Neuro 1.1 Midterm

what is the peripheral NS composed of?

• somatic (sensory/motor)

• autonomic (SNS, PNS, ENS)

• ganglia → neuronal cell body clusters in PNS

what is the central NS? what is it enclosed by?

• brain + spinal cord

• nuclei → cluster of neuronal cell bodies in CNS

• enclosed in meninges (dura, arachnoid, (CSF), pia mater)

where is gray matter (neuronal bodies) found? function?

• peripheral brain + central spinal cord

• dorsal/post. horn → receive pain + temp sensation

• ventral/ant. horn → send motor signal

• lat. horn → autonomic nerve (involuntary fxn like digestion + breathing)

where is white matter (myelinated axons) found? function?

• central brain + peripheral spinal cord

• asc. tract (sensory) → dorsal/post. column, spinothalamic, spinocerebellar, spinoreticular

• desc. spinal cord (motor) → corticopsinal, rubropsinal, tectospinal, vestibulospinal, reticulospinal

what are the components of a neuron?

• polarized cell for electrical comm.

• soma → nucleus, ER, golgi, mit., lysosome

• cytoskeleton → neuro/microfilaments, microtubules

• dendrite → synaptic contact (signal to soma)

• axon → uniform diameter, myelin + NOR

what are components of the axons?

• larger diameter + shorter length → inc. velocity of AP

• hillock → AP begins

• myelin → inc. AP speed via restricting ionic flow to NOR

• NOR → unmyelinated where ionic flow occurs (saltatory conduction)

what is the function of the CNS neuroglial cells?

• astrocyte

• oligodendrocyte

• microglia

• ependymal

• astrocyte → most, mechanical support, buffer EC environment (glutamate)

  • prevents neuronal toxicity

• oligodendrocyte → 1 myelinates multiple axons + axon integrity; can’t regenerate

• microglia → smallest, phagocytic, APC, release free radical + NO

• ependymal → form epithelial lining of ventricular space (sec. CSF)

what is MS? symptoms?

• autoimmune disorder → destroys oligodendrocytes in CNS

• symptoms: muscle weakness, tremors, tingling + numbness, diplopia/vision loss/nystagmus

what is the function of PNS neuroglial cells?

• schwann→ form myelin (1 cell for 1 axon), phagocyte; can regenerate

• satellite cells

what is guillain barre? DM neuropathy? symptoms?

• guillain barre → autoimmune (destroys schwann cells)

  • weakness starting @ lower limbs, ascends → respiratory failure

• DM neuropathy → high glucose (destroys schwann cells)

  • sensory loss, numbness, pain, burning

what is nernst potential (aka equilibrium or reversal potential)?

• 61.6 x log (So/Si)

• membrane potential (Vm) → near nernst potential of ion to which membrane potential has highest conductance

what are the steps of an action potential?

• RMP → ~ K nernst potential bc membrane has high conductance

• stimulus → AP if exceed threshold (if cont. stim. → rapid AP entire duration)

• depolarization → Na influx (less -), AP Vm ~Na nernst potential

• repolarization → Na close, K efflux (more -), AP Vm ~K nernst potential

• return to RMP

how are depolarization and repolarization effected by ion imbalances?

• depolarization → hyponatremia = AP prevented + upstroke rate dec./gone

• repolarization

  • hyperkalemia = extra K raises RMP → sustained depolarization + N channels inact. → no AP (muscle weakness)

  • hypokalemia = inc. AP duration via failure to repolarize (sustained muscle contraction)

what is the difference between absolute and relative refractory period?

• absolute (during de/repolarization) → all Na channel inactivated b4 peak of AP (prevents another AP)

• relative → some Na channels inactive + some closed (another AP can occur w/ stronger stim.)

  • hyperpolarization → via too much K efflux b4 K channels close (< -70 mV)

what are the characteristics of an electrical synapse?

• fast + bidirectional

• little modulation → pH + Ca

• present in embryonic neurons (less widespread), cardiac + smooth muscle, glia

what are the steps of an electrical synapse?

• AP arrives

• direct flow of ions

• gap jxn formation

• AP propagate

• signal transmission

what are the characteristics of an chemical synapse?

• slow + unidirectional

• lot of modulation: Ca, hypoxia, acidosis (coma), alkalosis (seizure)

• present in adult neurons

what are the steps of a chemical synapse?

