ANS

What is the Autonomic Nervous System (ANS)?

Controls involuntary bodily functions.

How does the ANS differ from the somatic nervous system?

ANS organs do not atrophy after nerve section.

What are the three main divisions of the ANS?

Sympathetic, parasympathetic, enteric.

Where do sympathetic fibers originate?

Thoracic and lumbar spinal cord.

Where do parasympathetic fibers originate?

Cranial nerves and sacral spinal cord.

What neurotransmitter is primarily used in the ANS?

Acetylcholine (ACh).

What neurotransmitter is released by most sympathetic postganglionic fibers?

Nor-adrenaline (NA).

What happens to heart rate under sympathetic stimulation?

It increases (tachycardia).

What is the effect of the parasympathetic system on GI motility?

It increases motility.

What is the action of the cholinergic system on blood vessels?

Stimulates vasodilation via NO release.

What effect does the parasympathetic system have on the pupil?

Causes miosis (constriction).

What is the role of ACh in the urinary bladder?

Stimulates detrusor muscle for micturition.

How do anticholinergic drugs affect salivation?

They decrease saliva production.

What is the effect of the sympathetic system on bronchial passages?

Causes dilation.

What happens to the heart under parasympathetic stimulation?

It decreases heart rate (bradycardia).

What is the effect of cholinergic drugs on gastrointestinal sphincters?

They relax sphincters.

What receptors are stimulated by ACh at the neuromuscular junction?

Nicotinic (N_M) receptors.

What is the primary action of the sympathetic system on the urinary outflow?

It decreases urine outflow.

What is the effect of the parasympathetic system on secretions?

It increases secretions.

What happens to the pupil under sympathetic stimulation?

It dilates (mydriasis).

What are directly acting drugs?

They activate muscarinic receptors directly or increase ACh availability.

What is the main use of methacholine?

Diagnosing bronchial hyperreactivity.

How does bethanechol function?

It stimulates urinary bladder without nicotinic activity.

What is the role of pilocarpine in glaucoma?

It causes pupillary constriction to reduce intraocular pressure.

What distinguishes carbachol from other drugs?

It acts on both nicotinic and muscarinic receptors.

What is the mechanism of indirectly acting drugs?

They inhibit acetylcholinesterase to prolong ACh action.

What is a key characteristic of physostigmine?

It is lipid soluble and can cross the blood-brain barrier.

Why is neostigmine preferred for myasthenia gravis?

It does not affect the CNS and has direct receptor action.

What is the consequence of atropine on the cardiovascular system?

It initially causes bradycardia, then tachycardia with higher doses.

What is the effect of anticholinergic drugs on the eye?

They cause mydriasis and cycloplegia.

How does scopolamine differ from atropine in CNS effects?

Scopolamine causes CNS depression, while atropine stimulates.

What happens if anticholinergic agents are used in glaucoma?

They are contraindicated due to increased intraocular pressure.