Autonomic Nervous System (ANS)

Autonomic Nervous System

After studying this chapter, readers should be able to:

1. Distinguish between the sympathetic and parasympathetic divisions of the autonomic nervous system.

2. Describe the relationship between preganglionic and postganglionic neurons.

3. Identify the two nerves that make up most of the preganglionic parasympathetic fibers in the body.

4. Explain dual innervation of the autonomic nervous system.

5. Differentiate between cholinergic and adrenergic neurons as to the neurotransmitter secreted and the type of neuron that secretes the neurotransmitter.

6. Describe the arrangement of sympathetic and parasympathetic neurons and ganglia.

7. Differentiate between nicotinic and muscarinic receptors.

8. Contrast the two types of cholinergic receptors.

9. Give examples of adrenergic and cholinergic effects upon various organs.

10. Summarize imbalances of the autonomic nervous system.

Overview

The autonomic nervous system (ANS) is part of the peripheral nervous system (PNS) (FIGURE 14-1). It mostly functions autonomously (independently), with-out conscious effort. It is also sometimes referred to as the involuntary nervous system or general visceral motor system. The ANS regulates the smooth muscles, cardiac muscles, and glands. It can respond to emotional stress and prepares the body for strenuous physical activity. Most peripheral nerve fibers lead to ganglia located outside the central nervous system (CNS) and control visceral muscles and glands highly independent of the brain and spinal cord. Important differences between the autonomic and somatic nervous systems include their effectors, efferent pathways and ganglia, and target organ responses to neurotransmitters.