CNS and Brain Development Flashcards
What type of tissues is covering the embryo early on?
simple cuboidal epithelium from the ectoderm
The neural plate is made of what epithelium and lies where?
formed by simple columnar epithelium that have transitioned from cuboidal. Lies along the dorsum.
Ultimately the nervous system is formed by what type of tissue type?
ectoderm
The neural groove is formed how?
extends cranially and caudally, as it originates in “the middle”
- neural folds are on either side of the groove
At 23 days, what is teh anterior/posterior neurpore after formation of neural tube?
These neuopore allow contact with the amniotic fluid in circulation, and defects can lead to nervous system defects.
- Superior closes at 27 days
- posterior closes at 30 days
What makes up the tripartite brain?
- prosencephalon
- mesencephalon
- rhombencephalon
What makes up the pentapartite brain?
- telencephalon (anterior)
- diencephalon (means thru, houses the thalamus)
-mesencephalon
- metencephalon
- myelencephalon
What is anencephaly?
failure of cranial end of neural tube to close. More severe than the failure of caudal end to close
What is holoprosencehpaly?
Failure of the prosencephalon to divide into two cerebral hemispheres.
-Associated with:
>eye deformity
>proboscis-type nose above the eye
>cleft lip/palate.
WHat is the best way to describe spina bifida occulta?
- failure of the inferior neuropore closure, which prevents the vertebral arch development in the caudal area.
- nervous function is generally normal
Which of the spina bifida is the more sever case?
cystica, affects the function of the spinal cord.
What is the best way to describe the spina bifida cystica, in general?
- sac-like cyst on caudal end of spine
- cord and meninges can be found in the cyst
- lower limb paralysis
- incontinence
What parts help make up the Telencephalon and what does each part give rise to?
- Lumina: lateral ventricles
- Floor: Basal nuclei, olfactory lobes and olfactory nerves
- Roof: Cerebral hemispheres
Motor function
What parts help make up the Diencephalon and what are each of the functions?
- Lumen: third ventricle
- Roof: epithalamus
- Walls: thalamus
- Floor: hypothalamus and infundibulum
The mesencephalon primordia are made up by what and have what function?
-Lumen: cerebral aqueduct, or duct of sylvius
-Roof=tectum: superior and inferior colliculi
Strong association with eyes
-Floor: tegmentum. nuclei from fore brain to hind brain
The metencephalon primordia is formed by what and these have what functions?
- Lumen: superior portion of the 4th ventricle
- Roof: cerebellum
- Floor: pons (area of multiple fiber tract crossing)
The myelencephalon and its substructures consist of what?
- Lumen: lower section of 4th ventricle
- Main unit: the medulla oblangata
- Roof: Posterior choroid plexus, where CSF is formed. Highly vascularized.
When during the embryonic stage does the nervous system develop?
end of 2nd to 8th week,
consists of the basic neurological pattern layout
What four CN pairs carry parasympathetic fibers?
- III, VII, IX, X
A pt undergoes a head trauma after a severe car accident. Presents to the ED mumbling incoherrently, unable to control his eye movement, and is not understanding what you are saying. What are the functional section sof the brain that are damaged?
- sensory
- motor
- cognitive
What is the best way to describe the spinal cord in terms of pathways for signaling?
- the first CNS encountered by incoming sensory information
- Last relay station for motor signals except some ANS
- coordinates reflex arcs
WHat is the peripheral nervous system?
transmission pathways between CNS and internal/external environment.
-consists of afferent and efferent
True/False
ANS can be a subdivision of the PNS, is entirely motor, and only innervates smooth muscles.
False:
can be subdivision of PNS
WHat is a Commissure?
Tract in the CNS that crosses form one side to the other
What is a nerve?
Bundle of axons in the PNS
WHat is a bundle of axons in the CNS?
Tract
What are two very important functions of the dendrite?
-contain receptors for neurotransmitters and conduct local potentials
What are the primary functions of the axons?
- conduct action potentials
- release neurotransmitters
- contain mitochondria, neurofilaments, neurotubules
What part of the neuron is myelinated, but not in all cases?
- axon is only part that is myelinated.
- not all schwann cell coverings result in myelination
The thoracolumbar region of spinal nerve gives rise to a branch that carries myelinated preganglionic fibers called____________.
white ramus communicans
The spinal nerve in the thoracolumbar region, has one small branch that carries unmyelinated postganglionic fibers back into the spinal nerve, ______________.
gray ramus communicans
Where is the highest concentration of neurotransmitters located in the neuron?
terminal boutons that house synaptic vesicles that contain neurotransmitters.
