How does the nervous system work

how does the nervous system work?
like where does it start and how does it end?
thanks

1. sensory receptors(efferent cells)- touch something
2. goes to spinal cord(interneurons cells)
3. transfer to afferent cells(brain cells)
then response travels back until you do what the brain says

EX: touch hot pot.
sensory receptors send the message to spinal cord then spinal send to brain then brain says take hand off and you take hand off.

The human nervous system is possibly the single most complex object in the entire cosmos, or at least the most complex object in our section of the galaxy. This is because it includes the brain, with ten billion neurons and many times more interneural connections. The human brain is a more dense source of complexity than anything we have yet seen, including the bodies of all animals and any variety of inanimate phenomena or objects.

However, the human nervous system is more than just the brain. All animals have a nervous system, but only vertebrates have a complex nervous system that include the central nervous system (CNS) and peripheral nervous system (PNS) as components. The central nervous system consists of the nerves and neurons found in the spine and brain, while the peripheral nervous system is everything else.

In older animals, the nervous system was mainly a sensor network connected directly to the skeletomuscular system, allowing external and internal causes to give rise to organism-centric effects called behaviors. In more complex organisms, the nervous system functions as an independent entity, processing inputs extensively before returning carefully chosen outputs. In all animals, including humans, the vast majority of this is unconscious, automatically executed by neural programs that have been hardwired by millions of years of evolutionary design.

The central nervous system is the most complex system and the most difficult to understand or reverse-engineer in any species, although efforts in this direction have had some success. For the purposes of this article, the central nervous system can be thought of as the brain and spine, which includes the brain stem. Further subdivisions are the province of cognitive science and neuroanatomy.