nerves Flashcards
what makes myelin sheaths in PNS
schwann cells
what are Glia
90% cells in CNS
astrocytes
oligodendrocytes
microglia
ependymal cells
astrocyte function
maintain external environment of neurons
surround blood vessels and produce BBB
Glia cells: oligodendrocytes function
form myelin sheaths in CNS
Glia cells: microglia function
phagocytic hoovers mopping up infection
Glia cells: ependymal function
produce CSF
resting membrane potential of neurons at equilibrium
-70mV
how is a membrane potential made
Na/K channel keeps coming and going equally
but leaky K+ channels let more out
membrane potential equilibrium potential is made when
electrical gradient is equal and opposite to conc gradient
what does a graded potential do
depolarises cell to threshold for action potential to happen
properties of graded potentials
graded- can be big or small
only act on short distances
can excite or inhibit
can be added together to make bigger
hyperpolarising- fast inhibition (IPSP)
a neurotransmitter- GABA lets Cl- in
va ionotropic receptors
hyperpolarising- slow inhibition (IPSP)
G protein is triggered by a neurotransmitter and lets K+ out
by metabotropic receptor
depolarising- fast excitation
neurotransmitter lets lots of Na+ in (and some K+ out)
ionotropic receptor
depolarising- slow excitation
neurotransmitter triggers G protein and
blocks leaky K+ channels
metabotropic receptor
what does the axon hillock do
fires the action potentials
the closer to the axon hillock
the bigger the signal
a signal with a slight time gap but same dendrite is called
temporal summation
a time gap but different dendrites creates
spatial summation
properties of an action potential
have a threshold
all or none
only encode intensity using frequency- not height
have a refectory period
self propagating
travel slowly
why cant action potentials trigger backwards
the the refectory period
neuromuscular junction 1
action potential in a motor neuron opens voltage gated Ca2+ channels- which helps make vesicles
to let out ACh
neuromuscular junction 2
ACh binds to nicotinic receptors in muscle
ligand gated Na/K channels create a graded potential (end plate)
then voltage gated ligand channels create action potential
how is ACh removed
acetylcholinesterase
why does the neuromuscular junction have a safety factor
post junctional folds mean the endplate potential has a short distance to travel to the voltage gated Na+ channels
so no synaptic integration
CNS synapses
multi synaptic
PNS synapses
monosynaptic
