Neurobiology - part 1 Flashcards
grey matter
neuronal cell bodies, dendrites, glial cells, synapses
white matter
axons and oligodendrocytes
types of glial cells
atrocytes - homeostatic regulators of neurons
oligodendrocyte - make myelin
microglia - macrophages of brain
peripheral sensitisation
nociceptors are sensitised A-delta and C fibres
central sensitisation
sensitisation within spinal cord/ brain (thalamus, amygdala)
allodynia
threshold of non-noxious stimuli is lowered
hyperalgesia
responsiveness to noxious stimuli increases
primary hyperalgesia - hyperalgesia at site of injury (C fibre sensitisation - peripheral mechanism implicated)
secondary hyperalgesia - hyperalgesia at uninjured areas (central mechanism implicated)
neuralgia
pain from nerves themselves
palsy
facial weakness due to tumours, stroke, trauma
brain is folded
gyrus - top of fold
sulcus - bottom of fold
two causes of stroke
ischaemia (blockage)
haemorrhage (bleed)
axon transport
using cytoskeleton filaments
fast anterograde - kinesin transports neurotransmitters and vesicles from cell body to axon terminal
slow anterograde - actin, myosin, microtubules carry soluble substances
fast retrograde - dynein transports lysosomes (containing surplus membrane, metabolites) from axon terminal to cell body
nernst potential
calculate voltage generated by specific ion at known concentration gradient across a membrane
types of Na+ channels
h gate - internal, inactivation (open in resting potential)
m gate - external, activation (open for depolarisation)
types of K+ channels
n gate - activation (open for repolarisation)
types of neurotransmitter receptors
ionotropic (ligand-gated ion channels) - directly linked to ion channel
metabotropic (G-protein coupled receptors) - uses secondary messenger
autonomic nervous system parasympathetic
fibres
neurotransmitters
preganglionic B fibres acetylcholine
postganglionic C fibres acetylcholine
autonomic nervous system sympathetic fibres
fibres
neurotransmitters
preganglionic B fibres acetylcholine
postganglionic C fibres noradrenaline
somatic nervous system
fibres to where
A-α fibres/ motoneuron to skeletal muscle
A-γ fibres/ motoneuron to muscle spindle
nociceptors fibres
A-δ fibres sharp pain, faster, myelinated
C fibres dull pain, slower, unmyelinated
dorsal column-medial lemniscus pathway
fine touch (discriminative)
1st neuron
- ipsilateral
- synapses at medulla at cuneate fasciculus nuclei (upper body), gracile fasciculus nuclei (lower body)
2nd neuron
- contralateral at medulla
- synpase at ventral posteriolateral nucleus at thalamus
3rd neuron
- to primary somatosensory cortex at post central gyrus
anterolateral system/ spinothalamic tract
crude touch (non-discriminative), pain
1st neuron
- ipsilateral
- synapse at dorsal column in spinal cord
2nd neuron
- contralateral at spinal cord
- synapse at ventral posteriolateral nucleus at thalamus
3rd neuron
- to primary somatosensory cortex at post central gyrus
trigeminothalamic system
fine touch (discriminative)
1st neuron
- ipsilateral enter pons via trigeminal ganglion
- synapse at chief/ principal sensory nucleus of TNC at medulla
2nd neuron
- contralateral at pons
- synapse at ventral posteriomedial nucleus at thalamus
3rd neuron
- sensory cortex at the post central gyrus
pain and temperature system/ spinotrigeminal tract
crude touch (non-discriminative)
1st neuron
- ipsilateral enter pons via trigeminal ganglion
- synpase caudalis nuclei of spinal trigeminal nuclei of TNC at medulla
2nd neuron
- contralateral at medulla
- synapse at ventral posteriomedial nucleus at thalamus
3rd neuron
- sensory cortex at the post central gyrus
somatogenic pain
with known cause localised in body tissue
e. g. nociceptive pain - activation of nociceptors
e. g. neuropatic pain - injury to nervous system
psychogenic pain
no known physical cause but processing of sensitive information in CNS is disturbed
nuclei for fine touch of the face
2nd and 3rd neuron synapse at chief/ principal sensory nucleus of TNC (CN V) at medulla
nuclei for nociception of the face
2nd and 3rd neuron synpase caudalis nuclei of spinal trigeminal nuclei of TNC (CN V) at medulla
plexus of Raschkow
A-δ and C fibres in core of pulp and cell rich zone of tooth for pulpal innervation and nociception
sensory receptors of skin which are A-β fibres
hair follicle (touch) Meissner corpuscle (light touch) Merkel cell (light touch) Pacinian corpuscle (vibration, pressure) Ruffini endings (stretch, temperature)
sensory receptors of skin which are A-δ and C fibres
free nerve ending (pain, heat, cold)
tonic activity
sensory receptors continuously fire action potential
rapid adapting mechanoreceptors (RA)
respond to application/ removal of stimulus (not maintained stimulus to prevent overstimulation)
e.g. hair follicle, Meissner corpuscle and Pacinian corpuscle
slow adapting mechanoreceptors (SA)
slow increase and decrease in response to application and removal of stimulus and maintain firing
e.g. hair follicle, Merkel cell, Ruffini ending
high discriminatory
small, numerous receptive field
low discriminatory
large, sparse receptive field
lateral inhibition
ability of activated neurons to inhibit activity of neighbouring neurons
convergence
many bipolar neurons converge into one neuron to synapse with second order neuron
increases efficiency of response
(spatial summation?? many EPSPs from multiple neuron -> neuron)
divergence
one neuron diverges into many neurons
increase response of brain to stimulation
(temporal summation?? many EPSPs from one neuron -> neuron)
