biology 141 the autonomic nervous system chapter 15
TRANSCRIPT
Biology 141Biology 141
The Autonomic Nervous The Autonomic Nervous SystemSystem
Chapter 15Chapter 15
OverviewOverview
The The CNSCNS spinal cordspinal cord brainbrain
The The peripheral nervous peripheral nervous systemsystem sensory-somatic nervous sensory-somatic nervous
systemsystem Responds to the external Responds to the external
environmentenvironment 12 pairs of 12 pairs of cranial nervescranial nerves
and and 31 pairs of 31 pairs of spinal nervesspinal nerves..
autonomic nervous autonomic nervous systemsystem
Responds to the internal Responds to the internal environmentenvironment
Parasympathetic nervous Parasympathetic nervous systemsystem
Sympathetic nervous Sympathetic nervous systemsystem
Divisions of the Nervous Divisions of the Nervous SystemSystem
ANSANS
Function:Function: operates without conscious control.operates without conscious control.
Regulation:Regulation: Control:Control:
hypothalamus and brain stem. hypothalamus and brain stem. receives input from limbic system and other receives input from limbic system and other
regions of the cerebrumregions of the cerebrum
Regulate activity of Regulate activity of smooth muscle, cardiac muscle & certain glandssmooth muscle, cardiac muscle & certain glands
ANSANS
Sensory receptors associated with Sensory receptors associated with interoceptors (receptors that monitor interoceptors (receptors that monitor internal environments)internal environments)
Located in blood vessels, viscera, smooth Located in blood vessels, viscera, smooth musclemuscle
ChemoreceptorsChemoreceptors Baroreceptors monitor BPBaroreceptors monitor BP
Internal pain - anginaInternal pain - angina MechanoreceptorsMechanoreceptors
Monitor vessel stretchMonitor vessel stretch
ComparisonComparisonSOMATIC vs. ANSSOMATIC vs. ANS
SSomatic omatic contains both contains both
sensory and motor sensory and motor neurons.neurons.
input from the input from the special and somatic special and somatic senses.senses.
sensations are sensations are consciously consciously perceived.perceived.
innervate skeletal innervate skeletal muscle to produce muscle to produce conscious, conscious, voluntary voluntary movements.movements.
effect of a motor effect of a motor neuron is always neuron is always excitation.excitation.
ComparisonComparisonSOMATIC vs. ANSSOMATIC vs. ANS
ANSANS contains both contains both
sensory and motor sensory and motor neurons.neurons.
Input from Input from interoceptors.interoceptors.
input not consciously input not consciously perceived.perceived.
may receive input may receive input from somatic senses from somatic senses and special sensory and special sensory neurons.neurons.
regulate visceral regulate visceral activities activities
Effect: exciting or Effect: exciting or inhibiting activities inhibiting activities of cardiac muscle, of cardiac muscle, smooth muscle, and smooth muscle, and glands.glands.
ComparisonComparisonSOMATIC vs. ANSSOMATIC vs. ANS
Somatic motor Somatic motor pathways pathways consist of a consist of a singlesingle motor motor neuronneuron
Autonomic motor Autonomic motor pathways pathways consists of consists of twotwo motor neurons in motor neurons in series series
Motor Neurons in SeriesMotor Neurons in Series
first autonomicfirst autonomic cell body in the CNS cell body in the CNS myelinated axon extends to an autonomic myelinated axon extends to an autonomic
ganglion or adrenal medullae ganglion or adrenal medullae second autonomicsecond autonomic
cell body in an autonomic ganglioncell body in an autonomic ganglion nonmyelinated axon extends to an effector.nonmyelinated axon extends to an effector.
Somatic has 1 motor neuronSomatic has 1 motor neuron
ANS has 2 motor neurons in seriesANS has 2 motor neurons in series
First motor neuron: First motor neuron: preganglionicpreganglionic
Preganglionic neuronPreganglionic neuron cell body in brain or spinal cord cell body in brain or spinal cord axon is myelinatedaxon is myelinated extends to autonomic ganglionextends to autonomic ganglion
Second motor neuron: Second motor neuron: postganglionicpostganglionic
Postganglionic neuronPostganglionic neuron cell body lies outside the CNS in an autonomic cell body lies outside the CNS in an autonomic
ganglionganglion axon is unmyelinated fiber that terminates in axon is unmyelinated fiber that terminates in
a visceral effectora visceral effector
First Neuron terminates in a First Neuron terminates in a ganglion or adrenal medullaganglion or adrenal medulla
Can use either NE or ACh as the neurotransmitterCan use either NE or ACh as the neurotransmitter
ANS Efferent BranchesANS Efferent Branches
The output (efferent) part of the ANS The output (efferent) part of the ANS is divided into two principal parts: is divided into two principal parts: the the sympathetic divisionsympathetic division the the parasympathetic divisionparasympathetic division
Organs that receive impulses from both Organs that receive impulses from both sympathetic and parasympathetic fibers sympathetic and parasympathetic fibers are said to have are said to have dual innervation.dual innervation.
