Lecture 29 Flashcards
Synaptic transmission between neurons
Occurs at the axo-dendritic synapse
Synaptic transmission between a neuron and muscle fiber
Occurs at the neuromuscular junction or ned plate.
The neuromuscular junction is an example of ______ transmission
excitatory synaptic transmission
Acetylcholine functions as a:
neurotransmitter (ACh)
End plate potential always ___
triggers an AP, which is then transmitted along the muscle fiber.
Ionic mechanisem of end-plate potentials:
Transient opening of ion channels selective to both Na+ and K+
Excitatory synapses mechanism:
Depolarisation of the postsynaptic membrane, called excitatory postsynaptic potential (EPSP)
Inhibitory synapses mechanism:
Hyperpolarisation of the post synaptic membrane, called the inhibitory post synaptic potential (IPSP)
Neurotransmitters of Excitatory synapses:
mainly glutamic acid (glutamate) or ACh
Neurotransmitters of inhibtory synapses:
mainly GABA or glycine
Ionic mechanism of IPSPs:
Usually transient opening
Two classifications of neurotransmitters:
Small molecule NTs(classical NTs), Neuropeptides (neuromodulators)
Small molecule neurotransmitters:
Usually fast action, and direct on post synaptic receptors.
Amino acids: glutamamte, GABA, glycine,
ACh
Amines: serotonin(5-HT), noradrenaline, dopamine
Neuropeptides:
- Large molecules that have a ‘metabotropic’ or indirect action in post synaptic receptors or modulatory actions on the effects of other neurotransmitters
- Slow and usually more diffuse action.
Eg. neuropeptide Y (NPY), substance P, Kisspeptin, Enkephaln
Factors determining synaptic action
-Type of neurotransmitter/neuromodulator
- Type of neurotransmitter receptor expressed in the postsynaptic membrane
- The amount of neurotransmitter receptor present in the postsynaptic membrane - synaptic plasticity: LTP or LTD
