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Autonomic Nervous System

Autonomic Nervous System. Chapter 16, 17, 18, 19, 20 Clinical Drug Therapy. Nervous System. Two main divisions Central Nervous System or CNS Peripheral Nervous System or PNS. Central Nervous System or CNS.

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Autonomic Nervous System

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  1. Autonomic Nervous System Chapter 16, 17, 18, 19, 20 Clinical Drug Therapy

  2. Nervous System • Two main divisions • Central Nervous System or CNS • Peripheral Nervous System or PNS

  3. Central Nervous System or CNS • Brain and spinal cord: receives and processes incoming sensory information and responds by sending out signals that initiate or modify a process.

  4. Peripheral Nervous System or PNS • Includes all the neurons and ganglia found outside the CNS • Afferent (sensory): modify motor output • Efferent:

  5. Afferent Neurons • Afferent neurons carry sensory input from the periphery to the CNS and modify motor output through the reflex arc.

  6. Efferent Neurons • Efferent neurons carry motor signals from the CNS to the peripheral areas of the body.

  7. ANS / SNS • Autonomic nervous system controls involuntary activities of smooth muscle, secretory glands and the visceral organs of the body such as the heart (involuntary activities of smooth muscle) • Somatic nervous system innervates the skeletal muscles and controls voluntary movement

  8. Autonomic Nervous System • Sympathetic Nervous System • Para sympathetic System • Enteric System

  9. The Race Horse and the Cow Sympathetic Nervous System Parasympathetic

  10. Sympathetic System • Fight or Flight – stimulated by physical or emotional stress (exercise or work), pain, hemorrhage, intense emotions, temperature extremes

  11. Sympathetic Nervous System • Protective mechanisms designed to help person cope with the stress or get away from it.

  12. Neurotransmitters • Neurotransmitters • Acetylcholine: skeletal muscle • Norepinepherine: stress response

  13. Norepinephrine and epinephrine • Both always present in the blood. • Norepinephrine varies according to the amount of stress present and will cause transient changes in heart rate and systemic arteries and veins. • Epinephrine is a constant in regulating heart rate, vasoconstriction in systemic arteries and veins and vasodilation of muscles and liver.

  14. Dopamine • Adrenergic neurotransmitter – essential for normal brain function. • Studies focus on connection between dopamine malfunction in schizophrenia and Parkinson’s Disease. • Role of dopamine in drug addition to drugs: stimulants and depressants.

  15. Protective Mechanisms • Intensity of response depends on Norepinephrine and epinephrine • Fight or flight

  16. Body Responses • Increase in blood pressure and cardiac output. • Increase blood flow to brain, heart and skeletal muscles. • Decrease blood flow to skin and organs not needed for “flight”. • Increase in glycogen for energy, mental activity, muscle strength, blood coagulation, respiratory rate, pupil dilation to aid vision, and increase in sweating.

  17. Fight of Flight Response • Can be a problem if the body stay in the “fight or flight” mode. • Type A personalities? • High stress environment? • Medications may be needed reduce the physiologic body responses.

  18. Parasympathetic Nervous System Rest and Digest Save energy Decreased heart rate

  19. Adrenergic Receptors • Norepinephrine and epinephrine interact with two adrenergic receptors • Alpha and beta • Alpha 1 • Alpha 2 • Beta 1 • Beta 2

  20. Alpha 1 • Alpha 1 receptors allows calcium ions to move into the cell and produce muscle contraction.

  21. Location Blood vessels Kidney Intestinal smooth muscles Genitourinary Eyes = blinking Pregnant uterus = contractions Male sexual organs = sexual function Effects of stimulation Vasoconstriction Release of renin (kidney) Relaxation Alpha 1

  22. Location Nerve endings Vascular smooth muscles Pancreatic beta cells Platelets Effects of stimulation Inhibits release of Norepinephrine Vasoconstriction Inhibit insulin secretion Aggregation or clotting Alpha 2

  23. Location Heart Kidneys Effects of stimulation Increase heart rate, force of contraction, automaticity and rate of atrial-ventricular function Increased renin release Beta 1

  24. Location Bronchioles Blood vessels Gastrointestinal tract Liver Urinary bladder Pregnant uterus Effects of stimulation Vasodilation Decreased motility and tone Glycogenolysis Relaxed detrusor muscle (bladder muscle) Relaxation of uterus Beta 2