• AP arrival

• Ca channel open

• vesicles fuse

• NT binding to receptor

• NT breakdown (to stop firing)

what is fatigue of synaptic transmission in chemical synapse? cause?

• excitatory synapses repetitively stim/ @ rapid rate → firing rate becomes less

• due to → NT store exhaustion, inactivation of post synaptic membrane receptors, dev. of abnormal ion conc. in post synpatic cell

what is post synaptic potential (PSP)? excitatory PSP? inhibitory PSP?

• change in membrane potential (Vm) → via flow fo charge

• excitatory NT (glutamate) → depolarizing PSP/ excitatory PSP (via inc. Na perm/open channels)

• inhibitory NT (GABA, glycine) → hyperpolarizing PSP/inhibitory PSP (via dec. Na perm/ open Cl channels)

what are catecholamines? what signaling do they use?

• dopamine, epinephrine, norepinephrine

• GPCR (Gaq, Gai, Gas)

what is the process catecholamine production? copper deficiency? dopamine B-hydroxylase deficiency?

• tyrosine → DOPA (via BH4) → dopamine (via B6) → NE (via dopamine B-hydroxylase)→ epinephrine (via SAM)

• low Cu → low NE + E (converts dopamine to NE)

• dopamine B-hydroxylase → low NE + E (dizziness + low BP)

what is the process of catecholamine action termination? presynaptic vs post synaptic degradation?

• reuptake (SLC6A2) or degrade (MAO or COMT) to vanillylmandelic acid (excrete)

• presynaptic: monoamine oxidase (MAO) → oxidize amine to aldehyde then acid (+ to -)

• postsynaptic: catechol-O-methyltransferase (COMT) → methylate phenol to inactivate NT

what is parkinson’s? symptoms? treatment?

• loss of dopamine neurons → dec. dopamine reaching basal ganglia

• symptoms: tremors, difficulty walking, dystonia, rigidity, bradykinesia, depression, GI issue, sweat

• Tx: DOPA or levodopa, synthetic agonists, inhibiting MOA

how does amphetamine affect catecholamines? side effects?

• inc. dopamine/NE release + reuptake

• side effect → wakefulness, physical activity, dec. appetite, rapid HR, irregular heartbeat, inc. BP + hyperthermia (twitch + itch)

what effect does cocaine have on catecholamines? side effects? physiological effects?

• block dopamine/NE reuptake by inhibiting DAT + NAT enzymes

• side effects → god-like euphoria, excited, confident/anxious, happy, panicky, risk-taking

• physiological → faster HR, raised body temp, feel sick/inc. want to go to toilet

what are indoleamine NTs? functions? production?

• serotonin + melatonin

• fxn: relaxation, memory, focus (no fear), circadian cycle-awake

• prod.: Trp → 5HT → serotonin (via B6) → NAS → melatonin (via SAM)

function of psilocin? function of SSRIs + MAO inhibitors?

• psilocin (mushroom) → serotonin receptor agonist = prolonged act. → psychedelic effect

• SSRIs + MAO inhibitor → prevent reuptake of serotonin = more left in synapse → prolonged act. (treats depression)

production of ACh receptors? ACh-esterase function?

• Ac-CoA → ACh (via B6) → ACh R (nicotinic/ionotropic and muscarininc/metabotropic)

• ACh-esterase → serine hydrolase that degrades ACh

which agents inhibit ACh-esterase? side effects?

• pesticides (chlorpyrifos) → inactivation → too much ACh in synapse → nerve cell dysfxn

  • confusion, low pulse, wheezing, clammy/sweaty skin, paralysis

• sarin (warfare agent) → suicide inhibition (irreversible bind)

  • excess muscle contraction (resp. failure, diarrhea), low BP, drooling, paralysis

histamine production? GABA production?

• histidine → histamine (via B6) → inflammation + bronchoconstriction (degraded by MAO)

• glutamate (main excitatory NT) → GABA (inhibitory) (via B6)

  • NMDA (glutamate) receptor antagonists → ketamine, amantadine, dextromethorphan, phencyclidine (PCP)

GABAA ionotropic (ligand gated) receptor process? GABAB metabotropic Gai-coupled receptors process?

• GABA binds → Cl influx → inhibit neuronal activity

• GABA binds → K efflux + Ca channel inhibition → suppress neuronal excitability

what are the GABAA (ligand gated) receptor agonists? what are they used for?

