Lecture 17: Autonomic Nervous System

Question 1

Describe the difference between sympathetic and parasympathetic arcs

Answer 1

NT used: parasympathetic = Ach, sympathetic = ACh/NE
spinal location of preganglionic bodies: parasymp= cranial/sacral, symp = thoracolumbar
location of postganglionic bodies: parasymp = close to/on target organ, symp= far from target
opposing effects for the most part
afferents are called general visceral afferents

Question 2

Describe the micturition response

Answer 2

When you want to go pee, signals travel along pelvic nerve. synapses at the pontine micturition center. Efferent has 3 branches. 1 goes through sympathetic nervous system to hypogastric nerve. This nerve is inhibited, which means the internal sphincter is no longer contracted. 1 goes through parasympathetic nervous system (pelvic nerve) to both the desultor muscle and the internal sphincter. it will contract and relax these respectively. Lastly, one must go through the somatic nervous system via the pudendal nerve to relax the external sphincter.

Question 3

How do autonomic reflex arcs differ from somatic reflex arcs?

Answer 3

cell bodies of preganglionic neurons in the CNS

postganglionic neurons in ganglia of PNS

Question 4

Describe the sympathetic reflex

Answer 4

preganglionic cells are in the lateral horn, exit via ventral root and enter paravertebral ganglia

3 fates from here. some synapse and go to the postganglionic fibers, some have collaterals that transmit rostrally or caudally, some pass through and enter splanchnic nerve to go to prevertebral ganglia