Anatomy Wicklein

Question 1

what does the neuropil consist of?

Answer 1

cell bodies, axons, dendrites, synapses and glia

Question 2

how are neurones in the CNS grouped and where are the mostly found in brain

Answer 2

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

Question 3

what are bundles of nerve fibres called

Answer 3

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

Question 4

what are the holes called in the bone that surrounds the CNS

Answer 4

foramen

Question 5

how do the meninges protect CNS and what is their structure

Answer 5

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

Question 6

what is the role of CSF and what is it formed by?

Answer 6

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

Question 7

what is the role of the blood brain barrier and what is it formed by

Answer 7

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

Question 8

what are sulci and gyri

Answer 8

sulci are grooves between segments called gyri, deep sulci are called fissures

Question 9

what are the 4 main lobes of brain

Answer 9

frontal lobe, temporal lobe, occital lobe, parietal lobe

Question 10

what is the function of the thalamus, cerebellum, hippocampus and cortex

Answer 10

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

Question 11

what makes up the thalamus? and what are their functions

Answer 11

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

Question 12

what are the inputs/ outputs of cerebellum?

Answer 12

inputs: vestibular system
outputs: deep cerebellar nuclei and then to thalamus, brainstem and spinal cord

Question 13

what are the four layers of the cerebellum

Answer 13

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

Question 14

what are the main output cells in cerebellum

Answer 14

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

Question 15

what do stellate and basket cells do?

Answer 15

stellate and basket cells run perpendicular to parallel fibres and perform surround inhibition.

Question 16

what do golgi cells do

Answer 16

golgi cells inhibit granule cells through feedback inhibition, this makes excitation brief, the result is that purkinje cells fire rarely

Question 17

what are the sections of the hippocampus? and how does information flow between them

Answer 17

dentate gyrus, Ca region, subiculum and entorhinal cortex

entorhinal cortex to dentate gyrus to CA3 to CA1 to subiculum which is output region

Question 18

how is cerebral cortex organised?

Answer 18

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

Question 19

how is the spinal cord segmented

Answer 19

from top to bottom: 
8 cervical segments
12 thoracic segments
5 lumbar segments
5 sacral segments
1 coccygeal segment
overall 31 segments

Question 20

what are the 2 ascending pathways and what do they control

Answer 20

spinothalamic: pain and temperature

dorsal column pathway: touch/proprioception

Question 21

how are peripheral nerves bundled together

Answer 21

in bundles called fasciculi bound together by endoneurium surrounded by perineurium, whole nerve is encased in epineurium

Question 22

which cranial/ spinal nerves are autonomic

Answer 22

oculomotor, vagus and glossopharyngeal are all parasympathetic. S2 and S4 are parasympathetic

all thoracic segments and 1st lumbar segment are sympathetic

Question 23

how do nerve length vary in parasympathetic/ sympathetic nerves, how do NTs differ

Answer 23

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