Biopsychology - Synaptic Transmission
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- Created on: 24-06-22 09:27
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- Synaptic Transmission
- Key Words:
- Excitation
- When a neurotransmitter, such as adrenaline, increases the positive charge of the postsynaptic neuron.
- This increases the likelihood that the neuron will fire and pass on the electrical impulse.
- When a neurotransmitter, such as adrenaline, increases the positive charge of the postsynaptic neuron.
- Neurotransmitter
- Brain chemicals released from synaptic vesicles that relay signals across the synapse from one neuron to another.
- Neurotransmitters can be broadly divided into those that perform an excitatory function and those that perform an inhibitory function.
- Inhibition
- When a neurotransmitter, such as serotonin, makes the charge of the postsynaptic neuron more negative.
- This decreases the likelihood that the neuron will fire and pass on the electrical impulse.
- When a neurotransmitter, such as serotonin, makes the charge of the postsynaptic neuron more negative.
- Synaptic transmission
- The process by which neighbouring neurons communicate with each other by sending chemical messages across the gap (the synaptic cleft) that separates them.
- Synapse
- The tiny gap between the end of the presynaptic neuron and the postsynaptic neuron.
- Excitation
- Neurotransmitters
- Neurotransmitters are chemicals that diffuse across the synapse to the next neuron in the chain.
- Once the neurotransmitter crosses the gap, it is taken up by the postsynaptic receptor site - the dendrites of the next neuron.
- Here, the chemical message is converted back into an electrical impulse and the process of transmission begins again in this other neuron.
- There are many types of neurotransmitters which have been identified in the brain, as well as in the spinal cord and some glands.
- Each neurotransmitter has its own specific molecular structure that fits perfectly into a postsynaptic receptor site (similar to the lock and key).
- Neurotransmitters have specialist functions, e.g. acetylcholine (ACh) is found at each point where a motor neuron meets a muscle, upon its release - it will cause muscles to contract.
- Chemical transmission - synapses
- Neurons communicate with each other within groups known as neural networks.
- Each neuron is separated from the next by a synapse.
- The synapse includes the space between them (called the synaptic cleft) as well as the presynaptic terminal and postsynaptic receptor site.
- Signals within neurons are transmitted electrically (known as action potential).
- Signals between neurons are transmitted chemically by synaptic transmission.
- When the electrical impulse reaches the end of the neuron (the presynaptic terminal) it triggers the release of neurotransmitter from tiny sacs called synaptic vesicles.
- Summation
- Whether a postsynaptic neuron does fire is decided by the process of summation.
- The excitatory and inhibitory influences are summon:
- If the net effect on the postsynaptic neuron is excitatory = postsynaptic neuron is more likely to fire - and, the inside of the synaptic neuron becomes positively charged.
- If the net effect on the postsynaptic neuron is inhibitory = postsynaptic neuron is less likely to fire.
- Once the electrical impulse is created it travels down the neuron.
- The action potential of the postsynaptic neuron is only triggered if the sum of the excitatory and inhibitory signals at any one time reaches the threshold.
- Excitation and Inhitibion
- Neurotransmitters have either an excitatory or inhibitory effect on the neighbouring neuron.
- The neurotransmitter serotonin causes inhibition in the receiving neuron = results in the neuron becoming more negatively charged and less likely to fire.
- The neurotransmitter adrenaline (an element of the stress response and it is also a hormone) causes excitation of the postsynaptic neuron by increasing its positive charge and making it more likely to fire.
- Neurotransmitters have either an excitatory or inhibitory effect on the neighbouring neuron.
- Key Words:
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