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Nervous Tissue and Organization/ Autonomic Nervous System
LECOM Yr 1
172
Anatomy
Graduate
08/09/2011

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Cards

Term
what does the CNS develop from?
Definition
the neural tube
Term
what do the PNS and ANS develop from?
Definition
the neural crest
Term
where do neural crest cells migrate?
Definition
to the dorsal side of the neural tube
Term
what composes the CNS?
Definition
the brain and spinal cord
Term
what composes the PNS?
Definition
spinal (dorsal root) ganglia, peripheral nerves
Term
what composes the ANS?
Definition
sympathetic, parasympathetic and enteric nervous systems
Term
what is a nucleus in relation to the nervous system?
Definition
a group of neurons with related function and connections
Term
what does white matter contain?
Definition
myelinated axons
Term
what is myelin formed by?
Definition
oligodendroglia cells
Term
True or false: all the cells of the nervous system are derived from the neural tube.
Definition
True
Term
what can be found in the gray matter?
Definition
neuronal cell bodies and processes, astrocytes, microglia and some oligodendroglia
Term
what does white matter contain?
Definition
myelinated axons formed by oligodendroglia
Term
True or false: all CNS cell types except microglia are derived from the neural tube
Definition
True
Term
what is the origin of the microglia?
Definition
bone marrow
Term
what type of cells are microglia cells?
Definition
phagocytic
Term
what are neurons?
Definition
specialized cells derived from the neural tube or the neural crest; excitable cells specialized to process and communicate information
Term
True or False: the human CNS, the brain and spinal cord, has 200 or more functionally and morphologically distinct neuronal type
Definition
True
Term
where are ependymal cells found?
Definition
line ventricles of the brain and central canal of spinal cord
Term
what do choroid plexus cells secrete?
Definition
CSF
Term
what are the 2 types of astrocytes?
Definition
fibrous (white matter) and protoplasmic (gray matter)
Term
what can be found in neuronal membranes?
Definition
ion channels, receptors, and synaptic specializations
Term
True or False: different populations of neurons produce different neurotransmitters and neuropeptides
Definition
True
Term
what are the 3 regions of a neuron?
Definition
receptor region, conductive region, and effector region
Term
True or false: all neurons have a cell body or soma
Definition
True
Term
what does the cell body of a neuron contain?
Definition
the nucleus and virtually all of the protein synthetic organelles
Term
what does the receptor region contain?
Definition
the cell body or soma, dendrites
Term
where can an action potential originate?
Definition
the axon hillock
Term
what type of chromatin does the nucleus of a neuron contain?
Definition
euchromatin
Term
neuronal cytoplasm is typically (basophillic or acidophillic)?
Definition
basophillic due to large amount of RER
Term
what are nissl bodies?
Definition
made up of RER and polysomes; reflect the high level of synthesis of membrane and secreted products
Term
when dendrites branch off, what is it called?
Definition
dendritic arborization or dendritic tree
Term
what allows for analysis of a neurons function and relations with other neurons?
Definition
the shape and orientation of the dendritic arbor
Term
what part of the dendrites have nissl substance?
Definition
proximal parts
Term
when using a nissl stain, what cannot be fully appreciated or seen?
Definition
dendritic arbors
Term
spines, thorns or gemmules are specialized regions of?
Definition
synaptic contact
Term
if you want to be most influential on a neuron, you want to be closest to?
Definition
the cell body
Term
do dendrites exhibit an action potential?
Definition
no
Term
what are the receptive parts of the neuron?
Definition
the cell body and dendrites
Term
all the inputs, excitatory and inhibitory summate to cause a?
Definition
graded potential
Term
how many axons does a neuron typically have?
Definition
1
Term
do axons stain with nissl stains (cresyl violet)?
Definition
no because they have no RER or ribosomes
Term
describe the axon
Definition
tend to have uniform diameters along their entire length; they do not taper like dendrites; their contours are smooth; they branch at obtuse angles and can have branches called collaterals that come off at right angles
Term
what are telodendria?
Definition
the terminal arborizations of axons; when an axon reaches a target area
Term
when neurofilament synthesis goes up, axon diameter goes up or down?
Definition
up (direct relationship)
Term
what are the types of things you see in slow axonal transport?
