AUTONOMIC NERVOUS SYSTEM = visceral nervous system or visceral motor systems

Terdiri dari: Motor fibers (visceral efferent) stimulasi smooth muscle, modified cardiac muscle, glandular (secretory cells)

Visceral afferent afferent

component of autonomic reflexes, konduksi impuls visceral pain, regulasi visceral function.

Tdpt 2 efferent neurons (multipolar) di autonomic path, smntara hanya single neuron yg ada di somatic path Autonomic nervous system: Controlling centers di hypothalamus dan brainstem central autonomic fibers synaps di preganglionic neurons di gray matter of brainstem dan spinal cord preganglionic fibers (kebanyakan myelinated) keluar dari CNS synaps di multipolar neurons di autonomic ganglia postganglionic fibers (unmyelinated) mmbentuk terminal networks di target tissue Scr anatomis dan fungsional, autonomic system terdiri dari divisi sympathetic dan parasympathetic.

Anatomical distinction: (1) lokasi presynaptic cell bodies (2) nerve apa yg mengkonduksi presynapticfibers dari CNS

Functional distinction: neurotransmitter yg berbeda norepinephrine pd sympathetic dan ACh pdparasympathetic.

SYMPATHETIC NERVOUS SYSTEM

sympathetic acts in sympathy with the emotions

menyiapkan tubuh utk fight or flight (emergency situations): HR, dilatasi pupil, kulit berkeringat, darah dialihkan dari kulit dan intestinal tract ke skeletal muscles, sphincter di alimentary dan urianay tract tertutup. Cell bodies of presynaptic neurons: @ intermediolateral cell columns (IML) atau nuclei of spinal cord mrpkn bagian dari gray matter pd segment thoracic (T1-T12) dan upper lumbar (L1-L2 atau L3) (thoracolumbar)

IMLs terorganisasi somatotopically tersusun

sesuai tubuh (cell bodies yg terlibat dlm inervasi kepala terletak di superior, yg terlibat dlm inervasi pelvic viscera dan lower limbs trletak di inferior).

Letak cell bodies of postsynaptic neurons:

Paravertebral (sympathetic trunk/chains) ganglia :tdiri dr 20-25 pasang di sepanjang vertebral column

Prevertebral (collateral atau autonomic plexus)

ganglia : di sepanjang abdominal aorta, pd plexus yg ada di sekeliling origin of main branches of aorta. Autonomic plexus ganglia menerima preganglionic fibers dari splanchnic nerves dan mengirim postganglionic fibers ke viscera via perivascular plexus di sekitar arteri2 yg mensuplai abdominal dan pelvic viscera.

axon dari presynaptic neurons (preganglionic fibers) meninggalkan spinal cord lwt anterior roots masuk ke anterior rami of spinal nerves T1-L2 or L3 keluar lwt white rami communicantes masuk sympathetic trunks 4 possible courses di dlm sympathetic trunks:

1.

Ascend sympathetic chains synapse di higher paravertebral ganglion [superior atau middle cervical ganglion, atau di stellate ganglion (stellate trdiri dr fusi inferior cervical dan 1st thoracic ganglia; ada di dpn neck of the 1st rib)]. Postganglionic fibers mensuplai head, neck, upper limbs, heart, dilator muscle of pupil. Synapse di level of entry (di ganglion terdekat) Postganglionic fibers mensuplai pemb darah dan kelenjar jeringat di teritori nerve2 tsb. Descend synapse di lower paravertebral ganglion (lumbar atau sacral ganglia). Postganglionic fibers memasuki lumbosacral plexus utk distribusi blood vessels dan kulit dari lower limbs. Traverse the chain (tidak synapse) dan keluar sbg abdominopelvic splanchnic nerves, trdr dari:

2. 3.

4.

Thoracic splanchnic nerves (greater, lesser,least) pass through lower 8 thoracic ganglia menembus diafragma synapse di celiac, superior mesentric ganglion, dan di aorticorenal ganglia.

