powerpoint ® lecture slides prepared by betsy c. brantley valencia college c h a p t e r © 2013...

PowerPoint® Lecture Slidesprepared byBetsy C. BrantleyValencia College

C H A P T E R

© 2013 Pearson Education, Inc.

8

The Peripheral and Autonomic Nervous Systems


Chapter 8 Learning Outcomes

• Section 1: The Peripheral Nervous System

• 8.1 • Describe the major components of a spinal nerve, and discuss

dermatomes and shingles.• 8.2

• Name the 12 pairs of cranial nerves, give their primary functions, and identify their innervations.

• 8.3 • Define a nerve plexus and identify the four major plexuses and their

patterns of distribution.• 8.4

• Describe a sensory pathway and a motor pathway.• 8.5

• Define reflexes and describe the steps in a stretch reflex and withdrawal reflex.



• 8.6• CLINICAL MODULE Explain the value of reflex testing and how

higher centers control reflex responses.• 8.7

• CLINICAL MODULE Describe the roles of the nervous system in referred pain, Parkinson's disease, rabies, cerebral palsy, amyotrophic lateral sclerosis, Alzheimer's disease, and multiple sclerosis.



• Section 2: The Autonomic Nervous System

• 8.8• Describe the organization and functions of the sympathetic and

parasympathetic divisions of the autonomic nervous system.• 8.9

• Describe the innervation patterns of the sympathetic and parasympathetic divisions of the autonomic nervous system.

• 8.10• Describe the effects of sympathetic activation and

parasympathetic stimulation, and outline the anatomical and functional characteristics of each relative to neurotransmitter release.


The Peripheral Nervous System (Section 1)

• Central Nervous System

• Processes sensory information and responds

• Peripheral Nervous System (PNS)

• Network of peripheral nerves

• Structurally divided into:

• Cranial nerves – 12 pairs; connect directly to brain

• Spinal nerves – 31 pairs; connect directly to spinal cord


Peripheral nerves

Cranial nerves

Lumbar spinal nervesSacral spinal nerves

Coccygeal nerve

Cervical spinal nerves

Thoracic spinal nerves

Spinal nerves

Peripheral nervous system

Figure 8 Section 1


Spinal Nerve Structure (8.1)

• Each segment of spinal cord is connected to a pair of spinal nerves

• A series of connective tissue layers surrounds each nerve

• Epineurium

• Outermost covering

• Dense network collagen fibers

• Perineurium

• Divides nerve into bundles of axons, or fascicles

• Endoneurium

• Innermost layer

• Delicate connective tissue around individual axons


Spinal nerve structure

Blood vessels Fascicle Schwann cellMyelinatedaxon

Epineurium

Perineurium

Endoneurium

Connective TissueLayers of a Spinal Nerve

Figure 8.1 11


Spinal Nerve Rami (8.1)

• Each spinal nerve branches into:

• Rami (singular ramus)

• Dorsal ramus – innervates muscles, joints, skin of back

• Ventral ramus – innervates structures in lateral and

anterior trunk and limbs

• In thoracic and upper lumbar segment, carry motor

output of sympathetic division of autonomic nervous

system ("fight or flight" response)

© 2013 Pearson Education, Inc. Figure 8.1 22

Dorsal rootDorsal root

ganglion Dorsal ramus

Spinalnerve

Ventralroot

Ventral ramus

SympatheticganglionAutonomic

nerve

Spinal nerve branches


Spinal Nerve Patterns of Distribution (8.1)

• Dermatome

• Specific region of skin surface monitored by single pair of

spinal nerves

• Boundaries overlap to some degree

• C1 typically lacks sensory branch

• Face innervated by pair of cranial nerves

• Clinically important to diagnose specific location of spinal

nerve or spinal cord damage


Dermatomes

Figure 8.1 33

Anterior Posterior

C2

C3

C2–C3

C2–C3

C3

C4

C5C4

C5

T1T2

T2

T3T4T5T6T7T8T9T10T11T12T9

T12

T11

T10

T8

T7

T6

T5

T4

T3

T2

C5L1L2

L3L4

L5

T1C7

S4S3S2

L1 S5

C8

L5S1

S2L2

L3

L4

S1

L5

L5

L3

L2

L1

C6

C8

C7T1

T2


Shingles (8.1)

• Viral infection of dorsal root ganglia

• Caused by varicella-zoster virus

• Same herpes virus causes chickenpox

• Attacks neurons within dorsal roots of spinal

nerves and sensory ganglia of cranial nerves

• Produces painful rash and blisters on skin along

path of sensory nerve and associated dermatome


Shingles


Module 8.1 Review

a. Identify the three layers of connective tissue of a

spinal nerve and identify the major peripheral

branches of a spinal nerve.

b. Describe a dermatome.

c. Explain the etiology (cause) of shingles.