Parasympathetic and Parasympathetic and SympatheticSympathetic
ParasympathetParasympatheticic
SympatheticSympathetic
Dual innervationDual innervation
Dual innervationDual innervation one speeds up one speeds up
organorgan one slows down one slows down
organorgan Sympathetic NS Sympathetic NS
increases heart increases heart raterate
Parasympathetic Parasympathetic NS decreases NS decreases heart rateheart rate
Anatomy of Autonomic Motor Anatomy of Autonomic Motor PathwaysPathways
ComponentsComponents Preganglionic neuronPreganglionic neuron
SympatheticSympathetic ParasympatheticParasympathetic
Autonomic gangliaAutonomic ganglia Postganglionic neuronPostganglionic neuron Autonomic PlexusAutonomic Plexus
Preganglionic NeuronsPreganglionic Neurons
SympatheticSympathetic Also called Also called
thoracolumbar divisionthoracolumbar division Cell bodies in the lateral Cell bodies in the lateral
horns of the gray horns of the gray matter in segments T1-matter in segments T1-T12 and L1-L2T12 and L1-L2
Axons are called the Axons are called the thoracolumbar outflowthoracolumbar outflow
ParasympatheticParasympathetic Also called Also called
craniosacral divisioncraniosacral division Cell bodies in the brain Cell bodies in the brain
stemstem cranial nerve nuclei III, cranial nerve nuclei III,
VII, IX, and XVII, IX, and X Cell bodies in the lateral Cell bodies in the lateral
gray horns of segments gray horns of segments S2-S4S2-S4
Axons are called Axons are called craniosacral outflowcraniosacral outflow
Autonomic GangliaAutonomic Ganglia
SympatheticSympathetic 2 groups2 groups
Sympathetic trunk ganglia Sympathetic trunk ganglia (Vertebral chain ganglia)(Vertebral chain ganglia)
lie in a vertical row on either lie in a vertical row on either side of the vertebral columnside of the vertebral column
Innervate above the Innervate above the diaphragmdiaphragm
Prevertebral ganglia Prevertebral ganglia (collateral)(collateral)
Anterior to vertebral column Anterior to vertebral column close to large arteriesclose to large arteries
Innervate below the Innervate below the diaphragmdiaphragm
Autonomic GangliaAutonomic Ganglia
ParasympatheticParasympathetic 1 group: terminal ganglia1 group: terminal ganglia
Located near or in visceraLocated near or in viscera
Postganglionic NeuronsPostganglionic Neurons
postganglionic postganglionic neuron can be neuron can be branched to branched to receive signals receive signals from multiple from multiple ganglionic ganglionic locations.locations.
Autonomic Plexuses: Autonomic Plexuses: Tangled neural networks that lie along major Tangled neural networks that lie along major
arteries.arteries. Major autonomic Major autonomic
plexusesplexuses Cardiac: supplies the Cardiac: supplies the
heart, heart, Pulmonary: supplies Pulmonary: supplies
the lung, the lung, Celiac (solar): liver, Celiac (solar): liver,
gallbladder, stomach, gallbladder, stomach, pancreas, spleen, pancreas, spleen, kidney, reproductive kidney, reproductive organs organs
Major autonomic Major autonomic plexuses plexuses superior mesenteric: superior mesenteric:
small and large intestines small and large intestines inferior mesenteric: large inferior mesenteric: large
intestines intestines Renal: kidneys and Renal: kidneys and
ureters ureters Hypogastric: pelvic Hypogastric: pelvic
visceraviscera
Structure of the Sympathetic Structure of the Sympathetic DivisionDivision
Preganglionic – Preganglionic – leave spinal cord leave spinal cord through ventral through ventral rootroot
Enter the ganglion Enter the ganglion via the white via the white ramusramus
Synapse with Synapse with postganglionicpostganglionic
Leave via gray Leave via gray ramusramus
Terminates on Terminates on visceral effectorsvisceral effectors
3 Pathways of Sympathetic Fibers3 Pathways of Sympathetic Fibers
Spinal nerve routeSpinal nerve route out same levelout same level
Sympathetic chain Sympathetic chain routeroute up chain & out up chain & out
spinal nervespinal nerve Collateral ganglion Collateral ganglion
routeroute out splanchnic out splanchnic
nerve to collateral nerve to collateral ganglionganglion
Divergence of Sympathetic NeuronsDivergence of Sympathetic Neurons
Divergence: Divergence: 1 preganglionic cell synapses on 1 preganglionic cell synapses on
many postganglionic cellsmany postganglionic cells
Mass activation due to Mass activation due to divergencedivergence multiple target organsmultiple target organs fight or flight response explainedfight or flight response explained
