The Structure and Function of Neurons Flashcards
Neuron - cell body
Contains nucleus, which contains all genetic material of the cell
Neuron - dendrites
Branch like structures that project from the cell body. Carry impulses from other neurons towards the cell body.
Neuron - axons
Carry impulses away from the cell body down the length of the neuron
Neuron - myelin sheath
A layer that covers the axon and speeds up the electrical impulse
Neuron - Nodes of Ranvier
Segments the myelin sheath. They speed up transmission of the impulse by forcing it to ‘jump’ across gaps along the axon
Neuron - terminal buttons
At the end of the axon and communicate with the next neuron in the chain across the synaptic gap by using neurotransmitters
What is a sensory neuron?
Found in receptors and carry nerve impulses to the spinal cord and brain. When the impulses reach the brain, they are translated into sensations such as vision, hearing, taste or touch to give information about the environment. Some neurons stop at the spinal cord, allowing for quick research actions.
What is the structure of the sensory neuron?
Long dendrites and short axons
What is a relay neuron?
Found in the brain and spinal cord, and allow sensory and motor neurons to communicate. They are found between sensory input and motor output.
What is the structure of a relay neuron?
Short dendrites, and long or short axons
What is a motor neuron?
Found in the CNS and control muscle movement. When they are stimulated, they release neurotransmitters that bind to the receptors on the muscles to trigger a response.
What is the structure of a motor neuron?
Short dendrites and long axons
What is the first stage of synaptic transmission?
Dendrite picks up NTs and sends an action potential through the cell body and along the axon to the terminal button.
What is the second stage of synaptic transmission?
Once the action potential has reached the terminal button, it needs to be transferred to another neuron. To achieve this it must cross the synaptic gap between pre and post synaptic neuron.
What is the third stage of synaptic transmission?
Synaptic vesicles store NTs - chemical messengers that convert the impulse to a chemical message
What is the fourth stage of synaptic transmission?
As the impulse reaches the synaptic vesicle, they release the NTs that cross the synaptic gap
What is the fifth stage of synaptic transmission?
The NT diffuses across the synaptic gap then binds to the specialist receptors on the surface of the next cell that recognise it and match that particular cell - eg dopamine receptors recognise dopamine
What is the sixth stage of synaptic transmission?
Once the next cell is activated the receptor molecules produce either an excitatory effect or an inhibitory effect depending on the summation of activity at a post synaptic level.
What is the seventh stage of synaptic transmission?
It is completed by a process called reuptake. This is where the NT is taken back up/recycled by the pre-synaptic neuron
What are the key areas of synaptic transmission?
Synaptic vesicle
Terminal button
Synaptic gap
Receptor
Neurotransmitters
Post synaptic neuron
What is a neurotransmitter?
Chemicals that are released from the end of brain cells that allow them to communicate with each other and relay messages to different areas of the brain. As one neuron releases an NT, receptors on other neurons pick up this message and relay it to the next neuron. Neurotransmitters affect the transfer of an impulse to another neuron or muscle.
What is an excitatory effect?
They create a positive charge, making the neuron more likely to fire. This rise in action potential will increase activity.
What is an inhibitory effect?
They create a negative charge, making the neuron less likely to fire. This fall in action potential will decrease activity.
