THE AUTONOMIC NERVOUS SYSTEM

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THE AUTONOMIC NERVOUS SYSTEM
D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY
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ORGANIZATION OF THE NERVOUS SYSTEM
BRAIN SPINAL CORD
CENTRAL NERVOUS SYSTEM (CNS)
AFFERENT NERVES
EFFERENT NERVES
PERIPHERAL NERVOUS SYSTEM
EXTERO- RECEPTORS
INTERO- RECEPTORS
SOMATIC
AUTONOMIC
EFFECTOR ORGANS
SKELETAL MUSCLES
SMOOTH AND CARDIAC MUSCLES AND GLANDS
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THE AUTONOMIC NERVOUS SYSTEM

• TWO NEURON CHAINS
• SYMPATHETIC
• PARASYMATHETIC

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ORGANIZATION OF THE AUTONOMIC NERVOUS SYSTEM
BRAIN
SPINAL CORD
TARGET ORGANS
SYMPATHETIC GANGLIA
PARASYMPATHETIC GANGLIA
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TWO NEURON CHAINS
PRESYNAPTIC NEURON
EFFECTOR ORGAN
SPINE
POSTSYNAPTIC NEURON
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SYMPATHETIC
SYMPATHETIC GANGLIA (NEAR SPINE)
EFFECTOR ORGAN
SPINE
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PARASYMPATHETIC
PARASYMPATHETIC GANGLIA (NEAR EFFECTOR ORGAN)
EFFECTOR ORGAN
SPINE
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AUTONOMIC CONTROL IS IN BRAIN STEM

• HYPOTHALAMUS
• PITUITARY
• PONS
• MEDULLA

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PARASYMPATHETIC

• GANGLION NEAR EFFECTOR ORGAN
• LONG PREGANGLIONIC NEURONS
• SHORT POSTGANGLIONIC NEURONS
• COUCH POTATO
• POSTGANGLIONIC NEURONS ARE CHOLINERGIC
• CRANIAL AND SPINAL NERVES

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SYMPATHETIC

• GANGLION NEAR SPINE
• SHORT PREGANGLIONIC NEURONS
• LONG POSTGANGLIONIC NEURONS
• FLIGHT OR FIGHT
• POSTGANGLIONIC NEURONS ARE ADRENERGIC
• THORACIC AND LUMBAR NERVES

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EFFECTS OF ANS
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DUAL INNERVATION OF MOST VISCERAL ORGANS

• MOST INNERVATED BY BOTH SYSTEMS
• EFFECTS ARE OPPOSITE IN MOST CASES
• TONIC ACTIVITY
• DOMINANCE

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EFFECTS OF PRE AND POSTGANGLIONIC
NEUROTRANSMITTERS PHYSIOLOGY AND PHARMACOLOGY

• NOREPINEPHRINE (ADRENERGIC)FLIGHT OR FIGHT
  REACTION (SYMPATHETIC POSTGANGLIONIC)
• ACETYLCHOLINE (CHOLINERGIC) COUCH POTATO
  RESPONSE (PARASYMPATHETIC POSTGANGLIONIC AND ALL
  PREGANGLIONIC).

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ACETYLCHOLINE (CHOLINERGIC) COUCH POTATO
RESPONSE (PARASYMPATHETIC POSTGANGLIONIC AND ALL
PREGANGLIONIC).

• NICOTINIC RECEPTORS (PREGANGLIONIC)
• MUSCARINIC RECEPTORS (POSTGANGLIONIC)

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NICOTINIC RECEPTORS (PREGANGLIONIC)

• ACTIVATED BY ACETYL CHOLINE ENDOGENOUSLY AND
  NICOTINE EXOGENOUSLY
• BLOCKED BY CURARE AND HEXAMETHONIUM

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MUSCARINIC RECEPTORS (POSTGANGLIONIC)

• ACTIVATED BY ACETYL CHOLINE ENDOGENOUSLY AND
  MUSCARINE EXOGENOUSLY
• BLOCKED BY ATROPINE

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THE ADRENAL MEDULLA SECRETES EPINEPHRINE

• ANALOG TO A LARGE POST GANGLIONIC SYMPATHETIC
  NERVE TERMINAL
• IS AN ENDOCRINE GLAND SECRETES THE HORMONE INTO
  THE BLOOD

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TYPES OF RECEPTORS

• ALPHA MORE SENSITIVE TO NOREPINEPHRINE
• BETA MORE SENSITIVE TO EPINEPHRINE

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ALPHA RECEPTORS

• ALPHA-1 POSTSYNAPTIC TARGET CELLS OF
  SYMPATHETICALLY INNERVATED ORGANS
• ALPHA-2 PRESYNAPTIC TERMINALS OF CHOLINERGIC
  NERVE FIBERS

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BETA RECEPTORS

• BETA-1 EPINEPHRINE AND NE EQUALLY POTENT
• BETA-2 RESPOND BETTER TO EPINEPHRINE THAN TO NE
  (PROBABLY TO CIRCULATING HORMONE THAN TO
  NEUROTRANSMITTER)

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FACTORS AFFECTING THE CONCENTRATION OF NE IN THE
JUNCTIONAL CLEFT

• NEURONAL UPTAKE
• DIFFUSION INTO CAPILARIES
• UPTAKE INTO EFFECTOR CELLS

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AUTONOMIC REFLEXES

• REFLEX ARCS MIMIC SOMATIC SPINAL REFLEXES
• DEFICATION AND URINATION AMONG OTHERS

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REFERRED PAIN

• PAIN PATHWAYS FROM VISCERA SHARE SECONDARY
  NEURONS WITH SOMATIC PAIN NEURONS
• HYPERALGESIC ZONES