Nervous System

Peripheral Nervous System: Autonomic Nervous System

Comparison of Sympathetic and Parasympathetic Innervation

Many organs are innervated by both the sympathetic and parasympathetic division of the autonomic nervous system.

Effector Effect of Sympathetic Innervation Effect of Parasympathetic Innervation
Cardiac muscle
Heart Increases heart rate, force of contraction, and blood pressure Decreases heart rate, force of contraction, and blood pressure
Smooth muscle
Eye Dilation of pupil; focusing for distance vision Constriction of pupil; focusing for near vision
Stomach and intestines Decreases peristalsis; contracts sphincters Increases peristalsis; relaxes sphincters
Lungs Relaxation; airway diameter increases Contraction; airway diameter decreases
Arrector pili of hair follicles Contraction that results in erection of hairs (“goose pimples”) No known effect
Urinary bladder Relaxation of urinary bladder; constricts sphincter Contraction of muscular wall; relaxation of internal sphincter to eliminate urine
Reproductive organs Ejaculation of semen in men Erection of penis (men) or clitoris (women)
Sweat Increases secretion None (not innervated)
Lacrimal (tears) None (not innervated) Stimulates secretion
Salivary Decreases secretion of digestive juices Increases secretion of digestive juices
Adrenal Secretion of epinephrine and norephinephrine by adrenal medullae None (not innervated)


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