Sweat glands, cutaneous vessels and arrector pili
Target & receptor · M3 sweat (cholinergic) α1 vessels & hair β2 muscle arterioles
Purely sympathetic targets with no parasympathetic supply. Eccrine sweat glands are the famous exception — driven by sympathetic postganglionic fibres that release acetylcholine onto M3 receptors — while cutaneous arterioles and arrector pili respond to noradrenaline on α1.
Traced from the start
- Sympathetic (thoracolumbar) outflow
- Intermediolateral cell column T1–L2 via white rami communicantes
- Paravertebral sympathetic chain ganglia (including stellate)
- Superior cervical ganglion
- Adrenal medulla
- Grey rami communicantes to spinal nervesInternal and external carotid plexuses (oculosympathetic pathway)Circulating adrenaline and noradrenaline
- Sweat glands, cutaneous vessels and arrector pili
Detail
- Eccrine sweat glands
- Sympathetic cholinergic fibres → M3 → thermoregulatory and emotional sweating; blocked by antimuscarinics and botulinum toxin
- Cutaneous arterioles
- α1 constriction shunts blood centrally in cold and shock (pale, cool, clammy skin with slow capillary refill)
- Skeletal muscle arterioles
- β2 dilatation from circulating adrenaline during exercise and 'fight or flight'
When it goes wrong
Anticholinergic toxidrome (tricyclic overdose, antihistamines, Datura)
Hot dry flushed skin, mydriasis, urinary retention, tachycardia and delirium — 'dry as a bone' separates it from the sympathomimetic toxidrome (amphetamine, cocaine), which is diaphoretic
Primary focal hyperhidrosis of palms or axillae
Treat by blocking the cholinergic synapse: aluminium salts, topical glycopyrrolate, intradermal botulinum toxin, then T2–T3 sympathectomy for refractory cases
Practise this structure
16 questions in the bank tagged Skin.
A 45-year-old woman presents with a painful, swollen, red area on her right forearm that developed over the past two days. She reports a minor cut from gardenin…
Mechanisms of disease · common
A 45-year-old woman with diabetes mellitus presents with a painful, rapidly expanding area of redness on her thigh. She has a fever of 39°C (102.2°F) and hypote…
Mechanisms of disease · middle twist
A 65-year-old man presents with purple spots on his forearms and hands that appeared over the past few days. He denies pain, itching, or trauma. His medical his…
Mechanisms of disease · middle twist
A biopsy of the tracheal epithelium shows a single layer of cells with nuclei at different levels, cilia, and mucus-secreting goblet cells. Which of the followi…
Foundations · common
Which of the following is TRUE about stratified columnar epithelium?
Foundations · niche
Which function is performed by stratified cuboidal epithelium?
Foundations · common