Autonomic Nervous System Lecture Slides

Physiologic Anatomy of the Sympathetic Nervous System Visceral motor neuron (preganglionic) located in the (intermedio)lateral horn of the spinal cord from T-1 to L-2.

Axons travel to ganglionic neuron via 1 of 3 paths:

1. enter the sympathetic chain via the white ramus and terminate there or ascend or descend a few segments before terminating 2. enter via the white ramus and exit via a splanchnic nerve and terminate in a prevertebral (collateral) ganglion 3. Enter via the white ramus and exit via a splanchnic nerve and terminate in the adrenal medulla Figure 60-2; Guyton & Hall

Sympathetic Nervous System

Figure 60-1; Guyton & Hall

Sympathetic Organization

Sympathetic Chain

Figure 16.4a

Collateral Ganglia

Adrenal Gland

Sympathetic Distribution

Parasympathetic Nervous System

Figure 60-3; Guyton & Hall

Parasympathetic Organization

Parasympathetic Distribution

Neurotransmitters

Receptors of the Autonomic Nervous System adrenergic receptors

sympathetic preganglionic neuron

postganglionic neuron

parasympathetic

nicotinic receptors

muscarinic receptors

Pharmacology of the Sympathetic Nervous System • adrenergic or sympathomimetic drugs act like norepi and epi • these drugs have an effect which is much more prolonged than that of either norepi or epi – isoproterenol stimulates both beta1 and beta2 receptors (e.g. increases heart rate) – albuterol stimulates only beta2 receptors (e.g. bronchodilation)

• some drugs act indirectly by increasing the release of norepi from its storage terminals – amphetamine

Pharmacology of the Sympathetic Nervous System Example - drugs that block the effect of norepi and epi • beta blockers – beta1 - metoprolol

Pharmacology of the Parasympathetic Nervous System • parasympathomimetic drugs – nicotine • activates nicotinic receptors

• cholinesterase inhibitors – neostigmine • potentiates the effect of acetylcholine

• antimuscarinic drugs – atropine • blocks the effect of acetylcholine on effector cells