Parasympathetic nervous system

Question 1

Parasympathetic division

Answer 1

Also known as craniosacral division
Keeps body energy use low
Inhibitory effect on many tissues and organs

Question 2

Parasympathetic neuroeffector pathway

Answer 2

From brain (spinal cord)
Preganglionic neurone
Ganglion
Postganglionic neourone
Effector Cell

Question 3

Acetylcholine receptors

Answer 3

Nicotinic: at ganglia (and brain and neuromuscular junction), Iontrophic: Ion channel receptor regulates transport of Sodium and Potassium ions.

Muscarinic: at autonomic target tissues (and brain), Metabotrophic: G-Protein coupled to second messenger alters Potassium and Calcium ions.

Question 4

Parasympathetic control of pupil diameter

Answer 4

Acetylcholine —> M3 muscarinic receptors
—> circular muscle contraction
—> miosis/pupil constriction

Muscarinic antagonist
—> blocks circular muscle contraction
—> passive pupil dilation/mydriasis

Question 5

Parasympathetic control of focussing eye

Answer 5

Ciliary muscle relax:
Suspensory ligaments contract
Lens flattens
Focus for distant vision

Ciliary muscle contracts:
Suspensory ligaments relax
Lens gets fatter
Focus for near vision

Question 6

Cycloplegia

Answer 6

Paralysis of ciliary muscle
Loss of accommodation

Question 7

Mydriatic drugs

Answer 7

Eye inspection and surgery

Question 8

Antiglaucoma and Miotic drugs

Answer 8

Glaucoma and rapid pupil closure (surgery)

Question 9

Anticholinesterases

Answer 9

Enhancement of parasympathetic stimulation

Question 10

Parasympathetic cotransmission stimulates

Answer 10

Low: ACh released
High: ACh and VIP released