What is the best way to categorize or describe what a splanchnic nerve is>
- paired visceral nerve that carries visceral efferent fibers and efferent fibers to and from organs, respectively.
What serves as the site of postganglionic sympathetic nerve cell body location?
paravertebral ganglia
At what point is the synapse between preganglionic myelinated sympathetic neurons and postganglionic non-myelinated sympathetic neurons?
paravertebral ganglia
What is a reflex arc?
- path that travels from CNS and returns back to.
- minimal components of sensory and motor pathway
What are interneurons used for?
- modulate the interaction between the afferent and efferent neurons in a reflex arc
- aka: association neurons
What is the difference between mono-/polysynaptic pathways and what kind is most common?
> mono: one synapse between efferent and afferent pathways
> poly: contain interneurons. lengthening the time between stimulus and reaction.
What are commons states of a neuron?
- resting: cell potential is -65mv
- excited: cell potential of -45mv due to Na influx
- inhibited: cell potential -70, due to influx of Cl, or loss of K ions
What is generally included in a somatosensory axis?
sequence of structures involved in transmission of sensory signal from peripheral receptors to higher brain centers
What components are included in the the somatosensory axis pathway?
- peripheral receptors
- afferent neurons
- spinal cord
- brain stem
- reticular substance (pons, medulla, mesencephlon)
- cerebellum
- thalamus
- cerebral cortex.
What goes wrong when the somatosensory axis does not exist?
- there will be no organization from incoming signals or where they need to go.
- further more tells brain how to respond and if it is important to respond at the time or not.
How are the afferent neurons organized in the somatosensory axis?
- primary: synapse in posterior horn of spinal cord or sensory nuclei or brain
- secondary: synapsed in thalamus
- tertiary: synapse in the somesthetic area of cerebral cortex.
The sequence of structures that transmit an action potential from high brain center to skeletal muscles consists is known as?
skeletal motor nerve axis
What are the main components of the skeletal motor nerve axis?
- motor cortex of cerebrum
- effectors (skeletal muscles)
- efferent nerve pathway: upper motor neurons and alpha motor neurons
Describe Ach, where it is secreted and its effect when secreted.
excitatory
secreted by:
- pyramidal cells (cerebral cortex)
- basal nuclei neurons
- alpha motor neurons
- preganglionic neurons ANS
- postganglionic neurons para
- postganglionic of sympa
What is decremental conduction that occurs within dendrites?
- gradual loss of potential when depolarization spreads from site of initiation
- due to partial permeability of K and Cl ions
What is electrotonic conduction that occurs in a dendrite?
direct spread of electrical current via ion conduction in dendritic fluids without generating an action potential
What characteristics will result in electrotonic conduction in a dendrite?
- few voltage gated Na channels in membranes
- thresholds that are too high for action potentials to occur.
When the excitatory rate of a neuron remains above the excitation threshold, what will the neuron do?
- will continue to fire repetitively until the neuron falls below the threshold
What influences the firing rate of a dendrite?
- normal excitatory rate
- changes in excitatory rate that are influenced by superimposition of additional excitatory or inhibitory signals
What four CN pairs carry parasympathetic fibers?
- III, VII, IX, X
A pt undergoes a head trauma after a severe car accident. Presents to the ED mumbling incoherrently, unable to control his eye movement, and is not understanding what you are saying. What are the functional section sof the brain that are damaged?
- sensory
- motor
- cognitive
What is the best way to describe the spinal cord in terms of pathways for signaling?
- the first CNS encountered by incoming sensory information
- Last relay station for motor signals except some ANS
- coordinates reflex arcs
WHat is the peripheral nervous system?
transmission pathways between CNS and internal/external environment.
-consists of afferent and efferent
True/False
ANS can be a subdivision of the PNS, is entirely motor, and only innervates smooth muscles.
False:
can be subdivision of PNS
WHat is a Commissure?
Tract in the CNS that crosses form one side to the other
What is a nerve?
Bundle of axons in the PNS
WHat is a bundle of axons in the CNS?
Tract
What are two very important functions of the dendrite?
-contain receptors for neurotransmitters and conduct local potentials
What are the primary functions of the axons?
- conduct action potentials
- release neurotransmitters
- contain mitochondria, neurofilaments, neurotubules
What part of the neuron is myelinated, but not in all cases?
- axon is only part that is myelinated.
