THE AUTONOMIC NERVOUS SYSTEM D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY
Dec 24, 2015
ORGANIZATION OF THE NERVOUS SYSTEM
BRAINSPINAL CORD
CENTRALNERVOUSSYSTEM (CNS)
PERIPHERALNERVOUS SYSTEM
AFFERENT
NERVES
EFFERENT
NERVES
EXTERO-RECEPTORS
INTERO-RECEPTORS
SOMATIC AUTONOMIC
EFFECTORORGANS
SKELETALMUSCLES
SMOOTH AND CARDIAC MUSCLES AND GLANDS
ORGANIZATION OF THE AUTONOMIC NERVOUS SYSTEM
SYMPATHETIC
GANGLIA
TARGET
ORGANS
BRAIN
SPINAL CORD
PARASYMPATHETIC
GANGLIA
PARASYMPATHETIC
• GANGLION NEAR EFFECTOR ORGAN• LONG PREGANGLIONIC NEURONS• SHORT POSTGANGLIONIC NEURONS• “COUCH POTATO”• POSTGANGLIONIC NEURONS ARE
CHOLINERGIC• CRANIAL AND SPINAL NERVES
SYMPATHETIC
• GANGLION NEAR SPINE
• SHORT PREGANGLIONIC NEURONS
• LONG POSTGANGLIONIC NEURONS
• FLIGHT OR FIGHT
• POSTGANGLIONIC NEURONS ARE ADRENERGIC
• THORACIC AND LUMBAR NERVES
EFFECTS OF ANSORGAN S PHEART + -BLOODVESSELS
CONSTRICT(MOSTORGANS)
DILATE (HEART
AND SKELETAL)
DILATE (PENISAND CLITORIS)
BRONCHIOLES DILATE CONSTRICT
PUPIL DILATE CONSTRICT
DIGESTION INHIBIT ENHANCE
DUAL INNERVATION OF MOST VISCERAL ORGANS
• MOST INNERVATED BY BOTH SYSTEMS
• EFFECTS ARE OPPOSITE IN MOST CASES
• TONIC ACTIVITY
• DOMINANCE
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).
ACETYLCHOLINE (CHOLINERGIC): “COUCH POTATO” RESPONSE (PARASYMPATHETIC
POSTGANGLIONIC AND ALL PREGANGLIONIC).
• NICOTINIC RECEPTORS (PREGANGLIONIC)
• MUSCARINIC RECEPTORS (POSTGANGLIONIC)
NICOTINIC RECEPTORS (PREGANGLIONIC)
• ACTIVATED BY ACETYL CHOLINE ENDOGENOUSLY AND NICOTINE EXOGENOUSLY
• BLOCKED BY CURARE AND HEXAMETHONIUM
MUSCARINIC RECEPTORS (POSTGANGLIONIC)
• ACTIVATED BY ACETYL CHOLINE ENDOGENOUSLY AND MUSCARINE EXOGENOUSLY
• BLOCKED BY ATROPINE
THE ADRENAL MEDULLA SECRETES EPINEPHRINE
• ANALOG TO A LARGE POST GANGLIONIC SYMPATHETIC NERVE TERMINAL
• IS AN ENDOCRINE GLAND: SECRETES THE HORMONE INTO THE BLOOD
ALPHA RECEPTORS
• ALPHA-1: POSTSYNAPTIC TARGET CELLS OF SYMPATHETICALLY INNERVATED ORGANS
• ALPHA-2: PRESYNAPTIC TERMINALS OF CHOLINERGIC NERVE FIBERS
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)
FACTORS AFFECTING THE CONCENTRATION OF NE IN THE
JUNCTIONAL CLEFT
• NEURONAL UPTAKE
• DIFFUSION INTO CAPILARIES
• UPTAKE INTO EFFECTOR CELLS
AUTONOMIC REFLEXES
• REFLEX ARCS MIMIC SOMATIC SPINAL REFLEXES
• DEFICATION AND URINATION AMONG OTHERS