Structure and Function of Nervous Tissue Flashcards
the human nervous system consists of 2 anatomically separate but functionally interdependent divisions called the ________ and the ________
central nervous system, peripheral nervous system
the central nervous system includes the ______ and ______
spinal cord, brain
the peripheral nervous system contains ______ elements that conduct information into the ________ and ______ elements that conduct signals from the central nervous system to _______
sensory, central nervous system, motor, effector cells
the type of morphology that is most common for neurons is the ______
multipolar
the ______ neuron is found in olfactory systems or used for vision
bipolar
the ________ neuron is found in sensory ganglia of cranial and spinal nerves
pseudounipolar
all neurons have the same general functional specialization to rapidly and precisely receive
and transmit ______ from one cell to another where the _______ receive information and _____ transmit information.
information, dendrites, axons
each neuron of the body has a single axon that divides, extending one branch/projection into
_________ to receive sensory information while the other branch extends into ______ to transmit that information into spinal cord or brain
peripheral tissue, central nervous system
the presynaptic terminal of a neuron houses the _______ waiting for release
neurotransmitters
the postsynaptic contacts contains the ______
neurotransmitter receptors
presynaptic terminals are characterized by presence of numerous vesicles containing ________ and contain _______ to provide ATP
neurotransmitters, mitochondria
the postsynaptic contacts consisting of clustered neurotransmitter ______ and their associated proteins
receptors
Neurons communicate via ______
synapses
Glutamate is the major _______ neurotransmitter in the central nervous system and activation of its glutamatergic synapses makes a neuron ______ likely to fire a signal
excitatory, more
GABA is the major _______ neurotransmitter in the central nervous system and activation of its GABAergic synapses makes a neuron _____ likely to fire a signal
inhibitory, less
the 4 steps of neurotransmitter vesicle based transport include budding, diffusion or motor driven movement, ______ and _______
tethering, fusion
fusion of a vesicle involves recognition of _______ and _______ proteins, which interlock and force the donor and acceptor membranes together and trans-membrane receptors are thus delivered to the target membrane, and cargoes released into ______
v-SNARE, t-SNARE, synaptic cleft
SNARE-dependent fusion of synaptic vesicles and neurotransmitter release is highly _________ dependent
calcium
during synaptic vesicle transmission once the v-SNAREs and t-SNAREs connect, ca2+ enters and binds to ca2+ binding sites on ______ in the SNARE bundle allowing for the pores to open and neurotransmitters to be ______
v-SNAREs, released
________ from clostridium botulinum and clostridium tetani bacteria cleave synaptic vesicle SNAREs
Neurotoxins
Fusion of neurotransmitter vesicles is triggered when voltage-gated calcium channels in the presynaptic terminal ______, triggering rapid calcium influx.
open
dendritic spines are sites of post-synaptic ______
input
Communication in the nervous system exploits a
property common to all cells, namely using
________ and _______ to actively distribute ions non-uniformly across the membrane resulting in a _______ existing across the membrane
pumps, channels, voltage potential
The axon initial segment is highly enriched in
voltage-gated ______ channels that open when
membrane voltage goes ______ a threshold value
Na+, above
at the axon body, graded voltage change spreads passively and ______ with distance from site of input and integration results from summation of multiple _____
declines, inputs
an action potential is an all-or-none response that propagates to the end of the axon and is triggered when membrane potential reaches a _______ value.
critical (‘threshold’) (-55)
If the excitatory inputs ‘win’, membrane potential rises above a _______ which triggers opening of voltage-gated _______ channels at the axon initial segment, resulting in a large influx of ______ ions which is the first step of the action potential
threshold value, sodium, positive
Neurofilaments are a type of neuron-
specific _______ filaments
intermediate
Neurons have large amounts of “Nissl material”, which can be detected by _______ dyes that bind acidic components due to the major “Nissl material” being ______
basic, RNA
axon initial segment can only be identified with more specialized methods, but contains high levels of _____ and _____ channels and is more likely where action potential is _______, but initiation site may vary from neuron to neuron
Na+, K+, first generated
Many axonal proteins are synthesized in the neuron ______
cell body
Proteins are delivered to the axon by _______
axonal transport
Axonal transport is an energy dependent process that supplies axons with the ______ required for their structure and function and the integrity of the axon is absolutely dependent on ______
proteins, axonal transport
anterograde is a type of axonal transport from _______ to _____
cell body, axon tip
retrograde is a type of axonal transport from _____ to _____
axon tip, cell body
Anterograde transport is controlled by ________ proteins and retrograde transport is controlled by ______ motor proteins and both types of motor protein carry cargoes along _______ motor proteins.
