THE AUTONOMIC NERVOUS SYSTEM

Transcription

1 THE TOPICS Nr Judit Rosta

2 I propose the term 'autonomic' nervous system for the sympathetic system and the allied nervous system of the cranial and sacral nerves and for the local nervous system of the gut. (John Newport Langley, 1898)

3 Autonomic Peripheral Efferents System of motor nerve cells to involuntary structures : (Gaskell, 1916) Autonomic ( automatic control ) maintain cardiovascular, gastrointestinal Vegetative (function) and thermal homeostasis and organization of stress responses

4 Menitmeter

5 Autonomic control of a target organ: (smooth muscle, cardiac muscle, glands) source of innervation (sympathetic-parasymp.,dual-not dual) the activity of the nerves (tonic or phasic) the effect of nervous activation (contraction-relaxation, stimulating/inhibiting secretion, +/- cardiac effects etc.) neurotransmitter using which receptor (muscarinic cholinergic, alpha (1 or 2) or beta (1, 2 or 3) adrenergic, perhaps NANC mechanism) peripheral or central nervous structures control nervous activityvegetative reflexes

6 each tissue supplied by two sets of fibers with opposite characters Dual innervation-antagonistic effects PARASY THE SYMPATHETIC TRUNK: PARAVERTEBRAL CHAIN Thoracolumbar origin SY AND THE PARA SYMPATHETIC : CRANIO-SACRAL DIVISION (flank on both sides) PARASY Sympathy?: as cooperation and coordination of organs

7 NOTICE! Structure (location of ganglia) Fiber type (myelinization) Neurotransmitters (Ach, NE,E) SYMPATHETIC PARASYMPATHETIC

8 Menitmeter How does look like the autonomic innervation? Choose the typical presynaptic arrangement of an autonomic neuron! Common presynaptic arrangements:

9 How does look like the autonomic innervation? Autonomic ground plexus ((Falck, 1962) VARICOSITY: contain the enzymes necessary to synthesize or degrade transmitters Network of varicose terminal axons containing norepinephrine in iris Burnstock (1988) Autonomic neural control mechanisms. With special reference to the airways. In: Kaliner, M.A., Barnes, P.J. (Eds.) cotransmitters: Ach+ATP, Norepinephrine+NPY (act on their own receptors!)

10 ACETYLCHOLINE Parasympathetic (and sudomotor sympathetic) Notice! Acetylcholinesterase (AchE) Choline reuptake Botulinum TOXIN Physostigmin Botulinum toxin blocking AchE blocking-muscarinic Atropine-antimuscarinic ATROPINE Cotransmitter: Ach + VIP, NO

11 Cotransmitter: NE + NPY, ATP CATECHOLAMINES NOTICE! Synthetisation-vesicles NE-terminals, E-adrenal med. Metabolism by: COMT, MAO Neuronal reuptake Autoreceptor blocked by cocaine!

12 SKELETAL MUSCLE! BLOOD VESSELS RECEPTORS At low concentration of Adrenaline b2 effect predominates vasodilation (anticipation) At high plasma concentration of Adrenaline a1 effect predominates vasoconstriction LUNG b2 M1,2,3 - + Adrenaline (Epinephrine) is far more potent beta-adrenoceptor agonist than NA. Importance of circulating A in arrythmias and bronchi HEART

13 AUTONOMIC PHARMACOLOGY -MIMETICS (+): 1. increase synthesis/release of NT 2. decrease degradation of NT 3. use receptor agonist Sympathomimetic e.g.: Amphetamine increases NE synthesis and release -LYTICS: 4. block synthesis of NT 5. block release of NT 6. use receptor antagonist Antimuscarinic effect: M-AchR antagonist (Atropine)

14 AUTONOMIC PHARMACOLOGY CURARE (-) BOTULINUM TOXIN (-) nachr nachr NICOTINE PRAZOSIN (-) PROPRANOLOL (-) COCAINE(+) b-ar a-ar ISOPROTERENOL (+) nachr AMPHETAMINE (+) E: b>a nachr ATROPINE PHYSOSTIGMINE (AchE inhibitor) M-AchR 9/19/2018 nachr

