Muscarinic Effects

When ACh stimulates muscarinic receptors, some effects are…

Eyes:

• Miosis (pupil constriction)
• Lacrimation (tear secretion)
• Accommodation for near vision (the lens of the eye becomes set for reading)
• Decreasing intra-ocular pressure (useful for glaucoma)

Digestive tract (remember it helps with digestion):

• Saliva secretion which breaks food down
• Stomach acid secretion
• Peristalsis

Other effects:

• Decreased heart rate
• Bronchial constriction (makes it hard to breath in asthmatics)
• Enhanced urination (by relaxing the sphincter and contracting the bladder)

Again, all these are parasympathetic effects from acetylcholine stimulating the muscarinic receptor.