- not all schwann cell coverings result in myelination
The thoracolumbar region of spinal nerve gives rise to a branch that carries myelinated preganglionic fibers called____________.
white ramus communicans
The spinal nerve in the thoracolumbar region, has one small branch that carries unmyelinated postganglionic fibers back into the spinal nerve, ______________.
gray ramus communicans
Where is the highest concentration of neurotransmitters located in the neuron?
terminal boutons that house synaptic vesicles that contain neurotransmitters.
What is the best way to categorize or describe what a splanchnic nerve is>
- paired visceral nerve that carries visceral efferent fibers and efferent fibers to and from organs, respectively.
What serves as the site of postganglionic sympathetic nerve cell body location?
paravertebral ganglia
At what point is the synapse between preganglionic myelinated sympathetic neurons and postganglionic non-myelinated sympathetic neurons?
paravertebral ganglia
What is a reflex arc?
- path that travels from CNS and returns back to.
- minimal components of sensory and motor pathway
What are interneurons used for?
- modulate the interaction between the afferent and efferent neurons in a reflex arc
- aka: association neurons
What is the difference between mono-/polysynaptic pathways and what kind is most common?
> mono: one synapse between efferent and afferent pathways
> poly: contain interneurons. lengthening the time between stimulus and reaction.
What are commons states of a neuron?
- resting: cell potential is -65mv
- excited: cell potential of -45mv due to Na influx
- inhibited: cell potential -70, due to influx of Cl, or loss of K ions
What is generally included in a somatosensory axis?
sequence of structures involved in transmission of sensory signal from peripheral receptors to higher brain centers
What components are included in the the somatosensory axis pathway?
- peripheral receptors
- afferent neurons
- spinal cord
- brain stem
- reticular substance (pons, medulla, mesencephlon)
- cerebellum
- thalamus
- cerebral cortex.
What goes wrong when the somatosensory axis does not exist?
- there will be no organization from incoming signals or where they need to go.
- further more tells brain how to respond and if it is important to respond at the time or not.
How are the afferent neurons organized in the somatosensory axis?
- primary: synapse in posterior horn of spinal cord or sensory nuclei or brain
- secondary: synapsed in thalamus
- tertiary: synapse in the somesthetic area of cerebral cortex.
The sequence of structures that transmit an action potential from high brain center to skeletal muscles consists is known as?
skeletal motor nerve axis
What are the main components of the skeletal motor nerve axis?
- motor cortex of cerebrum
- effectors (skeletal muscles)
- efferent nerve pathway: upper motor neurons and alpha motor neurons
Describe Ach, where it is secreted and its effect when secreted.
excitatory
secreted by:
- pyramidal cells (cerebral cortex)
- basal nuclei neurons
- alpha motor neurons
- preganglionic neurons ANS
- postganglionic neurons para
- postganglionic of sympa
What is decremental conduction that occurs within dendrites?
- gradual loss of potential when depolarization spreads from site of initiation
- due to partial permeability of K and Cl ions
What is electronic conduction that occurs in a dendrite?
direct spread of electrical current via ion conduction in dendritic fluids without generating an action potential
What characteristics will result in electronic conduction in a dendrite?
- few voltage gated Na channels in membranes
- thresholds that are too high for action potentials to occur.
When the excitatory rate of a neuron remains above the excitation threshold, what will the neuron do?
- will continue to fire repetitively until the neuron falls below the threshold
What influences the firing rate of a dendrite?
- normal excitatory rate
- changes in excitatory rate that are influenced by superimposition of additional excitatory or inhibitory signals
What are the three forms of spina bifida cystica?
- meningocele
- meningomyelocele
- myeloschisis
What is thebest way to describe spina bifida meningocele?
symptoms vary based on location of the meninges that are found within the sac.
-can affect spinal cord function
How is meningomyelocele best described?
the sac contains cord and meninges
- incontinence
- lower limb paralysis
- formed by abnormal spinal cord growth
How is myeloschisis best described?
most severe form of spina bifida when the caudal neural fold does not close.
What happens to produce the Arnold Chirari deformity?
- cerebellum and medulla elongate through foramen magnum.
- medulla and pons can be underdeveloped
What are the consequences of having developed Arnold Chiari?
- hydrocephalus
- malformation of CN: XI XII VIII
- affect hearing, lat eye mvmt, tongue/face muscles
What is the collective name for the basal nuclei that are located in the telencephalon?
corpus striatum
The medulla contain nuclei that help control what functions within the body?
balance and equilibrium
- sensation
- states of arousal
- vital reflexes
- nuclei related to cerebellum
What are vital reflexes the myencephalon is responsible for?
- cardiac center
- vasomotor center
- respiration related centers
What two areas are located in the metencephalon?