Splanchnic nerves jg memberikan direct input ke medulla of adrenal gland (presynaptic fiber melewati celiac ganglion tanpa synapse). Postganglionic fibers brsama cabang dr aorta mencapai GI tract, stomach, liver, pancreas, kidney.

Lumbar splanchnic nerves pass through upper 3 lumbar ganglia dan bertemu di dpn bifurkasi 1. 2.Sympathetic trunk neurons give rise to 3 types of postganglionic fibers:

abdominal aorta superior hypogastric plexus hypogastric nerves inferior hypogastric plexus

Perivascular travel di sepanjang dinding pemb darah ke tujuannya. Cth: postsynaptic sympathetic fibers yg distribusinya ke kepala: cell bodiesnya di sup cervical ganglion cephalic arterial branch periarterial plexus of nerves (mengikuti cabang dari carotid arteries) Spinal pass via gray communicating rami to each spinal nerve. Cth: fibers yg distribusinya ke neck, body wall, dan limbs: memasuki semua cabang dari 31 pasang spinal nerves (trmasuk posterior rami) utk stimulasi konrtaksi pemb darah (vasomotion) dan arrector muscles yg berkaitan dgn rambut (pilomotion, goose bumps), dan juga menyebabkan sweating (sudomotion)

Visceral pass directly to viscera. Cth: fibers utk viscera di thoracic cavity (e.g., heart, lungs, esophagus): pass through cardiopulmonary splanchnic nerves memasuki cardiac, pulmonary, dan esophageal plexus PARASYMPATHETIC NERVOUS SYSTEM

3.

Scr umum mempunyai efek counterbalancing the sympathetic system. Efeknya berhubungan dgn protection, rest, dan pemulihan organ dan bodily funtions.

Parasympathetic outflow dari dari CNS adalah craniosacral:

a.

Cranial parasympathetic system: (inervasi ke kepala dan mendominasi inervasi thoracic dan abdominal viscera lwt CN X)

1)

2)

Edinger-Westphal nucles Oculomotor nerve ciliary ganglion postganglionic fibers inervasi sphincter of pupil dan ciliary muscle Superior salivatory nucleus Facial nerve pterygopalatine ganglion (inervasi lacrimal dan nasal glands) dan submandibular ganglion (inervasi submandibular dan sublingual glands) Inferior salivatory nucleus Glossopharyngeal nerve otic ganglion inervasi parotic gland Dorsal nucleus of vagus serta neuron2 yg tersebar di di dkt caudal part of nucleus ambiguus Vagus nerve synapse di mural (on the wall) atau intramural (in the wall) ganglia of heart, lungs, lower esophagus, stomach, pancreas, gall bladder, small intestine, dan ascending dan transverse parts of colon.

3) 4)

b.

Sacral parasympahtetic system: (inervasi ke pelvic viscera; descending dan sigmoid colon, rectum)

Lateral gray matter of S2, S3, dan S4 preganglionic fibers

descend di cauda equina keluar lwt pelvic sacral foramina mnjd pelvic splanchnic nerves bbrp synapse di ganglion cells di dinding distal colon dan rectum, sisanya synapse di pelvic ganglia (dekat dgn pelvic sympathetic ganglia) postganglionic sympathetic fibers suplai detrussor muscle of bladder, tunica media of int oudendal a. dan cabang2nya ke cavernous tissur of penis or clitoris. Sacral parasymphatica mengontrol defekasi, urinasi, dan ereksi. VISCERAL AFFERENTS Normalnya, aktivitas visceral tdk dapat dirasakan Visceral afferent fibers memberikan informasi mengenai kondisi internal tubuh informasi ini lalu diintegrasikan di CNS dpt men-trigger visceral atau somatic reflexes, atau keduanya.

a.

3 tipe dasar visceral pain:

b.

