Nervous Tissue Flashcards
What gives rise to neuroblasts
Neuroepithelial cells form embryonic neuroectoderm
Neuroblasts give rise to what
neurons of the central nervous system (brain and spinal cord)
Neural crest cells are derived from what and give rise to what
Neuroectoderm and give rise ot neurons and neuroglial cells of the PNS
The neural tube has what kind of epithelium
Pseudostratified epithelium
The Neural tube is composed of pseudostratified epithelium that composed of what zones
Ventricular zone
Intermediate zone
The ventricular zone of the neural tube is made up of
Ventricular cells
The intermediate zone of the neural tube is what
area of destruction of excess neurons via apoptosis
What is the cortical plate (mantle layer)
area around the neural tube
composed of postmitotic neurons
Future gray matter (cell bodies, dendrites and unmyelinated axons)
What is the marginal layer
Area outside of the mantle layer
contains axons
future white matter (mylinated axons)
The ventricular zone gives rise to what
ependymoblasts, immature neurons, and glioblasts
Ependymoblasts develop into what
choroid plexus and ependymal cells and remain associated with the lumen fo the neural tube
Glioblasts migrate to the what and give rise to what
cortical plate (mantle layer) and give rise to astrocytes and oligodendrocytes
what are non-neuronal cells typically derived from embyronic neural crest tissue (expect microglia)
Glial cells
where does myelinization occur
In the cortical plate
Nerve tissues have irritability what does that mean
Specialized to receive stimuli
Nerve Tissue has conductibility what does that mean
Specialized to transmit impulses
Nonconductive cells that support and protect the neurons
neuroglial cells
Fundamental structural and functional unit of the nervous system
Neurons
What conducts impulses
Neurons
What are the two cellular components of nerve tissue
Neurons and neuroglial cells
What are the 3 parts of a neuron
Cell body (soma)
Dendrites
Axon
What part of a neuron houses the nucleus
The cell body
Nissl bodies (substance) of the cell body consists of what
RER and free ribosomes
The cell body has an extensive ____ visible with light microscopy and elaborate ___ strucutes
RER, Golgi
The cell body of neurons has abundant ____ and _______
Microtubules (neurotubules) and intermediate filaments (neurofilaments)
does the cell body of a neuron have abundant mitochondria
Yes
what are formed from lysomes and accumulate with age of the nueron
Lipofucsin
Cell bodies are associated with ______ and local potentials
Ligand gated channels
The cell bodies of neurons have what kind of channels
Ligand gated
The Nissl substance of the dendrites contains what
mitochondria and other cytoplasmic components as the cell body except the Golgi body
Dendrites may be studded with what
Dendritic spines
The dendrites tend to taper _____ and may branch
Distally
Dendrites are associated with what kind of channels
ligand gated channels
Dendrites have ligand gated channels and thus have what kind of potentials
local potentials
What is the site of origin of the axon
axon hillock
The axon hillock is devoid of what
Nissl substance
The axon hillock is associated with what
AP generation
The axon is associated with what kind of channels and potentials
voltage gated cation channels and action potentials
Axons contain _____ and _____
mitochondria and microtubules
Axons lack what three things
RER, ribosomes, and golgi apparatus
Axons have constant ____ throughout their length
Diameter
The axon terminates in branching
telodendrites
Telodenrites contain _____ and ____
synaptic vesicles and related proteins
Telodenrites form the ______
presynaptic membranes
what form the presynaptic membranes
telodendrites
Axons may be enclosed within a
mylein sheath
What is the purpose of dendritic spines
further increase surface area
Neurons can be according to
function, number of processes, length of axon
What are the 3 types of neurons by function
Sensory (afferent) neurons
Motor (efferent) neurons
Interneurons
Sensory (afferent) neurons function
Transmit sensory impulses from sensory receptors to CNS
What is the function of motor (efferent) neurons
Transmit impulses from CNS to a muscle or gland
Somatic motor neurons innervate what
skeletal muscles
Autonomic motor neurons innervate
glands, cardiac and smooth muscle
The autonomic motor neurons are divided into
parasympathetic and sympathetic neurons
Interneurons function
Transmit impulses within CNS and between sensory and motor neurons
What are the three classifications of neurons according to number of processes
Multipolar neurons, bipolar, Pseudounipolar
What classification according to number of processes are the most common morphological type
Multipolar neurons
Multipolar axons characteristics
single axon and multiple dendrites