Cranial Nerves (8.2)

• 12 pairs of cranial nerves

• Classified as sensory, special sensory, motor, or

mixed

• Name relates to appearance or function

• Roman numeral corresponds to position on brain


Cranial nerves

Figure 8.2

Trochlear Nerve (IV)Optic Nerve (II)

Motor nerve to muscles of mastication

Trigeminal Nerve (V)

Motor nerveto facialmuscles

Facial Nerve (VII)

Sensory nerveto tongue and soft palate

VestibulocochlearNerve (VIII)

Cochlear branch

Vestibular branch

Sensory nerve toposterior tongue

Motor nerve topharyngeal muscles

GlossopharyngealNerve (IX)

Trigeminalnerve (V)

Facial nerve (VII)

Vestibulocochlearnerve (VIII)

Glossopharyngealnerve (X)

Vagusnerve (X)

Vagus Nerve (X)

Olfactory Nerve (I)

Olfactory bulb

Olfactory tract

Pituitary gland

Pons

Medullaoblongata

To tonguemuscles

To sternocleidomastoidand trapezius muscles

Sensory nervesMotor nerves

KEY

Oculomotor Nerve (III)

Abducens Nerve (VI)

Hypoglossal Nerve (XII) Accessory Nerve (XI)


Cranial Nerves I, II, III (8.2)

• Olfactory nerve (I)

• Function: special sensory

• Innervation: olfactory epithelium

• Optic nerve (II)


• Innervation: retina of eye

• Oculomotor nerve (III)

• Function: motor

• Innervation: extrinsic and intrinsic eye muscles and eyelid muscle

(levator palpebrae superioris)


Olfactory bulbOlfactory tract

Pons

KEYSensory nervesMotor nerves

Olfactory Nerve (I)

Pituitarygland

Medullaoblongata

Olfactory nerve


Cranial nerves going to and from the eye

Figure 8.2 11


KEY

Optic Nerve (II)

Oculomotor Nerve (III)

Trochlear Nerve (IV)

Abducens Nerve (VI)


Cranial Nerves IV, V, VI (8.2)

• Trochlear nerve (IV)

• Function: motor

• Innervation: superior oblique muscle

• Trigeminal nerve (V)

• Function: mixed

• Innervation: sensory – parts of face, lips, palate, tongue; motor –

muscles of mastication

• Abducens nerve (VI)

• Function: motor

• Innervation: lateral rectus muscle


Trigeminal nerve

Figure 8.2 11


Trigeminalnerve (V)

Motor nerve to muscles of mastication

KEY

Trigeminal Nerve (V)


Cranial Nerves VII, VIII, IX (8.2)

• Facial nerve (VII)

• Function: mixed

• Innervation: sensory – taste receptors anterior 2/3 tongue; motor –

muscles of facial expression, lacrimal gland, salivary glands

• Vestibulocochlear nerve (VIII)


• Innervation: cochlea (hearing), vestibule (motion and balance)

• Glossopharyngeal nerve (IX)

• Function: mixed

• Innervation: sensory – posterior 1/3 of tongue, pharynx, palate; motor –

pharyngeal muscles and parotid salivary gland



Facial nerve (VII)

Sensory nerve to tongue and

soft palate

Motor nerveto facialmuscles

KEY

Facial Nerve (VII)

Facial nerve


Vestibulocochlear nerve

Figure 8.2 11


KEYCochlear

branch

Vestibular branch

Vestibulocochlear Nerve (VIII)

Vestibulocochlear nerve (VIII)


Glossopharyngeal nerve


KEY

Sensory nerve toposterior tongue

Motor nerve topharyngeal muscles

Glossopharyngealnerve (X)

Glossopharyngeal Nerve (IX)


Cranial Nerves X, XI, XII (8.2)

• Vagus nerve (X)

• Function: mixed

• Innervation: sensory – pharynx, ear, diaphragm, visceral organs;

motor – palate and pharyngeal muscles; visceral organs

• Accessory nerve (XI)

• Function: motor

• Innervation: skeletal muscles of palate, pharynx, larynx,

sternocleidomastoid and trapezius muscles

• Hypoglossal nerve (XII)

• Function: motor

• Innervation: tongue muscles



KEY

Vagus Nerve (X)

Vagusnerve (X)

Vagus nerve



KEY

To sternocleidomastoidand trapezius muscles

Accessory Nerve (XI)

Figure 8.2 11

Accessory nerve



KEY

HypoglossalNerve (XII)

To tonguemuscles

Hypoglossal nerve

Figure 8.2 11


Module 8.2 Review

a. Identify the cranial nerves by name and number.

b. Which cranial nerves have motor functions only?

c. Which cranial nerves are mixed nerves?


