Neuron and introduction flashcards

From Iusmphysiology

---

Revision as of 17:18, 8 January 2011

def. of homeostasis resistance to change

came up with "homeostasis" Claude Bernard

recognized internal temperature control Claude Bernard

Walter Canon developed the concept of homeostasis

showed internal mechanisms controlled resistance to change Walter Canon

opposing forces are balanced equilibrium

no net transfer between compartments equilibrium

equilibrium movement is equal and opposite

equilibrium doesn't require energy to be maintained

steady state nothing is changing

requires energy to maintain steady state

interstitial fluid is the same as the plasma without... proteins (found in plasma but not...)

three components of feedback system sensor, effector, regulated variable

negative feedback is to stabilizing as positive feedback is to destabilizing (is to positive feedback as negative stabilizing is to...)

amount of body water in cells 2/3

aldosterone effect at the kidney release of potassium

aldosterone released by adrenal cortex

triggers adrenal cortex release of aldosterone high plasma K+

The ____ has higher K+ concentrations (cytoplasm, ECF) cytoplasm

In Nernst equation, chemical term is RT ln ([Xi] / [Xo])

In Nernst equation, electrical term is zxFVm

electrochemical force over a membrane (Ex) defined as Ex = 61.54 / Zx * Log [x0] / [xi]

normal resting cellular potential -70 mV

number of Na and K pumped by Na/K ATPase 3 Na out, 2 K in

two Na/K ATPase inhibitors (poisons) ouabain, digoxin

significance of D loop in ion channels sits in channel and determines specificity

simple spread (bumping of ions) along axon is called passive depolarization

approximate neuron voltage threshold for depolarization -55 mV

E sub-K represents what? the voltage at most negative hyperpolarized state

Tetrodotoxin inhibits what? voltage-gated Na channels

this type of AP conduction spreads in all directions passive conduction

the s4 domain is important to voltage-gated channels because it... senses the voltage

primary location of Na channels in neurons axon hillock and axon

absolute refractory period is responsible for what unique feature of APs? unidirectional travel

unidirectional travel of APs is enforced by the absolute refractory period provided by non-fxnal time of sodium channels

schwann cells wrap up to how many times around an axon 200

width of a node of ranvier 2 micrometers

channels found in nodes of ranvier lots of Na channels, no K channels

saltatory conduction is due to presence of myelin

why is saltatory conduction faster faster to have ions bump along in cytoplasm than to have to open every Na channel along the membrane

decay of AP caused by Resistance of cytoplasm, resistance of membrane (loos of ions / signal), non-fxn of Na channels

reason there is no hyperpolarization in nodes of ranvier because there are no K+ channels

orthodromic (synonym for) forward (unidirectional) conduction of AP

increased length constant, faster or slower faster

saltatory conduction length constant lower than passive conduction length constant? no, higher, faster

MS (mechanism, NS distribution) autoimmune rxn against myelin; CNS

CMT (mechanism, NS distribution) genetic, non-fxnal myelin; PNS

Guillian-Barre (mechanism, NS distribution) autoimmune after infection (molecular mimicry); PNS

Krabbe disease (mechanism, NS distribution) genetic, non-fxnal lysosomal protein, poor degradation of ga lactosylcera m ide beta-galactosidase; CNS and PNS

demyelination symptoms (4) slower conduction, total blockage, ectopic spike generation, cross-talk

expression of what determines shape of AP Na and K channels

main determinant of AP velocity diameter of axon

two connexon hemichannels make one gap jxn

gap jxns open in the presence of Ca++

connexins (of gap jxns) have how many domains 4

gap jxns have how many connexin subdomains 6

influx of what ion causes vesicle release in a neuron Ca++

three types of NT vesicles clear (40-50 nm), dense (100 nm), large dense (200)

clear NT vesicles hold ach, glycine, GABA, glutamate

glutamine or glutamate an NT? glutamate

large dense NT vesicles contain signaling peptides

Ca2+BS, Synaptobrevin, Syntaxin1, Snap25, NSF, Munc18 (fxn in vesicle release) detecting Ca++, Docking, Zipper formation, zipper formation, regulated, regulator

difference between short and long vesicle fusion: short fusion, vesicle can be reused

interface of neuron and muscle motor plate

these types of neuron fibers innervate more than one muscle fiber A-alpha neurons

EPP end plate potential (the influx of Na and Ca through Ach-ligated channels)

D loop on nicotinic channel selects for positively charged ions

GABAr has positively charged aa on it's D loop and lets in Cl, a negative ion

cardiac muscarinic receptors (one specific mechanism, result) increase polarization, decrease heart rate

rate the delay of the three synapse types (ionotropic, muscarinic, electrical) electrical < ionotropic < muscarinic

AP splitting performed with which type of synapse (electrical or chemical) electrical

this type of synapse holds pre and post cells together electrical

which is faster: chemical or electrical synapses electrical

easier to regulate: chemical or electrical synapses chemical (think kinases and phosphatases affecting ion channels)

memory fxns via chemical or electrical synapses chemical

constant use synapses use this type of vesicle release ribbon

ribbon vesicle release is also known as disk vesicle release

ribbon vesicle release uses this molecular motor kinesine

this protein tethers ribbon to presynaptic membrane bassoon

NO pathway (from production to activation) Ca+ rises, NO synthase activated, NO diffuses, activates adenylyl cyclase, PKG activated

NO signaling between neurons one-way or two-way? two-way

rate of anterograde axonal transport 0.5 meters / day

motor for anterograde axonal transport kinesin

motor for retrograde axonal transport dynein

cytoskeletal structure as rails for axonal transport microtubules

this type of synapse is good for syncronizing electrical

amplifying signal : chemical synapse :: decreasing signal : electrical synapse

astrocyte processing of glutamate takes up NT glutamate from cleft, processes to glutamine, releases for EAAT xport into presynaptic

mechanisms of AP modulation (2) spacial summation, temporal summation, activation of K+ influx channels

characteristic that distinguishes between two simultaneous AP input dendrite diameter

facilitaiton (definition) transient increase of the EPP / PSP during high frequency nerve stimulation

potentiation (definition) long-lived increase in release of NT at synapse because of high frequency nerve stimulation

synaptic depression (define) temporary decrease in synaptic transmission because of high stimulation and lack of NT / vesicles

habituation (define) slow loss of synaptic transmission because of low stimulation

myasthenia gravis (mechanism) autoimmune: antibodies against nicotinic receptor

Lambert-Eaton syndrome (mechanism) autoimmune: antibodies against the presynaptic Ca2+ channel

acetocholine esterase inhibitors (2) pyridostigmine, DFP

pyridostigmine, DFP (mechanism, effect) inhibit ache, increase signaling at synapse

botox (mechanism, therapy for (3)) inhibits NT vesicle fusion; cervical dystonia, strabismus, and spacticity