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NEURONS AND SYNAPTIC TRANSMISSION - Coggle Diagram
NEURONS AND SYNAPTIC TRANSMISSION
neurons
sensory neurons = these carry messages from the PNS to CNS. They have long dendrites and short axons
relay neurons = these connect the sensory neurons to the motor or other relay neurons. they have short dendrites and short axons
neurons are nerve cells that process and transmit messages through electrical and chemical
motor neurons = these connect the CNS to effectors such as muscles and glands. they have short dendrites and long axons
structure of neuron
dendrites protrude from the cell body. these carry nerve impulses from neighbouring neurons towards the cell body
the axon carries the impulses away from the cell body down the length if the neuron
cell body includes a nucleus, which contains the genetic material of the cell
the axon is covered in a fatty layer - myelin sheath - protects the axon and speeds up the electrical transmissions of the impulse
the gaps along the myelin sheath are called nodes of Ranvier. speed up the transmissions by forcing it to jump across the gaps along the axon
at the end of the axon are the terminal buttons that communicate with the next neuron in the chain across the gap (synapse)
locations of neurons
sensory neurons are located outside the CNS, in clusters in the PNS know as the ganglia (skin)
relay neurons are found within the brain
motor neurons in the CNS but also have long axons which form part of the peripheral nervous system PNS
process of synaptic transmission
electrical impulses trigger release of neurotransmitters from synaptic vesicles
neurotransmitter diffuse across the synaptic cleft
electrical impulses (action potentials) reach the presynaptic terminal
neurotransmitters bind to receptors on the postsynaptic membrane
excitation and inhibition
the neurotransmitter serotonin causes inhibition in the receiving neuron, resulting in the neuron becoming negatively charged and less likely to fire
dopamine 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