Structure of Bipolar neurons
Have two processes, one at each end of the spindle-shaped neuron
Bipolar neurons are round in association of what
special senses such as olfactory and visual
Structure of Pseudounipolar neurons
Have a single process from the cell body that bifurcates into a central and peripheral process
Where are Pseudounipolar neurons found
Found in ganglia alongside spinal cord (dorsal root ganglia)
What are the two types of neurons classified by length of axon
Golgi I and Golgi II
Structure of golgi I neurons
neurons with long axons which leave the grey matter of which they are part
Structure of golgi II neurons
Neurons with short axons which ramify through gray matter
What is a bundle of axons (fibers) in the PNS
Nerve
What is a bundle of axons (fibers) in the CNS
Tract
Aggregation of cell bodies and dendrites in the PNS
Ganglion
Aggregation of cell bodies and dendrites in the CNS
Nucleus
The epineurium covers what
the entire nerve
The epineurium is composed of what
Type I collagen and fibroblasts
The epineurium is supplied by what
Blood and lymphatic vessels
Is the epineurium a thick fibrous coat
Yes
The Perineurium is composed of
dense CT
What does the perineurium cover
Covers bundles of axons (fascicles) within the nerve
The epithelial-like fibroblasts on inner surface of the perineurium are joined by
tight junctions
- Zonulae occludens - Provide a permeability barrier - This layer has to rejoined in microsurgery for limb reattachment
What layer has to be rejoined in microsurgery for limb reattachment
Epithelial-like fibroblasts on inner surface are joined by tight junctions
Which layer makes up the blood nerve barrier
Perineurium
What is the blood nerve barrier
endothelial cells of vessels are also linked by tight junction
What is the endoneurium composed of
Type III collagen
The endoneurium is surrounds what
individual fibers and Schwann cells
Which layer of microarchitecture is thin layer of reticular CT around nerve fibers
Endoneurium
What are ways nerve membranes are specialized
Receptors, ion channels, Presynaptic membrane, Postsynaptic membrane,
Ligand-gated channels are located on
dendrites and cell bodies
Potassium channels are located on what part of neuron
Axon
Voltage-gated sodium channels are located on what part of a neuron
Axon
Voltage-gated calcium channels are located on what part of a neuron
Axon
Characteristics of presynaptic membrane
Synaptic vesicles, vesicular docking proteins and synapsin filaments, dense bodies, Mitochondria, voltage-gated calcium channels
Postsynaptic membrane characteristics
Receptors and ligand-gated ion channels
Anterograde direction
cell body toward distal end of axon
Anterograde utilizes what
Kinesin
Rates of transport for anterograde
slow (1-6mm per day), Intermediate (50-100mm per day), Fast (400mm per day)
Slow anterograde transport has how many systems and what are they called
Two, SCa and SCb
Slow transport is only used in what direction of transport
Anterograde
What uses SCa anterograde transport
preassembled microtubles and neurofilaments
What uses SCb anterograde transport
Enzymes, actin, clathrin
What uses intermediate anterograde transport
mitochondria and other membrane-bound organelles
What uses fast anterograde transport
Synaptic vesicles and neurotransmitters
Fast anterograde transport utilizes
Microtubule motors
Is it true the active velocity fro the three speeds of anterograde transport is the same but the slower ones stop more
yes
What is retrograde transport
from axon to cell body
Retrograde transport utilizes what
cytoplasmic dynein
What does retrograde transport carry
endocytosed material and recycled proteins
What is the rate of retrograde transport
100-300 mm/day
Viruses tend to use what type of transport
Retrograde
what are non-neuronal cells typically derived from embryonic neural crest tissue
Glial cells “glue cells” (except microglia)
Glial cells serve in various support function in the ___ and ___
PNS and expecially in the CNS
Are glial cells capable of cell division under appropriate conditions
Yes
what are the types of Glial Cells
Atrocytes, Oligodendrocytes, Schwann Cells, Microglial cells, Ependymal Cells
Astrocytes are derived from what
Neural crest (neuroepithelium)
Astroctyes are found in what system
CNS
Astrocytes have numerous ______ with expanded feet (______) that terminate on capillaries or the pia mater
Processes, pediceles
Where are fibrous astrocytes found
predominately in the white matter
Which astrocytes have long processes with few branches
Fibrous
Where are protoplasmic astroctyes found
predominantly in the gray matter
Which astrocytes have shorter processes with many short branches
Protoplasmic astrocytes
What are the functions of Astrocytes
- Regulate composition of intercellular environment or entry of substances into it
