Biopsychology - 02 Neurons & Synaptic Transmission Flashcards
What are the 3 basic parts of a neuron?
Cell body
Dendrites
Axon
What is the role of the myelin sheath?
It speed up transmissions by insulating the neurons
What is an action potential?
It shoots an electrical charge down the axon to its terminals in the neighbouring neurons
What are neurons?
Cells that are specifically designed to carry neural information throughout the body
What are the 3 types of neuron and what order do they go in?
Sensory
Relay
Motor
How does a neuron work? (4 steps)
1- dendrites carry nerve impulses from neighbouring neurons towards the cell body
2-Information passes along axon (covered in myelin sheath that protects the axon and speeds up transmission) in the form of electrical impulses.
3-At the end terminal buttons communicate with the next neuron across synapse
4-Neurotransmitters bind to receptor sites on the dendrites of the next neuron in order to pass on the signal
what charge does the inside of a neuron have in a resting state?
Negatively charged
What happens in electrical transmission? (4 steps)
-neuron is activated by a stimulus
-inside becomes positively charged for a split second
-causing an action potential to occur
-electrical impulse travels down axon towards end of neuron.
What direction do the impulses travel in a sensory neuron?
From PNS to CNS
Where are the sensory neurons found?
Various locations around the body like eyes, ears, tongue and the skin
What do the sensory neurons do?
Convert information from sensory receptors into neural impulses which are then translated into sensations when they reach the brain.
Where are relay neurons found?
in the brain and spinal cord (CNS)
What do relay neurons do?
They connect sensory neurons to motor neurons or other relay neurons and allow sensory and motor neurons to communicate with each other.
What direction do the impulses travel in a motor neuron?
From the CNS to the PNS
Where are the motor neurons located?
In the CNS but project their axons outside the CNS
What do motor neurons do?
Form synapses with muscles and control their contractions
Release neurotransmitters that bind to receptors on muscles and triggers a response that leads to motor movement
What is synaptic transmission?
The process by which nerve impulses pass across the synaptic gap from one neuron to another
What are the 6 steps of synaptic transmission?
1-Action potential arrives at axon terminal of presynaptic neuron
2-Vesicles in axon terminal contain neurotransmitters
3-Action potential causes vesicles to move forwards and fuse with presynaptic membrane and release neurotransmitters into synaptic gap
4-Neurotransmitters diffuse across synaptic cleft and binds to receptor sites on dendrite of next neuron
5-Receptors recognise the neurotransmitters and behave accordingly
6-neurotransmitters are recycled (reuptake) or broken down by enzymes at the end of the process
Why is synaptic transmission unidirectional?
Impulses at synapses only travel in one direction, from the presynaptic neuron to the postsynaptic neuron
neurotransmitter are only found in the presynaptic neuron and receptors only postsynaptic neuron membrane
What is inhibition?
When a neurotransmitter increases the negative charge of the postsynaptic neuron which decreases the likelihood that the neuron will fire and pass on the electrical impulse
What is an example of inhibition?
Serotonin
Responsible for calming the mind and body, inducing sleep and filters out unnecessary excitatory signals
What is excitation?
When a neurotransmitter increases the positive charge of the postsynaptic neuron.
This increases the likelihood that the neuron will fire and pass on the electrical impulse
What is an example of excitation?
Dopamine
Switches on the nervous system
What does summation control?
Whether a postsynaptic neuron fires or not
What happens if the net effect on the postsynaptic neuron is inhibitory?
The postsynaptic neuron is less likely to fire
What happens if the net effect on the postsynaptic neuron is excitatory?
The postsynaptic neuron is more likely to fire, the inside of the postsynaptic neuron momentarily becomes positively charged
