?
Continuation of the action potential is less likely
83
What are 4 common neurotransmitters?
1. Acetylcholine
2. Gamma-Aminobutyric Acid
3. Dopamine
4. Seratonin
84
Acetylcholine (ACh)
PNS/CNS, excitatory at NMJ
85
Gamma-Aminobutyric Acid (GABA)
CNS, inhibitory
86
Dopamine
Excitatory or inhibitory (depending on the receptor), emotional responses, addictive behaviours, skeletal muscle tone
87
Seratonin
excitatory or inhibitory (depending on the receptor), sensory perception, temperature regulation, mood, sleep, appetite
88
Neuroglia
-Support, nourish, and protect neurons
-With injury and/or disease, neuroglia multiply to fill the spaces formerly occipied by neurons
89
What are the 4 types neuroglia of the CNS?
1. Astrocytes
2. Oligodendrocytes
3. Microglia
4. Ependymal cells
90
Astrocytes
-Help form blood-brain barrier (BBB)
-Provide nutrients to neurons
91
Oligodendrocytes
-Form/maintain the myelin sheath of CNS neurons
92
Microglia
-Phagocytotic (similar to tissue macrophages)
-Remove debris, phagocytize microbes
93
Ependymal cells
-Line the cavities of the brain and spinal cord
-Produce and assist in circulation of cerebrospinal fluid (CSF) clear, colourless fluid that circulates around brain and spinal cord (protects brain and spinal cord from injury)
94
Blood-Brain Barrier (BBB)
-Specialized barrier prevents passage of materials from the blood and the brain (and its surrounding fluid)
-Protects brain from harmful substances
-Thick basement membrane, tight junctions
95
What is Neuroglia of the PNS?
Schwann Cells
96
Schwann Cells
-Cells that encircle axons in the PNS
-Form myelin sheath of PNS axons
-Involved in regeneration of PNS axons
97
Central Nervous System (CNS) includes?
Brain and Spinal Cord
98
Peripheral Nervous System (PNS)
-Cranial nerves and their branches
-Spinal nerves and their branches
-Ganglia
-Enteric plexuses
-Sensory receptors
99
Nucleus
Cluster of neuronal cell bodies in the CNS (plural: nuclei)
100
Ganglion
Cluster of neuronal cell bodies in the PNS (plural: ganglia)
101
Tract
Bundle of axons in CNS
-Tracts interconnect neurons in the spinal cord and brain
102
Nerve
Bundle of axons in PNS
-Spinal Nerves: connect the spinal cord to the periphery
-Cranial Nerves: connect the brain to the periphery
103
Spinal Nerves
Connect the spinal cord to the periphery
104
Cranial Nerves
Connect the brain to the periphery
105
Grey Matter
Collections of cell bodies and unmyelinated nerve fibres in the CNS
106
White Matter
Collections of myelinated axons in the CNS
107
Spinal Cord
-Encased in vertebrae (bones of the spine)
-Extends from the bottom part of the brain stem to the 2nd lumbar vertebra (L2)
-At L2, it tapers into a structure called the conus medullaris
-Cauda Equina: the roots of the spinal nerves below the conus medullaris
*Spinal cord ends at L2
108
Cauda Equina
The roots of the spinal nerves below the conus medullaris
109
Neck/Cervical
C1-C7
110
Thoracic
T1-T12
111
Lumbar
L1-L5
112
Sacrum
S1-S5
113
Structure around Spinal Cord
-White matter surrounding an inner core of grey matter
-Anterior median fissure and posterior median sulcus: 2 grooves that divide the white matter into right and left sides
-Central canal: small tube in the centre if the SC that contains CSF
114
Anterior median fissure and posterior median sulcus
2 grooves that divide the white matter into right and left sides
115
Central canal
Small tube in the centre if the SC that contains CSF
116
Grey Matter
-Each side is divided into regions called horns
-Posterior Horn (a.k.a dorsal): axons of incoming sensory neurons and interneurons
-Anterior Horn (a.k.a ventral): motor nuclei
-Lateral Horn: Present in thoracic, upper lumbar, sacral portions, they contain the sympathetic nuclei
117
Posterior Horn (a.k.a dorsal)
Axons of incoming sensory neurons and interneurons
118
Anterior Horn (a.k.a ventral)
Motor nuclei
119
Lateral Horn
Present in thoracic, upper lumbar, sacral portions, they contain the sympathetic nuclei
120
What are the 3 horns in grey matter?
