1 / 71

Autonomic nervous system

Autonomic nervous system. ANS functions below the level of consciousness and control the visceral functions. ANS supplies all organs except skeletal muscles (supplied by somatic system). Autonomic nervous system. Autonomic nervous system. TRANSMITTERS OF ANS:

Download Presentation

Autonomic nervous system

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Autonomic nervous system • ANS functions below the level of consciousness and control the visceral functions. • ANS supplies all organs except skeletal muscles (supplied by somatic system).

  2. Autonomic nervous system

  3. Autonomic nervous system TRANSMITTERS OF ANS: • Acetylcholine is the nerve transmitter of preganglionic nerves of both parasympathetic and sympathetic nervous system. • Acetylcholine is the nerve transmitter of postganlionic nerves of parasympathetic nerves system.

  4. Autonomic nervous system TRANSMITTERS OF ANS: • Norepinephrine is the major nerve transmitter of postganglionic nerves of sympathetic system. • Acetylcholine is the nerve transmitter of postganlionic nerves of sympathetic nervous system supplying sweat glands.

  5. Autonomic nervous system • PARASYMPATHETIC NS: The preganglionic nerves arise from 1. Midbrain – III cranial nerve. 2. Medulla – VII, IX and X cranial nerve. 3. Sacral part of spinal cord – S - 2, 3, 4 • SYMPATHETIC NS: The preganglionic fibers originate from the thoracolumbar region of the spinal cord.

  6. Parasympathetic nervous system CHOLINERGIC TRANSMISSION: • Acetylcholine is synthesized by the enzyme choline acetyltransferase (ChAT). • Release of acetylcholine occurs by exocytosis with the influx of calcium ions. • Inactivation by acetyl cholinesterase is the major mechanism for termination of action of Ach.

  7. Autonomic nervous system • Acetylcholine is hydrolyzed by the enzyme Cholinesterase There are two types of cholinesterase – • Acetyl cholinesterase(true)– present at all neuromuscular junction. It hydrolyses specifically Acetylcholine. • Butyryl Cholinesterase(Pseudo)– present in plasma and liver. It hydrolyzes procaine and suxamethonium.

  8. Autonomic nervous system

  9. Parasympathetic nervous system Acetylcholine acts on two types of receptors: • Nicotinic receptors. • Muscarinic receptors.

  10. Autonomic nervous system Types of nicotinic receptors:

  11. Autonomic nervous system Types of muscarinic receptors: M1, M2, M3, M4, M5

  12. Autonomic nervous system ACETYLCHOLINE: • No therapeutic implications • Diffuse action • Rapid hydrolysis

  13. Autonomic nervous system ACETYLCHOLINE: HEART: M2 RECEPTORS • Decrease in the heart rate • Decrease in the conduction • Decrease in the contraction BLOOD VESSELS: M3 • Vasodilation via the release of nitric oxide

  14. Autonomic nervous system ACETYLCHOLINE : GIT: M1/M3 • Increase the tone and peristalsis. • Increase the secretion of the GIT glands and lacrimal gland. • Relax the sphincter. URINARY BLADDER: M3 • Contraction of detrusor. • Relaxation of trigone and sphincter.

  15. Autonomic nervous system • ACETYLCHOLINE : RESPIRATORY TRACT : • Constriction of bronchus • Increases the secretions of the respiratory tree.

  16. Autonomic nervous system ACETYLCHOLINE : EYE : • IRIS has parasympathetic innervation and acts on muscarinic receptors present on Circular or Sphincter muscle and Ciliary muscle (M 3 receptors ) • Radial muscle has alpha 1 receptors.

  17. Autonomic nervous system

  18. Autonomic nervous system

  19. Autonomic nervous system

  20. Autonomic nervous system ACETYLCHOLINE : • EYE : It causes the spasm of accommodation by contraction of ciliary muscle which causes the zonula to relax, thus allowing the lens to become more convex . • Thus vision is fixed for near objects.

  21. Autonomic nervous system Nicotinic action of Acetylcholine : • Autonomic ganglia ( N N ) – both parasympathetic and sympathetic are stimulated . • Skeletal muscle ( N M ) : Contraction of the fibers.

  22. Autonomic nervous system

  23. Autonomic nervous system CHOLINERGIC AGONISTS • CHOLINE ESTERS– Acetylcholine, Methacholine, Carbachol, Bethanechol • CHOLINOMIMETIC ALKALOIDS– Pilocarpine • ANTICHOLINESTERASES

  24. Autonomic nervous system

  25. Autonomic nervous system DRUGS AFFECTING CHOLINERGIC TRANSMISSION : • ANTICHOLINESTERASES- Neostigmine • INHIBITING CHOLINE CARRIER -Hemicholinium • INHIBITION OF VESCICULAR STORAGE - Vesamicol • INHIBITION OF RELEASE – Botulinium toxin

  26. Autonomic nervous system Choline esters– Acetylcholine, Methacholine, Bethanechol • poorly absorbed from the stomach • poor lipid solubility • poor BBB penetration

  27. Autonomic nervous system

  28. Autonomic nervous system • CHOLINE ESTERS: • Methacholine and Bethanechol have no nicotinic actions • Methacholine has prominent CVS action • Carbachol and Bethanechol on GIT and Urinary bladder. • Carbachol and Bethanechol are resistant to the hydrolysis by AchE

  29. Autonomic nervous system CHOLINOMIMETIC ALKALOIDS– Pilocarpine • Pilocarpine – stimulates only muscarinic receptors • Used in chronic simple glaucoma, acute congestive glaucoma and as miotic.

  30. Autonomic nervous system ANTICHOLINESTERASES AGENTS • These agents inhibit the AchE present in the synaptic regions . • Thus they prolong the existence of Ach released from the nerve endings. • These are of two types Reversible Anti - ChE Irreversible Anti - ChE

  31. ANS • Irreversible Anti-ChE agentsare insecticides and nerve gas poisons • Insecticides– Organophosphorus compounds - Parathion, Malathion, Diazinon (TIK-20), Echothiopate • Nerve gas poisons – Soman, Sarin, Tabun

  32. Nerve Agents Organophosphate insecticides Cholinesterase inhibitors Pralidoxime Enzyme active site Cholinesterase generator Chemical antagonist

  33. ANS ANTICHOLINESTERASES AGENTS • Reversible : Short : Edrophonium Medium: Neostigmine, Physostigmine, Pyridostigmine, Tacrine

  34. ANS ANTICHOLINESTERASES

  35. ANS ANTI-CHOLINESTERASES AGENTS • Mechanism of action :Acetyl cholinesterase (AchE) is an enzyme withanionicand esteratic site. • Acetylcholine (Ach ) involves attraction of the positive charge N+ of Ach and anionic site; acetylation of serine leading to the acetylated enzyme. • The acetylated enzyme reacts with the water to produce acetic acid and free enzyme within milliseconds.

More Related