- Structural support
- Blood-brain barrier
- Development of cerebral cortex
- Potassium sink
- Secretion of neuron trophic factors
- Uptake/metabolism of neurotransmitters
- Help form noncollagenous scar tissue after injury to CNS
What is the major component and additional components of the blood brain barrier
Main- Tight junctions between endothelial cells
additional- the basal lamina of the endothelial cells
- The perivascular astrocyte end-feet (pediceles)
Oligodendrocytes are derived from what
Neural crest (neuroepithelium)
Oligodendrocytes are only found in the
CNS
What are the functions of the Oligodendrocytes
- Closely associated with neuron cell bodies in gray matter and function as satellite cells
- Surround axons of unmyelinated fibers in gray matter
- Myelinate axons in the CNS
Each oligodendrocyte myelinates
several axons in the CNS
What are Schwann cells derived from
Neural crest (neuroepithelium)
What are the functions of Schwann cells
Myelinate axons in the PNS
Each Schwann cell mylinates
a section of a single axon in the PNS
Microglial cells are derived from what
macrophage precursors (bone marrow)
What are Microglial cell functions
Phagocytic in the PNS
Recruit leukocytes across the blood-brain barrier
Modulate initiate and progression of immune response along with astrocytes
Microglia-mediated neurotoxicity takes place when _______ bind to PRRs and tigger an excessive immune response
Pathogen-associated molecular patterns (PAMPs)
What is the massive microglial response to tissue damage that can be repetitive or destructive
Microgliosis
What are pattern recognition receptors (PRRs) responsible for
are responsible for phagocytic functions
(identification of pathogens , production of pathogens, and production of extracellular superoxide, release of pro-inflammatory factors and removal of toxic substances by phagocytosis
What are some examples of the ligands that can be recognized by several PRRs
amyloid-beta peptide (alzheimer’s disease), alpha- synuclein (Parkinson’s disease), and Human immunodeficiency virus (HIV)
What are the histoligical characteristics of Ependymal Cells
Ciliated Cuboidal Cells
What are the ependymal cells derived from
from Neuroepithelium
Where are ependymal cells found
In the ventricular system of the CNS and in the Choroid plexus
What are the functions of the ependymal cells
Function in Transport and in the choroid plexus they may be principle cell type that secrete cerebrospinal fluid
Satellite cells are derived from what
The neural crest
Where are satellite cells found
form moons (crescents) around cell bodies in ganglia
What is the function of Satellite cells
Insulators
The choroid epithelium is formed by _____ linked by _____ with apical ______
Cuboidal cells, tight junctions, microvilli
The choroidal epithelial cells produce what
CSF
What is ependymal epithelium linked by ______ with apitcal _____ and _____
belt desmosomes, microvilli and cilia
What are tanycytes
specialized ependymal cells found in the third ventricle, have basal processes extending through the astrocytic processes layer to form end-feet on blood vessels.
Tanycytes are linked to each other and to ependymal cells by what
tight junctions
What wraps around the axon in the PNS
Schwann cell plasma membrane
The Schwann cell cytoplasm is “squeezed” out, leaving behind ______ layers of membrane in PNS myelination
concentric
What is the intraperiod line
Electron-dense line created by extracellular space between adjacent outer leaflets during PNS mylenation
What are the internal and external mesaxon in the PNS mylenation
outer and innermost points of fusion between the outer leaflets (extracellular leaflets)
What is a transmembrane protein that forms homodimers
Major Protein Zero
Major Protein Zero is only found in the
PNS
Homodimers form ______ with the opposing outer leaflets
Homotetramers
The cytoplasmic domains in the intraperiod line may have ______ functions
signaling
Charcot-Marie-Tooth disease is related to what part of PNS
Mutations of Major Protein Zero which is part of the intraperiod line
What is major protein zero replaced by in the CNS
Proteolipid protein, which has four homophobic domiains
Mutations in proteolipids lead to what disease
Pelizaeus-Merzbacher disease
What is Charcot-Marie Tooth Disease
Demyelinating disorder of the PNS characterized by the progressive loss of both motor and sensory functions of the distal legs, Type 1B and Type 2 are caused by mutations in myelin protein zero (MPZ)/major protein zero
What is the major dense line
Electron-dense line created by cytoplasmic space remnant between adjacent innner leaflets during mylenation
What is an abundant protein associated with the inner leaflets in both the PNS and CNS
Myelin Basic Protein