Definition
cytoskeletal components: tubulin, neurofilament proteins, actin
Term
what are the purpose of microtubules in the axon?
Definition
important as tracks for fast anterograde and retrograde axonal transport
Term
what are found in axons?
Definition
microtubules and neurofilaments
Term
neurofilaments and microtubules are transported by what type of transport?
Definition
slow axonal transport as polymers
Term
when neurofilaments and microtubules reach the axon terminals what happens?
Definition
they are disassembled
Term
describe the anterograde component of fast axonal transport
Definition
conveys membranous organelles and membrane bound proteins away from the cell body toward the axon terminals
Term
describe the retrograde component of fast axonal transport
Definition
conveys worn organelles and endocytosed materials, such as growth factors, toxins and viruses
Term
what does the Rabies virus bind to?
Definition
ACh receptor of motor neurons innervating infected muscle cells; retrogradely transported to cell body where it can replicate
Term
what are the 2 types of synapses?
Definition
chemical and electrotonic
Term
what are the most common type of synapses?
Definition
chemical synapses
Term
what is an important component of neurotransmitter release?
Definition
the influx of calcium
Term
what are 4 neural tube derivatives of CNS glial cells?
Definition
ependymal, choroid plexus cells, astrocytes, and oligodendroglial cells
Term
what is the bone marrow derived derivative of CNS glial cells?
Definition
microglial cells
Term
the anterograde component of fast axonal transport uses what as a motor protein?
Definition
kinesin
Term
what is used as a motor protein for the retrograde component of fast axonal transport?
Definition
dynein
Term
what are the 2 types of astrocytes?
Definition
fibrous and protoplasmic astrocytes
Term
where are fibrous astrocytes typically found?
Definition
in the white matter and are also called white matter astrocytes
Term
where are protoplasmic astrocytes typically found?
Definition
in the gray matter
Term
describe fibrous astrocytes
Definition
form structural support for the white matter tracts; have long slender processes packed with intermediate filaments that are composed of the protein glial fibrillary acidic protein
Term
describe protoplasmic astrocytes
Definition
have short, thick, bushy processes; have relatively fewer intermediate filaments than fibrous astrocytes and stain less intensely with antibodies to GFAP; these cells act as supportive cells for neurons; there is substantial evidence that they make growth factors
Term
describe characteristics of the blood brain barrier
Definition
the CNS has continuous capillaries with tight junctions; around the capillaries are astrocytic endfeet; experimental studies show that astrocytes induce capillaries to form the blood brain barrier
Term
what is an astrocytic tumor (astrocytomas)?
Definition
tumors involving cells derived from astrocytes are the most common type of primary brain tumor; they comprise 80-90% of all glial tumors in adults
Term
True or False: Astrocytomas have a tendency to become more anaplastic with time
Definition
True
Term
what is the mean survival time of an astrocytoma?
Definition
8-10 months
Term
True or False: Astrocytic tumors seldom metastasize to the rest of the body
Definition
True
Term
Some oligodendrocytes act as _____ _____ near neurons.
Definition
satellite cells
Term
Described by chronic demyelinating disease of the CNS with multiple plaques of demylenization
Definition
multiple sclerosis (MS)
Term
what are the CNS plaques (scars) formed by in MS?
Definition
astrocytes
Term
what is MS characterized by?
Definition
remission and relapse
Term
what are oligodendroglia?
Definition
myelinating cells of the CNS; myelinate up to 50 or more axons
Term
how prevalent is MS in the USA?
Definition
1 in 1000
Term
has the pathogenesis of multiple sclerosis been determined?
Definition
no
Term
what are some of the common symptoms of MS?
Definition
unilateral visual impairment, double vision (diplopia), paresthesias (pins and needles), ataxia (unsteadiness), vertigo, fatigue
Term
Are microglia derived from the neuroectoderm?
Definition
no
Term
where are resting macrophages in the CNS derived from?
Definition
bone marrow precursor cells (monocytes)
Term
where do bone marrow precursor cells migrate to?
Definition
migrate into the CNS during the development of CNS vasculature
Term
what is the term for the microglial nuclei that enlarge and elongate due to CNS injury?
Definition
rod cells
Term
what are gitter cells?
Definition
microglia that become phagocytic due to increased damage to the CNS
Term
