Parasympathetic Nervous System (PNS) Definition
- The Parasympathetic Nervous System (PNS) are drugs that mimic or enhance the effects.
- They promote “rest and digest” functions by stimulating muscarinic and nicotinic receptors, leading to effects such as reduced heart rate, increased glandular secretions, and enhanced digestive activity.
Cholinergic Agonists (Parasympathomimetics)
- Mimic acetylcholine, stimulating the PNS.
- Effects: ↓ Heart rate, ↑ Secretions, ↑ Smooth muscle activity.
- Examples: Pilocarpine (glaucoma), Bethanechol (urinary retention).
Cholinesterase Inhibitors
- Prevent acetylcholine breakdown, enhancing its action.
- Uses: Myasthenia gravis (pyridostigmine), Alzheimer’s disease (donepezil).
Anticholinergics (Parasympatholytics)
- Block acetylcholine, inhibiting PNS activity.
- Effects: ↑ Heart rate, Bronchodilation, ↓ Secretions.
- Examples: Atropine (bradycardia), Ipratropium (COPD, asthma).
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