  25. Location Blood vessels of kidney, heart, and other viscera Effects of stimulation Vasodilation Dopamine

  26. Parasympathetic Nervous System Functions stimulated by PNS: Resting, reparative, or vegetative function

  27. Body Responses • Dilation of blood vessels in skin • Decrease heart rate (bradycardia) • Increase secretion of digestive enzymes • Constriction of smooth muscle of bronchi • Increase in sweat glands • Contraction of smooth muscles of urinary bladder • Contraction of smooth muscle of skeletal system

  28. Neurotransmitter • Acetylcholine • Two types of cholinergic receptors • Nicotinic: located in motor nerves and skeletal muscles • Muscarinic: located in internal organs, cardiovascular, respiratory, GI and GU

  29. Autonomic Drugs • Drugs used due to their ability to stimulate or block activity of the sympathetic or parasympathetic nervous system.

  30. Effect of Drugs • Drugs that act of ANS usually affect the entire body. • Effects depend on whether you are trying to stimulate or inhibit function.

  31. Receptor Activity • Drugs are developed to stimulate or inhibit particular subtypes of receptors. • More selective on particular body tissues. • Decrease adverse effects on other body tissues – side effects.

  32. Simulation of SNS • Stimulation of sympathetic nervous system can be divided into drug classifications: • Adrenergic • Sympathomimetic • Alpha and beta adrenergic agonists

  33. Agonist • In pharmacology an agonist is a substance that binds to a specific receptor and triggers a response in the cell.

  34. Blockage of SNS • Drugs that inhibit sympathetic nervous system are classified as • Antiadrenergic • Sympatholytic anticholinergic

  35. Stimulation of PNS • Parasympathetic nervous system stimulation drug classifications • Cholinergic • Parasympathomimenic • Cholinomimetic

  36. Blocking of PNS • Drugs that inhibit parasympathetic stimulation are classified as: • Anticholinergic • Parasympatholytic • Cholenergic blocking drugs

  37. Classifications: SNS • Sympathetic nervous system drug classifications • Adrenergic - stimulating • Antiadrenergic - blocking

  38. Classifications: PNS • Parasympathetic nervous system drugs • Cholinergic • Anticholinergic

  39. Adrenergic Drugs Chapter 17

  40. Adrenergic Drugs • What do they do? • Stimulation of the sympathetic nervous system.

  41. Mechanism of Action • Three mechanisms: • Directly with alpha 1 or beta-adrenergic receptors on surface membrane. • Indirect effects of postsynaptic adrenergic receptors. • Mixed action – combination of action on direct and indirect receptor.

  42. Heart • Direct stimulation of receptors • Alpha 1 - Vasoconstriction of blood vessels which increases blood pressure – pressor or vasopressor effect. • Beta 2 - increased force of myocardial contraction - Increased speed of electrical conduction in the heart.

  43. Lungs Asthma and COPD (Chronic Obstructive Pulmonary Disease): Beta 2 drugs or bronchodilators are used to relieve broncho-constriction and broncho-spasm.

  44. Pregnancy • Adrenergic drugs used to relax uterine muscles in preterm labor.

  45. OTC Adrenergic Drugs • Common cold: anti-histamines • Allergy: nasal or oral to relieve nasal congestion

  46. Adrenergic Drugs • Epinephrine • Pseudoephedrine – Sudafed • Isoproterenol (Isuprel) • Phenylephrine (Neo-Synephrine) • Clonidine (antihypertensive)

  47. How does one choose a drug? • How emergent is the situation • PO or IM or IV

  48. Allergic Response • Runny nose, itchy eyes, cough • Asthma: Cough with bronchospasms, difficulty breathing or SOB (shortness of breath) • Anaphylactic shock – edema of airway

  49. Allergy Response • Nasal congestion, itchy eyes, non-productive cough • Seasonal response to environmental causes • Commonly mixed with other drugs in cold medications

  50. Pseudoephedrine • Therapeutic classification: allergy, cold, and cough remedies, nasal drying, and decongestants. • Indications: symptomatic management of nasal congestion associated with acute viral upper respiratory tract infection. Most often used in combination with other drugs. • Action: stimulates Alpha and beta-adrenergic receptors – vasoconstriction in respiratory tract mucosa – possible bronchodilation • Therapeutic effects: reduction of nasal congestion, and swelling of nasal passages.

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