5. synaptic transmission Flashcards
what is the key term for synapse
junction between two nerve cells - consists of a minute gap across which impulses pass by diffusion of a neurotransmitter.
allows neurons to communicate with each other.
what is the key term for synaptic cleft
gap between two neurons which chemical messages travel across.
what is the key term for synaptic transmission
process by which one neuron communicates with another.
information is passed down axon as an action potential - once is reaches the end of the axon it needs to be transferred to another neuron or tissue.
what is the key term for action potential
electrical impulse that carries information along the axon.
what is the key term for neurotransmitters
chemical messengers that transmit a message from a nerve cell across the synapse to a target cell - allows communication between neurons in the brain and spinal cord.
what is the key term for presynaptic neuron
neuron before the synapse that is passing the message along.
what is the key term for post synaptic neuron
neuron after the synapse that receives the message.
what is the key term for vesicles
sacs containing neurotransmitter waiting to be released.
what is the key term for receptors
a protein that receives neurotransmitters into the post synaptic neuron when a neurotransmitter binds to it.
what is the key term for enzymes
proteins that break down excess neurotransmitter.
how do neurotransmitters work
key and lock - only certain neurotransmitters fit into certain receptors.
also have specialised functions - acetylcholine is found in synaptic clefts between motor neurons and muscles. when these are transmitted the muscles will contract.
what is the process of synaptic transmission
vesicles release neurotransmitters into the synaptic cleft.
neurotransmitter binds to receptor and activates them.
excess neurotransmitter is taken up by the presynaptic neuron and enzymes are released to break down the remaining neurotransmitter.
vesicles are replenished with new and reused neurotransmitter.
what is summation
neurotransmitters at a synapse depend on how much is released and the action of it on the post synaptic neuron.
the post synaptic potentials may be excitatory or inhibitory depending on how close they bring the post synaptic neuron to the threshold required to produce an action potential.
when a neuron receives excitatory or inhibitory inputs and the same time then they add together - if number of excitatory inputs are sufficiently greater it will result in an action potential and the transmission of a nerve impulse. this addition of inputs is called summation.
what is excitation
occurs when receptor stimulation results in an increase in the positive charge of the post synaptic neuron which increases the likelihood if the neuron firing.
for example - adrenaline causes excitation by increasing a neurons positive charge and makes it more likely to fire.
what is inhibition
occurs when receptor stimulation results in an increase in the negative charge of the post synaptic neuron which decreases the likelihood if the neuron firing.
for example - serotonin causes inhibition in the neighboring neuron causing it to be negatively charged and thus less likely to fire.
