Neurotransmitters Flashcards
What is the basic structure of the of the neurone?
axon- rapid signal transfer dendrites- information comes here via spines on dendrites soma- where all different signals coming into the cell integrate synaptic terminal
What biological molecules are common neurotransmitter?
Amino Acids e.g. glutamate Amine e.g. noradrenaline neuropeptides e.g. opiod peptides
What happens to neurons when they receive multiple signals?
all the signals are integrated to produce diverse functional responses
Describe the activation of the CNS synapse?
Action potential causes VGCC tho open = influx down concentration gradient into the pre-syaptic neuron. This causes the transmitter to be released and diffuse across cleft and then bind to receptors on post synaptic neuron. If they are excitary neurotransmitters this causes VGSC to open there Na+ influx into post synaptic neurone and can cause action potential.
What does the sodium potassium pump do?
Causes the resting membrane potential to be reset after action potential has occured in pre-synaptic neuron
How are neurotransmitters released from the vesicles?
1- membrane depolarised 2-Ca2+ channels open 3- Ca2+ influx into presynaptic neurone 4- This causes vesicles be docked(move onto memebrane) primed, and then to fuse with membrane 5-vesicle exocytosis 6-transmitter release
What is electrochemical transduction?
For the process of neurotransmitter release it includes everything for the Calcium influx to the neurotransmitter being released
How does the rapid release process occur?
1- vesicles are filled with neurotransmitter due to pump in vesicle membrane 2- vesicle is the docked in the SYNAPTIC ZONE 3- Vesicles and pre-synaptic membrane have proteins put on surface (vesicular proteins), enabling fusion and exocytosis
What do neurotoxins do?
They target vesicular proteins
Give examples of some neurotoxins?
Alpha latrotoxin (from black widow spiders) stimulates transmitter release to depletion Zn2+ dependent endopeptidases inhibit transmitter release Tetanus toxin C tetani causes paralysis Botilinum toxin C botulinum causes flaccid paralysis and food poisoning
What are the requirements for transmitter release?
Calcium influx Transmitter containing vesicles must be docked on the presynaptic membrane Protein complex formation between the vesicle membrane and the cytoplasmic proteins to enable both vesicle docking and a rapid response to the Ca2+ entry leading to membrane fusion and exocytosis ATP needed Vesicles must be recycled so they can be reused
What are the 2 main classes of receptors?
Ion channel receptor - Fast response (miliseconds) - mediate all fast excitatory and inhibitory transmission response(secs G-protein coupled receptors- slow (secs and minutes)
Examples of G-protein coupled receptors ?
Muscarinic receptors- type of ACh recepetor on the heart
What do inhibitory and excitatory receptors do?
Excitatory- depolarisation Inhibitory-hyperpolarisation
What are the 2 main types of glutamate receptors?
AMPA receptors: -Linked to Na+ channels so that when glutamate binds VGSC open causing influx into post synaptic neurone -Majority are fast excitatory synapses -Have a rapid onset so they open and close very quickly and desensitise quickly NMDA receptors: -Slow component of excitatory transmission -LINKED TO Na+/Ca2+ channels so allow both to pass into the cell -serve as coincidence detectors as they are only activated due to another input elsewhere on cell. The NMDA receptors detect this signal and became activated as a result. -underlie learning mechanisms