10/19 ANS

Question 1

• Describe the autonomic nervous system generally

Answer 1

o Supplies visceral tissue (smooth muscle, glands)

o Two division two neuron motor system. The two divisions provide dual innervation and are antagonistic.

Question 2

• Know the characteristic sand anatomical- physiological-pharmacological differentiation of the Sympathetic and Parasympathetic visceromotor divisions

Answer 2

o Sympathetic: fight or flight. Visceral organ vasoconstriction; decreased motility. Skin vasoconstriction—increased bp. Muscle vasodilation enhances contractility. Increased cardiac function. Bronchii and pupil dilated. Adrenal medulla-energy mobilization. Piloerection and increased sweating. Alpha receptors generally excitatory. B1-excitatory in heart, B2-inhibit smooth muscle, B3 lipolysis.
o Parasympathetic: Project to muscarinic Ach receptors with are generally excitatory. Effect of atropine (antimuscarinic) is to block Ach-MR coupling.
o All sensory and contextual inputs mediated by hypothalamus

Question 3

• Location of sympathetic and parasympathetic ns in spinal cord

Answer 3

o Sympathetic: T1-L3, intermediolateral cell column in lateral horn
o Parasympathetic: S1-S5 (preganglionic), intermediate gray zone, brain stem (CN III, VII, IX, and X)

Question 4

• What is the enteric nervous system

Answer 4

o Intrinsic mucosal neurons that can operate independent from CNS. Regulates inner circular smooth muscle layer with outer longitudinal layer. Interganglionic fiber tracts connect intrinsic enteric plexuses. Intrinsic reflexes are triggered in response to distention or chemical stimuli.
o ANS interacts via the vagus nerve to dorsal motor n of vagus

Question 5

• Understand the principles of visceral sensory system and their differences with the somatic sensory system

Answer 5

o Lack of perceptual awareness in normal conditions. Difficult to study. Visceral sensory afferents (to CNS) are 90% unmyelinated with free nerve ending peripheral terminal. Low peripheral receptor density in visceral tissue and sparse neuronal representation in cerebral cortical perception areas. Cell bodies in DRGs and CN sensory ganglia.