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nerve cells - Coggle Diagram
nerve cells
nerve impulse
electrical message down axon of neuron
regenerated at points
resting potential
messages develop from disturbances
electrical gradient
polariisation
difference in charge in/out of cell
-70MV inside cell
state of the neuron prior to impulse
ions
selectively permeable membrane
passing of some ions
potassium
partially closed at resting
opens to return to state
calcium
sodium
closed at resting
closed after action potential
chloride
gradients
electrical
pulls potassium in
leak out carrying positive charge
concentration
difference in distribution of ions
channels
sodium potassium pump
protein complex
active transport
3 sodium ions 2 potassium in
later restores distribution
build up of sodium is toxic if unusual
maintain electric gradient
voltage activated
regulate sodium and potassium
membrane permeability depends on voltage difference
sodium potassium channels
drugs block channels and prevent action potential
novocain
depolarisation when sodium channels opened
action potential
messages by axons
resting stable until stimulated
depolarisation
decrease toward 0
hyperpolarisation
increase difference in electrical charge
threshold of excitation
level above stimulation
massive depolarisation
refractory period
after action potential
neuron resists production
relative refractory
taKes stronger stimulus for AP
absolute refractory
membrane cannot produce action potential
neurons
blood brain barrier
mechanism surrounding brain
blocks chemicals
neurons in brain dont regenerate
immune system destroys damaged cells
active transport
protein mediated
pump chemicals from blood to brain
brings glucose, hormones and vitamins
vertebrae neurons
depend on glucose
passes through blood/brain barrier
neurons need oxygen supply
vitamins
thiamine
for glucose
deficiency leads to death of neurons
korsakoffs syndrome
myelin sheath
axons
interrupted by nodes of ranvier
potential regenerated
chain of positively charged ions
myelin insulates material of fats and proteins
saltatory conduction
jumping of action potential
conserves energy
admits sodium
multiple sclerosis
destroyed myelin sheath
poor muscle coordination
provides rapid conduction of impulses
neurons without axons
depolarise/hyperpolarise
stimulation
graded potentials
vary in magnitude of membrane potential
only exchange info with neighbours
cells
human nervous system
neurons
motor
soma in the spinal chord
receives excitation from other neurons
conducts impulses
axon to muscle
sensory
highly sensitive to stimulation
light
sound
touch
components
soma/cell body
contains nucleus, mitochondria and ribosomes
responsible for metabolic work
covered with synapses
axon
myelin sheath to insulate
contains interruptions
nodes of ranvier
action potential
responsible for transmitting nerve impulses
other neurons/muscles/organs
presynaptic terminals on end
axon release for communication
efferent
exciting with info away
intrinsic
dendrites/axons completely contained within
afferent
admitting info to structure
dendrites
surface lined with synaptic receptors
increase surface area
dendritic spines
more info received
presynaptic terminals
end of branches on axon
releasing chemicals between neuron and cells
gila
microgila
remove waste
oligodendrocytes
build myelin sheath
supply nutrients
astrocytes
synchronise activity
take up chemicals by axon
radial gila
embryonic development
differenciate into neurons
astrocytes
animal cell
mitochondria
perform metabolic activities
ribosomes
synthesise proteins
nucleus
contains chromosomes
endoplasmic reticulum
transport proteins
membrane
separates inside and outside