Rev. 6/15/07 BSC 1085
Dr. Vince Scialli
NERVOUS SYSTEM
LEVEL OF ORGANIZATION
LECTURE 3
“ANS”
AUTONOMIC NERVOUS SYSTEM ~ ANS
Nothing to do with conscious thoughts ~ TOTAL SUBCONSCIOUS
VITAL for survival
Physiological processes continue without conscious thought
Can survive for decades (coma) without conscious
thought as long as ANS is functioning & nurtured
ANS ~ Coordinates & Adjusts ~ 24 / 7
Cardiovascular
Respiratory
SYMPATHETIC DIVISION
Digestive
PARASYMPATHETIC DIVISION
Urinary & Renal
Reproductive
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We’ve prolonged life . . .
Learned to manipulate the ANS with drugs & procedures
EG: Heart Attack Survivability today
Blood Pressure Control
Diabetes Control
Coma victims can live for years
AUTONOMIC NERVOUS SYSTEM ~ Overview
CNS ~ Brain & Spinal Cord
PNS ~ Peripheral Nervous System ~ everything NOT CNS
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Ascending Pathways ~ “Sensory” Division ~ “Afferents”
Somatic Sensory ~ info from . . . skin & skeletal muscle
Exteroceptors ~ conscious to sensory cortex
Proprioceptors ~ subconscious to cerebellum
Visceral Sensory ~ info from . . . visceral organs
Enteroceptors ~ subconscious to brain stem
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Descending Pathways ~ “Motor” Division ~ “Efferents”
Somatic Motor ~ commands to . . . skeletal muscle
From Motor Cortex ~ voluntary & conscious
From Basal Nuclei & Cerebellum ~ subconscious
From Mesencephalon ~ bright light & loud sound
Autonomic Nervous System or “Visceral” Motor
From Brain to . . . organs, glands, smooth
& cardiac muscle
Sympathetic Division ~ EMERGENCY
Parasympathetic Division ~ NON EMERGENCY
Autonomic Nervous System Structures ~ Visceral Motor Only
Carries efferent motor commands ~ from brain to visceral organs
Controls: Organs . . . glands . . . smooth & cardiac muscle
Commands originate in HYPOTHALAMUS
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AUTONOMIC NUCLEI ~ brain stem & ventral spinal cord
Grey matter nuclei in CNS only . . . RELAY switching stations
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AUTONOMIC GANGLIA ~ grey matter nuclei ~ in PNS ONLY
Final RELAY switching stations
Route efferent commands to specific visceral organs
Also called “peripheral ganglia” . . . not called nuclei in PNS
Sympathetic Ganglia . . . serve sympathetic NS
Parasympathetic Ganglia . . . serve parasympathetic NS
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VISCERAL MOTOR NEURONS ~ in CNS & PNS . . carry commands
Connects CNS w/ PNS in autonomic ganglia
Connect autonomic ganglia w/ visceral effector organs
1st Order Neurons . . . “visceral motor neurons” from
hypothalamus
2nd Order Neurons . . . “pre-ganglionic” neurons
3rd Order Neurons . . . “post-ganglionic” neurons
Visceral Motor Neurons (ANS ONLY)
1st Order Neurons ~ “Visceral Motor Neurons”
Hypothalamus (Brain) to autonomic nuclei in brain stem
Hypothalamus (Brain) to autonomic nuclei in spinal cord
Release Neurotransmitter: ACH only
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2nd Order Neurons ~ “Pre-ganglionic Neurons”
Autonomic nuclei in brain to autonomic ganglia
Via cranial nerves ~ head & throat area
Autonomic nuclei in spinal cord to autonomic ganglia
Via spinal nerves ~ rest of body
Release Neurotransmitter: ACH only
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3rd Order Neurons ~ “Post-ganglionic Neurons”
Also called ~ “Ganglionic Neurons”
Connect autonomic ganglia to “effectors” or organs
Release ~ several neurotransmitters . . . main difference
Control specific visceral organ response
Parasympathetic Division: ACH only
Sympathetic Division: Several Neurotransmitters
Adrenalin (Epinephrine & Nor-epinephrine)
ACH & NITRIC OXIDE
Autonomic Nervous System Divisions . . . 3 Divisions
Enteric Division ~ Autoregulation . . . Self Regulation
Intrinsic Division ~ no other part of NS required
Nerves located in walls of GI Tract ~ self regulate organs
Controls digestive reflex activities ~ independent of CNS
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Sympathetic & Parasympathetic Division’s
Both Sympathetic & Parasympathetic Divisions innervate the same organs for the most part with opposite effects. . .
