Nervous system overview Flashcards
lecture 1
What are the parts of the CNS?
cerebrum
- cortex (outer layer of brain)
- internal structures
subcoritcal:
diencephalon
- thalamus
- hypothalamus
brainstem
- midbrain
- pons
- medulla oblongata
cerebullum
spinal cord
the words posterior and anterior are synonymous with what words?
posterior - dorsal
anterior - ventral
What is grey matter composed of? what is its function?
composed of the neurons and glia (cell bodies), and the connection between neurons
where info processing of the brain occurs
What is white matter composed of? What is its function?
composed of axons carrying info between parts of the nervous system
What is meningitis?
inflamed or infected meninges
- can be life threatening due to inflammatio nwithin the enclosed cranial cvity putting pressure on teh brain
- both viral and bacterial forms
What is encephalitis?
condition when the pathogen gets through the pia mater and infectsthe brain tissue directly (inflammed brain tissue)
What are the meninges?
dura mater (periosteal layer, meningeal layer)
arachnoid mater
pia mater
What does the word hematoma breakdown into meaning?
hemato - blood
oma - tumor/mass
what is a extradural/epidural hematoma?
lemon shaped
rapidy expanding hemorrage under arterial pressure peels the dura away from the inner surface of the skull, forming a lens shaped biconvex hematoma that often does not spread past the cranial sutures where the dura is tightly apposed to the skull
What is a subdural hematoma
cresent or banana shaped
subdural hematomas are typically crescent shaped and spread over a large area. density depends on the age of the blood. acute blood is hyperdense and bright on CT. after1-2 weeks the clot liquifies and may appear isodense
Where, in relation to the meingeal layers, is epidural anesthesia administered?
outside of dura –> not puncturing meninges
- processes sensory info from the limbs, trunk and internal organs
- controls body movemetns directly
- regulates many visceral functions
- conduit for the transmitting ascending sensory info and descending motor info to/from the brain
spinal cord (cns)
What is the PNS somatic nervous system composed of?
nerves and collections of cells within ganglia
What is peripheral neuropathy?
what are some causes and symptoms ?
sensory nerve damage:
- unusual sensations
- pain from light touch
- burning
- numbness
- tingling
- balance problems
motor nerve damage:
- muscle cramping
- twitching
- reflex abnormalities
roles of PNS somatic nervous system?
- acts as the interface between teh CNS and the world in relation to the body
- monitors the condition of the body internally and externally and affects behavioral changes in response to those conditions
roles of PNS autonomic nervous system?
- regulates the visceral organs, vasculature and glands
- consists of sympathetic and parasympathetic divisions
- division function in harmony
what are the two major cells types in the nervous system?
- neurons - signaling cells
- glia - support cells
What are the parts of a neuron?
cell body
axons
dendrites
roll of cell body, axons and dendrites (neurons)
cell body: receives many direct inputs
axons: transmit signals ;generate and conduct APs
Dendrites: receive inputs from axons via synapses
Where is a unipolar cell found ?
smooth muscle
where is a bipolar cell found?
retina
What is the role of a pseudo-unipolar cell?
some sensory info
what are the 3 types of multipolar cells?
- motor neuron of spinal cord
- pyramidal cells of hippocampus
- purkinje cells of cerebellum
What are afferent signals?
sensory, dorsal
what are efferent signals?
motor, ventral
sensory neurons:
what is primary (1st order) neuron?
secondary (2nd order) neuron?
teritiary (3rd order) neuron?
- carry signals from the peripheral receptor to the spinal cord or medulla
- carry signals from the spina lcord or medulla to the thalamus
- carry signals from the thalamus to the primary seonsry cortex
where are upper motor neurons located?
completely in the central nervous system
- cell bodies in cortex or brainstem synapsewit hlower motor neurons
Where are lower motor neurons located?
part of neuron is in CNS and part is in the PNS
- cell bodies in the spinal cord or brainstem - axons form spinal and cranial nerves
What are the glia of the CNS?
what are the glia of the PNS?
