Welcome to the Autonomic Nervous System

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Welcome to the Autonomic Nervous System!

• Brought to you by CSI and Gordy Kokx

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The Peripheral Nervous System

• Is divided into the somatic and autonomic
  components.
• The somatic controls voluntary movements (i.e.
  skeletal muscles)
• The autonomic controls involuntary responses
  (i.e. stress, rest)

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AUTONOMIC NERVOUS SYSTEM

• The Automatic Nervous System
• Controls the function of most tissues in the body
  (not muscles)
• BP
• GI secretions and motility
• Urinary bladder function
• Sweating and body temp

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Autonomic Nervous System

• Adrenergic
• (Sympathomimetic)
• Increases heart rate
• Bronchodilates
• Dilates Pupils
• Decreases GI tract
• Decreases lacrimation
• Decreases urination
• Fight or Flight

• Cholinergic
• (Parasympathomimetic)
• Decreases heart rate
• Bronchoconstricts
• Constricts Pupils
• Increases GI tract
• Increases lacrimation
• Increases urination
• Rest and Digest

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Autonomic Nervous System

• Functions
• To maintain or quickly restore homeostasis
• Sympathetic and parasympathetic branches affect
  body in antagonistic ways

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AUTONOMIC NERVOUS SYSTEM

• SYMPATHETIC
• Fight or Flight
• PARASYMPATHETIC
• Rest and Digest

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ADRENERGIC AGENTS

• SYMPATHOMIMETIC
• Ex epinephrine, adrenalin
• Many therapeutic uses - alpha and beta agonist
• Decongestants, vasopressors, bronchodilators,
  mydriasis

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Think about this

• Sympathomimetic drugs Mimic the Sympathetic
  Nervous System.
• What do you think Parasympathomimetic drugs do?

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Autonomic Nervous System

• Cell bodies of neurons in these two divisions (Pg
  70)
• Located in different areas of CNS
• Leave at different levels
• Sympathetic leave from thoracic and lumbar
  regions of spinal cord
• Parasympathetic leave from cranial and sacral
  portions of spinal cord

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Pre Postganglionic Neurons

• A two-neuron chain exists in a series between the
  CNS and effector organs
• Consists of a preganglionic neuron located in the
  CNS and a postganglionic neuron located in the
  periphery

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Pre Postganglionic Neurons

• Preganglionic fibers pass between CNS and ganglia
• Postganglionic fibers pass between ganglia and
  effector organ

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Pre and Postganglionic Fibers

• Preganglionic fibers
• Solid lines
• Postganglionic fibers
• Broken lines

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Pre Postganglionic Neurons

• Sympathetic ganglia
• Many lie close to spinal cord
• Others lie approximately midway between spinal
  cord and effector organ
• Parasympathetic ganglia
• Lie close to or within the walls of effector
  organ
• Synapse
• Junction between two neurons

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Autonomic Conduction Pathways
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2 Important Neurotransmitters

• Acetylcholine Cholinergic
• Norepinephrine Adrenergic
• Check out others on the web link!

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Acetylcholine

• Neurotransmitter for ganglionic synapse between
  preganglionic and postganglionic fibers of
  sympathetic and parasympathetic divisions
• Also the neurotransmitter at the junction between
  the parasympathetic postganglionic fiber and
  effector cell

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Acetylcholine

• Fibers that release acetylcholine are known as
  cholinergic fibers
• All preganglionic neurons of the autonomic
  division and all postganglionic neurons of the
  parasympathetic division are cholinergic

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Norepinephrine

• Neurotransmitter between the sympathetic
  postganglionic fiber and the effector cell
• Fibers that release norepinephrine are adrenergic
  fibers
• Most postganglionic neurons of the sympathetic
  division are adrenergic
• Few are cholinergic

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Autonomic Nervous System

• Stimulation of the sympathetic nerves causes
  excitatory effects in some organs and inhibits
  effects in others
• Example Increases Heart Rate, but decreases GI
  motility
• Likewise, parasympathetic stimulation causes
  excitation in some organs but inhibition in others

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Autonomic Nervous System

• Both systems function continuously and
  occasionally react in a reciprocal fashion
• Most organs are dominantly controlled by one of
  the two systems
• You might consider them a teeter totter.