What is the function of myelin basic protein
May function to stabilize lipids in the leaflets
Many forms of myelin basic protein are created by what
splicing of single gene
What are schmidt-lanterman clefts (incisures)
residual areas of cytoplam within the major dense lines
In the PNS a single axon is embedded in a
Schwann cell
oligodendrocytes are derived from what
glioblasts
The cell body of the _________ is not closely associated with the myelin sheath as the body of a _______
Oligodendrocyte, Schwann Cell
Each ______ provides myelin sheath to several axons
Oligodendrocyte
Each _____ forms a myelin sheath around a single axon
Schwann cell
There is no _____ associated with the myelin sheath in the CNS
Basal Lamina
Which of the nervous system do not have basal lamina associated with their myelin sheath
CNS
Myelinated axons in the CNS lack a supporting _______, as do nerves in the PNS
CT
The inner and outer layers of myelin end in separate loops near the node of Ranvier and no cytoplasm of the _______ is trapped. In _______ cells, the cytoplasm is retained
Oligodendrocytes, Schwann cells
In the CNS, the surface of the node is contacted by _____ . In the PNS, the node is covered by _______
Astrocyte process, Schwann cell process
The cytoplasmic process of adjacent oligodenrocytes do not _______. The space is occupied by an ______
interdigitate, astrocytic end-foot process
Cytoplasmic process of adjacent Schwann cell in the PNS ______ at the node region
interdigitate
Apposed membranes of myelinating Schwann Cells are linked by _____
autotypic junctions
Why are Autotypic junctions named autotypic
because they are found between membranes of the same cells
______ are seen between the axoleema surrounding the axon and the cytoplasmic loops adjacent to the nod of Ranvier (paranoidal loops) in PNS
Heterotypic tight junctions
What are observed between interdigitating cell processes of adjacent Schwann cells and the incisors of Schmidt-Lanterman
Autotypic tight junctions
_____ is concentrated in the paranoidal region and the incisors of Schmidt-Lanterman
Connexin 32
Connexin 32 (Cx32) is expressed in
Schwann Cells
Mutations in Cx32 gene determine the demyelinating X-linked _______
Charcot-Marie-Tooth Disease
Myelin Protein zero (MPZ) is synthesized by
Schwann Cells
Myelin protein zero (MPZ) interact with each other (_____) to stabilize apposed plasma membranes as )_______
homodimers, homotetramers
The intracellular tail of MPZ has what
Signaling factors
IN the CNS the hemophiliac interaction of plasma membrane-associated ______ stabilizes adjacent stacks of membranes of oligodendrocytes
Proteolipid protein (PLP)
Proteolipid protein (PLP) has a ______ with short and long extracellular loops and two intracellular tails
Tetraspanin structure
Myelin basic protein is common in
both the PNS and CNS
The structure of Proteolipid protein (PLP)
tetraspanin structure, Two extracellular loops and four transmembrane domains with the N-termininal and the C-Terminal being intracellular tails
What are the microscopic features of Multiple Sclerosis
Infiltration of inflammatory cells (T cells and Macrophages) inside and around multiple sclerosis plaques; and plaques of astrocytic aggregates
What are four components of the presynaptic membrane
Voltage-gated calcium channels, SNAPs bind synaptic vesicles to presynaptic membrane, Vesicle docking proteins, Synapsins
What are synapsins
filaments in the presynaptic membrane
What are SNAP receptors found in presynaptic and synaptic vesicular membranes
Vesicle docking proteins
Fusion of presynaptic vesicles is mediated by what two interacting cytosolic proteins
NSF (N-ethylmaleimide-sensitive fusion) and SNAPs (for soluble NSF attachment proteins)
SNAPs and NSF are recruited by ____ to induce fusion of vesicle and target membrane
SNAREs
What are the components of postsynaptic membrane responsible for the synapse
Neurotransmitter receptors
Neuronal chemical messengers ___________ are stored in synaptic vesicles and transported to the synaptic terminal by anterograde transport
Acetylcholine, glutamate, y-aminobutyric acid (GABA) and others
Anterograde transport is mediated by
Kinesin
once neurotransmitters are taken up by the post synaptic membrane they are degraded by the
Mitochondrial enzyme monamine oxidase (MAO)
What are the 6 types of synapses
Axosomatic Axoaxonic axodendritic axospinous excitatory inhibitory
Axon terminal synapses with the neuron cell body
Axosomatic
Axon terminal synapses with another axon terminal
Axoaxonic
Axon terminal synapses with a dendrite
Axodendritic
Axon terminal synapses with a dendritic spine
Axospinous
More positive end-plate potential (closer to threshold)
Excitatory
More negative end-plate potential (farther form threshold)
Inhibitory
