chapter 9

Nervous System

Efferent Divisions of the PNS

• Somatic (pertaining to the body) nervous system

  • Voluntary

  • Excitatory

  • Movement, muscle cell excitation

• Autonomic (involuntary, unconscious) nervous system

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

  • Excitatory or inhibitory

  • Two subdivisions

    • Parasympathetic nervous system = rest and digest

    • Sympathetic nervous system = emergency response, fight/flight

Autonomic Nervous System

• Autonomic nervous system – two-neuron organization in the autonomic system

  • Preganglionic neurons: have cell bodies in the CNS

  • Postganglionic neurons: have cell bodies in the autonomic ganglia

• Ganglion – group of cell bodies

Sympathetic Nervous System

Sympathetic Division

• Fight or flight reaction

  • *Think scared (both start w/ letter S)

• Norepinephrine (NE, a catecholamine)

• Epinephrine (E, a catecholamine)

• Acetylcholine (ACh, a neurotransmitter)

• Short preganglionic neurons; long postganglionic neurons

• Prepares body for intense physical activity in emergency

  • Increased heart rate, blood glucose concentration, blood flow to skeletal muscles

  • Pupil dilation

Parasympathetic Nervous System

Parasympathetic Division

• Rest and digest process

  • *Think “impaired” from food coma because you need to digest all the food XD

• Acetylcholine (ACh)

• Long preganglionic neurons; very short postganglionic neurons

• Opposite effects of sympathetic nervous system

  • Slowed heart rate

  • Dilation of visceral organ blood vessels

  • Increased digestive activity