Download the autonomic nervous system

THE AUTONOMIC NERVOUS
SYSTEM
D. C. MIKULECKY
PROFESSOR OF PHYSIOLOGY
ORGANIZATION OF THE
NERVOUS SYSTEM
BRAIN
SPINAL CORD
CENTRAL
NERVOUS
SYSTEM (CNS)
AFFERENT
EFFERENT
NERVES
NERVES
EXTEROINTERORECEPTORS RECEPTORS
EFFECTOR
ORGANS
PERIPHERAL
NERVOUS
SYSTEM
SOMATIC
SKELETAL
MUSCLES
AUTONOMIC
SMOOTH AND
CARDIAC MUSCLES
AND GLANDS
THE AUTONOMIC NERVOUS SYSTEM
• TWO NEURON CHAINS
• SYMPATHETIC
• PARASYMATHETIC
ORGANIZATION OF THE AUTONOMIC
NERVOUS SYSTEM
BRAIN
SPINAL CORD
TARGET
ORGANS
SYMPATHETIC
GANGLIA
PARASYMPATHETIC
GANGLIA
TWO NEURON CHAINS
PRESYNAPTIC
NEURON
EFFECTOR
SPINE
ORGAN
POSTSYNAPTIC
NEURON
SYMPATHETIC
SYMPATHETIC
GANGLIA (NEAR SPINE)
SPINE
EFFECTOR
ORGAN
PARASYMPATHETIC
PARASYMPATHETIC
GANGLIA (NEAR
EFFECTOR ORGAN)
SPINE
EFFECTOR
ORGAN
AUTONOMIC CONTROL IS IN
BRAIN STEM
•
•
•
•
HYPOTHALAMUS
PITUITARY
PONS
MEDULLA
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 ANS
ORGAN
HEART
BLOOD
VESSELS
S
+
P
-
CONSTRICT(MOST
ORGANS)
DILATE (HEART
DILATE (PENIS
AND CLITORIS)
)
AND SKELETAL
BRONCHIOLES
DILATE
CONSTRICT
PUPIL
DIGESTION
DILATE
CONSTRICT
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
TYPES OF RECEPTORS
• ALPHA: MORE SENSITIVE TO
NOREPINEPHRINE
• BETA: MORE SENSITIVE TO
EPINEPHRINE
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
REFERRED PAIN
• PAIN PATHWAYS FROM VISCERA
SHARE SECONDARY NEURONS
WITH SOMATIC PAIN NEURONS
• HYPERALGESIC ZONES