Visceral motor neuron (preganglionic) located in the (intermedio)lateral horn of the spinal cord...

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

Figure 60-2; Guyton & Hall

Physiologic Anatomy of the Sympathetic Nervous System

3. Enter via the white ramus and exit via a splanchnic nerve and terminate in the adrenal medulla

Sympathetic Nervous System

Figure 60-1;Guyton & Hall

Sympathetic Organization

Figure 16.4a

Sympathetic Chain

Collateral Ganglia

Adrenal Gland

Sympathetic Distribution

Figure 60-3;Guyton & Hall

ParasympatheticNervous System

Parasympathetic Organization

Parasympathetic Distribution

Neurotransmitters

Receptors of the Autonomic Nervous System

sympathetic

parasympathetic

preganglionic neuron

postganglionic neuron

nicotinic receptors muscarinic receptors

adrenergic 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