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AUTONOMIC NERVOUS SYSTEM
PART OF EFFERENT DIVISION OF PERIPHERAL NERVOUS
SYSTEM
ANATOMY OF THE ANS
• PRESYMPATHETIC NEURON -- CELL BODY IN CNS
• POSTSYMPATHETIC NEURON --CELL BODY IN PERIPHERAL NERVOUS SYSTEM
• AUTONOMIC PLEXUS
PARASYMPATHETIC VS SYMPATHETIC DIVISIONS
EMBRYONIC DEVELOPMENT
SYMPATHETIC DIVISION• LOCATED IN LATERAL HORNS IN GRAY MATTER• T-1 TO L-2• THORACOLUMBAR• LEAVES SPINAL CORD THROUGH VENTRAL
ROOMS• ENTER VENTRAL RAMI OF SPINAL NERVES• ENTER SYMPATHETIC CHAIN GANGLIA• SYMPATHETIC TRUNKS
SYMPATHETIC NERVOUS SYSTEM
• RAMI COMMUNICANTES– WHITE– GRAY
SYMPATHETIC CHAIN GANGLIA
• PARAVERTERBRAL GANGLIA
• SYMPATHETIC TRUNK
• WHITE RAMI COMMUNICANTES– MYELINATED– CARRY IMPULSES FROM SPINAL NERVE
TO CHAIN GANGLIA
• GRAY RAMI COMMUNICANTES
FATE OF PREGANGLIONIC NEURONS UPON ENTERING
SYMPATHETIC CHAIN GANGLIA
MAY SYNAPSE WITH POSTGANGLIONIC IN
SYMPATHETIC CHAIN GANGLIA AT THE SAME LEVEL
• RETURN TO SPINAL NERVE TO INNERVATE EFFECTORS. GRAY RAMI COMMUNICANTES ARE FORMED BY UNMYELINATED POSTGANGLIONIC AXONS AS THEY PASS FROM CHANIN GANGLIA TO SPINAL NERVES
MAY TRAVEL UP OR DOWN WITHIN SYMPATHETIC TRUNKS
BEFORE SYNAPSING WITH POSTGANGLIONIC NEURONS THAT SUPPLY EFFECTORS IN
SKIN, HEAD, OR THORAX
MAY PASS THROUGH SYMPATHETIC CHAIN GANGLIA
WITHOUT SYNAPSING AND SYNAPSE WITH
POSTGANGLIONIC NEURONS IN COLLATERA GANGLIA
• SUPPLY VISCERA OF ABDOMINOPELVIC CAVITY
PARASYMPATHETIC SYSTEM
PARASYMPATHETIC DIVISION• PREGANGLIONIC NEURON CELL BODIES LOCATED
IN BRAIN NUCLEI OR IN LATERAL PORTIONS OF GRAY MATTER IN SPINAL CORD (S-2 THROUGH S-4)
• FIBERS DO NOT TRAVEL THROUGH RAMI OF SPINAL NERVE
• DO NOT INNERVATE SWEAT GLANDS, ARRECTOR PILI, AND CUTANEOUS BLOOD VESSEL
• MOST BLOOD VESSELS ARE NOT INNERVATED BY PARASYMPATHETIC
PREGANGLIONIC PARASYMPATHETIC AXONS
IN CRANIAL NERVES• III,VII,IX AND X
• SYNAPSE WITH POSTGANGLIONIC NEURONS IN GANGLIA
• NEAR STRUCTURES INNERVATED
SACRAL PREGANGLIONIC PARASYMPATHETIC AXONS • LEAVE VENTRAL ROOTS OF SPINAL
NERVES
• FORM A PELVIC NERVE THAT SUPPLIES VISCERA OF PELVIC CAVITY
ANATOMICAL DIFFERENCES BETWEEN THE DIVISIONS
• LOCATION OF PREGANGLIONIC NEURON CELL BODIES
• FIBER LENGTH
LOCATION OF PREGANGLIONIC NEURON CELL BODIES