Adrenal glandAdrenal gland modified cluster of postganglionic modified cluster of postganglionic
cell bodies that release epinephrine cell bodies that release epinephrine & norepinephrine into blood& norepinephrine into blood
Horner’s SyndromeHorner’s Syndrome
Sympathetic innervation to one side Sympathetic innervation to one side of the face is lost (mutation, injury, of the face is lost (mutation, injury, or disease).or disease). Affects outflowAffects outflow
Drooping of eyelidDrooping of eyelid Constricted pupilConstricted pupil Lack of sweating Lack of sweating
Structure of the Structure of the parasympathetic divisionparasympathetic division
PreganglionicPreganglionic CranialCranial
As part of a cranial As part of a cranial nervenerve
SacralSacral From ventral root of From ventral root of
spinal nervespinal nerve Terminal gangliaTerminal ganglia
In the walls of visceraIn the walls of viscera PostganglionicPostganglionic
Innervate smooth Innervate smooth muscle and glands of muscle and glands of the visceral wallsthe visceral walls
Parasympathetic Cranial NervesParasympathetic Cranial Nerves
Oculomotor nerveOculomotor nerve ciliary ganglion in orbitciliary ganglion in orbit irisiris
Facial nerveFacial nerve pterygopalatine and submandibular pterygopalatine and submandibular
ganglionsganglions supply tears, salivary & nasal secretionssupply tears, salivary & nasal secretions
GlossopharyngealGlossopharyngeal otic ganglion supplies parotid salivary glandotic ganglion supplies parotid salivary gland
Vagus nerveVagus nerve supply heart, pulmonary and GI tract as far supply heart, pulmonary and GI tract as far
as the midpoint of the colonas the midpoint of the colon
Parasympathetic Sacral NerveParasympathetic Sacral Nerve
Form pelvic Form pelvic splanchnic splanchnic nerves nerves
ANS NeurotransmittersANS Neurotransmitters Classified as either cholinergic or Classified as either cholinergic or
adrenergic neurons based upon the adrenergic neurons based upon the neurotransmitter releasedneurotransmitter released
AdrenergicAdrenergic
CholinergicCholinergic
ANS NEUROTRANSMITTERSANS NEUROTRANSMITTERS
CholinergicCholinergic Produce and release acetylcholine (ACh)Produce and release acetylcholine (ACh)
All sympathetic and parasympathetic All sympathetic and parasympathetic preganglionicpreganglionic
All parasympathetic postganglionicAll parasympathetic postganglionic Only sweat gland sympathetic postganglionicOnly sweat gland sympathetic postganglionic
AdrenergicAdrenergic Produce and release norepinephrin (NE)Produce and release norepinephrin (NE)
Most sympathetic postganglionic Most sympathetic postganglionic neurons(noradrenalin)neurons(noradrenalin)
Cholinergic Neurons Cholinergic Neurons
Excitation or inhibition depending upon Excitation or inhibition depending upon receptor subtype and organ involved.receptor subtype and organ involved.
Cholinergic ReceptorsCholinergic Receptors Cholinergic receptors Cholinergic receptors
integral membrane proteins in the postsynaptic plasma integral membrane proteins in the postsynaptic plasma membrane. 2 types: membrane. 2 types: Nicotinic and muscarinicNicotinic and muscarinic
Activation of Activation of muscarinic receptors muscarinic receptors
excitation or inhibition excitation or inhibition Muscarinic receptors Muscarinic receptors
are found on plasma are found on plasma membranes of all membranes of all parasympathetic parasympathetic effectorseffectors
(viscera, smooth (viscera, smooth muscle)muscle)
Activation of Activation of nicotinic receptors nicotinic receptors
excitation excitation Nicotinic receptors Nicotinic receptors
are found on are found on postsynaptic cells of postsynaptic cells of ANS cells and at NMJANS cells and at NMJ
Adrenergic Neurons Adrenergic Neurons Adrenergic neurons release norepinephrine (NE) )Adrenergic neurons release norepinephrine (NE) )
from postganglionicfrom postganglionicsympathetic neurons onlysympathetic neurons only
Excites or inhibits organsExcites or inhibits organs NE lingers at the synapse until enzymatically inactivatedNE lingers at the synapse until enzymatically inactivated Effects triggered by adrenergic neurons typically are longer Effects triggered by adrenergic neurons typically are longer
lasting than those triggered by cholinergic neurons.lasting than those triggered by cholinergic neurons.
