Nervous System Cell Biology Flashcards
1
Q
Neuronal processes
A
Dendrites and axons
2
Q
Cells whose main function is rapid intercellular communication
A
Neurons
3
Q
Each neuron is surrounded by a plasma membrane and an extracellular _______________ (similar to epithelial cells)
A
basal lamina
4
Q
RER is formed into large bodies in the neuronal cell cytoplasm. By light microscopy these bodies are clearly visible and are termed ___________
A
Nissl bodies (substance)
5
Q
Main site for receiving incoming signals (signal reception) from other neurons
A
Dendrites
6
Q
Only ________ potentials occur in dendrites because no voltage gated Na+ channels are present
A
graded
7
Q
Dendrites are branched into dendritic _______, which increase surface area for synaptic contact
A
spines
8
Q
____________ contain Nissl bodies, are larger in diameter than axons, and are not myelinated
A
Dendrites
9
Q
Absence of Nissl substance in a neuronal process indicates:
A
axon
10
Q
Main function is to convey information away from cell body to a target cell
A
Axons
11
Q
Does not contain protein synthesis machinery (Nissl or Golgi) because it would interfere with action potential propagation
Does contain a lot of mitochondria
A
Axon
12
Q
Action potential is initiated at the ___________ (signal integration) that is generally not myelinated, devoid of Nissl bodies and Golgi, and subject to graded potentials, where voltage gated Na+ channels are activated if threshold is reached
A
axon hillock
13
Q
Steps of synaptic transmission
A
- AP reaches terminal
- V-gated Ca2+ ch. opens
- Influx of Ca2+ induces vesicle docking and/or formation of pore complex
- NT released into synaptic cleft and binds ligand-gated channels or G protein-couple receptors (with then act through 2nd messengers of G protein gated ion channels)
- NT removed from cleft via degradation (Acetylcholinesterase or re-uptake
14
Q
Anterograde axon transport protein
+ end directed (towards axon terminals)
Can be fast or slow
A
Kinesin
15
Q
Retrograde axonal transport protein
- end directed (towards nucleus)
Fast only
A
Dynein
16
Q
PNS glial cells
A
Schwann cells
Satellite cells
17
Q
Myelinate axons in PNS
A
Schwann cells
18
Q
Provide direct support to neurons (around cell body) in PNS
A
Satellite cells
19
Q
CNS glial cells
A
Oligodendrocytes
Astrocytes
Microglia
Ependymal cells
20
Q
Myelinate axons in CNS
A
Oligodendrocytes
21
Q
CNS glial cells that have many types and functions, such as maintaining the blood brain barrier
A
Astrocytes
22
Q
Resident macrophages of CNS
A
Microglia
23
Q
CNS glial cells that line the fluid-filled ventricles, produce and maintain CSF
A
Ependymal cells
24
Q
Junctions between two adjacent Schwann cells associated with peripheral nerves
A
Nodes of Ranvier
25
_______ proteins on the cytoplasmic side (Myelin Basic Protein, MBP) and the extracellular side (P0) of the plasma membrane contribute to the tight apposition of lipid bilayers of glial cells during myelination
Adhesive
26
Myelination requires the vitamin ______ because MBM must be methylated in order to function
Vitamin B12
27
____________ is a dynamic process, which involves the ensheathment of the axon by the glial cell and subsequently the extrusion of cytoplasm from parts of the glial cell
Myelination
28
The increased lipid content of the myelin sheath provides electrical _____________ for the underlying axon
insulation
29
One Schwann cell myelinates _______ segment of an axon
One
30
____________ syndrome is characterized by inflammatory response around nerve fibers with a T mediated response against myelin. Can be triggered by a respiratory or gastrointestinal viral infection, but the etiology is not known. The symptoms include tingling or crawling sensation, ascending weakness or paralysis, loss of muscle coordination and loss of cutaneous sensation.
Demyelinating disease result in decreased or lost ability to transmit electrical signals along nerve fibers.
