First, most modern neural networks are not actually modeled after biological synapses. They use an artificial neuron that allows Back Propagation to work, rather than Perceptron, which is a much more accurate representation.
When you feed the output of one network to the input of another network, you really only created one large network, not two separate networks. It just happens that in this case parts of the networks will be trained independently.
, . , . , . , , , , , . "" , "" . , , "", .
.