Neuron Flashcards
NEURON:
perikaryon (what/name), neurite (what), ganglion vs. nucleus, nucleolus (for), neurolemma (for)
association neuron - where, interneuron
neurite - unipolar (what can be absent), pseudopolar, bipolar, multipolar (+ example & most common)
nissl substance - where (2), for, color
lipofucin - what, describe, significance
melanin - what, describe/region, related to
brain & spine layers (3.2)
- perikaryon/cell body/soma
- neurite: process; extension of dendrite
- ganglion (cell bodies outside CNS), nucleus (inside)
- nucleolus: for rNA
- neurolemma: for protein & ribosome
- association neuron: in CNS; interneuron (between neurons)
- lipofucin: remnant of lysosome; pigment; harmless
- melanin: remnant of lysosome; black dots in substantia nigra; related to catecholamine-synthesizing ability of neurons which have dopamine as NT
neurite types
- unipolar: one process (single axon has one branch to CNS & one to peripheral); dendrite can be absent
- pseudopolar: one process divide into two; skin, sensory
- bipolar: 2 process; retina
- multipolar: most common; many dendrites
nissl substance
- in cytoplasm; not in axon
- for: synthesize protein
- gray; disappear during chromatolysis (denervated)
layers
- brain: dura > inner white > outer gray
- spine: inner gray > outer white (no axon = no nissl)
NEURON:
dendrite - what, number/example
axon - what, end as (2), function, most excitable segments (2), covered with, size x velocity, bouton derminal (what), bouton de passage (name + what/where)
DENDRITE
- extension of cell body
- for receiving signal
- more = more sensitive to touch
AXON
- uniform diameter, longest process that exits cell body; ends as terminal button or synapse
- for transmission of signal
- most excitable segment: motor segment, initial segment, rode of ranvier (sensory)
- covered with schwann cells
- size DP velocity
- bouton terminal: enlarged distal ends
- bouton de passage/varicosities: swelling in autonomic nerve
NEURON: Axon Transport
transport (2) from to, more common direction, assisted by (2)
fast - mm/day, (3), transports (2), direction + coating
slow - mm/day, needs (2), transport (3), direction
anterograde - other name, from to, what/for
retro - from to, what/for
axoplasmic flow - type, direction, uses (1)
axonal transport - type, direction, transport (2)
types
- transport neurotransmitters & organelles from cell body to synapse & vice versa
- anterograde»_space;>
- by microtubule & microfilament
fast axonal transport
- 400mm/day, mediated by ATP
- membrane vesicles, mitochondria, synaptic vesicles
- proteins & neurotransmitters
- anterograde (kinesin-coated), retrograde (dynein-coated)
slow axonal transport
- 1-3mm/day, guided by microtubules, need metabolic energy & Ca
- axoplasm, microfilament, microtubule
- anterograde only
direction
- anterograde/orthograde: from cell body to synapse; for neurotransmission
- retrograde: synapse to cell body; for lysosomal degradation
- axoplasmic flow: slow; anterograde only; use peristaltic waves
- axonal transport: fast; bi-directional; transport proteins & Ach-ase
NEURON: Neuroglia
number, type cell, function, smallest
astrocytes - absorb (3), store (1), passage (1), function (3), form (1), helps in what process, secretes what for what, replacement gliosis, fibrous vs. protoplasmic (matter + branching + filaments)
oligo - filaments, form (1), when form
microglia - looks like, function/when active
ASTROCYTES
- absorb GABA, glutamate, K
- stores glycogen (even if you fast you live)
- allows passage of metabolites (digestive)
- forms BBB
- scaffolding, electrical insulation (prevent leak of neurotransmitters), first defense
- helps in phagocytosis
- secretes cytokines for immune system