15 constricts sphincters Release of glucagon Glucose levels up

16 VEGETATIVE TONE tonic activity of the autonomic nervous system under resting condition - psy tone in the heart - sy tone in the arterioles - psy tone in the bronchi Predominance of a division! Pattern of action potentials rate of an autonomic fiber exerts tonic activity return individually below decreased effect at rest increased effect Evening Seminar Notes-Phys

17 Mentimeter How can we distuinguish between sympathetic and parasympathetic autonomic nerves? (1) a) Functionally, based on whether the effects can be attributed to the to rest and digest or the flight or fight group of responses b) Neurochemically, as the sympathetic nerves are all adrenergic and the parasympathetic nerves are all cholinergic c) Anatomically, as the sympathetic nerves stem from the thoracolumbal spinal cord segments, and the parasympathetics stem from the brainstem as well as from the sacral spinal cord segments

18 Mentimeter Choose, which of the followings can be used stimulate the urinary bladder following surgery: 1. M-AchR agonist MUSCARINE 2. 2.M-AchR- antagonist Atropine sympathomimetics like MAO inhibitors

19 CASE STUDY ANALYSIS Case: Antecedent: 10-years old boy, red face, disoriented, distracted manner, hot temperature Basic parameters: blood pressure 170/110 Hgmm, pulse 144/min! temperature 39.6! Flushed, hot, dry skin Dilated pupils! (mydriasis), cycloplegia (no accomodation) Neurological symptoms: amnesia, hallucination

20 CASE STUDY ANALYSIS SYMPTOMS COMMENT SY provocation and/or Psy dropout?? dilated pupils CONSIDER! -Compare heart effects and vasoactive effects -Source of ciliary muscles innervation (accomodation reflex) -Sudomotor effects (dry skin)

21 CASE STUDY ANALYSIS Symptoms Comment: BP:170/110 Hgmm HR: 144/min little effect on blood pressure (not so much muscarinergic vasodilation what can be suspended) speeds up the heart rate and increases conduction velocity= PSY tone decreased Flushed, hot, dry skin inhibited the activity of sweat glands T: 39.6 sweating sufficiently depressed and this elevated the body temperature Dilated pupils (mydriasis) Cycloplegia (no accomodation) Amnesia, Hallucination cholinergically innervated sphincter muscles of the iris relaxed accommodative ciliary muscle of the lens is blocked restlessness symptoms can be explained by loss of muscarinic effects

22 CASE STUDY ANALYSIS Case History: Ingestion of black seeds of a plant located near the house Diagnosis: Atropine Overdose ANTIMUSCARINIC INTOXICATION Course: Small doses of Physostigmine slowly intravenously administered Within 6 hours normal vital signs. The remainder of the stay was uneventful.

23 ATROPINE Atropine effect: M-AchR antagonist Overdose: ANTIMUSCARINIC INTOXICATION Course: PSY mimetic (Physostigmine) pinterest.com Physostigmine has side effects on skeletal muscles (Ach up)

24 Extracurrical Atropine and Antimuscarinic Alkaloids: The famous poison of Roman Emperors wives Datura stramonium: hallucinogen- fatally toxic Atropa Belladonna: medicine, cosmetic and poison Belladonna has a long history of medicinal applications in healthcare the devil breath aka SCOPALAMINE- an alkaloid of belladonna, is helpful in treating motion sickness Scopalamine: criminals in Colombia and Ecuador use the drug, which is said to remove a person s free will (TheGuardian)

25 ATROPINE Extracurrical More adverse effect Gastrointestinal tract Respiratory tract Urinary retention decreased bowel sounds, reduction of salivary secretion inhibits the secretion of nose, mouth, pharynx and bronchi produces bronchodilation Urinary sphincter contraction Therapeutic Uses of Atropine PREANAESTHETIC MEDICATION ANTIDIARRHEAL DRUG Can suppress bronchiolar secretions and reduce the risk of airway obstruction increase the heart beat when anaesthetic drug is going to be used in the treatment of irritable bowel movement OPTHALMOLOGICAL USES; against peptic ulcer; dries up breast milk

