Autonomic innervation of sweat glands (sympathetic cholinergic)
Core concept
- Eccrine sweat glands are the exception to the sympathetic rule
- Sympathetic postganglionic fibres, but they release acetylcholine, not noradrenaline
- Acting on muscarinic (M3) receptors -> sweat secretion
- -> "sympathetic cholinergic"
- The general pattern for comparison
| Pathway | Preganglionic | Postganglionic |
|---|---|---|
| Sympathetic (typical) | ACh -> nicotinic | Noradrenaline -> adrenergic |
| Sympathetic to eccrine sweat glands | ACh -> nicotinic | ACh -> MUSCARINIC |
| Sympathetic to adrenal medulla | ACh -> nicotinic | No postganglionic neuron - chromaffin cells secrete adrenaline directly |
| Parasympathetic | ACh -> nicotinic | ACh -> muscarinic |
| Sympathetic to renal vasculature | ACh -> nicotinic | Dopamine/noradrenaline |
- Apocrine glands (axilla, groin) are adrenergic and respond to emotional stimuli - the reason emotional sweating differs in distribution from thermoregulatory sweating
- Developmentally, sympathetic sweat gland neurons start noradrenergic and switch to cholinergic under target-derived signals - a classic neurotrophic switch
3 more sections, plus exam facts
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