Anatomy and Physiology Flashcards
What type of cell are neurons?
permanent cells that do NOT divide in adulthood
What organelle is NOT present in the axon of neurons?
RER
If an axon is injured, what type of generation occurs?
Wallerian degeneration = degeneration distal to the injury and axonal retraction proximally
This allows for potential regeneration of axon (if in PNS)
What is the function of astrocytes?
physical support repair K+ metabolism removal of excess neurotransmitter (NT) component of BBB glycogen fuel reserve buffer
If neural injury occurs, what is the response of astrocytes?
reactive gliosis
What are astrocytes derived from?
neuroectoderm
What is the function of microglia?
CNS phagocytes
What are microglia derived from?
mesoderm
HIV can infect what cell type?
HIV-infected microglia fuse to form multinucleated giant cells in the CNS
What is the function of myelin?
Wraps and insulates axons –> increases space constant and increases conduction velocity
What type of neurons are located in the CNS? PNS?
CNS - oligodendrocytes
PNS - Schwann cells
What myelinated the axons of neurons in the CNS?
oligodendroglia
What is the predominant type of glial cell in white matter?
oligodendroglia (1 cell can myelinated 30 axons)
What are oligodendroglia derived from?
neuroectoderm
What do oligodendroglia appear on H & E stain?
“fried egg” appearance
What diseases are associated with injury to the oligodendroglia?
Multiple sclerosis
progressive multifocal leukoencephalopathy (PML)
leukodystrophies
What disease destroys Schwann cells?
Guillain-Barre Syndrome
What tumor is associated with Schwann cells?
acoustic neuroma (type of schwannoma)
*If bilateral, strongly associated with neurofibromatosis type 2
What type of sense do Meissner corpuscles sense?
Where are they located?
What is their description?
Sense: dynamic, fine/light touch (position sense = proprioception)
Location: glabrous (hairless) skin
Description: large, myelinated fibers, adapt quickly
What type of sense do Pacinian corpuscles sense?
Where are they located?
What is their description?
Sense: vibration, pressure (e.g. monofilament test)
Location: deep skin layers, ligaments, and joints
Description: large, myelinated fibers, adapt quickly
What type of sense do Merkel discs sense?
Where are they located?
What is their description?
Sense: pressure, deep static touch (e.g. shapes, edges), position sense
Location: basal epidermal layer, hair follicles
Description: large, myelinated fibers, adapt slowly
What nerve fibers are slow and unmyelinated?
C fibers
What nerve fibers are fast and myelinated fibers?
A-delta fibers
What do free nerve endings sense?
pain and temperature
What must be rejoined in microsurgery for limb reattachment?
perineurium (permeability barrier)
Match the location of the neurotransmitter synthesized in the following area of the brain:
locus ceruleus (pons) ventral tegmentum and SNc (midbrain) Raphe nucleus (pons, medulla, midbrain) Basal nucleus of Meynert nucleus accumbens
locus ceruleus (pons) - NE
ventral tegmentum and SNc (midbrain) - DA
Raphe nucleus (pons, medulla, midbrain) - 5-HT
Basal nucleus of Meynert - ACh
nucleus accumbens - GABA
What NTs decrease in depression?
NE
DA
5-HT
What NTs increase in anxiety?
NE
What NTs decrease in anxiety?
5-HT
GABA
What NT changes are seen in Parkinson’s disease?
decrease in DA
increase in 5-HT
increase in ACh
What NT changes are seen in Hungtington disease?
increase in DA
decrease in ACh
decrease in GABA
What 3 structures form the BBB?
- tight junctions b/t nonfenestrated capillary endothelial cells
- basement membrane
- astrocyte foot processes
What 3 structures form the BBB?
- tight junctions b/t nonfenestrated capillary endothelial cells
- basement membrane
- astrocyte foot processes
How do glucose and amino acids cross the BBB?
slowly by carrier mediated transport
How do nonpolar/lipid-soluble substances cross the BBB?
rapidly via diffusion
What is the function of the BBB?
helps prevent bacterial infection from spreading into the CNS
restricts drug delivery to brain
Infarct and/or neoplasm destroys endothelial cell tight junctions and results in what pathology?
vasogenic edema
What is the function of the hypothalamus?
TAN HATS
Thirst and water balance Adenohypophysis control Neurohypophysis releases hormones produced in the hypothalamus Hunger Autonomic regulation Temperature regulation Sexual urges
What are the 2 inputs of the hypothalamus (areas not protected by the BBB)?
OVLT (organum vasculosum of the lamina terminalis - senses changes in osmolarity)
area pastrema (responds to emetics)
What are the 2 inputs of the hypothalamus (areas not protected by the BBB)?
OVLT (organum vasculosum of the lamina terminalis - senses changes in osmolarity)
area postrema (responds to emetics)
What does the lateral area of the hypothalamus control?
What happens if this area is destroyed?
What stimulates or inhibits it?