1. Posterior Horn (a.k.a dorsal)
2. Anterior Horn (a.k.a ventral)
3. Lateral Horn
121
White Matter
-Each side is divided into regions called columns
3 Regions: anterior columns (a.k.a ventral), posterior columns (a.k.a dorsal), lateral columns
-Each column contains bundles of axons (tracts) that have a common origin or destination
-Sensory Tracts (a.k.a ascending): consist on axons that conduct action potentials toward the brain
-Motor Tracts (a.k.a descending): consist of axons that conduct action potentials away from the brain
122
What are the 3 regions of white matter?
1. Anterior columns (a.k.a ventral)
2. Posterior columns (a.k.a dorsal)
3. Lateral columns
123
Sensory Tracts (a.k.a ascending)
Consist on axons that conduct action potentials toward the brain
124
Motor Tracts (a.k.a descending)
Consist of axons that conduct action potentials away from the brain
125
Brain Structure
1. Brain stem
2. Cerebellum
3. Diencephalon
4. Cerebrum
126
Brain Stem
-Continuous with spinal cord (SC, it is the part between the SC and the diencephalon
-3 Regions: medulla oblongata, pons, midbrain
-These regions also contain nuclei of specific cranial nerves
-The net-like reticular formation extends through the brainstem
127
3 Regions of Brain Stem?
1. Medulla oblongata
2. Pons
3. Midbrain
128
Medulla Oblongata
-Contains centres (nuclei) for the control of the heart rate, blood pressure, breathing, swallowing, and vomiting
129
Pons
-Contains centres for the control of breathing
130
Midbrain
-Contain centres for reflex visual activities (e.g. tracking moving objects, scanning stationary objects), hearing
-Contains nuclei called the substantia nigra - Neurons that make dopamine extend from it
131
Neurons that make dopamine extend from _____________________.
substantia nigra (nuclei)
132
Reticular Formation
-Net-like formation of neural tissue that spreads throughout the brain stem
-Contains the reticular activating system (RAS) which helps:
-Consciousness
-Maintain Attention
-Prevent sensory overload by filtering out insignificant info
-*Regulate muscle tone
133
Reticular Activating System (RAS) helps?
