Lecture 3: Cells of the Nervous System Flashcards
Neurons are the _ of the nervous system
main signalling units
Neuron:
from Greek, “sinew”,
“tendon”, “nerve”.
Neuron: the term was introduced by:
German anatomist
Heinrich Waldeyer in 1891.Previously, Camillo Golgi had used
the term “nerve cell”
Human brain: total number of neurons is estimated at
approximately
86 billion neurons (in humans)
Most neurons are concentrated in the
cerebral cortex and
cerebellum
Spinal Cord: contains about
197–222 million neurons (in
humans).
Neuron counts in the Peripheral Nervous System:
SOMATIC , including sensory neurons (afferent) and motor neurons
(efferent):
UNKNOWN
Neuron counts in the Peripheral Nervous System: AUTONOMIC: comprising sympathetic, parasympathetic, and enteric
divisions:
UNKNOWN
Neuron counts in the Peripheral Nervous System: ENTERIC
contains about 168 million neurons (in humans).
In the enteric nervous system (autonomic subdivision of the peripheral nervous system), neurons are clustered in:
The MYENTERIC (Auerbach’s) PLEXUS and SUBMUCOSAL (Meissner’s) PLEXUS of the gastrointestinal tracts
Most neurons in the vertebrate nervous system have
several
main features in common.
The cell body contains
the nucleus,
the storehouse of genetic information, and gives rise to two
types of cell processes, axons and dendrites.
transmitting element of neurons
Axons
Axons, the
transmitting element of neurons, can vary greatly in
length
Some axons can extend more than __ in the body
3m
Most axons in the
central nervous system are
very thin (between 0.2 and 20 µm in
diameter) compared with the diameter of the cell body (50 µm
or more)
Many axons are insulated by
a fatty sheath of myelin
that is interrupted at regular intervals by the nodes of Ranvier.
The action potential is the cell’s ___ signal
conducting
The action potential, the cell’s conducting signal, is initiated
either at
the axon hillock, the initial segment of the axon, or in
some cases slightly farther down the axon at the first node of
Ranvier.
Branches of the axon of one neuron (the presynaptic
neuron) transmit signals to another neuron (the postsynaptic
cell) at a site called:
the synapse
The branches of a single axon
may form synapses with as many as
1000 other neurons
the axon is the __ of the neuron
the output element of the neuron
dendrites (apical and basal) are the __ of the neuron
input elements of the neuron.
Together with the cell body, the dendrites receive
synaptic contacts from
other neurons
synapse:
signals called action potentials pass from an axon to a dendrite through junctions called synapses
A signal can have over 100000
dendrites :
signals come in through dendrites
These vast, tree-like branches grow up and out from the soma
Dendrites are thicker than axons and covered in synapses
Soma:
A cell’s body, home of the nucleus.
If you stretched out all the DNA in just one of your cells, it would be at least 6 feet long
Axon:
Signals go out through axons, which branch many times and stretch vast distances.
Neurons send action potentials down their axons and through synapses they’ve formed to communicate with other cells.
The longest axons in your body reach from your toes to your spine
Spinous neurons are characterized by the presence of:
Numerous dendritic spines on their dendrites (aspinous neurons lack these spines)
aspinous neurons lack
dendritic spines on their dendrites
Most excitatory synapses in the brain form on __
dendritic spines
Most excitatory synapses in the brain form on dendritic spines, meaning:
spinous neurons generally
receive a larger number of excitatory inputs
compared to aspinous neurons.
- Due to their spine structure, spinous neurons are
often associated with
greater synaptic plasticity,
allowing for more dynamic changes in neural
connections based on experience.
Due to their spine structure, spinous neurons are
often associated with greater synaptic plasticity,
allowing for
more dynamic changes in neural
connections based on experience.
Example neuron types:
Spinous:
Pyramidal neurons in the cerebral cortex
are a prominent example of spinous neurons
Example neuron types: Aspinous:
Some types of interneurons in the brain,
like certain stellate cells, are considered aspinous or
sparsely spinous.
Unipolar neurons, often referred to as
‘true’ unipolar neurons
Unipolar neurons, often referred to as ‘true’ unipolar neurons, feature:
a single process extending from the cell
body (soma), which then branches into dendrites or an axon.
In the context of human neurophysiology, the
term “unipolar” is sometimes mistakenly used in place of
pseudounipolar.
