Knowra Parasympathetic nervous system Parasympathetic nervous system The division of the autonomic nervous system that regulates involuntary organ and gland activity, generally supporting rest, digestion, and energy conservation.
Vagus nerve : The tenth cranial nerve, carrying sensory and motor signals between the brainstem and many organs. It carries most parasympathetic output to the heart, lungs, and digestive tract.
Autonomic nervous system : The nervous system division that regulates involuntary functions of organs, glands, and smooth and cardiac muscle. The parasympathetic system is one of its major divisions.
Rest and digest : A shorthand for physiological states favoring digestion, recovery, and energy storage over acute mobilization. It summarizes the conditions commonly associated with parasympathetic activity.
Sympathetic–parasympathetic balance : The changing interaction of sympathetic and parasympathetic influences on organ function. Their effects are not always simple opposites, and their relative influence varies by organ.
Heart rate variability : Variation in the time intervals between successive heartbeats, influenced by autonomic and other physiological factors. Some measures track vagal influences, but they are not direct readings of whole-body parasympathetic tone.
Craniosacral outflow : The parasympathetic pathways that arise from the brainstem and sacral spinal cord. These two origins supply the division's long-distance preganglionic fibers.
Sympathetic nervous system : The autonomic division that coordinates responses such as increased alertness, cardiac output, and energy mobilization. Its typical effects counterbalance or complement parasympathetic regulation.
Heart rate : The number of heart contractions per unit of time, regulated by intrinsic pacemaking and neural and hormonal inputs. Vagal parasympathetic signals can slow the sinoatrial node.
Dual innervation : The supply of an organ by two nervous pathways that can exert distinct or opposing effects. Many organs receive both sympathetic and parasympathetic input.
Vagal tone : A term for the influence of vagal pathways on physiological functions, especially heart rate. Its measurement and interpretation depend on the organ and method used.
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