The sympathetic and sympathetic nervous systems make up the autonomic nervous system, regulating involuntary functions. The first acts in situations of fight or flight, for example in an accident of self-actions such as: increased heart rate, pupil dilation, relaxes airways, among others. Neurotransmitters are released: adrenaline and norepinephrine. The parasympathetic system performs antagonistic functions by activating in relaxation situations: it decreases heart rate, contracts pupils, constricts airways. Acetylcholine is released as a neurotransmitter.
Well mechanical digestion involves physically breaking the food into smaller pieces but chemical digestion involves breaking down into simpler nutrients that can be used by cells.