• barbiturates → seizures, insomnia, epilepsy, anxiety

• benzodiazepine → muscle relaxant, panic disorder epilepsy, anxiety

• muscimol → psychoactive mushroom amanita muscaria

what triggers Mu receptors? pathway after? side effects? tolerance? treatment?

• endorphin (opioid) → trigger Mu R → Gai signaling → dec. AC activity → inhibit cAMP CREB

• side effects: relaxation, CNS + spinal analgesia, sedation, resp. inhibition, dec. GI motility, modulate NT/hormone release, altered mental state

• opioid tolerance: chronic exposure → upregulate cAMP + B-arrestin path to oppose opioid induced Gai signaling

• Tx → naloxone

what is the function of the frontal lobe? what is the function of the following components?

• prefrontal cortex

• primary motor cortex

• premotor cortex

• frontal eye field

• broca’s area

• movement, speech, planning

• prefrontal → behavior, personality, memory, emotional expression, executive fxn

• primary motor (precentral gyrus) → fine, skilled, voluntary muscle

• premotor → planning/coordinating movement

• frontal eye field → voluntary eye movement

• broca’s area (inf. frontal gyrus) → speech formation and production

  • lesion → incoherent speech

what is the function of the parietal lobe? primary somatosensory cortex? injury?

• proprioception + sense/recognize sensation

• primary somatosensory cortex (postcentral gyrus) → proprioception + sense of touch

• lesion → difficulty writing (agraphia) + inability to perceive objects normally (agnosia)

what is the function of the temporal lobe?

• hearing + recognizing audio

• hippocampus → learning, memory, storage, limbic system

  • damage → amnesia

• wernicke’s area (sup. temporal gyrus) → auditory cortex (understand speech)

  • lesion → wernicke’s aphasia (inability to comprehend)

function of the occipital lobe? function of limbic lobe?

• occipital (occipital gyrus) → see + recognize visual stimuli (object recognition)

• limbic (cingulate gyrus) → process emotion, memory, appetite, regulation of behavior

what are brodman’s areas? which areas are somatosensory?

• cerebral cortex divided into ~52 areas based on histological differences

• 1-3 → primary somatosensory cortex (ant. parietal)

• 5+7 → somatosensory association cortices (post. parietal)

what occurs if there is lesion to somatosensory brodman’s areas?

• 1 → texture discrimination deficit

• 2 → loss of size + shape discrimination (astereognosis)

• 3b → texture, size, shape discrimination deficit (astereognosis)

• 5 or 7 (hemispatial neglect) → can’t perceive anything on contralateral side + agnosia (can’t recognize familiar object or stimuli)

which brodman’s areas are motor? cognitive? visual? auditory

• 4 → primary motor cortex + 6 —> premotor/supplementary motor cortex

• 10 → high cognitive fxn (task manage, planning, working memory)

• 17 → primary visual cortex + 18,19 → visual association

• 41 → primary auditory cortex + 42 → secondary auditory cortex

what is the function of the forebrain? what composes it?

• sensory processing, endocrine structure, higher reasoning

• telencephalon + diencephalon

what the telencephalon (cerebral hemispheres) composed of? function of substantia nigra of basal ganglia? lesion?

• cerebral cortex, white matter, basal ganglia

• substantia: produces dopamine → smooth voluntary movement

• lesion (recall parkinson’s) → involuntary limb movement (wild, large amplitude, flinging)

what is the diencephalon composed of?

• hypothalamus, thalamus, pineal gland, neurohypophysis, retina

• thalamus → screen all incoming sensory data + relay to appropriate region; indirectly regulate consciousness

• hypothalamus → regulate basic biological needs (hunger, thirst, appetite, temp.)

what is the function of the thalamus nuclei?

• ant. → limbic system (emotional) → receives input from mammillary bodies + project to cingulate gyrus

• ventral: relay somatosensory info to primary cortex

• med. geniculate → relay sound frequency from inf. colliculus to primary cortex

• lat. geniculate → relay visual info from sup. colliculus to primary cortex

what are the ventral nuclei of the thalamus?

• ant. → relay signal from basal ganglia + cerebellum to motor cortex → motor planning

• lat. → relay signal to primary motor cortex → motor activity

• post. lat. (VPL) → relay signal from trunk + extremities

• post. med. (VPM) → relay signal from head + face

what are the nuclei of the hypothalamus?