True unipolar neurons have
traditionally been considered as
absent in the mature vertebrate nervous system (specific developmental stages
may display neurons with only one process)
Unipolar neurons are predominantly observed in
invertebrates, where they
form a prevalent neuronal population
Bipolar neurons bear :
an oval shaped cell body possessing two processes: one axon and one process functioning
as a distant dendrite
In humans, bipolar neurons serve as
sensory neurons
In humans, bipolar neurons serve as sensory neurons and are primarily found in
special sensory organs such as the olfactory epithelium, retina and vestibulocochlear apparatus
Describe pathway of bipolar neurons:
The terminal ramifications in the periphery receive signals from the sensory organs and combine into one
process that reaches the cell body. The axon transfers the signal from the cell body to the central nervous
system (CNS) and distributes impulses to second order afferent neurons. Both processes exhibit axonal
characteristics and can be encased in a myelin sheath which increases the speed of impulse conduction.
In bipolar neurons, both processes exhibit __ and can be __
In bipolar neurons, both processes exhibit axonal characteristsics and can be encased in myelin sheath whih increases the speed of impulse conduction
Pseudounipolar neurons consist of:
one short process which splits into two other processes
pseudounipolar neurons serve as
sensory neurons
pseudounipolar neurons, along with bipolar neurons, constitute:
The entierety of the primary sensory neurons within the human PERIPHERAL NERVOUS SYSTEM (PNS)
Pseudounipolar neurons are found in :
All sensory ganglia of cranial and spinal nerves (except for olfactory epithelium, retins and vestibulocochlear apparatus)
Pseudounipolar neurons are found in all sensory GANGLIA of CRANIAL and SPINAL nerves except for (3) :
(1) Olfactory epithelium
(2) Retina
(3) Vestibulocochlear apparatus
Pseudounipolar neurons can be considered as variations of:
Bipolar neurons
PSEUDOUNIPOLAR MIDDLE PARAGRAPH:
The peripheral/ distal process of the pseudounipolar neuron axon terminates in the :
Periphery
The peripheral/ distal process of the pseudounipolar neuron terminates in the periphery, where :
the terminal ramification respond to a wide range of stimuli (thus functioning as distant dendrites)
The peripheral/distal process of the axon terminates in the
periphery, where the terminal ramifications respond to a wide
range of stimuli, thus functioning as :
Distant dendrites
The second branch of the pseudounipolar neuron is known as:
the central / proximal process
The second branch of the pseudounipolar neuron , known as the central / proximal process is usually __ , terminating in __
The second branch of the pseudounipolar neuron, known as the central/proximal process, is usually SHORTER, terminating in the CNS
The second branch of the pseudounipolar neuron, known as the central/proximal process, is usually SHORTER, terminating in the CNS, where:
they distribute impulses to second order afferent neurons
Nerve impulses in pseudounipolar neurons can pass from the peripheral to central processes without:
The involvement of the cell body in signal processing
The cell body of unipolar neurons mainly retains
Trophic functions (i.e. support, nourishement, maintenance of the neuron)
Anaxonic neurons are:
Small neurons which LACK AN AXON,or the axon cannot be distinguished
from its many dendrites
Anaxonic neurons * because they lack an axon * don’t generate :
action potentials like typical neurons : they rely on graded potentials that influence neighbouring neurons, acting more like local interneurons
Since anaxonic axons lack axons and dont generate action potentionals, they rely on:
Graded potentials that influence neighbouring neurons, acting more like “local interneurons”
Can anaxonic axons release neurotransmitters?
yes
Anaxonic neurons release neurotransmitters, but unlike most
neurons:
They release them from their dendrites since they lack a distinct axon
Anaxonic neurons can typically be found:
where their modulatory functions are needed, such as in
the RETINA and OLFACTORY BULB
Dominant type of neurons in vertebrates:
multipolar neurons
Multipolar neurons are characterized by:
multiple processes: a single axon and numerous dendrites.
dendrites in multipolar neurons originate from:
different
regions of the cell body, displaying varying degrees of branching and directionality.
multipolar neurons are notable for:
their extensive diversity, manifesting in a wide range of sizes,
shapes and complexity within their dendritic tree.