True or false: CNS injury in adults causes permanent deficits
Definition
True
Term
True or False: CNS regeneration is severely limited in adults
Definition
True
Term
when astrocytes react to injury, what is it called?
Definition
gliosis
Term
describe gliosis
Definition
forms a glial scar; occurs when astrocytes react to injury; inhibit aonal regeneration
Term
what does the dorsal root ganglion contain?
Definition
sensory neurons that signal pain and temperature, touch, pressure, vibration, and proprioception
Term
what are the 3 connective tissues of the peripheral nerve?
Definition
epineurium, perineurium, and endoneurium
Term
where in the peripheral nerve is the site of the blood-nerve barrier?
Definition
perineurium
Term
what does guillan-barre syndrome affect?
Definition
the PNS only
Term
describe guillan-barre syndrome
Definition
acute inflammatory polyradiculoneuropathy; usually bilateral, symmetrical, motor weakness; may be an autoimmune disease; severe cases can lead to death; most cases resolve in 2-4 weeks
Term
can peripheral nerves regenerate after injury?
Definition
yes
Term
when is peripheral nerve regeneration best?
Definition
when the peripheral nerve is crushed since the CT sheaths stay intact
Term
what cells play a critical role in peripheral nerve regeneration?
Definition
schwann cells; become phagocytic and synthesize essential growth-promoting factors and cytokines
Term
what are the structural and molecular changes in a neuronal cell body triggered by when an axon is severed by trauma?
Definition
a loss of target-derived neurotrophic factors
Term
when an axon is severed (axotomy), the neuron exhibits the?
Definition
axonal reaction: the cell body swells, there is a dissolution of nissl substance (chromatolysis); the nucleus moves to an eccentric position
Term
what genes are up-regulated during the axotomy response?
Definition
actin and tubulin; needed for growth cone and axon regeneration
Term
what are down-regulated during the axotomy response?
Definition
neurofilament genes and genes associated with synaptic transmitters
Term
describe the 2 parts of the severed axon and which portion is attached where
Definition
proximal attached to neuronal cell body, distal separated from the cell body
Term
where does the proximal portion of the severed axon degenerate back to?
Definition
the next node of Ranvier (retrograde degeneration)
Term
what are the morphological changes to axotomy?
Definition
chromatolysis- dissolution of RER, movement of nucleus to eccentric positon
Term
what are the biochemical changes to axotomy?
Definition
decrease in synthesis of less-essential proteins (neurofilament proteins, transmitter proteins), increase in synthesis of proteins needed for axonal regeneration (tubulin and actin proteins)
Term
what is an axonal growth cone?
Definition
a motile structure that has a concentration of receptors for neurotrophic factor and laminin
Term
describe neural plate formation
Definition
At the beginning of the 3rd week of embryonic development, the notochord induces the overlying ectoderm to form the neural plate. By the end of the 3rd week, the lateral edges of the neural plate form neural folds and the depressed mid-region forms the neural groove.
Term
what is neurulation?
Definition
neural tube formation
Term
fusion of the neural folds in neurulation occurs in what directions?
Definition
rostro-caudal direction
Term
the neural canal is open to the amniotic cavity via what 2 pores?
Definition
rostral neuropore (cranial opening) and caudal neuropore
Term
what does closure of neuropores coincide with?
Definition
the establishment of a blood supply for the neural tube
Term
where is the spinal cord derived from?
Definition
the neural tube caudal to the 4th pair of somites
Term
what is the brain derived from?
Definition
the neural tube rostral to the 4th pair of somites
Term
what are the 3 zones of spinal cord development?
Definition
ventricular zone, intermediate zone, and marginal zone
Term
describe the ventricular zone in spinal cord development
Definition
region of cell proliferation; cells become neurons and macroglia
Term
describe the intermediate zone (mantle layer) in spinal cord development
Definition
neurons differentiate and form axons and dendrites
Term
describe the marginal zone in spinal cord development
Definition
area at edge of cord where longitudinal axon fasicles grow
Term
what does the alar plate become in spinal cord development?
Definition
becomes sensory (afferent) portion of cord
Term
what does the basal plate become in spinal cord development?
Definition
becomes motor (efferent) portion of the cord
Term
where is the dorsal (posterior) horn derived from?
Definition
the alar plate (sensory)
Term
