UNIT 3 - KA4
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What does the nervous system consist of
The nervous system consist of a complex network of nerve cells called neurons.
What is the function of neurons
Neurons receive and transmit electrical impulses (nerve impulses) and provide the body with a rapid means of communication and control
What are the three types of neuron
• Sensory • Inter • Motor
What does sim do
Sim does crazy actions A nerve impulse always travels: Dentrites ———> cell body ———> axon
Draw and label sensory neuron from left to right
Dentrites - axon - cell body - myelin sheath - axon terminals direction of nerve impulse ———>
What is a difference in the structure of sensory neuron to other neurons
The cell body sits part way along the axon and there are no Dentrites on the cell body
Draw and label inter neuron from left to right
Dendrites - cell body - axon - axon terminals
What is the difference in the structure of inter neurons to other neurons
The axon is very short and lacks myelination
Draw and label motor neuron from left to right
Dendrites - cell body - axon- myelin sheath - motor end ——— > direction of nerve impulse
Dendrite
Receive nerve impulse and pass them towards a cell body
Cell body
The control centre of the cells metabolism and contains clusters of ribosomes. And contains the nucleus and most of the cytoplasm
Axon
An axon is a single nerve fibre that carries nerve impulses away from a cell body
Myelin
Axons are surrounded by a myelin sheath which insulates the axon and increases the speed of impulse conduction
When is myelination completed
Myelination is not completed at birth, but continues from birth until adolescence
What happens to the response to stimuli in the first two years as a result of myelination
Responses to stimuli in the first two years of life are not as rapid or co-ordinated as those of an older child or adult
What can certain diseases do to myelin sheath
Certain diseases destroy the myelin sheath causing a loss of coordination
What is the function of glial cells
Glial cells produce the myelin sheath and support neurons
Where do neurons connect
Neurons connect with other neurons or muscle fibres at a synaptic cleft
What are the neurons before and after the synapse called
The neurone before the synapse is called the presynaptic neuron and the neuron after the synapse is called the post synaptic neuron
Where are neuron transmitters stored (1st stage of transmission at a synapse)
• Neurotransmitters are stored in the vesicles in the axon endings of the presynaptic neuron
Where are the neurotransmitters released (2nd stage of transmission at a synapse)
They (the neurotransmitters) are released into the (synaptic) cleft on arrival of an impulse
Where do they diffuse (3rd stage of transmission at a synapse)
• They (the neurotransmitters) diffuse across the cleft
What do neurotransmitters bind to (4th stage of transmission at a synapse)
• They (neurotransmitters)bind to receptors on the membrane of the postsynaptic neuron
Draw and label diagram of the synapse
Check jotter