Divisions ~ have opposing effects . . . but work in tandum
In normal situations . . . single target organs affected separately
Parasympathetic & Sympathetic Div. balance each other
Balance between Sympathetic & Parasympathetic Activation
Maintains constant homeostasis throughout the day
In crisis . . . Sympathetic Division Dominates . . . due to Adrenalin
ALL ORGANS RESPOND AT SAME TIME
Parasympathetic Division goes into hibernation
Responses due to difference in neurotransmitters
Sympathetic Parasympathetic
Epinephrine
Norephinephrine ACH only
ACH & Nitric Oxide
Sympathetic Division ~ stimulatory/excitement ~ emergency
Sympathetic Activation ~ “fight or flight” division
“All or none response” . . . all organs involved
Increased alertness ~ “Feeling on Edge”
Exertion, stressed, excitement, anxiety, nervous
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“Catabolic Division”
Energy utilization . . . breakdown of glucose
Breakdowns glycogen to glucose for ATP production
Consumes O2 to make ATP
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“Thoracolumbar Division”
Spinal nerves come off T1-L2
Pre-ganglionic Neurons ~ very short close to spinal cord
Secrete: ACH only
Post-ganglionic Neurons ~ very long
Secrete: Epinephrine
Nor-ephinephrine
ACH
Nitric Oxide
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Controlled By: Sympathetic Centers in Hypothalamus
& Reflex Centers in Brain Stem
Parasympathetic Division ~ inhibitory/rest ~ Non-emergency
Parasympathetic Activation ~ “rest & relax division”
ONLY SINGLE target organs involved ~ NO all or none
Feeling relaxed, sleepy, calm, non-stressed
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“Anabolic Division”
Energy conservation . . . glucose converted to glycogen
Stores glycogen for “future” ATP production
Preserves O2 . . . ATP not required
Stimulates visceral organ activity
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Craniosacral Division”
Innervated by cranial nerves & sacral spinal nerves
Pre-ganglionic Neurons ~ very long & synapse close to
or within target organs
Secrete: ACH ONLY
Post-ganglionic Neurons ~ very short
Secrete: ACH ONLY
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Controlled By: Parasympathetic Centers in Hypothalamus
& Reflex Centers in Brain Stem
Effects of Sympathetic & Parasympathetic Activation (PG 579) KNOW
Sympathomimetic Parasympathomimetic
Alert/On Edge Relaxed/Sleepy
Dilates Pupils Constricts Pupils
Bronchial Dilation Bronchial Constriction
Increase heart rate Slows heart rate
Increase BP Decrease BP
Decreases Saliva ~ dry Increases Saliva ~ watery
Decreases Digestion Increases Digestion
Decreased GI Motility Increased Digestive Motility
Energy Usage ~ catabolic Energy Storage ~ anabolic
Increased Metabolic Rate Decreased Metabolic Rate
Increased Temperature Lower Temperature
Sweating No effect on sweat glands
Constricts sphincters Dilates sphincters
No urination/defecation Urination/Defecation
Ejaculation/Orgasm Erection/Arousal/Glands
No Vessel Effects
Vasodilation/Vasoconstriction
Visceral Vasodilation ~ Due to ACH & Nitric Oxide
increases blood flow to brain & skeletal muscles
Peripheral Vasoconstriction ~ Due to Epinephrine & NE
decreases blood flow to skin
Sympathetic Division Structure ~ Thoraco-lumbar Division
Pre-ganglionic neurons ~ come off spinal cord at T1 - L2
Secrete: ACH only