Nerve Plexuses (8.3)

• Complex interwoven network of nerves

• Results from fusing small skeletal muscles (each with

separate ventral rami) into larger muscles during

development

• Four major plexuses

• Cervical

• Brachial

• Lumbar

• Sacral


Femoral nerveObturator nerve

Superior gluteal nerveInferior gluteal nerve

Pudendal nerveSaphenous nerveSciatic nerve

Median nerve

Ulnar nerve

Radial nerve

Thoracic nerves

Musculocutaneousnerve

Axillary nerve

Phrenic nerve

Sacral plexus

Lumbar plexus

Brachial plexus

Cervical plexusC1C2C3C4C5C6C7C8T1T2T3T4T5T6T7T8

T9

T10

T11T12

L1

L2

L3L4

L5S1

S2S3S4S5

Co1

Spinal nerve plexuses


Cervical Plexus (8.3)

• Ventral rami of spinal nerves C1–C5

• Innervates muscles of neck and into thoracic

cavity

• Phrenic nerve

• Provides nerve supply to diaphragm


Cervical plexus

Figure 8.3 22

Nerve Roots ofCervical Plexus

C1

C2

C3

C4

C5

Phrenic nerve


Brachial, Lumbar, and Sacral Plexuses (8.3)

• Brachial plexus

• Ventral rami of spinal nerves C5–T1

• Innervates pectoral girdle and upper limbs

• Lumbar plexus

• Arises from lumbar segments of spinal cord

• Innervates pelvic girdle and lower limbs

• Sacral plexus

• Arises from sacral segments of spinal cord

• Innervates pelvic girdle and lower limbs


Brachial plexus

Figure 8.3 33

Musculocutaneousnerve

Median nerveUlnar nerve

Radial nerve

Ulnar nerveMedian nerve


Lumbar and sacral plexuses

Figure 8.3 34

Lateral femoralcutaneous nerve

Femoral nerve

Obturator nerve

Superior gluteal nerve

Inferior gluteal nerve

Posterior femoralcutaneous nerve (cut)

Sciatic nerve

Saphenous nerve

Common fibular nerve

Superficial fibular nerve

Deep fibular nerve


Module 8.3 Review

a. Define nerve plexus and list the major plexuses.

b. Injury to which nerve plexus would interfere with

the ability to breathe?

c. List the major nerves of the brachial plexus.


Sensory Pathways (8.4)

• Posterior column pathway

• Carries fine touch, pressure, vibration, proprioception information

from peripheral receptors to primary sensory cortex in cerebrum

• First-order neurons

• Carry information from receptor to spinal cord (or brain stem)

• Second-order neurons

• Carry information from spinal cord (or brain stem) to thalamus;

cross over to other side of CNS

• Third-order neurons

• Carry information from thalamus to primary sensory cortex


Ventral nucleiin thalamus

Medullaoblongata

Spinalcord

Dorsal rootganglion

Third-orderneuronSecond-orderneuronFirst-orderneuronFine-touch, vibration,

pressure, andproprioception sensations

from right side of body

Midbrain

Sensory homunculus

Third order neurons

Second order neurons

First order neuronsStart

3

KEY

2

1

Sensory pathways

Figure 8.4 11


Motor Pathways (8.4)

• Corticospinal pathway

• Provides voluntary control over skeletal muscles

• Upper motor neuron

• Cell body in CNS processing center (primary motor cortex);

communicate with lower motor neurons

• Lower motor neuron

• Cell body in nucleus of brain stem or in spinal cord; communicate

with skeletal muscles

• Axons cross to opposite side in brain stem or spinal cord


Motor homunculus

To skeletalmuscles

Motor nucleiof cranial

nervesTo skeletal

muscles

Motor nucleiof cranial

nerves

Axons cross toopposite side

Cerebralpeduncle

Descendingaxons

Upper motorneuronLower motorneuronMedulla

oblongata

Spinal cord

Midbrain

KEY

To skeletalmuscles

Motor pathways

Figure 8.4 22


Homunculus (8.4)

