1. Lecture 3 Autonomic Nervous System

2. Chapter 20 Autonomic Nervous System n n Central Nervous System (CNS) - Brain and spinal cord n n Peripheral Nervous System (PNS) - Located outside the brain & spinal cord * Autonomic Nervous System (ANS) & the somatic n n The PNS receives stimuli from the CNS & initiates responses to the stimuli after it’s interpreted by the brain

3. Autonomic Nervous System n n ANS acts on smooth muscles & glands - Controls & regulation of the heart, respiratory. system, GI tract, bladder, eyes & glands - Involuntary - person has little or no control n n Somatic - voluntary - person has control (skeletal muscle)

4. ANS n n ANS has 2 sets of neurons: 1. Afferent (sensory) - sends impulses to the CNS for interpretation 2. Efferent - receives impulses (info.) from the brain & transmits from the spinal cord to the effector organ cells - 2 branches - sympathetic & parasympathetic nervous system

5. Figure 20-2. Sympathetic and Parasympathetic Effects on Body Tissues

6. ANS - Sympathetic nervous system (Adrenergic) n n Sympathetic Nervous System (adrenergic) Norepinephrine = neurotransmitter - Drugs that mimic = adrenergic drugs, sympathomimetics, or adrenomemetics * Adrenergic agonists - Drugs initiate a response - Drugs that block = adrenergic blockers, sympatholytics or adrenolytics * Adrenergic antagonists - prevent a response

7. ANS n n 4 types of adrenergic receptor organ cells: 1. Alpha-1 = vasoconstriction of blood vessels inc. blood return to heart, inc. circulation, inc. BP 2. Alpha-2 = inhibits release of norepinephrine dec. in vasoconstriction, dec. BP 3. Beta-1 = inc. in heart rate & force on contraction 4. Beta-2 = relaxation of smooth muscle in bronchi, uterus, peripheral blood vessels Dopaminergic = dilate vessels, inc. in blood flow - only dopamine activates this receptor

8. ANS - Parasympathetic Nervous System (Cholinergic) n n Parasympathetic or Cholinergic Nervous System Acetylcholine = neurotransmitter - Drugs that mimic = cholinergic drugs, parasympathomimetics Cholinergic agonists - initiates a response - Drugs that block = anticholinergic, parasympatholytics Cholinergic antagonists - prevents a response

9. ANS n n Sympathomimetic pathway Norepinephrine From adrenergic fiber Inc. heart rate Pupil dilation Adrenergic (sympathomimetic) agents Fight or Flight n n Parasymathomimetic pathway Acetylcholine From cholinergic fibers Dec. heart rate pupil constriction Cholinergic (parasympathomimetic agents)

10. Chapter 21: Adrenergics and Adrenergic Blockers n n Drugs that Stimulate the sympathetic Nervous System (adrenergics, adrenergic agonists, sypathomimetics, or adrenomimetics) n n Mimic the sympathetic neruotransmitters norepinephrine and epinephrine n n Act on one or more adrenergic receptor sites located on the cells of smooth muscles - heart, bronchioles, GI tract, bladder, eye n n 4 main receptors (alpha-1, alpha-2, beta-1, beta-2)

11. SYMPATHETIC RESPONSES

12. Sympathomimetics/ Adrenomimetics n n Stimulate adrenergic receptors: 3 categories 1. Direct-acting = directly stimulates receptors (epinephrine or norepinephrine) 2. Indirect-acting = stimulates release of norep. from terminal nerve endings (amphetamine) 3. Mixed-acting (indirect & direct) = stimulates receptor sites & release of norep. from nerve endings (Ephedrine)

13. Sympathomimetic Agents/ Adrenergics n n Action - Many of the adrenergic drugs stimulate more than one of the adrenergic receptor sites (alpha & Beta) n n Response = Inc. BP, pupil dilation, inc. HR, & bronchodilation n n Use = Cardiac stimulation, bronchodilator, decongestant n n Side effects = Hyperness in body

14. Sympathomimetics/Adrenergics n n Albuterol - Beta-2 agonist (bronchodilation) Use - bronchospasm, asthma, bronchitis SE - nervousness, restlessness CI - severe cardiac disease, HTN n n Epinephrine - stimulates alpha & beta Use - allergic reaction, cardiac arrest SE - nervousness, agitation CI - cardiac dysrhythmias

