Nervous system Flashcards
somatic nervous system
controls skeletal muscle
autonomic nervous system
things like blood pressure and eye function
segments and ridges of brain called
gyrus and sulcus
membranes surrounding brain called
meninges
parts of cerebrum
frontal lobe, temporal lobe, parietal lobe, occipital lobe
underneath the cerebrum in the diencephalon is the
thalamus and hypothalamus
parts of the brainstem
midbrain, pons, medulla oblongata
how many spinal nerves in spinal cord
31
afferent neurons
sensory neurons
efferent neurons
motor neurons
what do spinal tracts do
take information from the sensory neurons and sending it to the brain to tell it to do something or sending information down from the brain telling motor neurons to do something
soma
cell body of neuron
dendrites
receive information
axon hillock
the initial segment. triggers action potential
axon
sends action potential
axon terminals
release transmitter across synapse
interneurones found in
central nervous system
neurones in peripheral nervous system
afferent and efferent
types of glia
astrocytes, oligodendrocytes, microglia, ependymal cells
what glia forms myelin sheaths in the CNS
oligodendrocytes
what glia produce the cerebrospinal fluid
ependymal cells
what glia maintain external environment for neurons and surround blood vessels
astrocytes
what glia are phagocytic hoovers that mop up infection
microglia
where are glia found
CNS (make up 90% if it)
action potential
transmits signals over long distances
graded potentials
depolarise the cell to threshold and decide if an action potential should be fired. can summate
resting membrane potential
keeps cells ready to respond (inside of cells is negative relative to outside, usually -70mV)
what channels cause a resting membrane potential
leaky potassium channels. reached when electrical gradient is equal and opposite to concentration gradient
resting membrane potential shows what concentrations of ions outside and inside of cell
high potassium in, low sodium in, low chloride in
what does the sodium potassium pump do
establishes concentration gradient by putting 2 potassium in and 3 sodium out
how is the brain protected by changes in ion concentration in plasma
blood brain barrier- capillaries are especially tight
types of graded potentials
generator, postsynaptic, endplate, pacemaker
how are graded potentials decremental
they get smaller as they travel along the membrane so are only useful over small distances
graded potentials can either ____ or ____ a cell
excite (depolarising) or inhibit (hyperpolarising)
Inhibitory PostSynaptic Potentials are generated by
opening chloride channels or opening potassium channels
Exciting PostSynaptic Potentials are generated by
opening sodium/potassium channels or by closing leaky potassium channels
temporal summation
adds on to first stimulus later on, pushing closer or further away from threshold
spatial summation
have stimulus a and b at the same time so that response is greater
synaptic integration
summing the synaptic inputs to determine if the initial segment will reach threshold
types of synapse
axo-dendritic, axo-somatic, axo-axonic
what channels do the depolarising in an action potential
voltage gated sodium channels
what is an action potential and some properties of one
rapid depolarisation. have a threshold. can only encode stimulus intensity in their firing frequency, not their amplitude (cross threshold more, more intense, greater frequency), self propagating (one sodium channel opening triggers the next)
absolute refractory period
excitability of zero, cannot fire another action potential
how to speed up action potentials
large axons (wide diameter, long axons electrical impulses flow through easier. sodium channels can be wider spaced), myelination (increases membrane resistance and reduces membrane capacitance, less current is wasted)
diseases that cause demyelination
multiple sclerosis and Guillain barre syndrome. attack the myelin sheath. more current is lost between nodes
compound action potential
sum of many fibres and potentials recruited. electrical stimulation initiates action potentials in nerve trunk which travel down and the fastest conducted ones arrive at the end first. extracellularly recorded which means small peaks, not large ones. if enough little nibbles pass at the same time, a large one comes
A alpha fibres
largest myelinated- proprioception, motoneurons
A beta fibres
large myelinated. touch, pressure
A gamma fibres
small myelinated. motoneurons of muscle spindles
A delta fibres
smallest myelinated. touch, cold, fast pain
C fibres
unmyelinated. warmth, slow pain
what happens at neuromuscular junction
action potential in motor neurone, opens voltage gated calcium channels in presynaptic terminal which triggers calcium dependent exocytosis. acetylcholine (neurotransmitter) is released which binds to receptors. This opens ligand gated sodium potassium channels , cell depolarises as sodium flows in. End plate potential is caused
is end plate potential small or big
very big. about 40mV. always depolarises adjacent membrane to threshold
post junctional folds role in neuromuscular junction
ensure the end plate potential has a short distance to travel to voltage gated sodium channels
what makes CNS synapses complex
they have a range of neurotransmitters which each have several receptors, they have a range of postsynaptic potentials(IPSP, EPSP), arrangement of synapses, arrangement of wiring
five types of synaptic pathway
divergent, convergent, feedback inhibition, monosynaptic, polysynaptic
