W3: Neurones, Transmitters, Synapses And Receptors Flashcards
What do dendrites do?
Input from other neurones
What does the axon hillock do?
Axon potential generation
What does the axon do?
Impulse conduction/action potential propagation
What does the axon terminal/synaptic bouton do?
Release neurotransmitter
Roles of glial cells
Physical and metabolic support
Electrical insulation
Signalling
What are the properties of a gap junction (electrical synapse)?
- fastest channel
- direct transfer of ionic current
- bi-directional transfer of ions
- allows synchronous activity between cells
- glia-neurone, glia-glia communication
- found in cardiac myocytes
Properties of a chemical synapse
- unidirectional transfer of information - presynaptic to postsynaptic
- presynaptic terminal releases neurotransmitter to interact with postsynaptic membrane receptors
What is the process of neurotransmission dependent on?
Action potential dependent
Calcium dependent
Process of neurotransmission
- Action potential invades the nerve terminal
- Depolarisation of the presynaptic membrane triggers voltage gated calcium channels to open, leading to an influx of calcium ions.
- Synaptic vesicles fuse with the presynaptic membrane and neurotransmitter is released by exocytosis
- Diffusion across the synapse and neurotransmitter binds to the receptors on the post-synaptic membrane, depolarising it
- Rapid termination of the signal occurs
How is the signal at the synapse terminated?
Re uptake of neurotransmitter or enzymatic breakdown
What is a neurotransmitter?
Chemical messengers at the synapse
Amino acid neurotransmitters
Glutamate (major excitatory transmitter in the CNS)
GABBA (major inhibitory transmitter in the CNS)
Monoamine neutransmitters
Noradrenaline
Dopamine
5-HT
Where is ACh neurotransmitter more present in?
The PNS
What are receptors?
Recognition sites for neurotransmitters, causing an intracellular signal when bound to. Membrane spanning protein molecules. Specific to a neurotransmitter.