15. Adrenergic Agents n n Dopamine - alpha-1 & beta-1 stimulation Use - Hypotension, shock, inc. cardiac output, improve perfusion to vital organs SE - N & V, headache CI - V. Tach

16. Adrenergic Blockers (antagonists/sympatholytics) n n Block alpha & beta receptor sites (nonselective) n n direct or indirect acting on the release of norepinephrine and epinephrine n n Use - Cardiac arrthymias (HR), HTN ( cardiac output), angina (O2 demand) n n SE - CHF, bronchospasm, bradycardia, wheezing

17. Nonselective vs Selective Beta blockers n n Nonselective have an equal inhibitory effect on B1 & B2 receptors - - Drugs have lots of interactions due to lots of alpha/beta receptor sites throughout body - use with caution on clients with cardiac failure or asthma n n Selective B1 helpful in asthma clients

18. Adrenergic Blocking Agents n n Inderal (Propranolol) - Nonselective Use - angina, dysrhythmias, HTN, migraines SE - Many d/t nonselective CI - asthma, heart block > 1st degree n n Minipress (Prazosin) - A blocker Use - mild to mod. HTN SE - orthostatic hypotension n n Tenormin (Atenolol), Lopressor (Metoprolol) B1 (cardio) selective Use - mild to mod HTN, angina

19. Chapter 22: Cholinergics and Anticholinergics n n Cholinergics stimulate the parasympathetic nervous system n n Mimic the neurotransmitter acetylcholine n n 2 types of cholinergic receptors 1. muscarinic - stimulates smooth muscle & slows HR 2. nicotinic - affect skeletal muscle n n Many = nonselective & affect both receptors n n Some affect only the muscarinic receptors and not the nicotinic receptors

20. Parasympathetic Responses

21. Cholinergic Agents n n Direct acting - act on the receptors to activate a tissue response n n Indirect acting - inhibit the action of the enzyme cholinesterase (acetylcholinesterase - ACH) n n Major uses = Stimulate bladder & GI tone, constrict pupils (miosis), neuro- muscular transmission

22. Direct-acting Parasympathomimetic (cholinergic drugs)

23. Cholinergic Agent (Parasympathomimetics) n n Bethanechol (Urecholine) selective to muscarinic receptors, mimic action of acetylcholine Use - For urinary retention * Take on an empty stomach d/t inc. peristalsis * Alert- Never give IM or IV – circulatory collapse, hypotension, shock & cardiac arrest poss. n n Pilocarpine (Pilocar) - Ophthalmic - direct acting

24. Cholinergic Blocking Agents Anticholinergics/Parasympatholytics n n Drugs that inhibit action of acetylcholine (ACH) receptors n n Affects the heart, resp. tract, GI tract, bladder, eye, & exocrine glands. n n Allows the sympathetic nervous system to dominate n n Anticholinergic & cholinergic drugs have opposite effects n n Major responses = dec. in GI motility, dec. in salivation, dilation of pupil (mydriasis), inc. pulse rate

25. Anticholinergics n n Uses: Pre-op meds,bradycardia, GI/urinary antispasmodic n n SE: Dry mouth/mucus membranes n n Atropine Sulfate - Inhibits ACH blocks vagal effects on SA & AV nodes inc. conduction & inc. HR Use = Bradycardia, pre-up to dec. secretions, peptic ulcer disease SE = Many. Most frequent = dry mouth, blurred vision, urine retention, constipation

26. Anticholinergics n n Bentyl (Dicyclomine) - Inhibits ACH on muscarinic receptors & dec. GI motility Use - Irritable bowel syndrome SE - constipation, urinary retention, dry mouth n n Robinul (Glycopyrrolate) - Similar to above Use - pre-op to dec. secretions, GI disorders SE - Similar to above

27. Anticholinergics n n Anticholinergics effect the CNS & benefit people prone to motion sickness n n Scopolamine Patch - Classified as an antihistamine for motion sickness - Topical skin patch behind the ear x3 days Use = cruising on water, flying, car sickness Other drugs = Dramamine, Bonine SE = Dry mouth, visual disturbances d/t pupil dilation