kinesin, dynein, microtubules
Mutations in tubulins, dynein/dynactin, kinesins and specific cargo proteins can all cause inherited motor and sensory _______ due to deficits in axonal transport which causes progression of _______, ________, ________, and ______
neuropathies, Diabetes, Chemotherapy-induced neuropathy, Huntington Disease, Alzheimer’s Disease
Nissl material is far less detectable in dendrites and (especially) axons due to proteins mainly being made in the _______ and trafficked to distal locations
neuronal cell body
Rabies Virus, using axonal transport machinery, is carried in saliva of infected animal enters tissue after bite, travels up nerves via _______ axonal transport, enters spinal cord and travels to ______, and the virus then disseminates to _______ sites
retrograde, brain, extra-CNS
Herpes Simplex Virus (HSV) target other cells initially but use similar transport routes to rabies to enter and leave the _______
nervous system
glial cells are found in the _______ and _______
central nervous system, peripheral nervous system
the peripheral nervous system includes _______ cells that support cell bodies and _______ cells that secrete neurotropic factors and form _______ sheaths
satellite, schwann, myelin
the central nervous system contains ________, ________, _______ and ________ cells
oligodendrocytes, astrocytes, microglia, ependymal
oligodendrocytes form ______ sheaths in the CNS
myelin
astrocytes of the CNS support the CNS, help form the ________, regulate cerebral ________, secrete _______ factors and take up _____ and ________
blood brain barrier, blood flow, neurotropic, K+, neurotransmitters
microglia are modified _______ cells that act as scavengers
immune
ependymal cells of the CNS create ______ between compartments
barriers
in the PNS, individual ______ cells myelinate a single segment of a single axon
Schwann
70-75% of the dry weight of myelin sheaths is _______ and _______ which play a role in extrusion of cytoplasm which helps with myelin _______ and as well as _______ properties of adjacent membrane layers
lipids, proteins, compaction, adhesive
Myelination makes action potential conduction ______. because the insulating myelin increases membrane _______, so membrane depolarization can propagate further along the axon without needing the time-consuming process of action potential generation.
faster, resistance
the entire axon cannot be myelinated because there is a limit on how much _________ myelin can provide while still allowing space for enough axons, and axial resistance is not zero, so any membrane potential change will still _______ over distance within the axon
insulation (membrane resistance), decay
_______ channels are clustered at gaps in the myelin (Nodes of Ranvier) to re-boost the action potential.
sodium
Myelination also makes action potential propagation more ______ because the energy-dependent process of action potential generation is only needed at nodes and this is known as ______ conduction
efficient, saltatory
CNS axons are myelinated by ________, which extend multiple processes and a single ________ can myelinate multiple axon segments on multiple separate axons
oligodendrocytes, oligodendrocyte
Multiple Sclerosis is a _________ disease where patients have increase in __________ in Cerebrospinal Fluid and abnormal _______ function
CNS demyelinating, antibodies, T cell
Guillain-Barré syndrome is a
________ disease
PNS autoimmune demyelinating
adrenoleukodystrophy is an ________ disease, caused by failure to generate ________ which are one of the key lipids that makes up the myelin sheath
inherited demyelination, plasmalogens
inherited myelination diseases can cause problems with _______ myelination, _________, _________, or a combination of these
delayed, dysmyelination, demyelination
Central Pontine Myelinolysis is a metabolic demyelination disease caused by _______ in the central pons, occurs after rapid correction of ________ caused by alcoholism and/or malnutrition
demyelination, hyponatremia
Progressive Multifocal Encephalopathy is caused by a viral infection of ________ in patients with immunodeficiency
oligodendrocytes
astrocytes function in neurovascular coupling linked to the _______, regulation of intercellular ________ in brain, metabolic cooperation with _______ and regulation of _______ blood flow
blood brain barrier, fluid composition, neurons, cerebral
the blood brain barrier helps determine the composition of brain ________ by restricting ionic and fluid _______ between blood and brain and protects the brain from _________ in ionic composition that can occur after a meal or exercise where such fluctuations would disturb synaptic and axonal ______
interstitial fluid , movements, fluctuations, signaling
the cells involved in blood brain barrier formation and maintenance include _______, capillary _______ cells as well as the ______ and _______
astrocytes, endothelial, basal lamina, tight junctions
astrocytes provide neurons with _______ and _____
neurotransmitters, energy
Astrocytes mobilize ______ to produce lactate then neurons take up the lactate and convert it to pyruvate in order to generate energy via the TCA cycle which allows glucose to be used for other metabolic pathways and/or can protect neurons from _______
glycogen, low glucose
Astrocytes express _______ transporters, which take up excess ________ from the synaptic cleft and recycle it by converting it to ________
glutamate, glutamate, glutamine
microglia are immune cell in the CNS that are embryonically-derived, self-renewing tissue _______
macrophage
microglia are activated by physical injury and local inflammation and infection changes microglial morphology from
_______ to ______
ramified, amoeboid
Microglial have both beneficial and harmful effects in disease because they aid clearance of ______ tissue, but also secrete _______ that can exacerbate inflammation
damaged, cytokines
ependymal cells line the ventricles of the _______ and the ________ of the spinal cord and the ventricular system is involved in production and circulation of ________, which acts as a buffer and cushion for the brain and spinal cord
brain, central canal, Cerebrospinal
Fluid (CSF)
Ependymal cells form a simple cuboidal-to-columnar epithelium between the ______ and the ________ of the CNS and they have microvilli and cilia on their apical
surface.