• ant. → ant. (thermostat), suprachiasmatic (circadian), PVN + supraoptic (ADH)

• tubular → arcuate (appetite), VMN (satiety), dorsomed. (feeding + stress), lat. (hunger)

• preoptic → med. (GnRH) + ventrolat. (sleep)

  • links w/ pit. gland + regulate stress, metabolism, reproduction

• post. → mamillary bodies (memory + spatial nav.), post. (thermoreg.)

  • part of limbic system w/ hippocampus

what composes the brain stem? blood supply? reticular formation function? what are the main sensory tracts?

• midbrain + hindbrain

• blood supply → basilar a. + vertebral a.

• reticular formation (brainstem nuclei) → regulate cardiac + resp. fxn, behavioral response, sleep-wake cycle, aware/alert/conscious

• sensory tract → corticospinal, dorsal column med. lemniscus, ant. lat. spinothalamic

what is brown-sequard syndrome? ipsilateral symptoms? contralateral symptoms?

• functional hemisection cutting of lat. corticospinal + spinothalamic tracts

• ipsilateral → paralysis, loss of discriminative touch/proprioception + loss of pain/temp @ level of damage (dermatome)

• contralateral → loss of pain/temp 1-2 segments below lesion

what is the clinical criteria for confirming brain stem death?

• pt. irreversibly unconscious + incapable of breathing unaided (inc. plasma CO2 conc.)

• absence of gag, corneal, vestibulo-ocular reflexes

• fixed + dilated pupils of the eyes

• absence of motor response to stimulation

what is the function of the midbrain (mesencephalon)? nerves? lesions?

• motor movement of head/eyeball, pupillary size, audio/visual processing

• CN III + IV

• lesion → loss of CNIII/IV fxn, drooping eyelid (ptosis), pupils sluggish to fixed reactivity

what are the regions of the midbrain (mesencephalon)?

• pretectal: contains edinger-westphal nucleus → meidates pupillary light reflex + lens accommodation

• tegmentum: covering → ant. surface, contain red nucleus (motor coordination)

• tectum: ceiling → post., contains sup. + inf. colliculus

  • sup. (+ lat. geniculate): visual path + reflex → upward gaze

  • inf. (+ med. geniculate): auditory path + reflex → cochlear nuclei

what is the function of the hindbrain? what does it contain?

• autonomic fxn (resp. rhythms + sleep)

• metencephalon (pons + cerebellum)

• myelencephalon (medulla) → vasomotor (BP), cardio, resp. swallow, eye movement, vomit, sneeze, cough

what is the function of the cerebellum division of the metencephalon? lesion?

• flocculonodular lobe (balance), ant. lobe (fine motor skill), post. lobe (practiced/learned motor activities)

• lesion → difficulty walking, unsteady gait, slurred speech, nystagmus, tremor, vertigo

what is the function of the pons of the metencephalon? lesion? pneumotaxic and apneustic center function?

• arousal, sleep, motor control, muscle tone, breathing, taste

• lesion → pinpoint pupil, prolonged inhalation + hypoventilation

• pneumotaxic + apneustic → rate, pattern, intensity of breathing

what are the nuclei of the pons?

• sup. + inf. pontine → info btwn pons + cerebellum

• sup. olivary → auditory impulse from both ears (via cochlear nuclei)

• locus coeruleus → sec. NE; signal arousal + REM

• raphe → sec. serotonin, signal non-REM, mood + aggression

what are the nerves of the pons? what is the medial longitudinal fasciculus (MLF)? lesion?

• CN V, VI, VII, VIII → located @ pontomedullary jxn

• MLF → connects CN III, IV, VI (eyeball muscle)

  • lesion → failure of adduction past midline of eyes, leads to nystagmus

what are the fasciculi of the myelencephalon (medulla oblongata)?

• cuneate (C1-T6) → detect touch, proprioception, vibration from ipsilateral upper limb

• gracile (T6-S4) → detect touch, proprioception, vibration from ipsilateral lower limb

what are the nuclei of the myelencephalon?

• solitary → taste, carotid baroreceptors + chemoreceptors

• spinal of trigeminal nerve → somatic sensory from tympanic membrane, middle ear, upper pharynx, soft palate, post. 1/3 tongue

• inf. salivatory → PS fibers to otic ganglion + parotid gland

• tractus solitarius → autonomic reg.

• inf. olivary → reg. motor coordination + learning

what are the nerves of the myelencephalon? lesions?

• ant. portion → IX, X, XI, XII

  • nucleus ambiguus → rise to efferent fibers of vagus (X) + glossopharyngeal (IX)

• lesion → affected muscle weakness, loss of contralateral sensation, dysphagia, dysarthria, abnormal deep tendon reflex (corticospinal + corticobulbar tracts)

CN I function? lesion?

