The things that people think and feel, say and do are caused, one way or another, by electrochemical events occurring within and between the neurons that make up the nervous system, particularly those in the brain (80%)
Three types of neurons
Relay Neuron
Write one sentence about what the following features do
Nucleus
the control centre of a cell, which contains the cell's chromosomal DNA
Dendrite
Receives the nerve impulse or signal from adjacent neurons
Axon
Where the electrical signals pass along.
Myelin sheath
Insulates /protects the axon from external influences that might effect the transmission of the nerve impulse down the axon.
Nodes of ranvier
These speed up the transmission of the impulse by forcing it to ‘jump’
Terminal buttons
Terminal buttons send signals to an adjacent cell.
In a reflex arc, like the knee-jerk reflex, a stimulus, such as a hammer hitting the knee, is detected by sense organs in the peripheral nervous system, which conveys a message along a sensory neuron. The message reaches the central nervous system where it connects with a relay neuron. This then transfers the message to a motor neuron. This then carries the message to an effector such as a muscle, which causes the muscle to contract and, hence, the knee to move or jerk.
Synapse between two neurons.
Synaptic tramsmission
Neurotransmitters…
…are chemicals that are released from a synaptic vesicle into the synapse by neurons.
They affect the transfer of an impulse to another nerve or muscle
These neurotransmitters are “taken back up” into the terminal buttons of neurons through the process of reuptake
Or they are broken down by an enzyme
How a synapse works
A synapse
Action Potential
An action potential occurs when a neuron sends information down an axon, away from the cell body.
The action potential is an explosion of electrical activity - this means that some event (a stimulus) causes the resting potential to move forward
Excitation and inhibition
Synaptic connections can be excitatory or inhibitory – the difference lies in the action of the neurotransmitter at the postsynaptic receptor
Excitatory - they make it more likely the next neuron will fire (such as acetylcholine)
Inhibitory - they make it less likely the next neuron will fire (such as GABA)
Normal brain function depends upon a regulated balance between excitatory and inhibitory influences
Synaptic transmission
Sort the cards into the correct order and then write the details up on the flow diagram to show the process of synaptic transmission
