NEURO WK 2 Flashcards
structures of the neurone (5)
axon
dendrite
soma (cell body)
axon hillock and initial segment
synapse
4 functional regions of neurones
input
integrative
conductile
output
What does a ‘leaky’ nerve cell membrane mean? What law can represent this?
not a perfect insulator
ohm’s law V = IR
smaller diameter, greater resistance, narrower axon
methods of increasing passive currents spread ?? and therefore increase action potential velocity
increase axon diameter
more myelin
demyelinating disorders - what are they and give examples (2)
MS
GBS
damage to the myelin sheath -> nerve conduction impaired -> neurological symptoms
chemical neurotransmission - overview and its 9 steps
uptake of precursor
synthesis and storage of transmitter
calcium is needed for fusion
neurotransmitter will bind to a specific receptor and cause receptor to activate
3 types of synapse - what is the most common one?
axodendrite - very common
axosomatic
axoaxonic
2 types of neurotransmitters
inotropic - direct effect, nicotinic ACh receptor channel activation, usually excitatory
metabotropic - indirect effect through g-protein complex, muscarinic ACh receptor activation, inhibitory
Fast vs. slow EPSP
Excitatory postsynaptic potential
FAST = ligand gated, activation of nicotinic or ionotropic receptors. conduct sodium and potassium. eg ACh acting on inotropic receptor = fast EPSP
SLOW = muscarinic or G protein-coupled ACh receptors. closes potassium channel
main excitatory / inhibitory neurotransmitter of the brain ??
glutamate
GABA
2 TYPES OF GABA receptors
GABA A - ligand gated channels,
allows chloride ions to flow into the neuron
eg. benzodiazepines (e.g., diazepam), barbiturates, and alcohol.
GABA B - G coupled protein receptors
allows opening of potassium channels
eg. baclofen for muscle spasticity
different types of sensory modalities (5)
vision
auditory
gustatory
olfactory
touch - somatosensory
3 types of adaption. Adaptation determines the firing rate of sensory neurones in response to changing stimuli.
phasic or transient - rapid decrease, CNS
tonic or sustained - gradual decrease, CNS
peripheral or short term, sensory receptor level
low threshold unit / mechanoreceptors * - what fibre class and where does it terminate??
mechanoreceptors - light touch and pressure
alpha beta - large and fast
Meissner’s corpuscles - light touch, superifical
Pacinian corpuscles - pressure and vibration, deep
Merkel cells - sustained pressure and detecting objects
ruffini endings - sustained pressure and skin stretch
conduction velocity types (4), what is fastest conduction v / thickest myelination?? what type of sensory receptor do they conduct??
type A - FASTEST, big, myelinated, has motor and sensory functions
B - medium sized and time, lightly myelinated, motor fibers responsible for involuntary functions such as digestion, sweating, and cardiovascular regulation.
Adelta - small, myelinated, sharp pain
C - SLOWEST and small, unmyelinated, primarily sensory fibers responsible for transmitting sensations of pain, temperature
Brodmann areas (4)
Primary Motor cortex
Primary visual cortex
Primary somatosensory cortex
Broca/Wernicke’s area
Cutaneous receptors (5)
mechanoreceptors
thermoregulators
free nerve endings
nociceptors
hair follicle receptors/specialised
stretch reflex
aka myotatic or deep tendon reflex
extrapyramidal pathways - 4 tracts
neuronal coding in the primary motor cortex (4). What does the primary motor cortex control??
Brodmann area 4, pre-central gyrus
contralateral control
what are the 3 FORMS OF PAIN
nociceptive
neuropathic
mixed
What type of fibres mediate pain??
a delta and c fibres
allodynia
heightened sensitivity to touch, so that sensations that are typically not painful become painful
brown sequard syndrome
pain and temp on opposite side
ipsilateral
THE WHO ANALGESIC LADDER, what are the 3 steps ??
analgesics
weak opiods
strong opioids
NSAIDs mechanism
reversibly inhibit the COX1/2
What mediates opioid action?? what do opioid receptors produce??
opiod receptors, binding
what are the 3 classes of opioids receptors
GPCRs
Mu
delta
kappa
rods see in _____ light. rod system has more __________ than cones. Differences between rods and cones
rods - dim, low light
cones - day light
more rods than cones
what is the function of the dark current??
steady influx of sodium ions (Na⁺) into photoreceptor cells (rods and cones) in the absence of light.
this is essential for maintaining photoreceptor cells in a state of partial depolarization, and maintaining resting potential.
centre surround organisation / lateral inhibition
the OFF / ON pathway
6 LAYERS OF LATERAL GENICULATE NUCLEUS *
structures of the labyrinth
within the inner ear that consists of the bony labyrinth and membranous labyrinth. It houses the sensory organs responsible for hearing (cochlea) and balance (semicircular canals and otolithic organs),
High vs. low frequency - Which end of the basilar membrane is wider and how does this relate to pitch?
basilar membrane is narrower and stiffer at the base (near the oval window) and wider and more flexible at the apex (farther along the cochlear spiral).
base = high frequency
inner vs outer hair cells - the 2 types of hair cells
within the organ of Corti
function of otolith organs
utricle and saccule
responsible for detecting linear acceleration, changes in head position relative to gravity, and contributing to balance and postural control
INPUT AND OUTPUT TO / OF THE BASAL GANGLIA
What releases dopamine?? - What are the 2 methods??
substantia nigra and the ventral tegmental area (VTA)
phasic (burst) release in response to rewarding stimuli and tonic (steady-state) release to maintain baseline dopamine levels.
disorders of the Basal Ganglia - Parkinson’s, Huntington’s. What happens to the pathway?
PD - substantia nigra is affected
striatum (specifically the caudate nucleus and putamen