• olfactory → smell

• lesion → anosmia

CN II function? lesion?

• optic → visual info

• lesion → ipsilateral mononuclear visual field loss

CN III function? what muscles does it innervate? lesion?

• oculomotor → eyeball movement (adduction), upper eyelid elevation, pupil constriction (miosis), lens accommodation (edinger-westphal nucleus)

• innervates sup., inf., med., rectus + inf. oblique

• lesion → eye looks down + out (ext./lat. strabismus), diplopia, loss of parallel gaze, ptosis, fixed + dilated pupils (mydriasis), loss of near accommodation response (cycloplegia)

CN IV function? nucleus? lesion?

• trochlear → eyeball look down + inward (to nose) (via sup. oblique innervation)

• trochlear nucleus → beneath periaqueductal gray area (near midline, @ sup. colliculi (vision) in midbrain)

• lesion → eye looks up + in (vert. diplopia), result in: trouble going downstairs, difficulty reading, head tilts AWAY from lesion site

CN V function? nerves?

• trigeminal → innervate muscles for mastication, swallowing, ear

• nerves → spinal + principal nuclei

  • V1 (ophthalmic) → forehead, scalp, nose sensation

  • V2 (maxillary) → cheek, upper lip, nasal cavity sensation

  • V3 (mandibular) → jaw, lower lip, chin sensation + motor fibers (mastication)

    • also mesencephalic + motor nuclei

what are the V3 (mandibular) nerve nuclei?

• sensory → use trigeminothalamic path to relay somatic sensation from face, oral cavity (ant. 2/3 tongue), teeth to VPM

  • principal (main) → fine touch + vibration

  • spinal (desc.) → pain + temp

• mesencephalic → proprioception/kinesthesia from head, mastication muscle sensation, myotatic jaw jerk reflex

• motor → control mastication muscle, mylohyoid, ant. belly of digastric, tensor tympani (middle ear), tensor palati (swallow)

CN V (trigeminal) lesion? trigeminal neuralgia?

• lesion → loss of somatic sensation over skin of face, forehead, scalp, lips, ant. 2/3 tongue, teeth, jaw, weak chewing (jaw deviates to weak side), weak/loss of corneal reflex (blink), sensitivity to noise

• neuralgia (tic douloureux) → episodic “paroxysmal” pain, restricted to peripheral maxillary/mandibular division on one side

CN VI function? lesion?

• abducens → innervates lat. recuts muscle (eye) (lat. + down movement)

• lesion → inability to abduct eye (horizontal diplopia), med. directed squint (int./med. strabismus), parallel gaze loss

CN VII function? lesion?

• facial → motor fibers for facial expression, lower lip, stapedius, stylohyoid, post. belly digastric muscle, salivary gland, lacrimal gland, taste in ant. 2/3 tongue

• w/ CN V → controls corneal (blink) reflex

• lesion → bells palsy, droopy mouth corner, droopy eyelid (inability to blink/close), inability to wrinkle forehead, asymmetrical smile (can’t puff cheek), loss of taste ant. 2/3 tongue, noise sensitivity

CN VIII function? lesion?

• vestibulocochlear → balance + coordination

• lesion → vertigo

CN IX function? lesion?

• glossopharyngeal → taste from post. 1.3 tongue, sensation (int. tympanic membrane, oropharynx, epiglottis, soft palate)

  • info from carotid sinus baroreceptors + body chemoreceptors

  • nucleus ambiguus → eff. motor fibers

• lesion → dysphagia, loss of gag reflex, loss of somatic sensation (oropharynx, epiglottis, soft palate), loss of taste, altered carotid reflex

CN X function? lesion?

• vagus → motor axons to muscles of palate, larynx, pharynx (speech/phonation + swallowing)

  • nucleus ambiguus → eff. motor fibers

• lesion → dysphagia, dysarthria, nasal speech/hoarseness, loss of gag reflex (involves CN IX, X)

CN XI function? lesion?

• accessory → innervate SCM + trapezius

• lesion → inability to turn head to opposite side of injured nerve, weak shoulder abduction + ER, inability to shrug

CN XII function? lesion?

• hypoglossal → tongue movement + swallowing

  • motor → stylo, hypo, genioglossus

• lesion → inability of tongue movement, deviation of protruded tongue, weak muscles (slurred speech)