neuroscience

Electrical and chemical. Majority of synapses in human brain are chemical

• Direct transfer of current from one cell to the next
• -current goes throught gap junctions
• -each channel=connexon
• -connexons made up of connexin proteins

addtion of connexon

post synaptic poential. Small compared to action potential is 1mv

Bidirectional. Fast- no time delay . Ex escape reflexes in invertebrates

axon terminal with synaptic vesicles- store neurotransmitter

neurotransmitter receptors

attach the synaptic vesicle to active zone.

• presyneptic membrance by snare protiens. Acton potential arrives at axon terminal
• -voltage gated calcium channels open
• -calcium flows into presynaptic terminal
• vesicle fuses w/ presynaptic membrane
• -nerotransmitter released.
• vesicle recycled

• SNARE PROTEIN on synaptic vesicle
• - senses ca2+ increase and triggers release

Tetanus toxin released by bacteria has its effect by cutting snare protein.

synapse between neuron + muscle cell

• post-synaptic membrance-
• -is folded
• -larger surface area
• -many neuro-transmitter receptors

• aligned over folds
• -release of a large number of neurotransmitter molecules
• -large response in muscle cell to contraction
• -fail -safe

glutamate

Neurontransmitter binds to neuro transmitter gated ion channels and then ion channel opens and if channel permeable to Na+ ions then EPSP(excitatory postsynaptic potential)

GABA

inhibitory if neurotransmitter-gated ion channel is permable to CL- ions then IPSP (inhibtory post-synaptic potential)