When the propagated action potential reaches the at the end of the axon, channels are triggered to . calcium ions move from the down their concentration gradient. the entry of calcium triggers a series of events, resulting in fusion of with the neuron plasma membrane. neurotransmitter is subsequently released into the by exocytosis. approximately 300 vesicles are released per action potential.

When the propagated action potential reaches the Synaptic knob at the end of the axon,voltage-gated Ca+2 channels are triggered to open. Calcium ions move from the IF into the synaptic knob down their concentration gradient. The entry of calcium triggers a series of events, resulting in fusion of synaptic vesicles with the neuron plasma membrane. Neurotransmitter is subsequently released into the synaptic cleft by exocytosis. Approximately 300 vesicles are released per action potential. The above is an example of a nerve impulse transmission across a neuromuscular junction.

Stimulation of the membrane causes it to become highly permeable. The inside of the membrane becomes positively charged and the outside negatively charged. The membrane is then said to be depolarized. This constitutes the action potential.

the cladogram shown here shows similarities and differences among several classes of vertebrates. anatomically, the four have limb structure as their common ancestor. we might separate the mammals from the other three classes because they a) divergent; do not lay eggs b) identical; are warm-blooded c) varied; a four chambered heart d) homologous; have mammary glands