Biopsychology: Neurons and Synaptic Transmission
- Created by: mayono1
- Created on: 02-05-18 20:44
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- Neurons and Synaptic Transmission
- Types of neuron
- Sensory neuron - carries impulses from the PNS + receptors. They have long dendrites and short axons.
- Relay neuron - carries impulses from sensory neurons to motor neurons. They have short dendrites and short axons.
- Motor neuron - carries impulses from the CNS to effectors. They have short dendrites and long axons.
- The structure of a neuron
- The cell body contains the nucleus.
- Dendrites extend from the cell body. They carry electrical impulses from other neurons to the cell body.
- The axon is an extension of the neuron that carries impulses away. The axon is covered by a myelin sheath that protects it and increases the speed of impulses.
- The myelin seath has gaps of between 0.2mm and 2mm called nodes of Ranvier. They speed up the transmission of the impulse by forcing it to 'jump' across.
- At the end of the axon are terminal buttons that communicate with the next neuron in the chain across a gap known as the synapse.
- When a neuron is in a resting state the inside of the cell is negatively charged compared to the outside. When a neuron is activated by a stimulus, the inside becomes positively charged for a split second.
- This causes action potential and an electrical impulse travels down the axon towards the end of the neuron
- When a neuron is in a resting state the inside of the cell is negatively charged compared to the outside. When a neuron is activated by a stimulus, the inside becomes positively charged for a split second.
- At the end of the axon are terminal buttons that communicate with the next neuron in the chain across a gap known as the synapse.
- Synaptic transmission
- Neurons communicate with each other within groups called neuron networks. Neurons are separated by synapses.
- Signals are sent electrically WITHIN the neuron, but sent chemically BETWEEN neurons across the synapse.
- When the electrical impulse reaches the end of the neuron (the presynaptic terminal) it triggers the release of neuro-transmitter from synaptic vesicles.
- Neuro-transmitters are chemicals that diffuse across the synapse to the post synaptic receptor site.
- Each neuro-transmitter has its own specific molecular structure that fits into sites. They also have specialist functions.
- Neuro-transmitters have an excitatory or inhibitory effect on other neurons.
- Excititation = increases the likelihood that the neuron will fire and pass on the electrical impulse.
- Inhibition = decreases the likelihood that the neuron will fire and pass on the electrical impulse.
- Types of neuron
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