Controls hunger
Destruction –> anorexia
Inhibited by leptin
*If you zap your LATERAL nucleus, you shrink LATERALly
What does the ventromedial area of the hypothalamus control?
What happens if this area is destroyed?
What stimulates or inhibits it?
Controls satiety
Destruction (e.g. craniopharyngioma) –> hyperphagia
Stimulated by leptin
*If you zap your VENTROMEDIAL nucleus, you grow VENTRALly and MEDIALly.
What does the anterior area of the hypothalamus control?
What happens if this area is destroyed?
What stimulates or inhibits it?
Controls cooling and parasympathetics
*Anterior nucleus = cool off (cooling, and pArasympathetic)
A/C = anterior cooling
What does the posterior area of the hypothalamus control?
What happens if this area is destroyed?
What stimulates or inhibits it?
Controls heating and sympathetics
*If you zap your posterior hypothalamus, you become a poikilotherm (cold-blooded, like a snake)
What does the suprachiasmatic nucleus (SCN) area of the hypothalamus control?
What happens if this area is destroyed?
What stimulates or inhibits it?
controls circadian rhythm
What drives the sleep cycle?
the circadian rhythm which is driven by the SCN of the hypothalamus
What regulates the SCN?
the environment (e.g. light)
What is the pathway for secreting melatonin from the pineal gland?
SCN –> releases NE –> pineal gland –> releases melatonin
What are the two stages of sleep?
REM and non-REM sleep
What decreases REM sleep?
alcohol
benzodiazepines
barbiturates
NE
When does bedwetting, night terrors, and sleepwalking occur?
Stage N3 of Non-REM sleep
What is one treatment for bedwetting?
oral desmopressin acetate (DDAVP) - mimics ADH
What is one treatment for night terrors and sleepwalking?
benzodiazepines
What stage of the sleep cycle does bruxism occur?
Stage N2 of Non-REM sleep
During what stage of the sleep cycle do you have variable pulse and BP?
REM sleep
During what stage of the sleep cycle do you have dreaming, penile/clitoral tumescence, and possibly memory processing?
REM sleep
What is the order of the sleep cycle stages and what are their EEG waveforms?
Awake (eyes open) - beta Awake (eyes closed) - alpha Non-REM sleep Stage N1 - Theta Stage N2 - Sleep spindles and K complexes Stage N3 - Delta REM sleep - Beta
*At night, BATS Drink Blood.
Where does ADH originate from in the brain?
supraoptic nucleus in the hypothalamus
Where does oxytocin originate from in the brain?
paraventricular nucleus in the hypothalamus
What is the function of the thalamus?
major relay for all ascending sensory information except olfaction
What is the input, info, and destination for the VPL of the thalamus?
input: spinothalamic and dorsal columns/medial lemniscus
info: pain and temperature, pressure, touch, vibration, and proprioception
destination: primary somatosensory cortex
What is the input, info, and destination for the VPM of the thalamus?
input: trigeminal and gustatory pathway
info: FACE sensation and taste
destination: primary somatosensory cortex
* “M”akeup goes on the FACE (VP”M”)
What is the input, info, and destination for the LGN of the thalamus?
input: CN II
info: vision
destination: calcarine sulcus
* Lateral = Light
What is the input, info, and destination for the MGN of the thalamus?
input: superior olive and inferior colliculus of tectum
info: hearing
destination: auditory cortex of temporal lobe
* Medial = Music
What is the input, info, and destination for the VL of the thalamus?
input: basal ganglia, cerebellum
info: motor
destination: motor cortex
What is the function of the limbic system?
Collection of neural structures involved in emotion, long-term memory, olfaction, behavior modulation, and ANS function
What are the structures in the limbic system?
hippocampus, amygdala, fornix, mammillary bodies, and cingulate gyrus
What is a helpful pneumonic to remember the functions of the limbic system?
The famous “4 F’s”
Feeding Fleeing Fighting Feeling Sex
What is the function of the cerebellum?
modulate movement
coordination and balance
What are the deep nuclei of the cerebellum?
lateral –> medial
Dentate, Emboliform, Globose, Fastigial
*Don’t Eat Greasy Food
What physical findings are seen with a lateral lesion to eh cerebellum?
decreased movement of extremities (propensity to fall towards injured IPSILATERAL side)
What are findings seen with a medial lesion of the cerebellum?
truncal ataxia, nystagmus, and head tilting, wide based (cerebellar) gait, deficits in tranquil coordination
Typically bilateral motor deficits
What disease is associated with degeneration of the CNS, Lewy bodies, and loss of DA neurons?
Parkinson disease
What is the main component of Lewy bodies in Parkinson disease?
alpha-synuclein
Where is the location of the dopaminergic neurons affected in Parkinson disease?
substantia nigra pars compacta
What are physical symptoms of Parkinson disease?
*Parkinson “TRAPS” your body
"T"remor (at rest - pill rolling tremor) cogwheel "R"rigidity "A"kinesia "P"ostural instability "S"huffling gait
What are the genetics associated with Huntington disease?