Pure visceral pain Terasa di region of affected organ. Characteristically vague and deep-seated. Seringkali disertai sweating atau nausea. Penyebab: inflamasi/ulcerasi; obstruksi; sudden distention dari capsule; spasms atau kontraksi yg kuat; chemical irritants; mechanical stimulation; kondisi patologis (terutama ischemia) yg normal threshold of stimulation. Viscera insensitive thdp cutting atau burning Visceral reffered pain terasa di bag tubuh dgn inervasi yg sama Saat keparahan visceral pain , pain di-refer ke struktur somatik yg diinervasi oleh level segment spinal cord yg sama. convergence-projection theory of reffered pain: otak enginterpretasikan sumber noxious stimulation krn visceral dan somatic nociceptors mempunyai bbrp spinothalamic neurons yg sama.

Viscerosomatic pain Severe, steady pain pd abdominal wall directly overlying the inflamed organ. Krn penyebaran penyakit ke struktur somatik. Cth: parietal serous membrane (peritoneum dan pleura) kaya akan sensory supply dari intercostal nerves dan mereka sgt sensitif thdp acute inflammatory exudates. NEUROTRANSMITTER IN THE AUTONOMIC NERVOUS SYSTEM Ganglionic transmission Preganglionic neurons: cholinergic mengeluarkan acetylcholine (ACh) Receptors pd ganglion cells: nicotinic krn efek excitatory yg dpt diimitasi dgn locally applied nicotine. Junctional transmission

c.

Postganglionic fibers dan target tissue membentuk: neuroeffector juntions Sympathetic neuroeffector junction Chief transmitter: norepinephrine (noradrenaline) Postganglionic sympathetic system: scr umum adl adrenergic (pengecualian adl cholinergic sympathetic supply ke eccrine sweat glands over body surface)

Sympathetic junctional receptors (adrenoceptors) 1) Postjunctional adrenoceptors: inisiasi kontraksi1

2) 3)

smooth muscle di perpheral small arteries dan large arterioles, dilator pupillae, sphincters of alimentary tract dan bladder neck, vas deferens. Prejunctional 2 adrenoceptors (tdpt di parasympathetic dan jg sympathetic terminal): inhibit pelepasan transmitter. Pd sympathetic terminal dsbut autorecptors. Postjunctional 1 adrenoceptors: altivitas pacemaker di jantung dan kekuatan kontraksi ventrikel, menyebabkan pelepasan renin (sbg respon thdp penurunan BP yg drastis)

4)

2 adrenoceptors: merespon thdp circulating epinephrine (adrenaline) dan locally released norepinephrine. Postjuntional relaksasi smooth muscle (terutama di tracheobronchial tree dan accommodatory muscle of eye); ada jg di permukaan hepatocytes di liver (inisiasi glycogen breakdown) Prejuntional (on adrenergic terminals) promote pelepasan norepinephrine.

Parasympathetic neuroeffector junction Chief transmitter: Ach Postganglionic parasympathetic system: cholinergic

Parasympathetic juntional receptors muscarinic, krn dpt ditiru

oleh aplikasi drug muscarine. Muscarinic effects: HR melambat sbg respon thdp vagal stimulation dan kekuatan kontraksi ventrikel. Kontraksi smoothmuscle intestinal peristaltis, bladder emptying, accomodation of eye for near vision

Glandular secretion.

Other types of neuron Non-adrenergic, non-cholinergic (NANC) neurons ditemukan di kedua divisi dr autonomic system.

sebagian dopamine disekresikan ke kapiler dan sisanya berikatan dgn dopamine receptors di main (adrenergic) neurons dan menghasilkan mild inhibitory effect. NANC neurons terutama banyak tdpt di ganglion cells pd dinding alimentary tract dan di pelvic ganglia.

Pd sympathetic ganglia, small internuncial neurons melepaskan dopamine (prekursor norepinephrine) >50 peptide substances yg berbeda tlh diidentifikasi pd neuron2 ini. Kebanyakan berperan sbg

modulators (bekerja di pre- maupun post-junctional tuk mempengaruhi durasi dari aksi classic transmitters). Bbrp mrpkn cotransmitters (cth: dilepas bersama dgn ACh) Vasoactive Intestinal Polypeptide (VIP) = cotransmitter pd cholinergic supply ke salivary glands dan ke sweat glands. Mrpkn vasodilator yg kuat.

Nitric Oxide = transmitter di parasympathetic system; powerful smooth muscle relaxant.