Neural anatomy Flashcards
what process does an injured neuron undergo
Wallerian degeneration: the axon portion distal to the injury degenerates and the proximal portion contracts in order to regenerate (in PNS neurons)
what six functions do astrocytes accomplish
provide structure, repair, K+ metabolism, recycling of neurotransmitters, component of BBB, glycogen stores buffer
what is the molecular marker for glial cells
GFAP
what is reactive gliosis
proliferation of astrocytes in response to neural injury
which glial cell cannot be stained by Nissl
microglia
what does myelin do to the space constant (length constant) and conduction velocity
increases space constant and conduction velocity
which cell myelinates many neurons and which can only myelinate one neuron per cell
one oligodendrocyte myelinate many neurons (~30) while one Schwanna cell only myelinates one neuron
name three diseases in which oligodendrocytes are damaged/ dysfunctional
multiple sclerosis, PML (progressive multifocal leukoencephalopathy), leukodystrophies
in what autoimmune disease are Schwann cells destroyed
Guillain-Barre syndrome
what’s the most common type of schwannoma
accoustic neuroma, located in internal accoustic meatus (CN 8) –> tinnitus and hearing loss
what condition is bilateral accoustic neuroma associated with
neurofibromatosis type 2
name the two kinds of free nerve endings and their characteristics
C- slow, unmyelinated
A delta- fast, myelinated
what do free nerve endings sense
pain and temperature
what do Meissner’s corpuscles sense and where are they found
dynamic touch, fine/ light touch, position sense
found in glabrous (hairless) skin
where are Paccinian corpuscles found and what do they sense
found in the deep skin layers, ligaments and joints
sense vibration and pressure
where are Merkel discs found and what do they sense
basal epidermis layer of skin and in hair follicles;
they sense deep static touch (sharp edges), pressure, and position sense
what do the endoneurium, epineurium and perineurium surround, respectively
endoneurium- surrounds a single nerve fiber
perineurium- surrounds a fascicle of nerve fibers
epineurium- surrounds an entire nerve along with its vasculature
which nerve sheath has to be rejoined when reattaching a limb
perineurium
where is norepinephrine produced
locus ceruleus of the pons
where is serotonin (5-HT) produced
Raphe nucleus
where is dopamine produced
ventral tegmentum and substantia nigra pars compacta
where is acetylcholine produced
basal nucleus of Meynert
where is GABA produced
nucleus accumbens
what is the neurotransmitter profile for Huntington’s
decreased acetylcholine and decreased GABA
increased dopamine
what is the neurotransmitter profile for Parkinson’s
decreased dopamine
increased serotonin and increased ACh
what is the neurotransmitter profile for depression
decreased norepinephrine, decreased dopamine, decreased serotonin
what is the neurotransmitter profile for anxiety
increased norepinephrine, decreased serotonin, decreased GABA
what neurotransmitter is deficient in Alzheimer’s disease
acetylcholine
what three structures / layers form the blood brain barrier
non-fenestrated endothelium, basement membrane, astrocyte foot processes
name the two regions of the brain that are accessible by blood and what they do
OVLT (organum vasculosum of the lamina terminalis)= senses osmolarity
area postrema= senses emetic stimuli
what part of the hypothalamus produces ADH
supraoptic nucleus
what part of the hypothalmus produces oxytocin
paraventricular nucleus
what part of the hypothalamus causes hunger and what is it inhibited by
lateral hypothalamus; inhibited by leptin
what part of the hypothalamus produces parasympathetic stimulation and causes cooling
anterior hypothalamus
what part of the hypothalamus produces heating and sympathetic stimulation
posterior hypothalamus
what part of the hypothalamus controls circadian rhythms
suprachiasmatic
what part of the hypothalamus causes satiety and what hormone is it mediated by
ventromedial nucleus; stimulated by leptin
name the functions of the hypothalamus
TAN CHATS: thirst/ adenohypophysis control / neurohypophysis control / circadian rhythms / hunger / autonomic regulation / temperature / sex urges
what brain tumor can destroy the ventromedial nucleus of the hypothalamus leading to weight gain and hyperphagia
craniopharyngioma
the suprachiasmatic nucleus controls nocturnal release of what hormones?
