We are alive because of a number of systems within the body that work together.

These are:
S Our blood circulation and breathing systems,
S Our internal organ systems liver, kidneys etc,
S Our skin system, which extends inside our body
S Our nervous, electrical, and muscle systems,
S Our digestive and repairs systems,
S Our five main senses; Touch, sight, hearing, smells and taste which allow  us to react with the outside world.
S Our emotional systems, that affect our physiology and behaviour.
S Our mental systems that reflect our behaviours and attitudes.