Most common life-threatening disease of PNS
Guillain-Barre syndrome
31
The cytoplasm of the myelinating Schwann cell is ___________
continuous
32
______________ clefts allow for transport of materials to maintain myelin sheath (act as portals)
Schmidt-Lanterman clefts
33
Voltage gated Na+ channels are concentrated at ______________, not where myelin is
Nodes of Ranvier
34
Myelination enables ______________, where the action potential jumps between nodes
Saltatory conduction
35
Myelin insulates, which ___________ capacitance, such that voltage spike is transmitted over longer distance.
decreases
36
Voltage-gated channels at nodes propane action potential to next downstream node. K+ lead and refectory period of Na+ channels at upstream nodes prevent:
retrograde propagation
37
Multiple ______________ axon segments can be ensheathed by a single Schwann cell.
nonmyelinated
38
_____________ support peripheral ganglia neurons
Stellite cells
39
One _______________ can myelinated up to 12 axons in the CNS.
Oligodendrocyte
40
Form limiting barrier around all interfaces of CNS (at pia, ependyma, and blood/lymph vessels) - continuous barrier on the outside, and footplates on the inside
Regulate microenvironment via transport of metabolites, ions, and waste to and from neurons
Modulate neurotransmitter activity, particularly glutamate
Induce synapse formation
Form an electrically coupled network (use gap junctions to communicate with each other)
Respond to injuries (form a wall around injured tissue)
Astrocytes
41
Astrocytes undergo proliferation and ___________ (increased cell size) in response to pathological changes
Aka reactive gliosis or astrocytosis
hypertrophy
42
Actual blood-brain-barrier is formed by _______________ of CNS capillaries, but astrocytes play important role in the process
endothelial cells
43
Astrocyte contact with endothelial cells induces extensive ___________ to form between endothelial cells in CNS capillaries
tight junctions
44
___________ signal to pericytes, which to maintain vessel integrity
Astrocytes
45
Resident immune cells in CNS derived from monocytes
Activate and proliferate in some disease or injury states
Phagocytic and engulf cellular debris
Microglia
46
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Simple columnar (or cuboidal) ciliated epithelium that line the brain ventricles and spinal canal
Production and maintenance of CSF
```
Ependymal cells
47
Ependymal cells of ___________ in lateral ventricle and roof of 3rd and 4th ventricle secrete CSF which is circulated and modified by ependymal cells in other areas
Pumps out ion, water follows
choroid plexus
48
The cerebral cortex is organized as peripheral _______ matter (neuron cells bodies) and inner ________ matter (axonal tracts).
peripheral gray matter
| inner white matter
49
The cerebellum is organized as peripheral _______ matter (neuron cells bodies) and inner ________ matter (axonal tracts).
peripheral gray matter
| inner white matter
50
Connective tissue covering the CNS:
| Variations of dense irregular connective tissue
meninges
51
Dense irregular connective tissue with meningeal arteries/veins and nerves
Dura mater
52
A "potential space" in the meninges - normally the arachnoid adheres to the dura, but it can become separated by trauma/bleeding and thus become a space
(Bleed can peel apart layers and lead to this space)
Subdural space
53
Loose connective tissue adjacent to dura with struts (trabeculae) extending down to the pia mater - in the meninges
Arachnoid matter
54
A space between arachnoid and pia mater containing CSF and cerebral vasculature in the meninges
Subarachnoid space
55
Thin, delicate connective tissue of the meninges overlying the gray matter
Pia mater
56
The spinal cord is organized as ____________ white matter (axonal tracts) and __________ gray matter (neuron cell bodies)
peripheral white matter
| inner gray matter
57
Part of PNS that has afferent sensory neurons and efferent motor neurons
Somatic
58
Dense irregular connective tissue (often with large blood vessels and adipose tissue) that ensheaths a nerve bundle which contains multiple nerve fascicles
Epineurium
59
2-4 layers of cells (epithelioid myofibroblasts) that have contractile properties (myoid) and occluding junctions establishing a blood-nerve diffusion barrier (epithelioid)
Also surrounds vessels
Wraps around fascicles
Perineurium
60
Bundle
Fascicle
61
Basal lamina and delicate collagen fibrils associated with axons, Schwann cells, and endoneurial fibroblasts
(collagen type 1)
Endoneurium
62
How can you distinguish nerves in a tissue section from similar, wavy structures?
