Chapter 15 - Autonomic Nervous System

Question 1

How do impulses from the autonomic nervous system differ from somatic motor impulses?

Answer 1

ANS has 2 neurons from the CNS to the effectors (organs):

• preganglionic neuron goes from the cell body in the CNS (spine or brain)
• postganglionic neuron goes from the cell body in peripheral ganglion (group of cells found in the PNS, exists outside the spinal cord and the brain and is not enclosed in any protective structure.)

Somatic NS has one myelinated fiber from from the CNS to the effectors (skeletal muscle).

Question 2

What are the two division of the autonomic nervous system? Is either one exclusively excitatory or inhibitory?

Answer 2

ANS divisions:

• Sympathetic NS (Thoracolumbar division)
• Parasympathic NS (Craniosacral division)

Both divisions can be excitatory or inhibitory (depending on the receptors).
*Sympathetic generally excitatory, parasympathetic generally inhibitory.

Question 3

Receiving input from both the sympathetic and parasympathetic neurons is called…

Answer 3

dual innervation

Question 4

What kind of effect can dual innervation have?

Answer 4

• Antagonistic effect (one side enhances / one side suppresses)
• Cooperative effect (both divisions act of different effectors to produce the same effect)

Question 5

From what part of the spinal cord do sympathetic preganglionic neurons emerge?

Answer 5

lumbar and thoracic regions of the vertebral column

Question 6

What are three possible locations where synapse can occurs with the postganglionic neuron in the sympathetic division?

Answer 6

1. At the first sympathetic trunk ganglion it reaches (for organs above the diaphragm)
2. Ascend/descend the trunk ganglion, then synapse with a sympathetic trunk ganglion
3. Ascend/descend the trunk ganglion, pass by the sympathetic trunk ganglion and through the postganglion neuron without synapsing, then synapse with the prevertebral ganglion

Question 7

How does the area where a synapse occurs with the postganglionic neuron affect the resulting action?

Answer 7

Synapsing with the….

• Sympathetic trunk ganglia - supplies organs above the diaphragm
• Prevertebral ganglia - supplies organs below the diaphragm

Question 8

From what part of the spinal cord do parasympathetic preganglionic neurons emerge?

Answer 8

pons and medulla oblongata (for cranial nerves), sacral spinal cord

Question 9

What are possible locations where synapse can occurs with the postganglionic neuron in the parasympathetic division?

Answer 9

1. Cranial nerves
   - Oculomotor (III)
   - —–narrows pupil, focuses lens
   - Facial (VII)
   - —–nasal / salivary glands, produces tears
   - Glossopharyngeal (IX)
   - ——parotid salivary gland
   - Vagus (X)
   - ——controls viscera up to the colon, and cardiac, pulmonary, and esophageal plexuses
2. Sacral spinal cord

Question 10

What size distinctions are between neurons in the sympathetic and parasympathetic divisions?

Answer 10

Sympathetic division (terminal ganglia near spinal cord):

• preganglionic neurons - short
• postganglionic neurons - long

Parasympathetic division (terminal ganglia near target organs):

• preganglionic neurons - long
• postganglionic neurons - short

Question 11

What are the two main neurotransmitters found in the ANS? Are they inhibitory or excitatory?

Answer 11

1. Acetylcholine - (Cholerginic receptors)
   - -Nicotinic receptors excitatory
   - -Muscarinic receptors excitatory or inhibitory
2. Norepi - (Adrenergic receptors)
   - -Alpha receptors excitatory or inhibitory
   - -Beta receptors excitatory or inhibitory