Final answer:
The parasympathetic nervous system helps to slow the heart rate, lower blood pressure, and stimulate digestion as part of the 'rest and digest' response after 'fight-or-flight' situations.
Step-by-step explanation:
One of the effects of the parasympathetic nervous system (PNS) is the restoration of the body to a state of calm after the 'fight-or-flight' response triggered by the sympathetic nervous system. When activated, the PNS leads to several responses such as slowing of the heart rate, lowering blood pressure, and stimulation of digestion. These changes are primarily due to the release of the neurotransmitter acetylcholine (ACh), which targets organs to promote 'rest and digest' functions.