Physiological Effects of the Physiological Effects of the ANSANS
Autonomic ToneAutonomic Tone balance between sympathetic and parasympathetic balance between sympathetic and parasympathetic
activityactivity regulated by the hypothalamusregulated by the hypothalamus
Sympathetic ResponseSympathetic Response Supports rigorous functions and rapid ATP productionSupports rigorous functions and rapid ATP production Fight or flight responseFight or flight response
Parasympathetic ResponseParasympathetic Response Enhances rest and digestive functions, storage of ATPEnhances rest and digestive functions, storage of ATP
Fight or FlightFight or Flight
Alarm reaction Alarm reaction dilation of pupilsdilation of pupils IncreaseIncrease
heart rateheart rate respirationsrespirations BPBP Blood flow to skeletal musclesBlood flow to skeletal muscles Blood sugarBlood sugar
decrease in blood flow to nonessential organsdecrease in blood flow to nonessential organs Long lasting Long lasting
lingering NE in synaptic gaplingering NE in synaptic gap
PathwayPathway Autonomic ReflexesAutonomic Reflexes
ReceptorReceptor Responds to stimuliResponds to stimuli Transduce stimuli to action potentialTransduce stimuli to action potential
Sensory neuronSensory neuron Action potential travels to CNSAction potential travels to CNS
Integrating center (CNS)Integrating center (CNS) Interneurons relay sensory info to motor neuronsInterneurons relay sensory info to motor neurons
HypothalamusHypothalamus Brain stemBrain stem Spinal cordSpinal cord
2 Motor neurons (pre and post ganglionic)2 Motor neurons (pre and post ganglionic) Carries action potential from the CNS to an effector Carries action potential from the CNS to an effector
EffectorEffector Smooth or cardiac muscle, glandsSmooth or cardiac muscle, glands
Autonomic Control by Higher Autonomic Control by Higher CentersCenters
Major control and integration center: hypothalamusMajor control and integration center: hypothalamus
Output toOutput to Brain stemBrain stem
HeartHeart Blood vesselsBlood vessels Salivary glandsSalivary glands swallowingswallowing
Spinal cordSpinal cord IntestinesIntestines bladderbladder
Receives input Receives input fromfrom VisceraViscera OlfactionOlfaction GustationGustation Changes in tempChanges in temp OsmolarityOsmolarity Blood chemistry Blood chemistry
levelslevels Limbic systemLimbic system
DISORDERSDISORDERS
Raynaud’s phenomenonRaynaud’s phenomenon excessive sympathetic stimulation of excessive sympathetic stimulation of
smooth muscle in the arterioles of the smooth muscle in the arterioles of the digitsdigits
Result - vasoconstriction Result - vasoconstriction the digits (fingers and toes) become the digits (fingers and toes) become
ischemic (lack blood) after exposure to ischemic (lack blood) after exposure to cold or with emotional stress.cold or with emotional stress.
Digits may become necroticDigits may become necrotic
Autonomic DysreflexiaAutonomic Dysreflexia
Exaggerated response of sympathetic NS Exaggerated response of sympathetic NS in cases of spinal cord injury above T6in cases of spinal cord injury above T6 Sensory impulses from below the injury are unable to Sensory impulses from below the injury are unable to
ascend to the brainascend to the brain Causes mass stimulation of sympathetic nerves below Causes mass stimulation of sympathetic nerves below
the injurythe injury
ResultResult vasoconstriction which elevates blood pressurevasoconstriction which elevates blood pressure
parasympathetic NS tries to compensateparasympathetic NS tries to compensate slows heart rate, dilates blood vessels above the injuryslows heart rate, dilates blood vessels above the injury Produces a pounding headache, hypertension, flushed skin, Produces a pounding headache, hypertension, flushed skin,
profuse sweating above the injury and cool dry skin belowprofuse sweating above the injury and cool dry skin below can lead to seizure, stroke or heart attackcan lead to seizure, stroke or heart attack