• Map created by determining area of cortex devoted to

particular part of body and function

• Sensory homunculus

• Map of primary sensory cortex

• Proportions reflect number of sensory receptors in each region

• Motor homunculus

• Map of primary motor cortex

• Proportions reflect number of motor units innervated and degree of

fine motor control available


Module 8.4 Review

a. Define sensory homunculus.

b. Define corticospinal pathway.

c. Which side of the body does the right cerebral

hemisphere control?


Reflexes (8.5)

• Rapid, automatic response to specific stimuli

• Preserve homeostasis by allowing rapid adjustments in

function

• Reflex arc

• Receptor

• Sensory neuron

• Information processing

• Motor neuron

• Effector


Stretch Reflex (8.5)

• One of simplest and fastest reflex arcs

• Monosynaptic (one synapse involved)

• For example, patellar reflex

• Receptor – tap patellar tendon with hammer, receptors in

quadriceps muscle stretched

• Sensory neuron – carries stretch message directly to motor neuron

• Information processing – in patellar reflex, processing is in cell

body of motor neuron

• Motor neuron – carries message back to effector

• Effector – quadriceps muscle stimulated to contract


STEP 2Activation of a

Sensory Neuron

STEP 1 Arrival of the Stimulus and Activation of a Receptor

STEP 3InformationProcessingin the CNS

STEP 4Activation of a Motor Neuron

STEP 5 Response of a PeripheralEffector

Motor neuron(stimulated)

Sensory neuron(stimulated)

Contraction

Response

Effector

Receptor(muscle spindle)

REFLEXARC

Spinalcord

Stretch

KEY

Steps in a stretch reflex arc

Figure 8.5 11


Withdrawal Reflex (8.5)

• More complex than stretch reflex

• Involves multiple neurons

• Moves affected parts of body away from stimulus

• Receptor – pain receptors responding to tissue damage

• Sensory neuron – carries pain message to spinal cord

• Information processing – sensory neuron stimulates interneuron,

which activates motor neuron

• Motor neuron – carries message back to effector

• Effector – skeletal muscle contraction to pull away from stimulus


STEP 2 The activation of a

Sensory Neuron

STEP 1 The arrival of a Stimulus and Activation ofa Receptor

STEP 3 Information Processing

STEP 5 The Response of a PeripheralEffector

STEP 4 The Activation of a Motor Neuron

Dorsal rootganglion

To highercenters

REFLEXARC

Receptor

Stimulus

Effector

Sensory neuron(stimulated)

ExcitatoryinterneuronMotor neuron(stimulated)

KEY

Steps in a withdrawal reflex arc

Figure 8.5 22


Module 8.5 Review

a. What are the common characteristics of reflexes?

b. Define reflex and list the components of a reflex

arc.

c. In the patellar reflex, identify the response

observed and the effectors involved.


Reflex Tests (8.6)

• Activities in brain can facilitate or inhibit reflexes

• Facilitation of reflex – reinforcement

• Stretch reflexes often tested during physical exam to

provide information about status of spinal cord segments

• Biceps reflex

• Triceps reflex

• Ankle-jerk reflex


Clinical reflex tests

Figure 8.6 11

Bicepsreflex

Tricepsreflex

Ankle-jerkreflex


Babinski Sign and Plantar Reflex (8.6)

• In infants, stroking foot on lateral side of sole results in

fanning of toes – called positive Babinski sign

• As descending motor pathways develop, they inhibit this

reflex

• In normal adults, stroking foot on lateral side of sole results

in curling toes – called plantar reflex (negative Babinski

sign)

• Positive Babinski sign in adult indicates damage to CNS


Babinski sign

Figure 8.6 22

Babinski sign


Plantar reflex

Figure 8.6 33

Plantar reflex


Abdominal Reflex (8.6)

• Descending motor tracts can facilitate reflexes

• Abdominal reflex

• Light stroking of abdominal muscles produces reflexive

twitch moving navel toward stimulus

• Absence of reflex may indicate possible damage to

descending tracts


Abdominal reflex

Figure 8.6 44

Abdominal reflex


Module 8.6 Review

a. Define reinforcement as it pertains to spinal

reflexes.

b. What purpose does reflex testing serve?

c. After injuring her back, 22-year-old Tina exhibits

a positive Babinski reflex. What does this imply

about her injury?


