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