Chapter 9 -The Autonomic Nervous System

Somatic Nervous System

• pertaining to the body

• voluntary

• excitatory

• movement, muscle cell excitation

Autonomic Nervous System

• involuntary, unconscious

• regulates the activity of cardiac muscle, smooth muscle, and glands (visceral organs and blood vessels)

• excitatory or inhibitory

• two subdivisions

  • parasympathetic nervous system

  • sympathetic nervous system

parasympathetic nervous system

rest and digest

• blue

• ACh

• opposite effects of the other division

sympathetic nervous system 

emergency, fight-or-flight

• red

• norepineperine, epinephrine, and acetylcholine

• prepares body for intense physical activity in emergency

two neuron organization

• in the autonomic system

• preganglionic neurons 

• postganglionic neurons 

preganglionic neurons

have cell bodies in the CNS

postganglionic neurons

have cell bodies in the autonomic ganglia

sympathetic nervous system neurons

short pre-ganglionic neurons; long post-ganglionic neurons 

parasympathetic nervous system neurons

long pre-ganglionic neurons; very short (or within the organ itself) post-ganglionic fibers

sympathetic nervous system effects 

• increased heart rate

• increased blood glucose concentration

• increased blood flow to skeletal muscles 

• pupil dilation

parasympathetic nervous system effects

• opposite effects of the other division

• slowed heart rate

• dilation of visceral organ blood vessels

• increased digestive activity