Practical 7: Effect of parasympathotropic substances

on presentation practical.

What is the autonomic nervous system (ANS)?

The autonomic nervous system is part of the peripheral nervous system that controls visceral functions like heart rate, digestion, and respiratory rate, functioning largely below the level of consciousness.

• most autonomous functions are involuntary

What are the two main subsystems of the ANS?

1. Parasympathetic nervous system

2. Sympathetic nervous system

The work independently in some functions + together in others.

based on the site of action, drugs affecting the ANS are divided into 2 main groups:

1. Parasympathotropic agents

2. Sympathotropic agents

What are the types of parasympathotropic agents?

• name a representative

1. Parasympathomimetics (cholinergic agonists)

   • directly acting - acetylcholine

   • indirectly acting - neostigmine

2. Parasympatholytics (cholinergic antagonists)

   • atropine

What are the types of sympathotropic agents?

1. sympathomimetics (adrenergic agonists)

2. sympatholytics (adrenergic antagonists)

What are the two classes of cholinergic receptors?

1. Muscarinic - found in smooth muscles and glands; stimulation causes hypersecretion.

2. Nicotinic - located in neuromuscular junctions; stimulation causes muscular contraction.

Parasympathotropic agents acts on cholinergic receptors (as acetylcholine is the neurotransmitter in this part of ANS).

Drugs with parasympathomimetic activity are divided into 2 groups:

1. Directly acting (act like neurotransmitter acetylcholine - bind to cholinergic receptors)

   • pilocarpine

   • carbachol

2. Indirectly acting (inhibit the enzyme acetylcholine esterase - stops the degradation of acetylcholine)

   • physostigmine

   • neostigmine

drugs with parasympatholytic activity function?

these generally inhibit the function of the parasympathetic NS

• Atropine

• scopolamine

What is atropine?

Atropine is a naturally occurring tropane alkaloid used as a competitive antagonist for muscarinic acetylcholine receptors, classified as an anticholinergic drug.

List some uses of atropine.

1. Cycloplegic in ophthalmology

2. Mydriatic in ophthalmology

3. Resuscitation in bradycardia treatment

4. Premedication to inhibit secretion of salivary and mucus glands

5. Treatment for organophosphate poisoning.

What are the effects of parasympatholytics on pupils?

They lead to mydriasis (dilation of pupils) due to contraction of radial muscle fibers (dilatator pupillae) innervated by the sympathetic NS.

What causes miosis in the pupils?

Miosis occurs from the contraction of circular muscle fibers (sphincter pupillae) innervated by the parasympathetic NS, usually stimulated by parasympathomimetics.

How do parasympathotropic substances affect smooth muscles of the iris?

Parasympatholytic drugs increase sympathetic tonus, causing mydriasis, while parasympathomimetic drugs stimulate circular muscle fibers, causing miosis.

Sympathotropic agents do what?

Bind to the adrenergic receptors (because adrenaline and noradrenaline are the neurotransmitters in this part of ANS)

1. Sympatomimetic agents: adrenaline, noradrenaline

2. Sympatolytic agents: ergotamine

Atropine sulphate inj. MPPs.

AS: atropine sulphate

I: Anticholinergic agent, organophosphate and carbamate poisoning antidote. Premed. before general anaesthesia.

• cattle, horses, sheep and other animals

Hormotonin inj. MPPs.

AS: Neostigmine

I: Anticholinergic agent, horse, cattle, sheep, goat, swine, dogs, cats

• atony of GIT, atony of forestomachs in cattle

Buscopan inj. MPPs

AS: Butylscopolamine+ metamizole

I: antispasmodic and analgesic, domestic and food producing animals