Neuronal Communication Flashcards
function & type of ion channel of dendrites
receives input from neurons (local potentials)
chemically-gated ion channels
function & type of ion channel of the cell body (soma)
receives input from neurons (local potentials)
chemically-gated ion channels
function & type of ion channel of the axon hillock
summates the local potentials -> generates action potential
voltage-gated ion channels
function & type of ion channel of the axon
sends action potential down the axon
voltage-gated ion channels
function & type of ion channel of axon terminals
releases neurotransmitter to initiate a response in target cell
voltage-gated ion channels
meaning of pre-synaptic neuron
before the synapse
meaning of post-synaptic neuron
after the synapse
meaning of synapse
the junction between the pre-synaptic and the post-synaptic neuron
structure & function of neuronal input
the post-synaptic neuron receives input form the axon terminals of the pre-synaptic neuron
this input creates a local potential
how do neurons send signals to other cells?
by transmitting a chemical - a neurotransmitter
where is a neurotransmitter released from?
the pre-synaptic cleft, then crosses the synaptic cleft
what does the neurotransmitter bind to?
receptors on the post-synaptic cell, opening chemically-gated ion channels
excitatory neurotransmitter definition
Na+ enters neuron -> brings membrane potential CLOSER to threshold (depolarising)
inhibitory neurotransmitter definition
Na+ leaves neuron -> moves the membrane potential AWAY from threshold (hyper polarising)
steps of neuronal input
- pre-synaptic neuron releases excitatory neurotransmitter -> brings the neuron closer to threshold
- pre-synaptic neuron releases more excitatory neurotransmitter -> brings the neuron to threshold
- all of the inputs onto the neuron are summated (added) at the axon hillock -> if the axon hillock reaches threshold (-60mV) then the neuron will fire an action potential down its axon
function of integration in the axon hillock
all local (graded) voltage changes add up at the axon hillock if the net threshold at the axon hillock reaches -60mV then an action potential will fire
local potentials vs. action potentials
local potentials = small changes (graded response) in membrane potential at the cell body/dendrites -> INPUT
action potentials = propagate down the axon
local potentials function
graded response - depolarises or hyperpolarizes the membrane to different levels
does not propagate
chemical-gated ion channels
action potentials function
all or nothing - either the same size action potential or no action potential
depolarises to the same level (+30mV) each time
propagates down the axon
voltage-gated ion channels
3 steps of propagation of an action potential
- the action potential regenerates down the length of the axon fast*
1. voltage-gated Na+ channels closed - RMP = -70mV
2. voltage-gated Na+ channels open - Na+ enter neuron; membrane potential increases to +30mV
3. voltage-gated Na+ channels closed, voltage-gated K+ channels open - K+ leaves the neuron; membrane returns to RMP
propagation myelinated axons structure & function
myelin is made from a specialised cell called a Schwann cell, and it wrapped around the axon
the action potential regenerates at each gap between the myelin sheath
unmyelinated axons are fast
myelinated axons are really fast
5 steps of the output of neural communication
- depolarisation of axon terminal -> voltage-gated Ca2+ channels open -> Ca2+ enters axon terminal
- Ca2+ triggers neurotransmitter to be released from vesicles into the synaptic cleft
- neurotransmitter diffuses across the synaptic cleft
- neurotransmitter binds to its receptor (chemically-gated ion channel) on the post-synaptic membrane
- Na+ enters the post-synaptic cell -> depolarises post-synapse cell