The dendritic shaft contains _______. in contrast the dendritic spine cytoskeleton consists of ______ associated with the postsynaptic density
microtubules, actin filaments
Nuerotransmitter receptors and ion channels are localized in the
postsynaptic density
Tough thick sheet of dense fibrous CT
Dura Mater
In the cranial cavity it lines the inside of the cranial vault bone and serves as the periosteum
Dura Mater
Around the spinal cord, ______ forms a CT tube that is separated from the bone of the vertebral foramina by a space referred to as the epidural space
Dura Mater
Within the dura mater are large, endothelial-lined _______ that receive blood from the cerebral drainage as well as cerebrospinal fluid via the arachnoid villi
Venous Sinuses
Venous sinus receive blood from
cerebral drainage as well as cerebrospinal fluid via the arachnoid villi
a layer of _____ cells separate the dura mater form the subdural space
dural border cells
menix composed of delicate connective tissue
Arachnoid
What does menix mean
Singular form of meninges
The outer layer of the arachnoid faces the ______ and is made up of a single layer of ________
subdural space, arachnoid barrier cells
The arachnoid is attached to the underlying ____ by delicatee strands of CT called what
pia mater, arachnoid trabeculae
The spaces between the arachnoid and the pia mater are collectively referred to as the ______
Subarachnoid space
What fills the subarachnoid space
CSF
Arachnoid villi are mad up of what
arachnoid barrier cells
Arachnoid villi extend from
the outer suface of the arachnoid into the overlying venous sinuses of the dura mater and allow cerebrospinal fluid to flow form the subarachnoid space into the dural sinuses
What is the purpose of the arachnoid villi
They allow cerebrospinal fluid to flow form the subarachnoid space into the dural sinuses
What is a thin, delicate sheet of CT that lies directly on the surfaces of the brain and Spinal cord
Pia mater
Does pia mater follow the contours of the brain and dip into the sulci, lining them as well
Yes
Pia mater is _____ with the perivascular CT of the cerebral and spinal cord blood vessels
continuous
_____ is very tightly attached to the nervous tissue of the brain and spinal cord and cannot be removed without damaging the nervous tissue
Pia mater
what are runnels covered with pia mater
perivascular spaces
A blockage of the movement of CSF results in its accumulation in the ventricles and around the brain, a condition known as
hydrocephalus
what is a highly infolded simple cuboidal epithelium that extends into the ventricles form the roof plate
choroid plexus
Cuboidal cells of the choroid plexus are linked by _______ which form part of the CSF barrier
tight junctions
Apical microvilli and infolding of basal membranes with abundant mitochondria in the choroid plexus are indicative of what
Active transport
Capillaries to the choroid plexus are formed form endothelial cells that are ______
fenestrated
___, ___,___ pumps in the apical membranes of the choroid plexus cells pump fluid into the ventricular lumen causing a flow of water, solutes, and proteins from the capillaries through the choroid plexus epithelium into the ventricles
Na+, K+, ATPase
What is the simple cuboidal epithelium that lines the ventricles of the brain
Ependymal epithelium
Ependymal epithelium is linked by _____ and have ____, _____,and ____
Zonula adherens, microvilli, cilia, and abundant microvilli
What links ependymal cells
Zonula adherens
The basal domains of ependymal cells are in contact with the ______, forming the glia limitans, which is part of the blood-brain barrier
astrocytic processes
Astrocytes send processes to the surrounding ______ which is part of the blood-brain barrier
non-fenestrated
what in the third ventricle are tightly linked to the adjacent ependymal cells and send processes through the glia limitans to form end-processes on underlying blood vessels
Tanycytes
clusters of _____ neurons lie within the capsule of the dorsal root ganglia
pseudounipolar neurons
Are postganglionic axons form the dorsal root ganglia mylenated
yes
The dorsal root ganglia is surrounded by a capsule of CT called
epineurium
What are satellite cells derived from
The Neural crest
Satellite cells form a single layer around
The cell body of each neuron in the of the dorsal root ganglia
the surfaces of satellite cells facing away form neurons are in contact with
a basal lamina
Autonomic ganglia are encapsulated by the
epineurium
Autonomic ganglia have clustered _____ neurons
multipolar
clustered multipolar neurons of the autonomic nervous system receive input from
mylinated preganglionic neurons
The postganglionic axons of the autonomic nervous system are
not mylinated
Does the ANS have satellite cells around every neuron
Yes but less numerous than those in the dorsal root ganglia