AD
trinucleotide repeat disorder (CAG) on chromosome 4
What are physical symptoms of Huntington disease?
choreiform movements
aggression
depression
dementia
What are the NT changes seen in the brain in Huntington disease?
decrease in GABA and ACh
What lesion can be seen in the brain of Huntington disease?
atrophy of the caudate nuclei
A lesion to the contralateral sub thalamic nucleus (e.g. lacunar stroke) would result in what movement disorder?
hemiballismus (sudden, wild flailing of 1 arm +/- ipsilateral leg)
A lesion to the basal ganglia (e.g. Huntington disease) will result in what movement disorder?
chorea (sudden, jerky, purposeless movements)
AND
athetosis (slow, writhing movements - esp. in the fingers)
Myoclonus can commonly be seen in which diseases?
renal and liver failure
What is an essential tremor (postural tremor)?
action tremor, exacerbated by holding posture/limb position
What are treatments for essential tremors?
beta-blockers or primidone
Others self-medicate with EtOH
What is an intention tremor?
slow, zigzag motion when pointing/extending toward a target
Often seen with cerebellar dysfunction
What is a consequence or a lesion to the amygdala?
Are there are associated diseases with this lesion?
Kluver-Bucy Syndrome (hyperorality, hypersexuality, disinhibited behavior)
Assoc. with HSV-1
What is a consequence or a lesion to the frontal lobe?
Are there are associated diseases with this lesion?
Disinhibition and deficits in concentration, orientation, and judgement
What is a consequence or a lesion to the right parietal-temporal cortex?
Are there are associated diseases with this lesion?
Spatial Neglect Syndrome (agnosia of the contralateral side of the world)
What is a consequence or a lesion to the left parietal-temporal cortex?
Are there are associated diseases with this lesion?
agraphia, acalculia, finger agnosia, and left-right disorientation
What is a consequence or a lesion to the reticular activating system (midbrain)?
Are there are associated diseases with this lesion?
reduced levels of arousal and wakefulness
What is a consequence or a lesion to the mammillary bodies (bilateral)?
Are there are associated diseases with this lesion?
Wernicke-Korsakoff Syndrome (confusion, ataxia, memory loss, confabulation, personality changes)
Assoc. with thiamine (B1) deficiency and excess EtOH use; can be precipitated by giving glucose without B1 to a B1-deficient patient
What is a consequence or a lesion to the basal ganglia?
Are there are associated diseases with this lesion?
tremor at rest, chorea, or athetosis
Assoc. with Parkinson disease
What is a consequence or a lesion to the cerebellar hemisphere?
Are there are associated diseases with this lesion?
intention tremor, limb ataxia, and loss of balance
IPSILATERAL deficits –> fall towards side of lesion
*Cerebellar hemispheres are LATERALly located - affect LATERAL limbs
What is a consequence or a lesion to the cerebellar vermis?
Are there are associated diseases with this lesion?
truncal ataxia and dysarthria
*Vermis CENTRALly located - affect CENTRAL body
What is a consequence or a lesion to the sub thalamic nucleus?
contralateral hemiballismus
What is a consequence or a lesion to the hippocampus (bilateral)?
anterograde amnesia
What is a consequence or a lesion to the paramedic pontine reticular formation?
eyes look away from side of lesion
What is a consequence or a lesion to the frontal eye fields?
eyes look toward lesion
What are the physical findings in central pontine myelinolysis?
acute paralysis, dysarthria, dysphagia, diplopia, and loss of consciousness
What is the pathogenesis of central pontine myelinolysis?
massive axonal demyelination in pontine white matter tracts secondary to osmotic forces and edema (a result of overly rapid correction of HYPOnatremia)
What tracts are affected by central pontine myelinolysis?
corticospinal and corticobulbar tracts
What is a helpful pneumonic to remember whether central pontine myelinolysis will occur or cerebral edema will occur d/t Na+ correction?
“From low to high, your pons will die” (CPM)
“From high to low, your brain will blow” (cerebral edema/herniation)
What are signs of Broca aphasia?
nonfluent aphasia with INTACT comprehension
Broca area - inferior frontal gyrus of FRONTAL LOBE
What are signs of Wernicke aphasia?
fluent aphasia with IMPAIRED comprehension and repetition
Wernicke area - superior temporal gyrus of TEMPORAL LOBE
What are signs of global aphasia?
NONFLUENT aphasia with IMPAIRED comprehension
Both Broca and Wernicke areas affected
What are signs of conduction aphasia?
poor repetition but fluent speech, intact comprehension
Can be caused by damage to left superior temporal lobe and/or left supramarginal gyrus
*Can’t repeat phrases such as, “No ifs, ands, or buts.”
What are signs of transcortical motor aphasia?
nonfluent aphasia with good comprehension and repetition
What are signs of transcortical sensory aphasia?
fluent speech and repetition with POOR comprehension
What are signs of mixed transcortical aphasia?
confluent speech, poor comprehension, good repetition