26 Exemptions of Dual Innervation adrenal medulla arrector pili muscles SY sweat glands most blood vessels PSY lacrimal gland acini ciliary muscle musc. sphincter pupillae Bronchial smooth muscle musc.dilatator pupillae ventricle of the heart

27 HEART Predominance of PSY chronotropic effect: (incerased frequency of AP generation) dromotropic effect: (increased speed of AP propagation) The endogenous frequency of the pacemaker cells: 100 AP/min!!!!!!Psy tone heart rate: 72 beats/min The individual variation of the heart rate at rest is based mainly on the difference in the psy tone at rest

28 Nucl.Edinger- Westphal (oculomotor nucl.) INNERVATION OF THE PUPIL T1 NOTICE! Pupillary Light Reflex (PSY REFLEX!) SY The two distinct muscles ATROPINE SY: mydriasis PSY: myosis PSY

29 Horner s syndrome The loss of sympathetic Lesion of the superior cervical ganglion (tumor, trauma). Sympthoms: Horner s (triad)- ipsilateral Pancoast tumor Lost innervation of: 1. Miosis - pipullary dilator muscle 2. Ptosis - tarsalis muscle 3. Enopthalmus - orbitalis muscle 4. (Anhydrosis) - facial sweat glands 5. (Flush) - facial skin arterioles

30 BLOOD VESSELS WITHOUT DUAL INNERVATION Sympathetic VASOMOTOR TONE a1 keeps vasculatura and arterioles partially constricted and this maintains blood pressure (regulating amount of blood flow into the capillaries) Serum Ach caused endothelium-derived NOdependent relaxation carry out their function through the change of their diameters

31 Bronchi PSY Vagal nerve Bronchoconstriction, secretion (M1) parasympathetic preganglionar sympathetic postganglionar SY Bronchodilation, secretion (β2) - Circulating EPINEPHRINE smooth muscle bloodstream The bronchi don t have sympathetic innervation but adrenergic receptors are present which are activated by the circulating catecholamines. mucus secretion secretory gland contraction dilation Parasympathetic BRONCHOMOTOR Tone

32 Bronchial asthma: wall of the bronchus mucosa lumen chronic inflammation of the airway increased smooth muscle smooth muscle contraction (bronchoconstrion) increased smooth muscle contraction (bronchoconstrion) increased secretion of the glands in the airways THERAPY: Dilatation of the airways Respir Res. 2006; 7(1): 73. increase of the sympathetic effect decrease of the parasympathetic effect b2-agonist direct smooth muscle relaxation Atropin Anticholinergic effect Bronchodilatation

33 NICOTINE Notice! Nicotine stimulates the postganglionic neurons of both the sympathetic and parasympathetic divisions! The action of nicotine on acetylcholine receptors of the neuromuscular synapse is much less important than that on ganglia of the autonomic nervous system Different effects according to doses (Agonist/Antgonist) Nicotine lethal dose: mg Nicotine dosage in a traditional cigarette: 2 mg it would take smoking over 100 cigarettes in a short time period to ingest a lethal dose BUT: tobacco leaves through skin can produce high doses

34 Vegetative Functions: Integrative Function of the Spinal Cord The VEGETATIVE REFLEX spinal reflexes: erection defecation urination Micturition Reflex

35 Vegetative Functions: Supraspinal Stimuli- Brainstem control MEDULLA Nucl. Tractus Solitarii e.g. vasomotor (RVLM), respiratory, coughing centre interneurons Vegetative efferents HYPOTHALAMUS Thermoregulation: Endocrine response: TRH,tiroxin synthesis Preoptic area Visceral afferents Target organ Peripheral thermoreceptors Sympathetic vasomotor, sudomotor brainstem reflexes: e.g. touching cornea lacrimation; salivation, swallowing, vomiting, coughing, sneezing

36 Vegetative Functions: Supraspinal Stimuli- Central Coordination Vegetative stimulation correlates with activation in certain structures in CNS (etc. PAG, dorsal raphe nuclei) Limbic system, cortical areas Anticipation of exercise Heart rate, blood pressure and respiratory rate increased with anticipation Spinal shock-areflexia- loss of central excitatory impulses