Chapter 15: Autonomic Nervous System

autonomic nervous system

a motor nervous system that controls glands, cardiac muscle and smooth muscle, visceral (organ) motor system, INVOLUNTARY actions

receptors

nerve endings that detect, stretch, tissue damage, blood chemicals, body temp, and other internal stimuli

integrating center

interneurons in CNS

effectors

carry out end response

sympathetic division

prepares body for physical activity, stress, trauma, increases heart rate, BP, airflow, reduces blood flow and digestive tract, “Fight or flight”

parasympathetic division

calms many body functions reducing energy expenditure and assists in bodily maintenance, “resting and digesting”

autonomic tone

normal background rate of activity that represents the balance of the two systems according to the body’s needs

sympathetic tone

keeps most blood vessels partially constricted and maintains blood pressure, excites the heart but inhibits digestive and urinary function

parasympathetic tone

maintains smooth muscle tone in intestines, inhibits digestive and urinary function, inhibits the heart

somatic pathway

voluntary, motor neuron from brainstem/spinal cord with a long myelinated axon that reaches all the way to the skeletal muscle

autonomic pathway

signal must travel across two neurons to get to the target organ

preganglionic fibers

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

postganglionic fibers

leave the ganglion by way of the gray communicating ramus (unmyelinatied) forms a bridge back to the spinal cord, extend the rest of the way to the target organ

adrenal glands

located on superior poles of the kidneys, adrenal cortex (outer layer), adrenal medulla (inner core) secretes adrenaline and noradrenaline

enteric nervous system

the nervous system of the digestive tract, innervates smooth muscle and glands