Nervous System Flashcards
1
Q
Somatic nervous system correlates to?
A
Voluntary movements
2
Q
Autonomic nervous system correlates to?
A
Parasympathetic and sympathetic systems
3
Q
What is the structural and functional unit of the nervous system?
A
Neuron
4
Q
What are the four supporting glial cells of CNS?
A
Oligodendrocytes
Astrocytes
Ependymal cells
Microglial cells
5
Q
What are the two supporting glial cells of the PNS?
A
Schwann cell
Satellite cells
6
Q
What is another name for cell body Soma?
A
Perikaryon
7
Q
What is Nissl substance?
A
Aggregates of rER and polyribosomes
8
Q
What is a telodendron?
A
End of axon in terminal arborization
9
Q
What does each branch of a telodendron end in?
A
Boutons terminal
10
Q
Where are neurotransmitters held?
A
Terminal Bouton
11
Q
What do sensory afferent neurons do?
A
Convey information/impulses TO CNS, FROM receptors
12
Q
What do motor efferent neurons do?
A
Convey inorfmation/impulses to the target cells FROM CNS
13
Q
Where are interneurons/intercalated neurons located?
A
CNS and autonomic ganglia
14
Q
What do interneurons/intercalated neurons do?
A
Integrate sensory and motor neurons
15
Q
What is a multipolar neuron?
A
One axon and 2 or more dendrites
16
Q
Where are multipolar neurons located?
A
Brain, spinal cord, autonomic ganglia
17
Q
What is function of multipolar neuron?
A
Motor and interneurons
18
Q
What is a bipolar neuron?
A
One axon and one dendrite
19
Q
Where are bipolar neurons located?
A
Olfactory, retina, spiral ganglia of ear
20
Q
What is a pseudounipolar neuron?
A
One long peripheral process, one short central process
21
Q
Where are pseudounipolar neurons located?
A
Dorsal root ganglia
22
Q
What is the function of pseudounipolar neurons?
A
Sensory
23
Q
What is another term for sensory neuron?
A
Afferent neuron
24
Q
What is another term for motor neuron?
A
Efferent neuron
25
What is the cytoskeleton of neuronal cell body made of?
Actin filaments, intermediate filaments, microtubules with centrosome
26
What protein do microtubules hold?
Tau proteins
27
Why does soma/perikaryon have lipofuscin granules?
Lysosomal digestion
28
What are tau proteins?
They stabilize microtubules
29
What is the clinical representation of misfolded and abnormally phosphorylated tau proteins?
Alzhiemers disease
30
What other factor plays a role in Alzheimers disease
Amyloid plaques/neuritic plaques; aggregates of beta amyloid protein outside of neuronal regions
31
Are dendrites myelinated?
No
32
What is function of dendritic spines?
Increase surface area available for synaptic contact
33
What organelles are present in axon hillock?
Mitochondria, microtubules, neurofilaments, and vesicles; help with transport of substances down the axon
34
What is the region between axon hillock and myelin sheath?
Initial segment
35
What is importance of initial segment?
Initiation of action potential
36
What is the cytoplasm of an axon called?
Axoplasm
37
What does axoplasm contain?
Neurotubules/microtubules, neurofilaments, mitochondria, vesicles
38
What does neurotubules/microtubules of axoplasm provide?
Tracks along which material is transported to and from cell body
39
What does neurofilaments provide axoplasm?
Structural support
40
What is anterograde transport in axoplasm?
Movement of mitochondria/substances DOWN the axon, *Kinesin protein
41
What is retrograde transport in axoplasm?
Movement of mitochondria/substances UP the axon, *Dyenin protein
42
What is axoplasm surrounded by?
Axolemma
43
What is presynaptic destiny of axon?
Aggregation of dense material in cytoplasm, Site where vesicles attach
44
What is postsynaptic density of dendrite?
Aggregation of dense material in cytoplasm, site where receptor proteins and channels are prevalent
45
What is between presynaptic and postsynaptic densities?
Synaptic cleft
46
What is important feature of synapse structure?
ER that regulates calcium levels
47
What is an electrical synapse?
Terminal boutons containing gap junctions, permit movement of electrical current between cells
48
Where are oligodedrocytes, ependymal cells, and astrocytes derived from?
Neuroectoderm
49
Where are microglial cells derived from?
Mesoderm
50
Where are schwann cells and satellite cells derived from?
Neural crest
51
What does every internode of PNS represent?