multipolar neurons’ cell bodies may measure:
as small as 5 μm
in diameter or reach as large as 100 μm (exemplified by giant pyramidal cells (of Betz))
The cell body of multipolat neurons can take on various forms including:
OVOID, SPHERICAL, PYRIFORM (pear -shaped) or fusiform (spindle -like shaped)
The axon of multipolar neurons may be:
short or long
common subtypes of multipolar neurons (4):
(1) Pyramidal
(2) Stellate
(3) Purkinje
(4) Granule
Pyramidal neurons (type of bipolar neuron) are characterized by their cell body, whose shape resembles:
a teardrop or rounded pyramid
pyramidal neurons: the dendrites emerge either:
From the top of the pyramid (apical dendrite) or from the base (basal dendrites)
Each pyramidal neuron usually possesses:
a single apical (top) dendrite that is longer than the basal dendrites and extends numerous dendritic branches
pyramidal neurons can be found in:
-cerebral cortex (layers III and V)
- subcortical structures (hippocampus and amygdala)
Where can pyramidal cells be found in the cerebral cortex?
Layers III (external pyramidal layer)
Layers V (internal pyramidal layer)
Due to the diversity of pyramidal neurons, there are:
subtypes of pyramidal neurons
largest example of pyramidal cells
Giant pyramidal cells (of Betz)
giant pyramidal cells (of Betz) are the largest example of pyramidal
cells; they are located in:
the motor cerebral cortex
giant pyramidal cells (of Betz) are the largest example of pyramidal
cells; they are located in the motor cerebral cortex and are
considered as:
the origin for the pyramidal tract controlling
voluntary movements (upper motor neurons).
Stellate cells are
SMALL multipolar neurons (look like stars)
Stellate cells are small multipolar neurons found
mainly in (4):
(1) INTERNAL GRANULAR LAYER IV of cortex (excitatory),
(2) cerebellar cortex (inhibitory)
(3) spinal cord (mixed)
(4)reticular formation (mixed)
Stellate cells have many :
local dendrites with equal lengths
(isodendritic) that radiate uniformly in all directions
and a short arbored axon.
Isodendritic
dendrites with equal lengths –> STELLATE CELLS
In cortical layer IV, stellate cells mainly receive input from
the thalamus
In cortical layer IV, they mainly receive input from
the thalamus and are considered to be
high-fidelity
translators of thalamic input, maintaining strict
topographic organization and accurately and
efficiently convey sensory information received from
the thalamus to other parts of the cerebral cortex
Granule cells are
small oval-shaped
multipolar interneurons
Granule cells exert:
different functions and
neurochemical characteristics depending on
their location
granule cells are found in the (3):
(1) cerebellum (excitatory, NT: glutamate),
(2) the olfactory bulb (inhibitory, NT: GABA)
(3) the dentate gyrus (excitatory, NT: glutamate)
Granule cells in the CEREBELLUM:
- excitatory
- NT: glutamate
Granule cells in OLFACTORY BULB:
- Inhibitory
-NT: GABA
Granule cells in Dentate Gyrus:
- Excitatory
-NT: glutamate
Granule cells, particularly in the dentate gyrus, show
adult NEUROGENESIS
Granule cells, particularly in the dentate
gyrus, show adult neurogenesis, meaning
new granule cells can form throughout life,
contributing to learning and memory.
Purkinje cells are located in
the CEREBELLUM
Purkinje cells are located in the cerebellum, between
the molecular and granular layers
Purkinje neurons have:
large pear-shaped cell bodies and
characteristic fan-shaped dendritic trees which fill
the molecular layer.
Purkinje neurons are the only:
ONLY PROJECTION (EFFERENT) NEURONS OF THE CEREBELLAR CORTEX (all other neurons in the
cerebellum are intrinsic) and their axons
terminate in the cerebellar nuclei
Purkinje neurons are the only projections (efferent) neurons of the. erebellar cortex, their axons terminate in:
cerebellar nuclei
Purkinje neurons have an __ role, using __ as a neurotransmitter
they have an
inhibitory role, using gamma-aminobutyric acid
(GABA) as a neurotransmitter.
Multi-polar neurons come in
many shapes…
Multi-polar neurons: Classification by shape: Golgi types:Golgi type I neurons have
very long axons
that connect different parts of the system
Multi-polar neurons: Classification by shape: Golgi types:Golgi type II:
also known as
microneurons, have only short axons or
sometimes none
page 24
From a functional point of view, neurons can be classified
into (3) :
(1) Motor neurons
(2) Sensory neurons
(3) interneurons
Motor neurons:
facilitate the transmission of signals
from the CNS to effector organs, such as muscles and
glands.
