Anatomy Wicklein Flashcards
what does the neuropil consist of?
cell bodies, axons, dendrites, synapses and glia
how are neurones in the CNS grouped and where are the mostly found in brain
in CNS neurones can be in clusters called a nucleus or a sheet or layer called an area or lamina
the mid and hindbrain is mostly nuclei while the cerebellar cortex is mostly laminae
what are bundles of nerve fibres called
bundles of nerve fibres are called tracts, tracts that cross the midline of the brain are called a comissure if it is symetrical on either side of the midline or a decussation if it is asymmetrical
what are the holes called in the bone that surrounds the CNS
foramen
how do the meninges protect CNS and what is their structure
outer meninge: Dura mata: thick fibrous layer in bone
arachnoid mater is a thin delicate sheet which is connected to pia mater by thin web like strands called arachnoid trabeculae
Pia mater: thin membrane surrounding brain and spinal cord and blood vessels in CNS
in subarachnoid space CSF is kept
what is the role of CSF and what is it formed by?
absorbs shock, reduces effective weight of brain from 1.5kg to 50g, helps to keep extracellular milieu (buffer) constant, movement of CSF removes potentially toxic substances
CSF is produced by the choroid plexus which line the inner surface of the ventricles
what is the role of the blood brain barrier and what is it formed by
blood brain barrier controls which molecules get in to brain
molecules which are not transported through must cross plasma membrane, toxins and viruses are kept out
formed by endothelial cells of brain capillaries
what are sulci and gyri
sulci are grooves between segments called gyri, deep sulci are called fissures
what are the 4 main lobes of brain
frontal lobe, temporal lobe, occital lobe, parietal lobe
what is the function of the thalamus, cerebellum, hippocampus and cortex
thalamus: gateway to cortex; integration of sensory motor and autonomic information
hippocampus: learning and memory
cerebellum: co-ordination and control of movement, posture, balance, hand eye co-ordination (motor function)
cerebral cortex: analyze sensory information and combine it with memory to generate an understanding and complex behaviour, higher mental functions
what makes up the thalamus? and what are their functions
3 nuclei: associative, specific and diffuse
associative: connected to associate cortex, involved in sensory integration and memory of stimuli, emotional behavioural aspects
specific: process input from single sensory modality and project to specific cortical region
diffuse: projections throughout cerebral cortex and thalamus, responsible for arousal and cortical excitability
what are the inputs/ outputs of cerebellum?
inputs: vestibular system
outputs: deep cerebellar nuclei and then to thalamus, brainstem and spinal cord
what are the four layers of the cerebellum
molecular layer: basket and stellate cells, purkinje cell projections and
purkinje cell layer: purkinje cell bodies, and golgi cell projections
granular layer:granule cells, golgi cell bodies mossy fibres and purkinje cell axons
white matter layer: purkinje cell axons, mossy fibres
parallel fibres run through molecular layer to granular layer where they synapse to mossy fibres
climbing fibres are in all layers
what are the main output cells in cerebellum
purkinje cells, they are inhibitory neurones.
Purkinje cells are connected to mossy fibres indirectly through granule cells (only excitatory cells), each granule cell connects to 2000-3000 purkinje cells, with one synapse between each cell. Granule cells stimulate purkinje cells
also connects to climbing fibres directly and makes roughly 300 synapses. Climbing fibres inactivate purkinje cells after stimulation of purkinje cells by granule cells. Climbing fibres come from inferior olive which fires at about 10 Hz
what do stellate and basket cells do?
stellate and basket cells run perpendicular to parallel fibres and perform surround inhibition.
what do golgi cells do
golgi cells inhibit granule cells through feedback inhibition, this makes excitation brief, the result is that purkinje cells fire rarely
what are the sections of the hippocampus? and how does information flow between them
dentate gyrus, Ca region, subiculum and entorhinal cortex
entorhinal cortex to dentate gyrus to CA3 to CA1 to subiculum which is output region
how is cerebral cortex organised?
6 layers; layer 3 contains pyramidal cells that connect to other cortical areas, layer 4 is main input layer for sensory inputs from thalamus, layer 5 contains large pyramidal cells whose axons project out of cortex to spinal cord, layer 6 is part of feedback loop which regulates incoming thalamic activity
most cells are excitatory unlike in cerebellum
how is the spinal cord segmented
from top to bottom: 8 cervical segments 12 thoracic segments 5 lumbar segments 5 sacral segments 1 coccygeal segment overall 31 segments
what are the 2 ascending pathways and what do they control
spinothalamic: pain and temperature
dorsal column pathway: touch/proprioception
how are peripheral nerves bundled together
in bundles called fasciculi bound together by endoneurium surrounded by perineurium, whole nerve is encased in epineurium
which cranial/ spinal nerves are autonomic
oculomotor, vagus and glossopharyngeal are all parasympathetic. S2 and S4 are parasympathetic
all thoracic segments and 1st lumbar segment are sympathetic
how do nerve length vary in parasympathetic/ sympathetic nerves, how do NTs differ
both use nAchRs at preganglionic synapse
postganglion parasympathetic use mAchRs, in sympathetic alpha and beta adrenorecptors for adrenaline and noradrenaline are used
parasympathetic has long branched preganglionic neurones
sympathetic has short unbranched preganglionic neurones