ACTH, melatonin, norepinephrine and prolactin
what triggers release of melatonin from the pineal gland
norepinephrine
how is the suprachiasmatic nucleus regulated
environment (e.g. light)
what causes rapid eye movements during REM sleep
activity of PPRF (paramedian pontine reticular formation/ conjugate gaze center)
how often does REM sleep occur
every 90 minutes, but the duration of REM sleep increases through the night
what causes decreased REM sleep
alcohol, barbituates, benzodiazepines and norepinephrine
what’s the medical term for bedwetting and how do you treat it
enuresis; treat with DDAVP (preferred over imipramine)
what is used for night terrors and sleepwalking
benzodiazepines
what kind of EEG wave form is seen when a person is awake with eyes open
beta (highest frequency, lowest amplitude)
what kind of EEG wave form is seen when a person is awake with eyes closed
alpha
what kind of EEG wave form is seen when a person is in light sleep (non-REM stage N1)
theta
what kind of EEG wave form is seen when a person is in deeper sleep (non-REM stage N2)
sleep spindles and K complexes
what kind of EEG wave form is seen when a person is in deepest non-REM sleep (stage N3)
delta (lowest frequency, highest amplitude)
what kind of EEG wave form is seen when a person is in REM sleep and what bodily functions occur
beta; loss of motor tone, increased brain oxygen use, increased and variable pulse and BP, penile and clitoral tumescence can occur, memories are consolidated
what information is relayed through the VPL and from what tracts to where
pain and temperature (from spinothalamic tract), proprioception (from DCML) to primary somatosensory cortex
what information is relayed through the VPM and from where and to where
taste and facial sensation (from the trigeminal and gustatory pathways) to primary somatosensory cortex
what information is relayed through the VL and from where and to where
motor information is relayed from the basal ganglia and cerebellum to motor cortex
what information is relayed through the MGN and from where and to where
auditory information is relayed from the superior olive and inferior colliculus of the tectum to auditory cortex of temporal lobe
what information is relayed through the LGN and from where and to where
visual information from CN 2 is transmitted through the VL and goes to the calcarine sulcus of occipital lobe
what are the 5 F’s of the limbic system
feeling, fleeing, feeding, fighting and f*#$ (sex)
what are the anatomic structures of the limbic system
hippocampus, amygdala, fornix, mamillary bodies, and cingulate gyrus
name the four deep nuclei of the cerebellum
DEGF (“don’t eat greasy food”) dentate, emboliform, globose, fastigial
what are the cells of the cerebellum that are part of the input pathway
mossy fibers and climbing fibers
what are the cells of the cerebellum that are part of the output pathway
Purkinje fibers
describe the output pathway of the cerebellum
Purkinje fibers sent information to the deep nuclei then to the contralateral cortex via the superior cerebellar peduncle
what two penduncles send input to the cerebellum and which is contralateral vs. ipsilateral
middle and inferior cerebellar peduncles; middle peduncle comes from contralateral cortex, inferior cerebellar peduncle comes from ipsilateral spinal cord
what are the basic functions of the cerebellum
to modulate movement, to aid in coordination and balance
what separates the frontal and parietal lobes
the central sulcus
what separates the temporal lobe from the frontal lobe
the Sylvian fissure
what are the main areas of the frontal lobe
Broca’s, prefrontal cortex, frontal eye fields, premotor cortex, primary motor cortex and limbic orbitofrontal cortex
what are the main areas of the temporal lobe
Wernicke’s area, primary auditory cortex
what are the main areas of the parietal lobe
primary somatosensory cortex, secondary somatosensory area, and parietal association cortex
what are the main areas of the occipital lobe
principal visual cortex
what connects Broca’s and Wernicke’s areas
the arcuate fasciculus
what regions of the body are most richly represented in the cortex
hands (especially fingertips) and face (especially lips)
list the areas represented by the cortical homunculus in order from superio-medial to inferio-lateral
feet, legs, trunk, shoulder, arm, hand, neck, face, tongue
what is the consequence of bilateral amygdala lesion
Kluver-Bucy syndrome (hyperorality, hypersexuality, docility)
what condition is associated with Kluver Bucy syndrome
HSV-1
what results from lesion of the frontal lobe
disinhibition and deficits in orientation, concentration and judgment; reemergence of primitive reflexes
what is the consequence of a right parieto-temporal lesion
severe left spatial neglect (agnosia)
what are the deficits seen with a left parieto-temporal lesion and what is this constellation of symptoms called
agraphia, acalculia, finger agnosia, left-right disorientation
=Gerstmann syndrome
what is seen with a lesion of the reticular activating system (in the midbrain)
reduced arousal and wakefulness
what is seen with bilateral lesion of the mamillary bodies
Wernicke-Korsakoff syndrome: confusion, ophthalmoplegia, ataxia, memory loss (anterograde and retrograde amnesia), confabulation, personality changes
what conditions or risk factors are associated with Wernicke-Korsakoff syndrome
thiamine deficiency (often due to EtOH); thiamine deficiency can be precipitated by giving a deficient patient glucose before replacing vitamin B1
what results from lesion of the basal ganglia
resting tremor, chorea, athetosis
what results from lesion of the cerebellar hemisphere
intention tremor, limb ataxia, loss of balance (damage to cerebellum results in ipsilateral deficits= fall toward the side of the lesion)
what deficits are seen with cerebellar vermis lesion
truncal ataxia, dysarthria
what results from lesion of the subthalamic nucleus
hemiballismus
what results from lesion of the hippocampus
anterograde amnesia (inability to make new memories)
what clinical symptom is seen when there is a lesion of the PPRF (paramedian pontine reticular formation)
eyes look away from side of the lesion (PPRF controls saccades)
what clinical symptom is seen when there is a lesion of the frontal eye fields
eyes look toward the side of the lesion
what symptoms can central pontine myelinolysis cause
paresis, dysarthria, diplopia, dysphagia, LOC, and can cause “locked in syndrome”
what causes central pontine myelinolysis
rapid correction of hyponatremia “low to high your brain will die”
what is the cause of cerebral edema/ herniation
rapid correction of hypernatremia (going from high to low sodium) “high to low your brain will blow”
where is Broca’s area
inferior frontal gyrus of frontal lobe
where is Wernicke’s area
superior temporal gyrus of temporal lobe
what areas are impaired when there is global aphasia
both Wernicke’s and Broca’s areas
what area is damaged when a patient has conduction aphasia (inability to repeat, for example, “no ifs ands or buts”)
conduction aphasia= damage to arcuate fasciculus
what deficits would you see in a mixed transcortical lesion
nonfluent speech, poor comprehension, intact repetition
in terms of symptoms what is the exact opposite of conduction aphasia
mixed transcortical lesion
