The Synapse Flashcards
What is the soma of a neuron
Synthetic and metabolic centre
Contain nucleus, ribosomes, mito, ER
Integrate incoming signals that are conducted passively to axon hillock
What is the axon hillock
Site of initiation of the all or none AP
What is an axon
Conducts out out signals as APs to other neurones
Mediated transport of materials between soma and presynaptic terminal
What is a synapse
Point of chemical communication between neurones
What are key structural elements of the chem synapse
Pre and post synaptic mems sep by a narrow synaptic cleft
Matrix of fibrous extracellular protein in cleft that hold pre and post syn mems together
Vesicles in presynaptic terminal that store neurotransmitter
Mem differentiations - preysnaptically active zones around vesicles cluster
- postsyn contains neurotransmitter receps
What are the classifications of synapses
Gary’s type 1. - asymmetrical syn which mems differentiation on postsyn side is thicker than on presyn side
Excitatory
Grays you 2 - symmetrical synapses which mem differentiations are. Of similar thickness
Inhibitory
What are some types of synapse
Classed morphologicalky byy location of presyn terminal on postsyn cell
Axodendritic - axon to dendrite very common
Axosomatic - axon to soma common
Axoaxonic - axon to axon uncommon
What are the functional types of synapse
Excitatory - cns the transmitter is glutamate which activates postsyn cation, ionotropic glutamate receps which gen a local excitatory depo effect - excitatory postsyn potential
Inhibitory - cns transmitter GABA or glycine, activates postsyn anion receps gen a local inhib effect hyperporlarising - inhibitory postsyn potentail
What are the major amino acid neurotransmitters in the cns
Glutamate
GABA
Glycine
What is spatial summation
Many inputs converge upon a neurone to determine its output
What is a temporal summation
A single input may modulate output by variation in AP frequency of that input
What are temporal and spatial summations
Not isolated but are complementary processes
What are amino acid and amine neurotransmitters released form
Synaptic vesicles
What are peptide neurotransmitters released from
Secretory vesciles
What activates ionotropic ligand-gated ion channels
Glutamate GABA Glycine ACh 5-HT
All but ‘what’ can activate metabotrophic GPCR’s
Glycine
What are some amine neurotransmitters
ACh Dopamine Histamine Noradrenaline Serotonin
What are some peptide neurotransmitters
Cck
Somatostatin
TRH
Give an overview of neurochemical transmission
Intake precursor Syn transmitter Store transmitter Depo by AP Calcium influx through voltage activated calcium channels Calcium induced release of transmitter Receptor activation Enzyme mediated inactivation of transmitter Reuptake of transmitter
Glycine and glutamate occur in
All cells not just neurones
GABA and amines must be
Specially syn by neurones with specific enzymes
Where are the specific enzymes used for gaba and amine production produced and what do they do
Syn in cell body and trans to presyn terminal by axoplasmic transport
At terminal enzymes mediate syn within cyto of neurotrans form precursor subs
What concentrates neurotransmitters
Conc in vesicles by transporters embedded in vesicle mem
What is the syn and storage of neurotransmitters
Syn of precursor peptide by ribosomes at ER
Cleavage of precursor peptide in Golgi apparatus yielding active neurotransmitters
Sec granules bud off from the Golgi apparatus
Sec granules are trans to presyn terminal by fast axoplasmic trans
What are the key features of the exocytosis of amino acid and amine neurotransmitters
Synaptic vesciles ready for rapid release are held in apposition to presyn mem in docking SNARE complex
Depo fo presyn mem opens voltage activated calcium channels causing a rise in conc of calcium in vicinity of docked vesciles
Calcium binds to synaptotagmin-1 ion vesicle mem causing vesicle to fuse to presyn mem
Neurotransmitter diffuses from vesicle to cleft
Mem added to presyn terminal and retrieved by endocytosis
What are ligand gated ion channels
Aka, ionotropic receps
Consist of sep glycoproteins that form central, ion conducting, channel
Allow rapid change in perm of mem to certain ions
Rapidly alter mem potentail
What are GPCR’s
Aka metabotrophic receps
Receptor, G protein and enzyme sep
G protien couples receptor activation to effector modulation
Signalling via G proteins relatively slow in comparison to ligand gated ion channels
What are dendrites
Recieve inputs from other neurones and convey graded electrical signals passively to the soma