where is the ventral horn derived from?
Definition
the basal plate (motor)
Term
what are the 3 primary vesicles that form in brain development?
Definition
forebrain, midbrain, hindbrain
Term
what are the 5 secondary vesicles in brain development?
Definition
telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon
Term
what are the 3 flexures of brain development?
Definition
midbrain, pontine, cervical flexure
Term
what are the 2 components of the autonomic nervous system?
Definition
sympathetic and parasympathetic
Term
what are the 2 neuron systems in the autonomic nervous system?
Definition
preganglionic neuron in CNS, postganglionic neuron
Term
describe preganglionic neurons in the sympathetic nervous system
Definition
in the spinal cord lateral horn from T1-L2 or 3; some synapse in paravertebral ganglia; others travel via splanchnic nerves to prevertebral ganglia; cholinergic
Term
describe postganglionic neurons in the sympathetic nervous system
Definition
in paravertebral or some prevertebral ganglia; most are adrenergic except to eccrine sweat glands
Term
describe preganglionic neurons in the parasympathetic nervous system
Definition
located in the brainstem nuclei or sacral spinal cord; cholinergic
Term
describe postganglionic neurons in the parasympathetic nervous system
Definition
in wall of viscera, cholinergic
Term
what are some predominant features of a motorneuron in a slide?
Definition
euchromatic nucleus, prominent nucleolus, abundant Nissl substance
Term
Some neurons, such as the Purkinje cells of the cerebellum have dendrites characterized by _______ protrusions.
Definition
short
Term
what are neurofilaments believed to be important in maintaining?
Definition
axonal diameter
Term
what happens when retrogradely transported endosomes and multivesicular bodies reach the cell body?
Definition
they fuse with lysosomes; material is digested
Term
can lipofuscin be digested?
Definition
no; accumulates with age and in some diseases
Term
how are cell bodies and dendrites identified in double-label immunofluorescence?
Definition
green fluorescence
Term
how are synaptic terminals identified in double-label immunofluorescence?
Definition
red fluorescence
Term
what is the glia limitans?
Definition
the joined end-feet processes of astrocytes coating the pia mater
Term
what are examples of 2 toxins that are retrogradely transported?
Definition
tetanus toxin and ricin toxin
Term
the epidermis and neural tissue arose from what germ layer?
Definition
ectoderm
Term
the muscle and connective tissues arose from what germ layer?
Definition
mesoderm
Term
the epithelial linings of the GI tract and respiratory tracts arose from what germ layer?
Definition
endoderm
Term
the cerebral hemispheres arise from what secondary vesicle in brain development?
Definition
telencephalon
Term
the midbrain arises from what secondary vesicle in brain development?
Definition
mesencephalon
Term
the pons and cerebellum arise from what secondary vesicle in brain development?
Definition
metencephalon
Term
the medulla arises from what secondary vesicle in brain development?
Definition
myelencephalon
Term
the thalami arise from what secondary vesicle in brain development?
Definition
diencephalon
Term
what are the three components of the autonomic nervous system?
Definition
symphathetic, parasympathetic, and enteric
Term
where are the regions where migrating neurons may reside?
Definition
dorsal root ganglion, sympathetic ganglion, preaortic ganglion, organ plexus
Term
preganglionic neurons in the sympathetic are mainly? (cholinergic or adrenergic)
Definition
cholinergic (ACh)
Term
postganglionic neurons are mainly? (cholinergic or adrenergic)
Definition
adrenergic (epinephrine or norepinephrine)
Term
True or false: the sympathetic nervous system goes to all parts of the body.
Definition
True
Term
True or false: every spinal nerve has sympathetic innervation associated with it.
Definition
True
Term
the intermediolateral cell column is characteristic of the ______ cord.
Definition
thoracic
Term
the prevertebral ganglia receive preganglionic axons via the ______ nerves.
Definition
splanchnic
Term
where are preganglionic neurons that have their axons in the splanchnic nerves typically found?
Definition
in the intermediolateral cell column of the spinal cord at the following levels:
Greater T5-T9
Lesser T10-T11
Least (T11)-T12
Term
what viscera type do the greater, lesser, and least splanchnic nerves innervate?
Definition
abdominal viscera but arise in the thorax
Term
what are the 4 things an axon leaving the intermediolateral cell column may do once they enter the sympathetic chain?
Definition
They may ascend in the chain and synapse in more rostral ganglia.