Sensory neurons:
receive input from the periphery
and convey it to the CNS.
Interneurons
most neurons in the CNS can be
classified as neither motor nor sensory; since they
integrate, combine, process and further transmit the
signals received towards other brain regions, they can
be characterized as short axon (a.k.a. local
circuit) or long axon (projection, association or
commissural) interneurons
26/27
Afferent neurons
receiving information from other
brain areas.
Efferent (or projection) neurons
are considered
the principal neurons of every brain region, extending
their axons beyond the borders of the specific area
establishing connections with neurons of other regions
in the CNS.
Local circuit neurons (or intrinsic neurons or short axon interneurons)
have
shorter axons and connect with other neurons in their
close proximity, exerting their role as mediators
between other neurons of the same CNS area. These
neurons are also called SHORT AXON INTERNEURONS
Regarding their connections, nerve cells of every CNS area
can further be classified into (3):
(1) Afferent neurons
(2) Efferent (or projection) neurons
(3) Local circuit neurons
Excitatory Neurons:
facilitate the transmission of signals
that induce depolarization in neighboring neurons. This
depolarization increases the likelihood of generating an
action potential, subsequently activating the neurons.
Inhibitory Neurons:
Constituting a relatively small fraction
of the neural population, inhibitory neurons are
distinguished by their diverse expression of molecular
markers and firing properties. They form intricate circuits
that provide inhibition for a wide array of stimuli while also
regulating the activity of excitatory neurons.
Modulatory neurons:
Modulatory neurons release
neurotransmitters or neuromodulators to inflyence the
activity of other neurons.
They modify the SENSITIVITY or
RESPONSIVENESS of neurons to other signals and DO NOT DIRECTLY STIMULATE action potentials. They play a crucial role
in regulating neural circuits and shaping overall brain
function.
modulatory neurons modify:
the sensitivity or responsiveness of neurons to other signals
modulatory neurons do not:
directly stimulate action potentials
modulatory neurons play a crucial role in:
regulating neural circuits and shaping overall brain function
Neurons can also be categorized according to the
neurotransmitters which they release. Some common types are
the:
Glutamatergic
Cholinergic
GABAergic
Dopaminergic
neurons.
Glutamatergic neurons
produce and secrete glutamate, which
is the main excitatory neurotransmitter of the CNS
Pyramidal
neurons are principally categorized as
glutamatergic.
Cholinergic neurons secrete:
acetylcholine.
Cholinergic neurons are located
both in the PNS and the CNS
GABAergic neurons are
inhibitory neurons. Their neurotransmitter is
GABA, the main inhibitory neurotransmitter of the CNS.
examples of gabaergic neurons:
Purkinje cells and many
interneurons
Dopaminergic neurons produce and release
the monoamine
neurotransmitter dopamine
Dopaminergic neurons are mainly located in the (3):
(1) midbrain
(2) hypothalamus
(3) olfactory bulb
Examples of glutamatergic neurons (7):
(1) Pyramidal Neurons
(2) Spiny Stellate Cells
(3) Granule Cells
(4) Mossy Cells
(5) Retinal bipolar cells (on bipolar cells)
(6) Mitral and Tufted Cells
(7) Thalamocortical Neurons
Examples of glutamatergicl neurons: pyramidal neurons: Type / Location / Function
Examples of glutamatergic neurons: spiny stellate cells
Examples of glutamatergic neurons: granule cells
Examples of glutamatergic neurons: mossy cells
Examples of glutamatergic neurons: retinal bipolar cells (on bipolar cells)
Examples of glutamatergic neurons: mitral and tufted cells
Examples of glutamatergic neurons: thalamocortical neurons
Examples of GABAergic neurons: Basket cells
Examples of GABAergic neurons:
stellate cells
Examples of GABAergic neurons: purkinje cells
Examples of GABAergic neurons: medium spiny neurons (MSNs)
Examples of GABAergic neurons: PV+ interneurons
Examples of GABAergic neurons (SST + interneurons)
Examples of GABAergic neurons: Chandelier cells
Cholinergic neurons : type:
Excitatory or modulatory neurons
Cholinergic neurons: location:
Found in various regions, including:
* Basal forebrain (e.g., nucleus basalis of Meynert,
medial septum).