CNS:
- astrocytes
- ependymal cells
- microglial cell
- oligodendrocyte
PNS:
- satellite cell
- schwann cell
functions of astrocyte:
remember connects cell body with blood vessel
- helps form the blood brain barriet (BBB)
- regulates interstitial fluid composition
- provides structural support and organization to the CNS
- assists with neuronal development
- replicates to occupy space of dying neurons
functions of epedymal cell
- lines centricles of brain and cenral canal of spinal cord
- assists in production and circulation of CSF
functions of microglial cell
- phagocytic cells that move through the cns
- protects the CNS by engulfing infectious agents and other potential harmful substances
- phagyoctic cells = clean up duty; killing off bad stuff
functions of oligodendrocyte
- myelinates and insulates CNS axons
- allows faster action potential propagation along axons in the CNS
functions of satellite cell
- electrically insulates PNS cell bodies
- regulates nutrient and waste exchange for cell bodies in ganglia
functions of shwann cells
- surrounds and insulates PNS axons and myelinates those having large diameters
- allows for faster action potential propagation along an axon in the PNS
what is astrocytoma
type of cancer that can form in the brain or spinal cord; originates from astrocytes; most common adult brain tumors
what is glioblastoma
most malignant, aggressive and common form of astrocytoma; very abnormal-appearing cells, proliferation, areas of dead tissue and formation of new vessels, pronounced brain invasion and destruction, very fast progression
neuron classification by neurotransmitter
glutamatergic neurons
- glutamate
- majority produce an EXCITATORY response
so primary exictatory
both this and gabaergic neurons make about ~90% of NT in CNS
neuron classification by neurotransmitter
GABAergic neurons
- y-aminobutyric acid
- majority produce an inhibitory response
primary inhibitory
neuron classification by neurotransmitter
glycinergic neurons
- glycine
- majority produce an inhibitory response
neuron classification by neurotransmitter
cholinergic (acetylcholine)
- can produce excitatory, inhibitory, or modulatory responses in CNS
- excitatory neurontransmitter in the PNS
neuron classification by neurotransmitter
noradrenergic (norepinephrine)
- can produce excitatory, inhibitory or modulatory responses in CNS
neuron classification by neurotransmitter
adrenergic (epinephrine)
- can produce excitatory, inhibitory, or modulatory responses in CNS
neuron classification by neurotransmitter
serotonerigc (serotonin)
- can prodcue excitatory, nihibitory, or modulatory responses in CNS
neuron classification by neurotransmitter
dompaminergic (dopamine)
can produce excitatory, inibitory, or modulatory responses in CNS (basal ganglia)
neurotransmitter-drug therapies
drugs acting on the CNS primarily impact the synapse, increasing or decreasing ________ __________ or blocking reuptake of neurotransmitters into the synaptic terminal
neurotransmitter release
example of neurotransmitter drug therapies
caffeine increases _______ levels inthe brain, promoting alertness
glutamate
example of neurotransmitter drug therapies
benzodiazepines and barbiturates enhance _______ receptor function, causing sedation
GABA
example of neurotransmitter drug therapies
locally injected botox blocks the release of ________ to reduce the muscles ability to contract
achetylcholine
ventricular system/CSF
What are ventricles?
how many are there?
- labrynth of CSF-filled cavities that serve various supportive functions
how many?