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Nerve Impulse Transmission

• Acetylcholine combines with 2 major types of
  cholinergic receptor molecules
• Nicotinic and Muscarinic
• When acetylcholine binds to nicotinic receptors,
  there is an excitatory response (Nicotine)
• When it binds with muscarinic receptors, it may
  result in excitation or inhibition, depending on
  the target tissues in which the receptors are
  found (Mushrooms)

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Nerve Impulse Transmission

• Norepinephrine combines with adrenergic receptors
  within the membranes of the effector organ (alpha
  receptors and beta receptors)
• Binds to and activates both types of receptor
  molecules
• Has more affinity for alpha receptors

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Think about this

• Norepinephrine (Levophed) is an alpha adrenergic
  drug. That means it will cause vasoconstriction
  and a higher blood pressure.

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Nerve Impulse Transmission

• Epinephrine is an adrenergic substance
• Produced by the adrenal medulla
• Has nearly equal affinity for both receptors
• In tissues containing alpha and beta receptor
  cells, one type is more abundant and has a
  dominating effect

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Nerve Impulse Transmission
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ADRENERGIC AGENTS

• Isuprel Beta 1 and Beta 2
• Alupent Beta-2 selective
• Dopamine Alpha and Beta-1
• Dobutamine Beta-1selective
• Norepinephrine Alpha

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Question

• What side effects might you expect to see in a
  patient on a adrenergic medication?

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ADRENERGIC AGENTS

• SIDE EFFECTS
• Tachycardia
• Palpitations
• Tremors
• GI upset give with food

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Alpha AdrenergicBlocking Agents

• Alpha blockers block vasoconstriction and relax
  vascular smooth muscle
• Uses Primary cause is treating
  Hypertension
• Ex doxazosin (Cardura)

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Beta AdrenergicBlocking Agents

• Beta Blockers block heart rate and cause
  bronchoconstriction
• By slowing heart rate they lower blood pressure
• Beta-1 selective for asthmatics
• Ex esmolol
• metoprolol
• atenolol (Tenormin)

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BETA-BLOCKERS

• Use all with extreme caution in asthmatics
• Diabetics may mask hypoglycemia

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Question

• Why would it be dangerous to give a non-selective
  beta blocker medication to an asthmatic patient?

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CHOLINERGIC AGENTS

• PARASYMPATHOMIMETIC
• Ex urecholine postop/OB UO
• Pilocarpine miosis of eye IOP
• GI disorders paralytic illius

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Question

• What side effects might you expect to see in a
  patient taking a cholinergic drug?
• Hint Cholinergic Colon-Urgent

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CHOLINERGIC AGENTS

• SIDE EFFECTS
• N/V
• Diarrhea
• Abdominal cramping
• Dizziness
• Bradycardia
• Sweating

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ANTICHOLINERGIC AGENTS

• PARASYMPATHOLYTIC
• ACTION
• secretions
• peristalsis constipation
• Urinary retention
• Blurred vision dilate pupils

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ANTICHOLINERGICS

• USES
• Tx. of GI disorders
• Tx. of opthalmic disorders
• Bradycardia (Atropine)
• GU disorders
• Pre-op drying agent

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ANTICHOLINERGICS

• Examples
• Atropine Given in pre-op to
• dry secretions
• Decrease peristalsis
• Minimizes vagal response during intubation

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ANTICHOLINERGICS

• EXAMPLES
• Bentyl GI
• Antispasmotic, IBS
• Atropine/ Cyclogyl opthalmic
• Dilates pupil to examine, but Increases IOP, so
• DO NOT GIVE WITH GLAUCOMA

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Questions?