Nervous System Flashcards
Divisions of the peripheral NS
somatic sensory
somatic motor
visceral sensory
visceral motor
neurons characterisitics
- basic structural and functional unit
- cell body (soma) → contains: nucleus/golgi/ER/mit
- dendrites → relays info to cell body (telodendria - postsynaptic region releasing NT)
- axons → nerve fibres that transmit electrical impulses
neuroganglia
supportive structure (physically and metabolically) - 10:1 ratio to neurons - able to divide
astrocytes
CNS
- hold and guide neurons during fetal brain dev
- repair brain injury and neurotransmission
- forms BBB (prevent entry of substances from blood to brain)
microglial cells
- immune cell, dormant until activated
- via phagocytosis
ependymal cells
in ventricles → secretes CSF
- cilia facilitates movement
- acts as neuronal stem cells
oligodendrocyte
myelinated
- has phospholipid bilayer
relationship b/w mutiple sclerosis and myelin
eroded myelin → slows impulse conduction → slows motor functions
cells in peripheral NS
satellite cells
schwann cells
satellite cells
provide nutrients to cells
- surround neurons within ganglia → encompasses whole nerve fibres
schwann cells
are the oligodendrocyte in CNS
- myelinated → creates node of ranvier
saltatory conduction
myelinated conduction
nerve structure
axon → myelin sheath → endoneurium → fasicle → perineurium → epineurium
membrane potential
difference b/w charge inside (-70mV) and outside cell
- pump 3 Na out, 2 K in
steps of AP
1) stimuli from sensory cell → depol twd threshold
2) theshold reach → Na channel opens → depol
3) peak (+40mV) → K channel opens → repol
4) hyperpol (K leaves cells) → refractory period
5) K channel close → Na/K restore resting potential
what is impulse velocity dependent on
diameter of axon and myelination
synaptic transmission
- functional connection b/w pre & post synaptic neuron
- AP travels to telodendria to release NT
gap junction
electrical synpases
- chemicals move from 1 cell directly to another
chemical synapse
NT moves to synaptic → release chemical → triggers next AP
- Ca influx required for NT exocytosis
CN1
olfactory
CN2
optic
CN3
oculomotor - constricts pupils and elevates eyelids
CN4
trochlear → controls SUP oblique → controls I-M eye movement
CN6
abducent → LAT rectus → controls LAT eye movements
CN5
trigeminal
- V1 → opthalic
- V2 → maxillary
- V3 → mandibular
CN7
facial - muscles
- taste to ANT 2/3 tongue
- lacrimal & sublingual glands
CN8
vestibulocochlear
- hearing and balance
CN9
glossopharyngeal
- sensory 1/3 POS taste
CN10
vagus, THE autonomic nerve
CN11
spinal accessory
- motor to SCM and upper trapezius
CN12
hypoglossal
- muscle to tongue
- tongue points to direction of defective branch side
structure of CNS
gray (cell bodies and dendrites in cortex)
white (axons underlie the cortex)
tracts of CNS
bundle of axons
CSF
1o formed by choroid plexus
- absorbed into venous blood through arachnoid villi (500ml/day)
function of CSF
- suspend and cushion brain
- monitor changes in internal env
- vehicle for distributing hormones throughout CNS
BBB
regulate exchange of substances b/w blood and brain
- continuous layer of endothelial cells joined by tight junctions
- lipid soluble substances able to penetrate
- is incomplete in newborn and premature infants (prone to brain infection
brain stem
controls basic functions to maintain life (resp/cardiac/consciousness)
- pons + medulla oblongata + midbrain
cerebellum
control fine motor movements (affected in parkinsons)
- maintains equilibrium and posture
- planning and coordination
diencephalon
thalamus → relay centre for all sensory pathway to cerebral cortex
hypothalamus
cerebrum
4 lobes of the brain
frontal lobe
- 1o motor cortex → voluntary motor function
- pre-motor cortex → coordinate of complex movement and eye movement
- prefrontal cortex → personality, insight
parietal lobe
somatosensory cortex → processing of sensations and proprioception
temporal lobe
limbic association cortex and primary auditory cortex
- language comprehension
wenicke’s aphasia
compromised ability to understand speech → speak fluently but no sense
broca’s aphasia
loss of ability to produce language
occipital lobe
- 1o visual cortex → vision and coordination
- integration of all sensory input
basal nuclei (ganglia)
- contains limbic system → controls emotion
- relay point for nerve fibres
limbic system
located above diencephalon
- emotion and memory
hippocampus
part of cerebral cortex
- create new memories
- atrophy in alzheimers
amygdala
cluster of nuclei
- controls emotions
cingulate gyrus
loop of cerebral cortex over corpus callosum
- integrates sensory input and adds emotional content (i.e. rxn to pain)
blood supply to brain
originates from aorta
- anastomose to circle of willis
- susceptible to rupture and vascular disease
spinal cord
extension of brainstem
- L4/5 cauda epquina
ageing
- decrease of neurons in 30s
- decrease ability to maintain and synthesise new nerve cells
- dementia → consequence of degeneration of nerve cells
division of white matter
divided within each half of cord
→ into 3 white columns (funiculi)
→ further divided ANT/POS/LAT white columns
→ subdivided into spinal tracts
