Parasympathetic Nervous System Flashcards
Name the physiological responses in the parasympathetic nervous system (7)
Constricts pupil Stimulates saliva and tear production Constricts bronchi Slows heart Stimulates stomach, pancreas and intestines Stimulates urination Promotes genital erection
What are the effects of the parasympathetic nervous system on the heart?
Decreases force of contraction
Reduces heart rate
What are the effects of the parasympathetic nervous system on blood vessels?
ACh produces considerable vasodilation to systemic arteries
For less parasympathetic innervation to arteries
What are the effects of the parasympathetic nervous system on male genetalia?
Dilution of penile artery
Engorgement of corpus cavernosum
What are the effects of the parasympathetic nervous system on non-vascular smooth muscle?
Contraction of the bladder detrusor, airway, GI tract, uterus
What are the effects of the parasympathetic nervous system on the eye?
Contracts circular muscle -> narrowing of pupil
Allows lens to bulge, therefore focussing the eye
Name an industrial cholinesterase inhibitor in the parasympathetic nervous system and its use
Parathion - insecticide
What are the symptoms when ACh is inhibited in the parasympathetic nervous system?
Increased: Bowel motility Acid secretion Salivation Lacrimation
Bradycardia
Hypotension
Focussing problems (eyes)
Urination
Name the short acting cholinesterase inhibitors
Neostigmine
Physostigmine
Name the long acting cholinesterase inhibitors
Edrophonium
Parathion
Name the nicotinic cholinoceptors
N1 or Nm
N2 or Nn
Name the muscarinic cholinoceptors
M1, M2, M3, M4, M5
Where are the N1 cholinoceptors found?
Skeletal muscle
Where are the N2 cholinoceptors found?
Autonomic ganglia
CNS
Where are the M1 cholinoceptors found?
CNS
Peripheral neurones
Gastric parietal cells
Where are the M2 cholinoceptors found?
Atria, SAN, AVN
Where are the M3 cholinoceptors found?
Visceral smooth muscle,
secretory glands
Endothelial cells
Where are the M4/M5 cholinoceptors found?
CNS
Name the (2) selective agonists for nicotinic cholinoceptors
Nicotine
Lobeline
Name the (3) selective antagonists for nicotinic cholinoceptors
Tubocurarine
Hexamethonium
Pancuronium
Name the (3) selective agonists for muscarinic cholinoceptors
Muscarine, bethanecol, pilocarpine
Name the (4) selective antagonists for muscarinic cholinoceptors
Ipratropium
Atropine
Hyoscine
Pirenzepine
What is the enzyme and location for the M1 receptor?
Phospholipase C
Glands, secretory cells
What is the enzyme and location for the M2 receptor?
Adenylate cyclase (Gi)
Heart
What is the enzyme and location for the M3 receptor?
Phospholipase C (Gq)
Endothelial cells, visceral smooth muscle
GI secretions
What is the enzyme and location for the M4 receptor?
Adenylate cyclase (Gi)
CNS
What is the enzyme and location for the M5 receptor?
Phospholipase C (Gq)
CNS
What are odd numbered muscarinic receptors positively coupled with?
Phospholipase C
What are even numbered muscarinic receptors negatively coupled with?
Adenylate cyclase
What does negatively coupled mean?
Reducing the amount of cAMP
What happens in the heart when the beta gamma subunit activates a potassium channel?
The membrane potential hyperpolarises which limits activation
How does activation of M3 receptors contract non-vascular smooth muscle?
Increased activation of phospholipase C
calcium is released
binds to myosin light chain kinase
turns on myosin
Where are muscarinic receptors heavily expressed?
Endothelium
What happens to the calcium produced by M3 receptors in the endothelium?
Activates the NO synthase
NO binds to guanylyl synthase causing it to relax
What does activation of M3 receptors cause?
Increased: Saliva Tears Gut acid Sweat Phospholipase C Calcium release