• SYMPATHETIC --- LATERAL HORNS OF SPINAL CORD GRAY MATTER FROM T-1 TO L-2
• PARASYMPATHETIC --- BRAIN STEM AND LATERAL HRONS OF SPINAL CORD GRAY MATTER FROM S-1 THROUGH S-4
FIBER LENGTH
• SHORT SYMPATHETIC PREGANGLIONIC AXONS-LONG SYMPATHETIC POSTGANGLIONIC AXONS
• LONG PARASYMPATHETIC PREGANGLIONIC AXONS-SHORT PARASYMPATHETIC POSTGANGLIONIC AXONS
NEUROTRANSMITTERS OF THE AUTONOMIC NERVOUS
SYSTEMEPINEPHRINE VS
NOREPINEPHRINE
SITES FOR RELEASE OF ACETYLCHOLINE IN THE
PERIPHERAL NERVOUS SYSTEM
• NEUROMUSCULAR JUNCTIONS
• ALL PREGANGLIONIC NEURONS IN ANS
• ALL PARASYMPATHETIC POSTGANGLIONIC NEURONS
• SYMPATHETIC POSTGANGLIONIC NEURONS INNERVATING SWEAT GLANDS
SITES FOR RELEASE OF NOREPINEPHRINE IN THE
PERIPHERAL NERVOUS SYSTEM
• MOST SYMPATHETIC POSTGANGLIONIC NEURONS
• ADRENAL MEDULLA
RECEPTORS OF THE AUTONOMIC NERVOUS
SYSTEM• CHOLINERGIC
NICOTINICMUSCARINIC
• ANDRENERGICALPHA 1ALPHA 2BETA 1BETA 2
NICOTINIC RECEPTORS
• NICOTINE MIMICS EFFECTS• PRESENT ON POSTGANGLIONIC NEURONS IN GANGLI OF
THE ANS• ALSO ON SKELETAL MUSCLE AT NEUROMUSCULAR
JUNCTIONS• CHANNEL LINKED RECEPTORS• BLOCKED BY TETRAETHYLAMMONIUM--IN AUTONOMIC
GANGLIA• BLOCKED BY CURARE--AT NEUROMUSCULAR JUNCTION
MUSCARINIC RECEPTORS
• MUSCARINE MIMICS EFFECTS
• ON EFFECTORS SUPPLIED BY PARASYMPATHETIC POSTGANGLIONIC RECEPTORS
• G PROTEIN LINKED RECEPTORS
• BLOCKED BY ATROPINE
ANDRENERGIC RECEPTORS
• ALPHA
• BETA
• ALL ARE G LINKED RECEPTORS
• NON CHANNEL LINKED RECEPTORS
NOREPINEPHRINE
• BINDS WITH– ALPHA 1-- EFFECTIVELY– ALPHA 2 -- EFFECTIVELY– BETA 1-- EFFECTIVELY– BETA 2 --WEAKLY IF AT ALL
EPINEPHRINE
• BINDS EFFECTIVELY WITH– ALPHA 1-- EFFECTIVELY– ALPHA 2 -- EFFECTIVELY– BETA 1-- EFFECTIVELY– BETA 2 --EFFECTIVELY
ALPHA 1 RECEPTORS
• MOST COMMON ALPHA RECEPTOR
• ACTIVATES G PROTEINS
• G PROTEINS ACTIVATE ENZYMES
ALPHA 2 RECEPTORS
• LESS COMMON THAN ALPHA 1
• ACTIVATES INHIBITORY G PROTEINS
• REDUCE THE FORMATION OF cyclic AMP
BETA 1 RECEPTORS
• HEART AND KIDNEYS
• ACTIVATES G PROTEINS
• STIMULATES PRODUCTION OF cyclic AMP
BETA 2 RECEPTOR
• MOST COMMON BETA RECEPTOR
• ACTIVATES STIMULATORY G PROTEINS
IMPORTANCE OF DIFFERENT RECEPTORS
• AT LEAST PARTIALLY RESPONSIBLE FOR DIFFENCE IN ACTIVITY OF EPINEPHRINE AND NOREPINEPHRINE