-Consciousness
-Maintain Attention
-Prevent sensory overload by filtering out insignificant info
-*Regulate muscle tone
134
Cerebellum
-Posterior to brain stem
-Smoothes and coordinates skeletal muscle contraction
-Regulates posture and balance
135
3 Parts of the Diencephalon?
1. Hypothalamus
2. Thalamus
3. Epithalamus
136
Hypothalamus
-Major regulator of homeostasis
-Controls and integrates the autonomic nervous system
-Hormone production
-Emotion and behaviour (with limbic system)
-Eating, drinking
-Body temperature
-Circadian rhythm (a 24hr cycle in the biochemical, physiological and/or behavioural processes of living things)
137
Circadian rhythm
24hr cycle in the biochemical, physiological and/or behavioural processes of living things
138
Thalamus
-Major relay station for most sensory input to the cerebral cortex
139
Epithalamus
-Contains the pineal gland
-Involved in smelling (especially emotional responses to smells)
140
Cerebrum
-2 halves or hemispheres (right & left)
-Consist of:
-Outer rim of grey matter (cerebral cortex;
-Inner region of white matter (association areas); and
-Grey matter nuclei deep within white (basal ganglia)
141
Outer rim of Grey Matter
Cerebral Cortex
142
Inner region of White Matter
Association Areas
143
Grey Matter Nuclei deep within White
Basal Ganglia
144
Cerebral Cortex
-Contains sensory areas involved in perception
-Contains motor areas involved in the execution of voluntary movements
145
Association Areas (White Matter)
-Contain areas that deal with more complex functions like memory, emotions, reasoning, will, judgment, personality traits, intelligence
146
Basal Ganglia
-a.k.a basal nuclei
-Helps regulate the starting and stopping of movements
-Helps control subconscious contraction of skeletal muscles
-Helps suppress unwanted movement
-Helps to set resting muscle tone
-Functionally, basal ganglia are linked to substantia nigra
147
Limbic System
-Involved in emotion, smelling, and memory
-Includes parts of the hypothalamus, hippocampus, amygdala, and other nearby structures
148
Hippocampus
-Functions in memory (encoding, consolidation, and retrieval)
-Very important in converting short term memory into long term memory
149
Amygdala
Important in emotional function (esp. fear)
150
Meninges
-3 protective layers of connective tissue (CT) that encircle the brain and spinal cord (SC)
-They cover the Brain/SC up to the point where the nerves exit the spinal cord
151
What are the 3 protective layers (meninges) of connective tissue (CT) that encircle the brain and spinal cord (SC)?
1. Dura Mater
2. Arachnoid Membrane
3. Pia Mater
152
Dura Mater
Tough outer layer
153
Arachnoid Membrane
Middle layer
154
Pia Mater
Inner layer
155
Epidural Space
Adipose and CT- filled space between the wall of vertebral canal and dura mater (no epidural space in brain)
156
Subdural Space
Interstitial fluid-filled space between the dura mater and arachnoid membrane
157
Subarachnoid Space
CSF filled space between arachnoid membrane and the pia mater
158
Peripheral Nervous System (PNS)
All of the nervous tissue outside the CNS including:
-Cranial Nerves
-Spinal Nerves
-Ganglia
-Sensory Receptors
159
Cranial Nerves
-Paths of communication between brain and periphery
-12 pairs of nerves that exit from base of brain
160
Spinal Nerves
-Paths of communication between SC and the periphery
-31 pairs of spinal nerves
-Parallel bundles of axons (& their associated neurological cells) wrapped in several layers of CT
-Spinal nerves connect the SC to receptors, muscles, glands in all body parts of the body
-31 pairs numbered according to region and level of vertebral column from which they emerge
-1st pair of cervical nerves emerge from spinal cord between base of the scull and 1st cervical vertebra
-C1-C7 exit the spine above their corresponding vertebra
-C8 exits between C7 and T1 Vertebra
-Not all are aligne with their corresponding vertebrae - lumbar, sacral and coccygeal nerves descend from ~ L2 to their respective levels
161
What are 4 Spinal nerves ?
1. Nerve root
2. Anterior Root (ventral)
3. Posterior Root (dorsal)
4. Posterior/Dorsal Root Ganglion
162
Nerve Root
two bundles of axons that connect the spinal nerve to the SC
163
Anterior Root (ventral)
Bundle of motor axons
164
Posterior Root (dorsal)
Bundle of sensory axons
165
Posterior/Dorsal Root Ganglion
Swelling in the posterior root containing cell bodies of sensory (a.k.a. unipolar, primary afferent) neurons of the PNS
166
What are the 3 Connective tissues of a Spinal Nerve?
1. Endoneurium
2. Perineurium
3. Epineurium
167
Endoneurium
Innermost, covers the axon (whether it's myelinated or not)
168
Perineurium
Middle layer, covers fascicles (bundles of axons)*Perineurium & epineurium are highly vascularized
169
Epineurium
Outermost layer, covers spinal nerve
*Perineurium & epineurium are highly vascularized
170
3 Subdivisions of the PNS?
1. Somatic NS (SNS)
2. Autonomic NS (ANS)
3. Enteric NS (ENS)
171
*Somatic Nervous System (SNS)
-'Voluntary nervous system'
-Sensor neurons (a.k.a. 1st order neurons) convey info to the CNS (e.g. temp, pressure, pain ...)