- 2 lateral ventricles, one in each cerebral hemisphere
- third ventricle in the diencephalon
- fourth ventricle between brainstem and cerebellum
ventricular system/CSF
what is CSF?
clear, colorless fluid; a mixutre ofwater, proteins (at low concentrations), ions, neurotransmitters and glucose
ventricular system/CSF
where is CSF found?
occupies ventricular system, the cerebral and spinal subarachnoid spaces and the perivascular spaces in the CNS
ventricular system/CSF
what does CSF do?
serves to support the CNS (cushion and protect it from physical shock and trauma)
helps remove waste and deliver nutrients
ventricular system/CSF
What produces CSF?
choroid plexus
ventricular system/CSF
what is a modified vascular structure, that produces CSF and is present in each of the 4 ventricles
choroid plexus
ventricular system/CSF
what is the bulk flow of CSF
lateral ventricles –> 3rd and 4th ventricles, outward from teh basal foramina, upward around brainstem –> both the convexities of the hemispheres are downward to spinal subarachnoid space
all in subarachnoid space
ventricular system/CSF
how can CSF be used diagnostically?
- sinces it “bathes” the CNS, CSF can pick up chemicals and impurties in the brain and spinal cord
- analyizing it for bacteria, WBC count, glucose levels, protein or abnomral cells can help identify specific diseases in the CNS
- a spinal tap/lumbar puncture is a procedure that removes a sample of CSF
ventricular system/CSF
What is hydrocephalus
break down of word: water/brain
- inability of the body to absorb cerebrospinal fuids correctly; can also be a result of a narrow channel between ventricles which hinders the proper flow of the fluid.
enlarges ventricles puts a lot of pressure on brain
a symptoms of this could be a headache…what other symtpoms/signs could be present?
ventricular system/CSF
waht is a procedure that could be done for hydrocephalus?
ventriculoperitoneal shunt
knowledge check
what is the name of the passageway between the 3rd and 4th ventricle?
the cerebral aqueduct
arterial system
what disorders consitutues a major class of nervous system disease?
brain vasculature
(like a stroke)
arterial system
the principle source of nourishment for the CNS is ________, and _________ is necessary for cell funcion
glucos, and oxygen
arterial system
brain functions become severely disrupted when?
the blood supply of the CNS is interrupted, even briefly
arterial system
brain vasculature is closely related to?
the ventricular system and CSF
- most CSF is produced continually by the choroid plexus via secretion of ions from blood plasma
arterial system
to maintain a constant brain volume, CSF is returned to the blood through?
valves between the subarachnoid space and dural sinuses
arterial system
What are the 2 arterial systems?
- anterior (carotid) circulation
- posterior (vertebral-basilar) circulation
arterial system
the anterior (carotid) circulation is fed by what arteries?
internal carotid arteries
arterial system
the posterior (vertbral basilar) circulation is fed by what arteries?
vertebral arteries
arterial system
the diencephalon, midbrain and cortical surface receive blood from?
anterior and posterior circulations (cerebral arteries)
arterial system
where does teh brainstem receive blood from?
only from the posterior circulation
the brain stem namely is the cerebellum, pons, medulla
arterial system
why is the brainstem a compromised place?
only receives blood supply from the posterior cerebral artery circulation. no anastomosis connected here so if blood supply is losed the brainstem is compromised
arterial system
the spinal cord receives blood from?
vertebral arteries and systemic circulation (which also supplies muscle, skin and bones)
circle of willis
what areas of the circle of willis are at higher risk/severity of a lesion? label them on the circle of wilis
places that receive less blood supply.
based on the blocked artery, which deficits do you expect to see/which clinical tests would you do?
go over circle of willis
main parts of the human CNS
what are the two parts of the prosencephalon (forebrain)?
- telencephalon
- diencephalon
what structures make up the telencephalon?
- cerebral hemispheres
- cerebral cortex
- subcoritical white matter
- basal gangalia
- basla forebrain nuclei
What structures make up the diencephalon?
- thalamus
- hypothalamus
- epithalamus
What structures make up the mesencephalon (midbrain)?
- cerebral peduncles
- midbrain tectum
- midbrain tegmentum
What are the two parts that make up the rhombencephalon (hindbrain)?
- metencephalon (forms into pons and cerebellum)
- myelencephalon (forms into medulla oblongata)
What structures are apart of the metencephalon (hindbrain)?