FUNCTIONS OF THE AUTONOMIC NERVOUS SYSTEM
• DUAL INNERVATION
• FREQUENTLY (BUT NOT ALWAYS) HAVE OPPOSITE ACTIONS
• MOSTS ORGANS ARE PREDOMINANTLY CONTROLLED BY ONE DIVISION OR THE OTHER
PARASYMPATHETIC
• HOUSEKEEPING FUNCTIONS
• MAINTAINING BODY FUNCTIONS UNDER CALM CONDITIONS
• INDIVIDUAL ACTIVATION OF INDIVIDUAL ORGANS
SYMPATHETIC
• FIGHT OR FLIGHT
• HANDLES EMERGENCIES
• WIDESPREAD ACTIVATION
EXAMPLES OF ORGANS INNERVATED BY ANS
• HEART• BRONCHIOLES• BRONCHIAL GLANDS• IRIS OF EYE• CILIARY MUSCLE• SWEAT GLANDS• URINARY BLADDER• BLOOD VESSELS
HEART
• SYMPATHETIC• INCREASE RATE
OF CONTRACTION
• PARASYMPATHETIC• DECREASE RATE OF
CONTRACTION
BRONCHIOLES
• SYMPATHETIC• DILATION
• PARASYMPATHETIC• CONSTRICTION
BRONCHIAL GLANDS
• SYMPATHETIC• POSSIBLE
INHIBITION OF SECERETION
• PARASYMPATHETIC• STIMULATION OF
SECRETION
IRIS OF EYE
• SYMPATHETIC • DILATION OF
PUPIL • CONTRACTION OF
RADIAL MUSCLES
• PARASYMPATHETIC• CONSTRICTION OF
PUPIL• CONTRACTION OF
CIRCULAR MUSCLES
CILIARY MUSCLE
• SYMPATHETIC• SLIGHT
RELAXATION
• PARASYMPATHETIC• CONTRACTION• ACCOMODATES FOR
NEAR VISION
URINARY BLADDER
• SYMPATHETIC• RELAXATION
• PARASYMPATHETIC• CONTRACTION
BLOOD VESSELS
• SYMPATHETIC• CONSTRICTION • SKIN• SALIVARY GLANDS• ABDOMINAL
VISCERA• EXTERNAL
GENITALIA
• PARASYMPATHETIC• EXTERNAL
GENITALIA
ADRENAL MEDULLA
• SYMPATHETIC• STIMULATION OF
SECRETION
• PARASYMPATHETIC• NO EFFECT
LIVER
• SYMPATHETIC• INCREASED
RELEASE OF GLUCOSE
• PARASYMPATHETIC• NO EFFECT
SWEAT GLANDS
• SYMPATHETIC• STIMULATION OF
SECRETION
• PARASYMPATHETIC• NO EFFECT
THE AUTONOMIC NERVOUS SYSTEM AND SENSORY INPUTS
• ACTIVITIES OF ANS ARE MOTOR ONLY
• NEED INPUT FROM SENSORY SYSTEM
• TO MONITOR BODY FUNCTIONS AS A WHOLE AND INDIVIDUAL ORGANS
• ENTEROCEPTIVE RECEPTORS
• BELOW CONSCIOUS LEVEL
CONTROL OF THE AUTONOMIC NERVOUS
SYSTEM
• GENERALLY BELOW OUR CONSCIOUS CONTROL
• UNDER CERTAIN CIRCUMSTANCES VOLUNTARY CONTROL IS POSSIBLE– DUE TO CONNECTIONS BETWEEN ANS AND CNS– PRIMARILY IN BRAIN STEM AND SPINAL CORD
BIOFEEDBACK MECHANISMS
• EXERCISES MODIFY BODY FUNCTIONS
• VISUALIZATION
• RECITATION
MEDITATION AND THE ANS
• YOGA
• MEDITATION
• BREATHING THERAPY
• INHIBITS SYMPATHETIC NERVOUS SYSTEM
DRUGS AND THE ANS
• MEDICINAL
• SUBSTANCE ABUSE
MEDICINAL DRUGS