Contain more cells (Schwann, etc.) compared to connective tissue (not many cells in connective tissue)
More striped compared to smooth muscle due to extraction of lipids (i.e. myelin)
Ensheathed by perineurium
Nerves undulate in and out of the section, so some Schwann cell nuclei are seen in longitudinal section and others are in cross section
63
3 subdivisions of the autonomic system
Sympathetic, parasympathetic, enteric
64
Portion of the PNS that conducts efferent nerve impulses to smooth muscle, cardiac muscle, and glandular epithelium
Autonomic Nervous System (ANS)
65
_____________ motor neurons project directly to their target
Somatic
66
___________ motor neurons project to a 2nd (postsynaptic) motor neuron in a peripheral ganglion
Autonomic
67
For autonomic neurons, the NT at the first synapse (between pre and post-ganglia) is ___________
Acetylcholine
68
For autonomic neurons, the NT at the target organ depends on the system. For sympathetic the NT is _________.
Norepinephrine
69
For autonomic neurons, the NT at the target organ depends on the system. For parasympathetic the NT is _________.
Acetylcholine or nitrous oxide
70
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Features of the __________ division of ANS include:
craniosacral outflow
2nd neuron in organ wall
rest and digest
primarily cholinergic
```
Parasympathetic
71
Features of the ___________ division of the ANS include:
thoracolumbar outflow
2nd neuron located in para- or pre-veterbral ganglia
fight or flight
primarily noradrenergic
sympathetic
72
Autonomic motor neurons in peripheral ganglia are ____________ and supported by satellite cells
multipolar
73
______________ ganglia have multipolar neurons, eccentric nucleus, irregular capsule of satellite cells, disorganized fibers.
Autonomic
74
_______________ ganglia have pseudo unipolar neurons, central nucleus, regular capsule of satellite cells, bundled fibers.
Sensory (dorsal root)
75
Sensory (dorsal root) ganglia have ___________ neurons
unipolar
76
Autonomic ganglia have __________ neurons
multipolar
77
The ________ nervous system has more than 10^8 neurons in the gut wall, is semi-independent, and autonomously manages peristalsis, absorption, and secretion of fluids and enzymes
enteric
78
The __________ innervates the gastrointestinal tract, pancreas, and gall bladder
enteric nervous system
79
Enteric neurons are arranged in two interconnected plexus:
Submucous (Meissner's): within submucosa
| Myenteric (Auerbach's): between circular and longitudinal layers of muscularis [externa]
80
The enteric nervous system is regulated by:
both sympathetic and parasympathetic systems
81
The sympathetic and parasympathetic system provide which two things for the enteric nervous system?
1. second level of control of motility and secretion
| 2. Over-ride intrinsic enteric activity in times of emergency or stress
82
Cell bodies of sensory neurons reside in:
dorsal root ganglia
83
Nerve injury is followed by chromatolysis, retrograde and anterograde degeneration, and ____________ medicated removal of fiber.
macrophage
84
During nerve injury and regeneration in the PNS, the regenerating _____ sends off multiple sprouts (arrowheads)
axon
85
____________ proliferate to set up columns (bands of Bunger) along which the regenerating axon can migrate to reach its target
Schwann cells
86
_____ axons do not readily regenerate
CNS
87
Why do spinal cord injuries often lead to permanent paralysis?
Myelin doesn't break down as much in CNS
| Glial scars form, where astrocytes are inhibitory