CSF, Interstitial fluid (ISF)
The ISF-CSF barrier is distinct from, and much looser than, the ________
Blood Brain Barrier
the white matter of the spinal cord are bundles of _______ axons that contain ______
myelinated, oligodendrocytes
the grey matter of the spinal cord contain collections of ________ plus a large amount of _______
neuron cell bodies, astrocytes
the spinal ganglion or _______ contain cell bodies of ______ neurons, whose axons project into the ______ via dorsal root
dorsal root ganglion, sensory, spinal cord
the ventral root contains projections of ______ axons from spinal cord to innervate ______ and ________ cell bodies are in ventral part of spinal cord gray matter
motor, muscle, motor neuron
thee peripheral nervous system includes all neuronal elements outside the _______ and _______ where neuron cell bodies are
clustered together in ______ and axons generally exist in bundles termed nerves
brain, spinal cord, ganglia
_______ surround nerve cell bodies and provide trophic support to neurons in the peripheral nervous system
Satellite Cells
the ______ surrounds individual nerve fibers, the _______ encloses each fascicle and consists of concentric layers of connective tissue and the _______ encloses the entire nerve
endoneurium, perineurium, epineurium
the perineurium of peripheral nerves are a tubular sheath, composed of specialized concentrically oriented layers of flattened ______ cells, surrounded by continuous ________ and makes up the ________ barrier
perineurial, basement membrane (basal lamina), blood-nerve
the endoneurium of a peripheral nerve is made of ______
connective tissue
the epineurium of a peripheral nerve is made of _________ tissue, often also containing _______ tissue, that surrounds the nerve and also fills spaces between the nerve _______
dense irregular connective, adipose, fascicles
Peripheral nerves consist of neuronal axons, and cell bodies of these neurons are located in the spinal cord for _______ neurons or in ganglia near the spinal cord for _______ neurons
motor, sensory
the peripheral nervous system can regenerate after _______
injury
2-3 days after a nerve is injured ______ of the distal axon is triggered by impaired transport of axon survival factors past the injury site.
Wallerian
degeneration
around the same time as wallerian degeneration, the _______ barrier breaks down and allows influx of ______, which cooperate with ______ cells to digest myelin
blood-nerve, macrophages, Schwann
around 3 weeks after injury to a nerve _______ dedifferentiate, then proliferate and line up with remaining _________ which forms tubes called bands of _______ that guide regenerating axons
schwann cells, basement membrane, Bungner
3 months after injury to a nerve regenerating axon finally reaches target and re-establishes _______
synaptic
connection
In a PNS injury, myelin debris is rapidly _____ as macrophages enter and Schwann cells dedifferentiate. The damaged axon can usually regrow and reinnervate its target
cleared
In a CNS injury, myelin clearance is far less efficient and damaged oligodendrocytes often ______ due to limited ______ infiltration.The uncleared myelin debris contributes to the failure to _______, although the key factor is likely the poor _______ of adult CNS neurons
die, macrophage, regenerate, intrinsic growth capacity
The hippocampus, a brain region critical for ______ and ______, is readily seen by Nissl staining
learning, memory
Like spinal cord, brain can be subdivided into gray matter with neuronal cell bodies plus _______ and white matter with axons, usually myelinated, plus _______
astrocytes, oligodendrocytes