-Motor neurons conduct impulses (signals from the CNS to skeletal muscles only
172
Autonomic Nervous System (ANS)
Monitors (sensory) and controls (motor) body activities (cardiac, smooth muscle, glands) automatically
2 divisions: sympathetic nervous system (SyNS) and parasympathetic system (PaNS)
173
What are 2 divisions of Autonomic Nervous System (ANS)?
1. Sympathetic nervous system (SyNS)
2. Parasympathetic system (PaNS)
174
Sympathetic nervous system (SyNS)
-Fight or flight
-High sympathetic activity comes from being excited, scared, threatened
175
Responses of Sympathetic nervous system (SyNS)?
-Pupil dialation
-Increased Heart Rate, blood pressure
-Airway dilation
-Vasodilation of skeletal and cardiac mm.
-Glucose release
-Vasoconstriction in kidneys and the digestive tract
176
Parasympathetic system (PaNS)
-Rest and digest
-Conserve and restore energy systems
-Increased digestive and urinary functions
177
Autonomic Tone
-Balance between sympathetic and parasympathetic activity
-Regulated by hypothalamus
-Most organs have dual innervation (PaNS & SyNS)
-Few structures receive only sympathetic innervation (sweat glands, arrector pilli, kidneys, most BVs, adrenal medullae) - function is determined by increasing or decreasing sympathetic stimulation
-For normal functioning there needs to be a balance between sympathetic and parasympathetic activity
-Effects of sympathetic stimulation last longer and are more widespread than effects of parasympathetic stimulation
178
Autonomic Control
Major control and integration centre for the ANS is the hypothalamus
179
Enteric Nervous System (ENS)
-Sensory neurons that monitor chemical changes within the gastrointestinal (GI) tract and stretching of its walls
-Motor neurons control contraction of GI tract smooth muscle and secretions of GI organs (e.g. acid secretions by stomach)
180
Sensory Input
-Peripheral sensory receptor (e.g. unipolar neuron) detects stimulus
-Sensory input (in form of AP) travels along the axon to cell body in the dorsal rood ganglion (DRG); from DRG, the sensory axon may proceed in 3 ways:
1. Axon extends into white matter an travels up to brain as part of sensory tract (ascending)
2. Axon enters the dorsal horn and synapses with an interneuron - it's axon crosses over into white matter of opposite side and travels up to brain as part of a sensory tract
3. Axon enters dorsal horn and synapses with and interneuron which in turn synapses with a somatic motor neuron in the ventral horn as part of spinal reflex pathway
181
Motor Output occurs via 2 ways?
1. Somatic
2. Autonomic
182
Somatic
Axons from motor tract (descending) synapse with the somatic motor neurons in the ventral horn on the contralateral side - these axons extend through ventral root then spinal nerve to innervate skeletal muscles
183
Autonomic
Autonomic motor neurons in the lateral horn send output along axons which sequentially pass through the lateral grey horn, the anterior grey horn and the anterior root to enter spinal nerve. From spinal nerve, the axons of autonomic motor neurons synapse with another group of autonomic motor neurons which will innervate cardiac muscles, smooth muscles or glands
184
Metabolic Requirements of Nervous Tissue
-High metabolic rate
-Glucose is primary energy substrate for the nervous system but neurons have no glycogen stores (get it from blood or neuroglial cells)
185
Regeneration & Repair of Nervous TIssues
-Although nervous tissue can readily adapt, it has limited ability to regenerate
-In the PNS: damage to dendrites and myelinated axons can be repaired if the cell body is intact and schwann cells are active
-In the CNS: little or no repair of damaged neurons occurs
