After a stimulus results in initial depolarization of a region of cell membrane of a neuron:

After a stimulus results in initial depolarization of a region of cell membrane of a neuron, a threshold voltage is reached. ... -Voltage-gated sodium and potassium channels quickly close, and recovery begins. A large number of voltage-gated sodium channels quickly open, causing a rapid change in membrane potential.

answer:

it could come from a variety of sources.

explanation:

..although it was most likely developed through zoonotic transmission, where an infectious disease which usually afflicts when animals jump to humans.

answer:

Bones of the leg, ankle and foot: There are 62 lower extremity bones. They consist of 10 hip and leg, 14 ankle and 38 foot bones. The 10 hip and leg bones are the innominate or hip bone (fusion of the ilium, ischium, and pubis), femur, tibia, fibula, and patella (kneecap) on each side.

Explanation:

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