- pons
- cerebellum
What is contained in the pons, which is contained in the metencephalon?
- CN nuclei V-VIII
- Pontine nuclei
- Sleep and respiratory centers
What is contained in the cerebellum that is contained in the metenchephalon?
-contain peduncles which connect cerebellum to other parts of brain.
What is the function of the cerebellum in the metencephalon?
- coordinate muscle movement
- maintain equilibrium and posture
- synergistic muscle control
What are the names of the three peduncles and where do they travel to?
- inferior: to the medulla and spinal cord
- middle: connects to pons
- superior: connect to midbrain
What nuclei are contained in teh mesencephalon?
contain nuclei from the CN III-IV
The roof of the mesencephalon is responsible for what actions?
- visual reflexes (superior colliculi)
- auditory and olfactory reflexes (inferior colliculi)
What are important structures contained in the diencephalon?
thalamus
epithalamus
hypothalamus
A group of people are exposed to a foul smelling odor. Only person does not make any type of facial expression. Why?
The person may have a deficit or lesion to the epithalamus of the diencephalon.
- responds to odors to produce an emotional/visceral response
What part of the brain is responsible for temperature control, visceral activity, endocrine systems, and biorhythm oscillations?
The diencephalon.
What nuiclei are found in the telencephalon?
-basal nuclei that provide subconscious motor control and muscle tone
True/ False
The telencephalon is responsible for initiating muscle movement specifically in the cerebral cortex.
True
Postganlgionic fibers have what type of pathway?
-extend from paravertebral or prevertebral ganglion to the gut tube
Norepinephrine is what type of neurotransmitter from where?
- excitatory or inhibitory
- secreted from neurons in brain stem, hypothalamus, pons, and postganglionic neurons
Dopamins is a neurotransmitter from where and does what?
Generally inhibitory
-from neurons in substantia nigra
An toxin that increases the glycine production will most likely be found where?
- spinal cord synapses
- level of inhibition will increase
GABA is where and does what?
- secreted in spinal cord and cerebral cortex.
- inhibitory
Glutamate have what effect and localized where?
- excitatory
- secreted by sensory pathways entering CNS and cerebral cortex
What can affect whether or not a stimulus will proceed through the dendrite and actually generate an action potential?
- length of the dendrite
- presence of excitatory or inhibitory proteins
-strength of the stimulus initially
What is meant by synaptic delay?
- time it takes to transmit a signal from a pre- to postsynaptic neuron.
What is synaptic delay dependent on?
- time to release the NT
- time for NT diffusion across cleft
- action of NT on post synaptic neuron
- time for influx of Na ions
Fatigue of a synaptic transmission is best described as?
- multiple excitatory stimulus are able to be passed to postsynaptic neurons, for a certain amount of time. When the number of discharges decreases, the neuron is said to be fatigued.
A patient is brought to the ED for experiencing a tonic clonic seizure. While you begin your assessment, he enters another episode of seizure, which ends after a few seconds without any interventions being given. What is the primary mechanism controlling this?
- The fatigue of synaptic transmission, results in the “ending” of the episode, as the motor synapse lose their excitability.
- it is a protective mechanism against neuronal over excitability.
What is the normal effect of alkalosis on neuron excitability?
- this increases neuronal excitability making a person more prone to epileptic events
A rise in arterial blood pH from 7.4 to 7.6 results in alkalosis and will have what effect on neuron excitability?
- greatly increases neuronal excitability
A diabetic patient is mostly at risk for ultimately being admitted to the hospital for being hyper- or hypoactive?
-hypoactive
acidosis leads to decreased neuronal stimulation.
DM are at risk for developing acidosis, which will place them in a coma.
An MMA fighter was placed in a triangle choke. Shortly after the ref calls off the fight as the fighter goes limp and does not move for a few seconds. What does hypoxia do to neuronal transmission?
- inhibits neuronal tranmission almost completely
Medical students consume large amounts of coffee in order to study late nights. They could also consume theophyllin and theobromine to produce the same effects. What is that effect?
neuronal stimulation by reducing the threshold of the neurons
What is unique about strychnine and how it is able to increase the neuronal excitability of neurons?
- it inhibits the effects of inhibitory NT, thereby making the stimulus more efficient.
- very strong reaction to glycine from the spinal cord
How do anesthetics reduce the excitability of neurons, and why are they efficient at lasting for prolonged periods of time?
- the action membrane threshold is raised across the neuron.
- being lipid soluble can cause physical changes to the neuron membrane which further reduces the neuron response to excitatory stimulus.
- more lipid soluble= more changes and prolonged effect.