* Brainstem (e.g., pedunculopontine nucleus,
laterodorsal tegmental nucleus).
* Spinal cord (e.g., motor neurons in the ventral
horn).
Cholinergic neurons function:
Release acetylcholine (ACh) to modulate
synaptic activity and influence processes
cholinergic neurons:Function: Release acetylcholine (ACh) to modulate
synaptic activity and influence processes like:
- Arousal, attention, and learning (via basal forebrain
projections to the cortex and hippocampus). - Motor control (via brainstem projections to the
spinal cord and basal ganglia). - Autonomic nervous system regulation (via spinal
and peripheral cholinergic neurons).
Myasthenia gravis is
a neuromuscular
disease leading to fluctuating muscle
weakness and fatigability during simple activities.
Cholinergic neurons & myasthenia gravis: weakness is typially caused by:
circulating antibodies that block acetylcholine
receptors at the postsynaptic neuromuscular
junction, inhibiting the stimulative effect of the
neurotransmitter acetylcholine.
Myasthenia is treated
with:
(1) immunosuppressants
(2) cholinesterase inhibitors
(3) thymectomy (removing thymus gland)
Dopaminergic neurons type:
modulatory
dopaminergic neruons are found in
(1) midbrain : Substantia Nigra Pars Compacta (SNc), ventral tegmental area (VTA),
(2) Hypothalamus: Arcuate nucleus
Human dopamine pathways: Substantia nigra pars compacta (SNc): Projects to
the
striatum, forming the nigrostriatal pathway.
Human dopamine pathways: VTA projects to:
the cortex and limbic regions via the mesocortical and mesolimbic pathways
Human dopamine pathways: Arcuate nucleus: projects to :
the median eminence, regulating hormone release in the pituary
Dopaminergic neurons release dopamine to regulate various processes including:
(1) motor control
(2) reward and motivation
(3) Cognition and executive function
(4) Endocrine regulation
Dopaminergic neurons: Function: Release dopamine (DA) to regulate various processes, including: Motor control:
Via the nigrostriatal pathway, dysfunction
contributes to Parkinson’s disease
Dopaminergic neurons: Function: Release dopamine (DA) to regulate various processes, including: reward and motivation:
Through the mesolimbic pathway, critical
for reinforcement and addiction.
Dopaminergic neurons: Function: Release dopamine (DA) to regulate various processes, including:Dopaminergic neurons: Function: Release dopamine (DA) to regulate various processes, including: cognition and executive function:
Via the mesocortical pathway,
implicated in attention and decision-making.
Dopaminergic neurons: Function: Release dopamine (DA) to regulate various processes, including:Dopaminergic neurons: Function: Release dopamine (DA) to regulate various processes, including: Endocrine regulation:
Modulates prolactin secretion in the
pituitary gland.
Multiple sclerosis:
Axon loss is a factor in the neurological
symptoms of multiple sclerosis.
Stroke:
Physical damage to the brain from a stroke can kill
or disable neurons.
Traumatic brain injury:
Physical damage to the brain from
an injury, such as a hit to the head, can kill or disable
neurons.
Neurodegenerative diseases:
Axons can be damaged in
the early stages of neurodegenerative diseases like
Alzheimer’s disease, Parkinson’s disease, and motor neuron
disease.
Peripheral neuropathies:
Axon loss can contribute to
neurological symptoms of peripheral neuropathies
Diffuse axonal injury (DAI) is a
type of traumatic brain injury that occurs when the brain rapidly shifts within the skull, causing widespread damage to the long connecting nerve fibers (axons), leading to disruptions in brain communication and potentially resulting in coma, cognitive impairment, or physical disabilities
Axons can be damaged by:
nerve injury, or by the earliest
stages of neurodegenerative diseases.
Damaged axons can prevent
neurons from communicating
properly.
The adult brain can sometimes repair itself by
reverting
injured cortical neurons to an embryonic state, allowing them
to regrow axons.
Imaging techniques for diagnosing axonal injury
*Magnetic resonance imaging (MRI), particularly diffuse tensor
imaging (DTI), is the preferred imaging technique for
diagnosing diffuse axonal injury.
Glia cells
- Non-neuronal cells in the nervous system.
- Perform many support functions.
- Do not produce electrical impulses.
Glial cells far outnumber neurons:
there are between 10 and 50 times
more glia than neurons in the central nervous system of vertebrates.
