Synpatic Transmission Flashcards
What is chemical transmission?
Neurons communicate with each other within group called neural networks. Each neuron is separated from the next by an extremely tiny gap called the synapse. Signals within neurons are transmitted electrically however, signals between neurons are transmitted chemically across the synapse.
When the electrical impulse reaches the end of a the neuron (the presynaptic terminal) it triggers the release of neurotransmitter from tiny sacs called synaptic vesicles.
What a neurotransmitters and how do they wok?
Neurotransmitters are chemicals that diffuse across the synapse to the next neuron in the chain.
Once a neurotransmitter crosses the gap it is taken up by a postsynaptic receptor site on the dendrites of next neuron (axons take signals to synapse, dendrites take away). Chemical message can be converted back into an impulse continuing transmission. Direction of travel is one way.
Each NT has its own molecular structure that fits perfectly into a postsynaptic receptor site, lock and key, NT have specialist functions- ACH is found at each point where a motor neuron meets a muscle and upon its release the muscle contracts.
What is excitation and inhibition?
Neurotransmitters have either excitatory or inhibitory effect on the neighbouring neuron. Neurotransmitter serotonin causes inhibition in the receiving neuron, resulting in the neuron coming less negatively charged and likely to fire. In contrast, adrenaline cause excitation increasing its positive charge making it likely to fire
What is the process of summation?
The PSN firing is decided by the process of summation. The excitatory and inhibitory influences are summed if net effect is inhibitory than the PSN is less likely to fire and if excitatory more likely to fire. Once electrical impulse is created it travels down the neuron. Therefore, action potential of PSN is only triggered if the sum of excitatory and inhibitory signal at any one time reaches the threshold.