Post-ganglionic neurons ~ off sympathetic ganglia near cord
Secrete: NE E ACH NO
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3 Sympathetic Ganglia ~ Come off T1 – L2
Chain Ganglia . . . Collateral Ganglia . . . Adrenal Ganglia
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Chain Ganglia ~ “Para-vertebral Ganglia” ~ 22-26 TOTAL
Paired, lateral on both sides, & close to spinal cord,
Form Spinal & Sympathetic Nerves
Spinal Nerves
® eyes ~ dilate pupils (more light let in)
® salivary glands ~ inhibit salivation (dry mouth)
® body wall, skin, blood vessels, sweat glands, &
arector pili muscles
Sympathetic Nerves
® heart (↑ HR & blood pressure when excited)
® lungs (dilates bronchioles & airways) ~more air
3 Collateral Ganglia ~ “pre-vertebral ganglia”
Form Splanchnic Nerves
To specific organs in abdominal & pelvic cavity
Gastric nerve ® Stomach
Hepatic nerve ® Liver
Splenic nerve ® Spleen
Mesenteric nerves ® Intestines
Sympathetic Activation INHIBITS activity of these Organs
Celiac Ganglia INHIBITS ® stomach
DIGESTION liver
gall bladder pancreas
spleen
Superior INHIBITS ® small Mesenteric DIGESTION intestines
Ganglia
Inferior STIMULATES ® kidneys
Mesenteric
Ganglia FILLS ® bladder
Sex Arousal & ® sex organs
Secretions
INHIBITS ® large intestine
DIGESTION & rectum
Sympathetic Ganglia
Adrenal Medulla Ganglia MOST IMPORTANT
Adrenal Glands
Paired Glands ~ one on top of each kidney
Adrenal Medulla ~ center of adrenal gland
Pre-ganglionic neurons come off spinal cord & go directly to specialized “neuro-endocrine” cells in adrenal medulla
Neuroendocrine cells ~ specialized cells in adrenal medulla
Secretes “ADRENALIN” into blood stream
ADRENALIN ~ “sympathetic” neurotransmitters released
from Adrenal medulla
Epinephrine ~ 85% of adrenaline secretion
Norepinephrine ~ 15% of adrenaline secretion
Effects due to release of adrenaline into blood stream
Longer lasting that nerve impulses ~ circulation
Effects are NOT single or specific organ targeted
MANY organs of body affected at ONCE
“generalized all or none” response
Parasympathetic Division Structure ~ Craniosacral Division
Neurons come off brain stem & sacral spinal cord
Long Pre-ganglionic Neurons
BOTH SECRETE ACH ONLY
Short Post-ganglionic Neurons
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Pre-ganglionic neurons ~ VERY LONG
Neurons leave brain stem autonomic nuclei as Cranial N.
III Oculomotor Nerve ~ To eye muscles (constricts pupil)
VII Facial Nerve ~ To tear ducts, salivary glands (increase)
IX Glossopharyngeal Nerve ~ To salivary glands (watery)
X VAGUS NERVE ~ To thoracic & abdominal organs
Neurons leave autonomic nuclei in spinal cord ~ S2 – S4
Form “Pelvic Nerves” at S2 – S4
Pelvic Nerves join with Vagus Nerve
Innervate: Kidney, Bladder, Sex Organs,
Parts of Large Intestine (rectum)
Parasympathetic Ganglia ~ “Peripheral ganglia”
Located near target or within specific target orgas
Terminal Ganglia ~ located near target organs
Intramural Ganglia ~ located within target organs
NERVOUS SYSTEM
LEVEL OF ORGANIZATION
LECTURE 4
“ANS”
Autonomic Nervous System ~ Target Organs
Sympathetic Division ~ usually generalized body response
Generalized “all or none response” due to EPINEPHRINE
release in to blood circulation from Adrenal Medulla
Some single organ responses ~ due to NOREPINEPHRINE
Pupils dilate when entering dark room ~ specific
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