Despite their name, glia cells do not
commonly hold nerve cells
together. Rather, they surround the cell bodies, axons, and dendrites of
neurons.
glia are not directly involved in
information
processing, but they are thought to have at least seven other vital roles
most numerous of glial cells
Astrocytes
astrocyte shape:
Irregular, roughly star-shaped cell bodies.
astrocytes have long __ some of which terminate in __
LONG PROCESSES (brances, some ofwhich terminate in END-FEET)
Astrocytes : end feet: role:
- Some astrocytes form end-feet on the surfaces of
neurons in the brain and spinal cord and may play a role
in bringing nutrients to these cells. - Other astrocytes place end-feet on the brain’s blood
vessels and cause the vessel’s endothelial (lining) cells to
form tight junctions, thus creating the protective blood-
brain barrier.
Astrocytes help to:
maintain the right potassium ion concentration in
the extracellular space between neurons
(( When a nerve cell fires, potassium ions flow out of the
cell. Repetitive firing may create an excess of
extracellular potassium that could interfere with
signaling between cells in the vicinity. Because
astrocytes are highly permeable to potassium, they can
take up the excess potassium and so protect those
neighboring neurons))
Astrocytes take up:
neurotransmitters from synaptic zones after release
and thereby help regulate synaptic activities by removing
transmitters.
Microglia are
immune cells in the brain that help maintain
brain health and repair damage. They are a key part of the
brain’s immune system, and they also play a role in brain
development and aging.
Microglia function:
(1) eliminate harmful substances
(2) Regulate brain development
(3) Mediate inflammation
(4) present antigens
(5) Sustain the blood-brain barrier
(6) Repair injuries
Ependymal cells
Glial ciliated cells that line the brain’s ventricles and spinal cord central canal
Ependymal cells regulate:
the flow of cerebrospinal fluid (CSF) and other substances in and out of
the brain
Myelin-forming cells
Schwann cells and oligodendrocytes are glial cells
that produce myelin sheaths in the peripheral and
central nervous systems (PNS and CNS)
Myelin
insulates
xons, which allows for faster impulses
to travel
Schwann cells are mainly in the
PNS
oligodendrocytes are mainly in the
CNS
Schwann cells
myelinate (how many axons at a time) :
one axon at a time
oligodendrocytes can myelinate up to:
60 axons
Capacity for replication: Oligodendrocytes are
terminally differentiated and cannot replicate
after injury. Schwann cells can invade the CNS to
form new myelin sheaths.
Myelin disorders
Myelin disorders are diseases that damage the myelin sheath, which insulates nerves.
Damaged myelin can slow or stop nerve impulses, causing neurological issues.
Multiple sclerosis (MS):
An autoimmune disease that damages the myelin in the brain,
spinal cord, and optic nerve. It’s the most common demyelinating disorder.
Acute disseminated encephalomyelitis (ADEM):
A brief but widespread inflammation that
damages the myelin in the brain and spinal cord.
Neuromyelitis optica (Devic’s disease):
An autoimmune disease that causes inflammation
and myelin loss around the spinal cord and optic nerve.
Transverse myelitis:
Can be an early sign of MS or a relapse.
Balo’s disease:
A rare and potentially fatal form of MS
Leukodystrophy:
A demyelinating disease that affects the central nervous system.
Symptoms of myelin disorders:
Trouble walking or seeing, Changes in bladder and
bowel function, and Fatigue
Causes of myelin disorders:
- Infections
- Immune disorders
- Metabolic disorders
- Nutritional deficiencies
- Poisons
- Drugs or medications
- Excessive alcohol use
- Viral infections
- Loss of oxygen
- Physical compression
Radial Glial Cells
Arise from neuroepithelial cells after
neurogenesis. Function as neuronal
progenitors and scaffolds for migrating
neurons. Retained in the cerebellum
(e.g., Bergmann glia, regulating synaptic
plasticity) and retina (e.g., Müller cells,
supporting neurons)
Satellite Glial Cells
Small cells surrounding neurons in
sensory, sympathetic, and
parasympathetic ganglia. Regulate the
external chemical environment and are
involved in injury and inflammation (e.g., chronic pain).
Enteric Glial Cells
Found in the intrinsic ganglia of the
digestive system. Support homeostasis
and regulate digestive processes,
including muscular activity.
