The Nervous System Part 2

Question 1

1. What are the 2 parts of the autonomic nervous system
2. What types of nerves are present in the ANS?

Answer 1

1. Sympathetic and parasympathetic
2. Afferent (sensory) and efferent (motor) nerves

Question 2

Describe how the 2 neurons of the efferent pathway connect

Answer 2

• The preganglionic (1st) neurons leave the spinal cord/brain and
• Travel to a ganglion (para/sympathetic ganglion) where they synapse on the second neuron (postganglionic)

Question 3

1. What do the afferent nerves of the ANS travel from and to?
2. What are these sensory ganglia associated with?

Answer 3

1. Travel from viscera to cell bodies in sensory ganglia
   2a. Associated with cranial nerves in the case of cranial afferents accompanying the parasympathetic nerves
   2b. Associated with spinal nerves i.e. the dorsal root ganglia, in the case of afferents accompanying sympathetic or pelvic parasympathetic nerves

Question 4

What are many ANS afferents involved in measuring?

Answer 4

• Distension
• Lack of oxygen in organs

Question 5

Where are the cell bodies of the first efferent sympathetic neurons (preganglionic) located?

Answer 5

• Grey matter of T1 - L2-3 spinal cord segments only
  *For this reason the sympathetic nerves leaving the spinal cord are sometimes called the thoracolumbar autonomic outflow

Question 6

What do the preganglionic neurons synapse with?

Answer 6

• The preganglionic neurons synapse with the postganglionic neurons in sympathetic ganglia
• Which are named according to their position in relation to the vertebral column e.g. paravertebral (alongside) or prevertebral (in front of or anterior to)

Question 7

1. What are paravertebral ganglia?
2. What spinal nerves are they associated with?
3. What are the 3 pairs of cervical ganglia?

Answer 7

• Paired structures lying on either side of the vertebral column forming the sympathetic chain
• Cervical, thoracic, lumbar, sacral and coccygeal (connected by short branches - rami communicans)
• Superior, middle and inferior

Question 8

1. How are prevertebral ganglia positioned?
2. What do they connect with

Answer 8

1. Lie infront of the vertebral column enmeshed in plexuses
2. Receive preganglionic sympathetic axons which have passed through but not synapsed in the paravertebral ganglion

Question 10

What are the preganglionic axons which pass through the sympathetic chain without synapsing called?

Answer 10

• Splanchnic nerves

Question 11

1. What do the splanchnic nerves supply?
2. What fibres do they contain?

Answer 11

1. Supply the viscera above the diaphragm
2. Postganglionic sympathetic fibres that have synpased in cervical or upper throacic paravertrebral ganglia