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95 Cards in this Set
- Front
- Back
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where do sympathetics come from?
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thoracic and lumbar levels
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where do parasympathetics come from?
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cranial nerves and sacral level
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components of a reflex
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afferent limb, integrating center, efferent limb
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glia
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astrocytes, oligodendrocytes, microglia
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fxn of astrocytes
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regulate intercellular environment, trophic, contact blood vessels
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fxn of oligodendrocytes
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produce CNS myelin
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fxn of microglia
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macrophages
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path of CSF
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choroid plexus to subarachnoid space where it is absorbed by arachnoid granulations
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conductance
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measures the ease of flow of current between two points
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reciprocal of conductance
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resistance
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resting membrane potential
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membrane potential or voltage drop across the membrane due to separation of charge across the membrane (capacitor) in absence of any other stimuli or inputs.
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Fxn of Na+/K+ ATPase
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3Na+ out and 2K+ in per ATP hydrolyzed
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membrane time constant
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length of time it takes for 63% of total change in membrane potential to occur
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temporal summation
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when stimuli too small to elicit a response occur close enough together in time so that they add together and lead to a response--happens with longer time constants
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length constant
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distance at which ~37% of original change in membrane potential still occurs
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how are ions distinguished in ion channels?
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energy of hydration
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what forms selectivity filter of many voltage-gated ion channels?
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amino acids at tips of "pore loops"
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how does S4 voltage sensor work?
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positively-charged amino acids every third position of the S4 transmembrane spanning region makes region sensitive to changes in membrane potential, resulting in a "shift" in the position of the S4 in response to depolarization as these positive charges are "repelled" when the inside of the cell becomes more positive.
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How does Na channel inactivation work?
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Cluster of positive amino acids in intracellular loop between domains 3 and 4 of the Na channel protein is though to "swing up" and block the open channel from the inside. "Plug" stays in place until membrane becomes repolarized.
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Which channel inactivates rapidly despite maintained depolarization?
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Na+ channels
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what do tetrodotoxin and saxitoxin do?
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block flow of Na ions though pores.
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How does lidocaine work?
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binds to S6 region in 4th domain of Na channels and results in use-dependent inactivation of channel--keeps you captured in inactive state.
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what happens if you have incomplete inactivation of a mutant Na channel?
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prolonged depolarization and abnormal electrical activity
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what does myelin do to capacitance and conduction velocity?
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decreases capacitance
increases conduction velocity |
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what regulates thickness of myelin sheath?
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level of neuregulin expression
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what is saltatory conduction?
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aciton potentials only generated at nodes of Ranvier and not along every point along axon--MUCH faster and lower energy requirement because of less Na-K ATPase activity
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what fluid do scala tympani and scala vestibuli have and what is it like?
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perilymph
like CSF |
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what fluid does scala media have and what is it's predominant characteristic?
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endolymph
high [K+] |
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what does exocytosis of presynaptic vesicles require?
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influx of Ca2+ ions upon depolarization
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what are the small molecule neurotransmitters?
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dopamine, norepi, epi, 5-HT, histoamine, glutamate, GABA, glycine, acetylcholine
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what are the majorer larger neuropeptides and neurohormones?
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opioids, cannabinoids, vasopressin, oxytocin
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what are the excitatory ionotropic receptors?
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acetylcholine receptors
glutamate receptors 5-HT3 class of serotonin receptors Purinergic (adenosine and ATP) receptors |
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what are the inhibitory ionotropic receptors?
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GABA receptors (types A&C)
glycine receptors |
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what is predominant inhibitory transmitter in adult brain?
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GABA
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what is predominant inhibitory transmitter in the spinal cord?
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glycine
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what compounds can activate both ionotropic and metabotropic receptors?
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GABA, glutamate, serotonin, ATP, acetylcholine
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Definition of excitation
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action of NT is to drive membrane potential to value that is more depolarized than the threshold potential for generating an action potential
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definition of inhibition
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action of NT is to keep membrane potential from reaching Vthreshold
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what are GABA and glycine receptors permeable to?
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Cl-
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how do you terminate action of a NT?
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diffusion, reuptake, enzymatic degradation
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what is facilitation?
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increased release of NT with APs in rapid succession. Residual Ca2+ produces an increase in m per impulse
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what is synaptic depression?
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with prolonged, high frequency synaptic activity, the pool of releasable vesicles is depleted leading to diminished NT release and progressively smaller synaptic responses
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what is desentization?
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receptor channel does not conduct ions even though agonist is bound
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how do metabotrophic NT receptors work?
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binding of NT activates G proteins; causes GTP to replace GDP; activated G protein then activates enzyme(s) in 2nd messenger cascade
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two characteristic of metabotrophic receptors
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amplification and divergence
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how do tolerance and withdrawl develop?