- replacement gliosis: bye neuron = replace
- fibrous: white matter, few branching but many filaments in cytoplasm
- protoplasmic: gray matter, many branching but few filaments in cytoplasm
OLIGODENDROCYTE
- form myelin sheath
- no filaments in cytoplasm
- 16th week of gestation
MICROGLIA
- looks like macrophage
- active during infection = phagocyte
NEURON: Neuroglia
ependyma - where (2), main function (2), has (2) for (1.1), ependymocytes (2 where + for), tanycytes (where + controls), choroidal (where + prevent)
radial glial - like, when, function (2)
EPENDYMA
- in cavities in skull & canal in spine
- has cilia (for motility of CSF), microvilli (absorb)
- ependymocytes: in cavity of skull & canal of spine; for CSF delivery
- tanycytes: in 3rd ventricle; control pituitary hormones
- choroidal epithelial cells: in choroidal plexus; prevent leakage of CSF
- function: CSF, absorptive
RADIAL GLIAL CELLS
- like astrocytes
- during development = scaffolding & guide post for immature neurons
NEURON: Injury
CNS vs. PNS (2)
degeneration - distal axon (shape + axon + duration), proximal axon (duration), cell body (appear + event)
regeneration - how/axon, velocity
neuropraxia - structure, wallerian, sx (2)
axonotmesis - type 2-4 (structure + wallerian + layers)
neurotmesis - type 5 (what/layer)
- CNS: regenerate
- PNS: regenerate & reinnervate
DEGENERATION
- distal axon: wavy; bye schwann = axon disintegrate within 5-7 days
- proximal axon: same shit within 7 days
- cell body: inflamed; chromatolysis = bye nissl
REGENERATION
- schwann back to axon
- 3-5mm/day
NEUROPRAXIA / TYPE I
- myelin; no wallerian
- sx: motor & proprioception
AXONOTMESIS
- disrupted axon, wallerian
type 2
type 3
- endoneurium
type 4
- perineurium
NEUROTMESIS / TYPE 5
- epineurium; total cut of nerve
NEURON: AP
Na gate - (2) + when active/rest, K gate (1)
RMP (state of gates) > current = (event) > (?) gate open > peak = gate > gate = (?) = (event) > state > eventually
equilibrium - mV, what happens
threshold for gate opening & effect on graph
refractory
- what/significance + why
- absolute: naming channel, when/from to + who
- relative: when, AP, point A (gate stimulus + 15 vs. 60), point B (mV), point C (mV + gate status)
GATES
- RMP = all closed
- whatever gate is closed = channel name
Na Gate
- extracellular/activation gate
- intracellular/inactivation gate (open at rest)
K gate
- just intracellular
RMP
- current = depolarization > Na activation gate opens = Na influx > reach Na peak = Na inactivation gate closes = Na can’t enter anymore > K channel finally open = K outflux = repolarization > hyperpolarization > eventually go back to RMP
- equilibrium: 40mV, neuron dead
- threshold: 15mV, become positive
REFRACTORY
- when u cannot produce new AP since they all closed
absolute
- from firing til 2/3 repolarization
- Na inactivation gate is mostly closed during this so channels are inactive/cannot be stimulated
relative
- after 1/3 of repolarization = produce AP depending on magnitude
- point A: needs 60mV since most inactivation gates are still closed (K isn’t exiting yet)
- point B: needs 50mV
- point C: needs 18mV
NEURON: Impulses
orthodromic vs. antidromic
saltatory conduction - structure/how
the tables
- orthodromic: cell body to synapse
- saltatory conduction: jumping node of ranvier
nerve fiber types
- A alpha: proprioception & motor
- A beta: touch & pressure
- A delta: pain, cold, touch
- B: preganglionic, autonomic
- C dorsal: pain, temp
- sympathetic: postganglionin
other shit
- Ia: muscle spindle (A alpha)
- Ib: GTO (A alpha)
- II: muscle spindle, flowerspray (A beta)
- III: pain, cold, touch (A delta)
- IV: pain, temp (C dorsal)
susceptible
- hypoxia: B>A>C
- pressure: A>B>C
- local anesthetic: C>B>A