They may descend in the chain and synapse in more caudal ganglia.

They may pass through the chain without synapsing and go to a prevertebral ganglion.

They may synapse in the ganglion at the same spinal level from which they arose.
Term
what does the white communicating ramus contain?
Definition
myelinated preganglionic sympathetic axons
Term
what does the gray communicating ramus contain?
Definition
unmyelinated postganglionic axons
Term
postganglionic sympathetic neurons like to follow _____ _____ to reach their targets.
Definition
blood vessels
Term
what is Horner's syndrome characterized by?
Definition
ptosis (partial drooping eyelid) and miosis (small pupil)
Term
where are preganglionic neurons found in the parasymathetic branch?
Definition
located in the brainstem nuclei or sacral spinal cord; cholinergic
Term
where are postganglionic neurons found in the parasympathetic branch?
Definition
in the wall of viscera; cholinergic
Term
what are the 2 plexuses formed in the enteric nervous system?
Definition
submucosal (meissner's plexus) and myenteric (Auerbach's plexus)
Term
True or false: the enteric nervous system can work in the absence of input from the brain and spinal cord.
Definition
True; it is reflexive
Term
what does the myenteric plexus regulate?
Definition
peristalsis and sphincters
Term
what does the submucosal plexus regulate?
Definition
secretion by glandular epithelial cells; motility or muscularis mucosa; some may be sensory neurons that help signal presence of material in lumen
Term
what are the events involved in peristaltic reflex?
Definition
Bolus of material distorts mucosa

Enterochromaffin cells release serotonin (5-HT)

5-HT stimulates nerve endings in lamina propria
Cell bodies of these sensory neurons in the submucosal (Meissner’s) plexus

Sensory neurons activate motor neurons in myenteric (Auerbach’s) plexus
Term
what kind of nucleus does auerbach's plexus normally have?
Definition
eccentric nucleus
Term
what is hirschsprung's disease?
Definition
Also known as congenital aganglionic megacolon
There is a failure of neural crest cells to migrate into the distal colon
1:5000 births
Males affected more than females 4:1
Term
what is achalasia?
Definition
Formerly called cardiospasm
Onset 25-60 years
Men=women
Loss of myenteric neurons (Auerbach’s plexus) in lower the esophagus
Lower esophageal sphincter (LES) paralyzed in constricted state
Esophagus dilated
Acquired disease; usually a postviral infection
Term
pain afferents travel with the ________.
Definition
sympathetics
Term
stretch afferents travel with the _______.
Definition
parasympathetics
Term
what is referred pain?
Definition
Pain associated with visceral disease and inflammation is referred to the abdominal wall.

This is because visceral nociceptive (pain) afferents enter the spinal cord with somatic afferents.

All pain fibers run with the
sympathetic system and enter the spinal cord at the same segment that gives rise to the preganglionic efferents.
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