PARASYMPATHETIC DIVISION

DISTRIBUTION:

From thoracic & lumbar nerve roots

DISTRIBUTION:

From cranial & sacral nerve roots

STRUCTURE:

Presynaptic neuron short, secretes AC

Synapse in chain ganglion (or adrenal medulla)

Postsynaptic neuron long, secretes NE

(exception: short in adrenal medulla,

secretes mostly epinephrine)

STRUCTURE:

Presynaptic neuron very long, secretes AC

Synapse on or close to target organ

(e.g., celiac ganglion)

Postsynaptic neuron short, secretes AC

“FIGHT OR FLIGHT” RESPONSE:

Increased blood flow (except to viscera)

Increased heart rate, breathing, sweating;

contraction of arrector pili muscles

Lowered stimulatory thresholds (quicker and

more certain response, more alert)

Inhibition of digestion & peristalsis

Decreased prothrombin time (quicker clotting)

“REST AND RUMINATE” RESPONSE:

Decreased blood flow (but increased to viscera)

Slower, more relaxed heart rate, breathing;

arrector pili muscles inhibited

Raised stimulatory thresholds (less likely to

respond, response slower, less alert)

Stimulates digestion, peristalsis, sexual activity

Increased prothrombin time (slower clotting)

Abbreviations: AC = Acetylchloine; NE = Norepinephrine