• SYMPATHOMIMETIC
• SYMPATHOLYTIC
• PARA
SYMPATHOMIMETIC DRUGS
• ANDRENERGIC DRUGS THAT STIMULATE SYMPATHETIC NERVOUS SYSTEM
• EITHER NATURAL OR MAN MADE• EPINEPRINE• EPINEPHRINE• ISOPROTERENOL• DOPAMINE• EPHEDRINE• TERBUTALINE• PHENYLEPHRINE
EPINEPHRINE
• ALPHA AND BETA RECEPTORS
• ANAPHYLACTIC SHOCK
• ASTHMA
• BRONCHOSPASM
NOREPINEPHRINE
• ALPHA AND BETA RECEPTORS
• ELEVATE BLOOD PRESSURE IN HYPOTENSION
• ADMINISTERED INTROVENOUSLY
• LIMITED USES DUE TO SIDE EFFECTS
ISOPROTERENOL
• LIMITED USE DUE TO POOR ABSORPTION IN GI TRACT
• ADMINISTERED SUBLINGUALLY OR AS NASAL SPRAY FOR SOME CARDIAC ARRYTHMIAS
DOPAMIME
• PRECURSOR FOR NOREPINEPHRINE• LOW DOSAGES ACTIVATES BETA
RECEPTORS• HIGHER DOSAGES ACTIVATES
ALPHA RECEPTORS• USED FOR HYPOTENSION AND
RESISTANT CONGESTIVE HEART FAILURE
EPHEDRINE, TERBUTALINE, AND PHENYLEPHRINE
• EPHEDRINE– SIMILAR TO EPINEPHRINE– SLOWER TO BEGIN WORKING– LAST LONGER
• TERBUTALINE– BETA RECEPTOR– LITTLE CARDIAC STIMULATION
• PHENYLEPHRINE– CAUSES NASAL CONSTRICTION– USED IN COLD MEDICATIONS
SYMPATHOLYTIC
• ANDRENERGIC BLOCKING DRUGS
• REDUCE OR BLOCK EFFECTS OF SYMPATHETIC NERVOUS SYSTEM
• ALPHA BLOCKING AGENTS
• BETA BLOCKING AGENTS
ALPHA BLOCKING AGENTS
• LIMITED USES MEDICALLY– RAYNAUD’S DISEASE– AFTER FROSTBITE– ATERIOSCLEROSIS OBLITERANS
• VASODILATOR
• TALOZOLINE
• PHENTOLAMINE
BETA BLOCKING AGENT
• PRODUCES EFFECTS IN CARDIOVASCULAR SYSTEM
• REDUCE HEART RATE• REDUCE MYOCARDIAL CONTRACTION• REDUCED STROKE VOLUME• REDUCES CARDIAC OUTPUT AND OXYGEN
CONSUMPTION• LOWERS BLOOD PRESSURE OVER LONG
HAUL• PROPANOLOL
PARASYMPATHOMIMETIC
• CHOLINERGIC DRUGS
• VASODILATES PERIPHERAL BLOOD VESSELS
• CHOINE ESTERS
• CHOLINERGIC ALKALOIDS
• ANTICHOLINESTERASES
CHOLINE ESTERS
• BETHANECHOL
• INCREASES MOTILITY OF BOWEL AND BLADDER
CHOLINERGIC ESTERS
• PILOCARPINE
• CONSTRICTS PUPIL IN TREATMENT OF GLAUCOMA
ANTICHOLINESTERASES
• PHYSOSTIGIMINE– REVERSES EFFECTS OF ATROPINE
POISONING
• EDROPHONIUM CHLORIDE– MYASTHENIA GRAVIS DIAGNOSIS
• BLOCK ENZYME
• PROLONG ACTION OF AC h
PARASYMPATHOLYTIC DRUGS
• ATROPINE– PLANT ALKALOID (NIGHTSHADE)
– PUPIL DILATION
– FAST HEART RATE
– REDUCES SECRETION OF EXOCRINE GLANDS
– RELAXES SMOOTH MUSCLE
• ANTICHOLINERGIC• OPPOSES ACTION OF ACETYLCHOLINE