ONE schwann cells
52
What does every internode of PNS represent?
ONE schwann cell
53
What junctional complexes are found in nodes of ranvier?
Tight junctions
54
What do satellite cells surround?
Ganglion cells
55
What is role of satellite cell?
Structural and metabolic support for neural cell bodies, insulation and nutrition
56
Where are oligodendrocytes located?
Gray and white matter, predominantly in white matter
57
What are two types of oligodendrocytes?
Interfascicular- white matter
Perineuronal satellite cell- gray matter
58
What do perineuronal satellite cells do?
Regulate the neuronal microenvironment to protect neuron
59
What foot process covers the rode of ranvier?
Astrocytic foot process
60
What does oligodendrocytes NOT contain?
Glial fibers
61
What DO oligodendrocytes contain?
Microtubules
62
What does EM of oligodendrocytes show?
Inclusion bodies, clumps of chromatin, short cisternae of rER with mitochondria
63
What are two types of astrocytes?
Fibrous- white matter
Protoplasmic- gray matter
64
What junctional complexes do astrocytes hold?
Gap junctions
65
What do astrocytes contain that need a special stain to see?
GFAP, and intermediate filaments
66
What functions do astrocytes have?
Physical barrier between cells for protection, maintain ionic and pH equilibrium, modify chemical environment
Metabolize neurotransmitters, ex. Glutamate
67
What type of lining do astrocytes form around external surface of CNS?
Glial limitans
68
What type of lining do astrocytes form around blood vessels?
Perivascular feet
69
During injury, what do astrocytes proliferate into?
Phagocytic cells, forms glial scar
70
What do ependymal cells line?
3rd and 4th ventricle of brain, central canal of spinal cord
71
What is special feature about ependymal cells in the ventricles?
They do not rest on basal lamina, no basal lamina between cells and brain tissue
72
What do ependymal cells have on apical surface that moves CSF in the ventricles?
Microvilli and cilia
73
What are the intercellular junctions of ependymal cells?
Tight junctions
74
When the ependymal cells are modified to form layers of cuboidal epithelium in rich vasculature of choroid plexus, they do have a _____?
Basal lamina, formed by outgrowth of pia
75
What does choroid plexus secrete?
CSF, transport of water and electrolytes from capillary endothelium to form CSF
76
What are tanycytes?
Specialized ependymal cells present only in THIRD ventricle
77
What is special feature of tanycytes?
Basal processes extend through the astrocytic process layer to form end feet on blood vessels
78
What is function of tanycytes?
Control body weight and energy balance
79
What are microglial cells?
Phagocytic cells, remove debris of cells that die or during injury
80
What system are microglial cells part of?
MPS Mononuclear phagocytic system
81
Where are microglial cells prominent in?
Gray matter
82
When do the numbers of microglial cells increase?
During injury
83
What is PNS composed of?
Nerves, ganglia, nerve endings
84
What do epineurium and perineurium contain that endoneurium doesnt?
Blood vessels
85
What do peripheral nerve ganglia contain?
Cell bodies of ganglionic neuron, supporting satellite cells, nerve fibers
86
What are peripheral nerve ganglia associated with?
Cranial, dorsal root and autonomic ganglia
87
What is peripheral nerve sensory ganglia associated with?
Cranial ganglia, dorsal roots spiral ganglia
88
What type of neurons are in peripheral nerve sensory ganglia?
Pseudounipolar
89
What are sensory ganglia supported by?
CT capsule and internal framework
90
What are peripheral nerve autonomic ganglia?
Bulbous dilations associated with autonomic nerves, poorly defined capsule
91
Where are peripheral nerve autonomic ganglia located
Within organs, ex. GIT
92
Autonomic nerves use a two neuron circuit, what is involved?
First neuron of chain-preganglionic neurons located in CNS
Postganglionic fibers of second neruron-multipolar neurons located in peripheral autonomic ganglia
93
What is length of parasympathetic pre and post ganglions?
Long pre, short post
94
What is length of sympathetic pre and post ganglions?
Short pre, long post
95
Where are cell bodies of preganglionic sympathetic nerves located?
Lateral horn T1-L2
96
Where are cell bodies of preganglionic parasympathetic nerves located?
Medulla and midbrain, lateral horn S2-S4
97
Where are cell bodies of postganglionic sympathetic nerves located? (second order neurons)
Paravetebral neurons, sympathetic chain
98
Where are cell bodies of postganglionic parasympathetic nerves located? (second order neurons)
Ganglia always near effector organ
99
What is Endoneurium type of collagen?
