What Complex System?

Presenting complex systems/information in a way for people to understand it. 
- This is what I'm tackling.

Now what system?

Immune System
The Brain

Nerves and Pain:
- no pain centre in the brain, has no pain receptors

- Specialised nerve endings just underneath the skin are called nociceptors. They respond to 3 types of painful stimuli, thermal, chemical, mechanical. We haven't found any mechanical receptors, people don't know what happens beneath the surface when you wack your toe or prick your finger.

- Signals from all types of pain are conveyed on the spinal cord and brain by two types of fibre; fast conducting A delta fibres (coated in myelin, so slicker) and slower conducting C fibres. The A delta fibres give you sharp pain, the C fibres give you slow throbbing pain.

- Nociceptors only respond to disagreeable sensations. Normal touch signals are conveyed by different receptors on  separate set of A-beta nerves.

- Nerve signals travel at 120 metres a second, not too quick. However, reflexes aid us to respond quickly, it means the central nervous system can intercept a signal and act on it before passing it on to the brain. The spinal cord is an active part of sensory apparatus.

Nervous system divided in different ways. Anatomically there are two divisions, the central nervous system (brain and spinal chord). The nerves that come out of these are the peripheral nervous system. The system is then divided again into the somatic nervous system (controls voluntary movements) and autonomic nervous system (things you don't think about like heartbeat). The autonomic system is then broken down into sympathetic (responds to bodies needs and simple actions, fight or flight) and parasympathetic (looks after less urgent matters, rest and digest). Peripheral nervous system can heal and grow when damaged, ones in the brain, spinal chord cannot.