Biopsych - Neurons And Synaptic Transmission Flashcards
What is a neuron
Nerve cells
Process and transmit messages through electrical and chemical signals
In nervous system
What are the 3 different types of neuron
Sensory
Relay
Motor
What is the function of sensory Neurons
found in receptors such as the eyes, ears, tongue and skin, and carry nerve impulses to the spinal cord and brain.
• When these nerve impulses reach the brain, they are translated into ‘sensations’, such as vision, hearing, taste and touch.
• However, not all sensory neurons reach the brain, as some neurons stop at the spinal cord, allowing for quick reflex actions.
• Carry messages from the PNS to the CNS
Do all sensory neurones reach the Brain ?
No
Some stop at spinal cord
For quick reflex actions
What are relay neurones
Connect sensory Neurons to motor Neurons or other relay Neurons
So between sensory input and motor output
Allow communication between both Neurons
Found in the brain
Here decision about responding to a sensation take place
What are motor Neurons
Release neurotransmitters - bind to receptors on muscles
Trigger response
Lead to movement
Connect the CNS to effectors such as glands and muscles
So found in CNS
Describe structure of Neurons
Nucleus - genetic material
Dentrites - branch like structures
Carry nerve impulses from Neurons towards cell body
Axon - carries impulses away from the cell
Myelin sheath - speed up electrical transmission, covers axon for protection
Nodes of ranvier- - gaps between Msheath
Speeds up transmission of impulses - forces impulse to jump across gaps
Terminal buttons - end of axon , communicate with next neuron
What is a synaptic transmission
The process by which a neighbouring Neurons communicate with each other by sending chemical messages along the synaptic cleft
What are the two types of transmission
Electric transmission - firing of neuron
Chemical transmission - synapses
Explain electrical transmission
When a neuron is resting, the inside of the cell is negatively charged compared to the outside
- The neuron is activated by a stimulus
- The inside of the cell becomes positively charged 4. This causes action potential to occur
- This creates an electrical impulse which travels down the axon
What are neuro transmitters
Chemicals that diffuse across the synapse to relay signals from one neurone to another
Can either have inhibitory or excitatory effect on neighbouring Neurons
Explain excitation and inhibition
Neurotransmitters can be excitatory or inhibitory (most can be both but GABA is purely inhibitory).
• If the neurotransmitter is excitatory then the post synaptic neuron is more likely to fire an impulse.
• If the neurotransmitter is inhibitory then the post synaptic neuron is less likely to fire an impulse.
• The excitatory and inhibitory influences are summed, if the net effect on the post synaptic neuron is inhibitory, the neuron will be less likely to ‘fire’ and if the net effect is excitatory, the neuron will be more likely to fire.
Explain chemical transmission
Nerveimpulsetravelsdownanaxon(electricaltransmission).
2. Nerve impulse reaches the presynaptic nerve terminal.
3. Electrical impulse triggers the release of neurotransmitters from tiny sacs called synaptic vesicles.
4. The neurotransmitters are fired into the synaptic gap where they diffuse across the synapse.
5. Neurotransmitter binds with receptors on the post synaptic membrane
6. If successful the neurotransmitter is taken up by the post- synaptic neuron.
Resulting in excitation or inhibition of post synaptic membrane
Why can information only travel in one direction at a synapse
the synaptic vesicles containing the neurotransmitter are only present on / released from the presynaptic membrane
• the receptors for the neurotransmitters are only present on the postsynaptic membrane