Type 3
100
What is epineurium type of collagen?
Type 1
101
Where are the collagen fibers of endoneurium and perineurium synthesized from?
Schwann cells
102
What is present in endoneurium CT?
Macrophages and mast cells
103
What is special about perineural CT?
Specialized cells called perineurial cells, cells are contractile with actin filaments, each layer has a basal lamina on both surfaces
Forms blood nerve barrier
104
What does perineurial cells form?
Blood nerve barrier, forms tight junctions
105
Where is epineurium absent in?
Small nerves
106
What are the three parts of brain?
Cerebrum, cerebellum, brain stem
107
What does cortex or gray matter hold?
Nerve cell bodies, axons, dendrites, glial cells
108
Where is site of synapse?
Gray matter or cortex
109
What does medulla or white matter hold?
Myelinated axons of nerve cells, and glial cells
110
Cerebrum neocortex is organized into how many layers?
6 layers; molecular layer, external granular, external pyramidal, internal granular, internal pyramidal, multiform
111
Cerebellum is arranged in three layers, what are they?
Outer molecular layer, middle purkinjie layer, inner granular layer
112
Brain and spinal cord are covered by meninges, what are the three?
Dura mater, Arachnoid mater, Pia mater
113
What does dura mater consist of?
Thick sheet of CT, two layers; outer periosteal layer, inner meningeal layer, between two layers are dural venous sinuses
114
What is function of dural venous sinuses?
Drain venous blood from brain into internal jugular vein
115
What partitions does meningeal layer of dura form?
Falx cerebri, tentorium cerebelli
116
What does arachnoid mater consist of?
CT sheet, small tufts of arachnoid tissue projects into superior sagittal sinus to drain CSF into venous sinuses
117
What is subarachnoid space filled with?
CSF, blood vessels
118
What does pia mater consist of?
Delicate CT sheet, lies on surface of brain on glial limitans
119
What does pia mater follow penetrating branches of?
Large blood vessels of brain, narrow space between blood vessels and pia is called perivascular space
120
What does perivascular space hold?
CSF from subarachnoid space, facilitates movement of CSF deep into brain tissue
121
What is blood brain barrier?
Physiological barrier, extensive tight junctions, thick layer of basement membrane, astrocyte end feet, strong basal lamina
122
What are three layers of blood brain barrier basal lamina?
EC layer formed by laminin-4 and lamin-5
Astrocyte derived layer, formed by laminin and lamin-2
Collagen IV layer
123
A number of astrocyte released factors contribute to BBB integrity, including?
Glial derived neurotrophic factor GDNF
124
What cells are present with surrounding basal lamina of endothelial cell?
Pericytes
125
What do pericytes do for BBB?
Involved in restricted BBB permeability
126
What are two events in neuron response to injury?
Axonal degeneration, neural degeneration
127
Can axons of CNS regenerate?
No, due to myelin debris containing inhibitors of axonal degeneration, and due to BBB restriction of macrophage migration
128
Degeneration of axons in PNS of distal part is called?
Anterograde degeneration or Wallerian degeneration
129
Degeneration of axons in PNS of proximal part is called?
Retrograde degeneration or traumatic degeneration
130
Describe anterograde degeneration in PNS
Microtubules and cytoskeleton break down, axon fragments, this causes schwann cells to differentiate and results in breakdown of myelin sheath, remenants are phagocytized by schwann cells and phagocytes, then recruitment of monocyte derived macrophages occurs, complete disruption of blood nerve barrier along entire nerve, dedifferentiated schwann cells stop forming myelin, start to divide and arrange themselves longitudinally along external lamina
131
Describe axon regeneration in PNS
Schwann cells start to form bands of bungner, these bands guide growth of neurites to correct destination, schwann cells around regenerated axon redifferentiate and make myelin sheath
132
Describe retrograde degeneration in PNS
Axon proximal to injured site undergoes degeneration, this upregulate the gene C-jun, C-jun expression causes the cell body to undergo chromatolysis; neuron swells, nucleus and nissl substance is moved peripherally
133
Describe response to injury in CNS
If oligodendrocytes lose contact with axon, they undergo apoptosis, BBB is disrupted only at site of injury (not along entire length of axon), this limits infiltration of macrophages, myelin removal takes a very long time, astrocyte forms glial scar that replaces empty spaces left by degenerated axons