- pons
- cerebellum
What structure makes up the myelencephalon?
medulla
overall embryology
the body and all its structures arise from waht three embryonic tissue layers?
- endoderm
- mesoderm
- ectoderm
embryology
What is formed from the ectoderm line?
- skin
- neurons
nervous system development
talk about the development of the nervous system starting with the neural plate
- the neural plate is developed from a specialized portion of ectoderm
- the neural plate then forms a tubelike structure - the NEURAL TUBE- which the neurons and glial cells are derived
- the neural tube walls form teh CNS adn teh cavity forms the ventricular system which contains CSF
nervous ssytem development
the peripheral nervous system is formed from?
the neural crest
spinal cord development
what stimulates formation of the neural plate?
notochord
spinal cord development
a specialized set of neurons differentiatse into the ________ ________ _________, which will generate the neurons of the PNS
neural crest cells
spinal cord development
what closes forming the neural tube?
neural groove
spinal cord development
once the neural groove closes and forms the neural tube, the nueral crest cells have differentiated into sensory cells of what?
of the dorsal root ganglia
spinal cord development
tissue around the dorsla root ganglia form the __________, whichh will differentiate into what 2 things?
- somites
- differentiate into muscles and bones
spinal cord development
differentiation of the neural tube creates a dorsal sensory region, the _____ _______; and a ventral, motor region the ________ ________
alar plate
basal plate
spinal cord development
what differentiates into gray matter?
what is composed of axons/white matter?
- cells in the mantle differentiate into gray matter
- the marginal layer is composed of axons/white matter
what are the 4 different neural tube defects?
- anencephaly
- hydranencephaly
- encephalocele
- spina bifida
A = without Cephalo = brain/head. hydr(o) = water
cele = tumor/swelling
cranial neural tube defects
What is anencephaly?
- serious birth defect in which a baby is born without parts of the brain and skull
cranial neural tube defects
what is hydranencephaly?
serious birth defect in which the brain’s cerebral hemispheres are absent to a great degree and the remaining cavity are filled with CSF
cranial neural tube defects
what is encephalocele?
smaller skull defect with partial protrusion of the brain, typically in the frontal or occipital region
hydrocephalus is a frequent comorbidity
neural tube defects
what is spina bifida
a congenital neural tube defect of the spine in which part of the spinal cord and its meninges are exposed through a gap in the backbone
- spina bifida is the most common of the 4 neural tube defects
What is spina bifida occulta?
incomplete vertebral arch
- no lamina or spinous process; psinal cord, meninges, and CSF are contained inthe spinal canal; skin covering the defect and may be a dimple, a small patch of hair
What is meningocele?
no lamina or spinous process
- spinal cord is still within the spina lcanal, but there is a protrusion of the meninges and CSF outside of the spinal canal
What is myelomeningocele?
proturding sac contains components of the spinal cord, meninges and cerebral spinal fluid outside of the spinal canal
What are the two malformations associated with hydrocephalus?
swollen ventricles (fluid in the brain)
- chiari type I malformation: herniation of inferior cerebellar vermis
- chiari type II malformation: caudal herniation
disorders of forebrain development
what is holoprosencephaly?
what are risk factors?
- malformation resulting from abnormal gorwth and separation of the developing forebrain
3 types:
- alobar
- semi lobar
- lobar
risk factors:
- maternal DM
- fetal alcohol syndrome
- congenital infections
- trisomy 13
- genetic mutations
disorders of neuronal migration?
what is agyria?
the brain is virtulaly devoid of surface convolutions expected for age (smooth brain, no sulci/gyri)
disorders of neuronal migration
what is pachygyria
pach = thick
reduced number of gyri, and gyri present abnormally broad
disorders of neuronal migration
What is polymicrogyria
numerous abnormally ocnvoluted gyri
what deficits if any would be seen in those with agyria? pachygyria? polymicrogyria?
agyria:
pachygyria:
polymicrogyria:
