Pharmacology - Organization of the Nervous System:
Central
- Brain
- Chemoreceptor Trigger Zone
- Function: Nausea and emesis initiation
- Pro-emetic receptors: 5HT3, acetylcholine, histamine, dopamine, and opioid
Peripheral
- Somatic
- Function: voluntary control of skeletal muscles
- End-organ receptor: nicotinic acetylcholine
- Autonomic (involuntary regulator of homeostasis)
- Sympathetic
- Origin: T1-L2
- Function: ‘fight or flight’
- End-organ receptors: adrenergic
- Parasympathetic
- Origin: Cranial nerves 3, 7, 9, 10 and S2-4
- Function - ‘rest and digest’
- End-organ receptor: muscarinic acetylcholine
Table 1: Major physiologic effects of the autonomic nervous system.
System
Sympathetic
Parasympathetic
Eye
Pupillary dilation (α1)
Pupillary constriction
Cardiovascular
Increased heart rate (β1)
Increased conduction (β1)
Increased contractility (β1)
Coronary vasodilatation (β1)
Vascular smooth muscle contraction (α1/α2) and relaxation (β2)
Decreased heart rate
Decreased conduction
Decreased contractility
Respiratory
Bronchial smooth muscle relaxation (β2)
Increased bronchial secretion (α1, β2)
Bronchial smooth muscle contraction
Increased bronchial secretion
Gastrointestinal
Decreased wall motility and tone (β2
Sphincter contraction (α2)
Increased salivary gland secretion (α1, β2)
Increased wall motility and tone
Sphincter relaxation
Increased salivary gland secretion
Genitourinary
Bladder wall relaxation (β2)
Sphincter contraction (α1)
Uterine relaxation (β2)
Uterine contraction (α)
Bladder wall contraction
Sphincter relaxation
Uterine contraction
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