Dual innervation, sympathetic tone, parasympathetic tone, local and diffuse effects

Dual innervation

most organs are innervated by both the sympathetic and parasympathetic divisions

the two divisions usually have opposing effects on the same organ

What does dual innervation allow for

precise, moment-to-moment control of organ activity

Sympathetic tone (vasomotor tone)

a baseline level of sympathetic activity that is always present, even at rest

ex: a continual state of partial constriction of blood vessels

what does sympathetic tone do

keeps organs in a partially activated state, allowing quick increases or decreases in activity

parasympathetic tone

a baseline level of parasympathetic activity, especially prominent in resting conditions

dominates functions involved in rest, digestion, and energy conservation

Local effects occur when

neurotransmitters act only at a specific synapse or target organ

effects of local effects are

short lived and precise

local effects are typical of

parasympathetic responses

diffuse effects occur when

neurotransmitters or hormones affect many tissues at once

effects of diffuse effects are

widespread and longer-lasting

diffuse effects are typical of

sympathetic responses, especially via epinephrine/norepinephrine released from the adrenal medulla