8. Neurotransmitters Flashcards
What is the myelin sheath? (Neurotransmitters B&B)
Fatty tube placed around the axon by either an oligodendrocyte or by a schwann cell
How does the oligodendrocyte form myelin? (Neurotransmitters B&B)
- Central nervous system
- Around the axons in the brain and spinal cord
How does schwann cells for myelin? (Neurotransmitters B&B)
- Peripheral nervous system
- Wraps around peripheral nerves to form myelin
Why is the action potential considered and all or nothing response? (Neurotransmitters B&B)
It is the same size at each point along the axon
When the axon is myelinated, where do the action potentials occur and why? (Neurotransmitters B&B)
- Anywhere along the nodes of Ranvier
- As this is the only place where K+ and Na+ can pass through channels
What is the relationship between action potentials and nodes of Ranvier? (Neurotransmitters B&B)
- Depolarisation occurs at the nodes of Ranvier
- Decay along the myelinated sections
What are the two types of synapses? (Neurotransmitters B&B)
- Electrical synapse
- Chemical synapse
How does an electrical synapse work? (Neurotransmitters B&B)
Junctions between neurons are small and spanned by proteins which communicate
How does a chemical synapse work? (Neurotransmitters B&B)
Junction between the neurons is large and chemicals are released from the presynaptic neuron to the post synaptic neuron
What is the process of communication at the chemical synapse? (Neurotransmitters B&B)
- AP travel down the axon
- Depolarisation at synapse opens Na+ channels
- Influx of Na+ leads to neurotransmitter release
- Neurotransmitters bind & activate receptors on dendrites in post synaptic neuron
- Depolarisation/hyperpolarisation
- Stimulates the post synaptic soma
- If enough depolarisation, AP generated at the axon hillock
What is a neurotransmitter? (Neurotransmitters B&B)
Chemicals that are used to transmit information from the pre synaptic to post synaptic neurons
What is Dales Law? (Neurotransmitters B&B)
If a neurotransmitter is released by one of the neurones synaptic endings, the same chemical is released at all synaptic endings of that neuron
What is the process of neurotransmitter release? (Neurotransmitters B&B)
- Synaptic vesicle docked at the synaptic membrane
- Depolarisation opens Na+ channels
- Calcium influx
- Vesicles fuse with synaptic membrane and release neurotransmitter to the synapse
- Vesicle detaches from the docking zone
What does an inotropic receptor do? (Neurotransmitters B&B)
Opens the channel
What does a metabotropic receptor do? (Neurotransmitters B&B)
Activates the internal 2nd messenger system that changes the functioning of post synaptic cells