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covalent modification of existing receptors limits fxn. on slower time scale, drugs acting as ligand-gated ion channels can lose their effect because prolonged exposure to an agonist can lead to receptor-mediated sequestration, down-regulation, and changes in receptor subunit gene expression
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macroglia
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neuroectoderm, oligodendrocytes, astrocytes, ependymal cells, choroid plexus, radial glia
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microglia
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mesoderm, monocyte/macrophage
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cerebellary astrocytes
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molecular layer, Purkinje cell layer, granular layer, white matter
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brain's fibroblasts
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astrocytes--lay down BM and laminin
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where are ependymal cells and what are their function?
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line the ventricles and have cilila that move CSF within ventricles
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fxn of astrocytes
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structural support
tripartite synapse extracellular [K+] BBB & vascular regulation Trophic factors ECM proteins Detox Calcium wave communication Controls making and breaking of synapses Neuropath healing NMDA receptors Communicate via ATP--causes Ca2+ release |
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cells involved in neuroinflammation
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microglia, astrocytes, endothelial cells, perivascular cells, circulating immune cells
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what are the pharmacological approaches to controlling neuroinflammation?
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steroids, NSAIDs, antibiotics, cytokines and cytokine modulatory drugs, cannabinoids, vaccines
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what runs is large anterior median sulcus?
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anterior spinal artery
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what occupies subarachnoid space?
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CSF, arteries, veins
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where do motor fibers decussate?
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pyramidal decussation
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where are CN XI, X, IX?
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post-olivary sulcus at jxn between pons and medulla
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where does CN V emanate from?
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peduncle
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where does CN III emanate from?
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interpeduncular fossa
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where is the 4th ventricle?
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between the cerebellum and the brainstem
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what does facial colliculus contain?
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facial and abducens nerves
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what runs in lateral fissure?
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middle cerebral artery
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where are alar plates and what are they involved in?
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lateral brainstem
sensory fxn |
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where are basal plates and what are they involved in?
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medial brainstem
motor fxn |
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where are the autonomics in the spinal cord?
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sulcus limitans--lateral horn
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where are internal arcuate fibers?
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caudal medulla
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what will a tumor in the 4th ventricle compress?
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CN VI and VII
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what do raphe neurons make?
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serotonin
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where do fibers in red nucleus come from?
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superior cerebellar peduncle
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what does insular cortex control?
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autonomic and visceral responses
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portions of internal carotid artery
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cervical from bifurcation to skull
petrous in petrous part of temporal bone cavernous within cavernous sinus subarachnoid from exit from cavernous sinus to bifurcation into ACA & MCA |
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branches of petrous portion of ICA
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tympanic and pterygoid
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branches of intracranial ICA
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opthalmic, posterior communicating, anterior choroidal, ACA, middle cerebral
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branches of vertebral artery (from Subclavian)
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muscular and meningeal
posterior spinal PICA Anterior spinal artery |
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branches of basilar artery
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AICA, pontine arteries, SCA, posterior cerebral artery
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what makes norepinephrine?
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locus ceruleus
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what is Cushing reflex?
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with increased intracranial pressure, BP goes up to squeeze blood into brain. HR increases (vagal) and you may not want to decrease BP becuase it will compromise CBF
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what induces formation of BBB?
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astrocytic foot processes
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what does frequency of action potentials convey?
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intensity
(increased intensity of stimulus increases receptor potential which increases frequency of AP in peripheral axon) |
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what does adaptation convey?
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duration
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what does receptive field convey?
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location
(will respond to sensation anywhere in field, but highest response is closest to point of max sensitivity) |
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what are the largest fibers for?
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proprioception
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what are the smallest fibers for?
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dull/aching/burning types of pain
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where is dorsal nucleus of Clarke found?
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b/t C8 and L3
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cutaneous nerve domain
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area supplied by a particular branch
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dermatome
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area supplied by a particular spinal nerve
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what does Meissner's corpuscle detect?
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fine touch, motion detection
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what do Ruffini endings detect?
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stretch
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what do Pacinian corpuscles detect?
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vibration
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what do Merkel cell-neurite complexes detect?
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fine touch
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what are the proprioceptive mechanoreceptors?
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muscle spindles (stretch)
Golgi tendon organs Joint receptors |
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what is peripheral neuropathy?
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axon degneration that affects most metabolically active (longest) neurons first
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how does referred pain happen?
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visceral pain uses ALS--synapses on same neuron so brain doesn't know where pain came from
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what is the gate theory of pain?
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Aalpha and Abeta stimulate inhibitory neurons in dorsal horn that suppress pain fibers--rubbing will stimulate them
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