chapter 15 - autonomic nervous system

autonomic nervous system

motor system that controls glands, cardiac muscle, and smooth muscle

denervation hypersensitivity

exaggerated responses of cardiac and smooth muscle if autonomic nerves are severed

visceral reflexes

unconscious, automatic, stereotyped responses to stimulation involving visceral receptors and effectors

sympathetic division

prepares body for exercise, trauma, arousal, competition, anger or fear

parasympathetic division

calms many body functions reducing energy expenditure and assists in bodily maintenance

autonomic tone

normal background rate of activity the represents the balance of the two systems according to the bodys needs

parasympathetic tone

maintains smooth muscle tone in intestines, holds resting heart rate around 70-80 bpm

sympathetic tone

keeps most blood vessels partially constricted and maintains bp

preganglionic fibers

small myelinated fibers that travel from spinal nerve to the ganglion by way of the white communicating ramus

postganglionic fibers

leave the ganglion by way of the gray communicating ramus, forms a bridge back to the spinal nerve

adrenal cortex (outer layer)

secretes steroid hormones

adrenal medulla (inner core)

essentially a sympathetic ganglion that secretes a mixture of hormones into the bloodstream (adrenaline and noradrenaline)

enteric nervous system

• the nervous system of the digestive tract 

  • Does not arise from the brainstem or spinal cord (no CNS components)

Innervates smooth muscles and glands