Referred Pain (8.7)

• Sensation of pain in part of body other than actual source

• For example, a heart attack with pain felt in the left arm

• Visceral pain sensations can stimulate interneurons that

are part of the spinothalamic pathway

• Stimulates primary sensory cortex

• Feel pain in specific part of body surface


Referred pain

Figure 8.7 11

Heart


Parkinsons Disease (8.7)

• Neurons of substantia nigra damaged or secrete

less dopamine

• Basal nuclei become more active

• Raises skeletal muscle tone

• Produces rigidity and stiffness

• Difficulty starting and stopping voluntary

movements


Parkinson disease

Figure 8.7 22

Normal substantia nigra Diminished substantianigra in Parkinson patient


Rabies (8.7)

• Caused by virus

• Virus enters axon terminals

• Travels from terminals along axon into CNS

• Other toxins (heavy metals), some pathogenic

bacteria, and other viruses enter CNS by the same

path


Rabies

Figure 8.7 33

Virus travels withother materialsto the cell body.

Rabies viruses

Axon terminal


Cerebral Palsy (8.7)

• Number of disorders that affect voluntary motor

performance

• Appear during infancy or childhood

• Persist throughout life

• Caused by:

• Trauma with premature or stressful birth

• Maternal exposure to drugs (including alcohol)

• Genetic defect


Cerebral palsy

Figure 8.7 44


Amyotrophic Lateral Sclerosis (8.7)

• Progressive, degenerative disorder

• Affects motor neurons in spinal cord, brain stem, and

cerebral hemispheres

• Affects both upper and lower motor neurons

• Possibly underlying defect in axonal transport

• Destruction of CNS neurons causes atrophy of associated

skeletal muscles


Amyotrophic lateral sclerosis

Figure 8.7 55


Alzheimer's Disease (8.7)

• Progressive disorder

• Loss of higher-order cerebral functions

• Most common cause of senile dementia or senility

• Symptoms appear age 50–60 or later; occasionally affects

younger people

• 15 percent of those over age 65 in U.S. have some form

• Causes about 100,000 deaths each year

• Results in abnormalities in brain regions associated with

memory processing


Alzheimer’s disease

Figure 8.7 66

Abnormaldendrites,axons, and

extracellularproteins form

complexesknown as

Alzheimer'splaques.


Multiple Sclerosis (8.7)

• Characterized by recurrent incidents of demyelination

• Affects axons in optic nerve, brain, spinal cord

• Signs/symptoms:

• Partial loss of vision

• Problems with speech, balance, general motor coordination

• Time between incidents and degree of recovery vary

• One-third of cases progressive

• Typical onset age 30–40 years

• 1.5 times higher incidence in women than men


Multiple sclerosis

Figure 8.7 77

Demyelinatingneuron


Module 8.7 Review

a. Define referred pain.

b. Describe how rabies is contracted.

c. Describe amyotrophic lateral sclerosis (ALS).


The Somatic Nervous System (Section 2)

• Provides conscious and subconscious control over

skeletal muscles of body

• Lower motor neurons controlled by:

• Reflexes based in spinal cord or brain

• Upper motor neurons with cell bodies in nuclei of brain

or primary motor cortex


Somatic nervous system motor neurons

Figure 8 Section 2 11

Upper motorneurons in

primary motorcortex

Somatic motornuclei of brain

stem

Skeletalmuscle

Lowermotor

neurons

Spinal cord

Somaticmotornuclei ofspinal cord

BRAIN

Skeletalmuscle


The Autonomic Nervous System (Section 2)

• Controls visceral function outside our awareness

• Integrative centers in the hypothalamus

• Instead of single lower motor neuron, there are two motor

neurons in series

• Preganglionic neurons – cell bodies in brain stem and spinal

cord; part of visceral reflex arcs; communicate with:

• Ganglionic neurons – visceral motor neurons in peripheral

autonomic ganglia

• Innervate visceral effectors (cardiac muscle, smooth muscle,

glands, adipose tissue)


Autonomic nervous system motor neurons

Figure 8 Section 2 2

Visceral motornuclei in

hypothalamus

Preganglionicneuron

Visceral Effectors

Smoothmuscle

Glands

Cardiacmuscle

Adipocytes

Autonomicganglia

Ganglionicneurons

Preganglionicneuron

Autonomicnuclei inbrain stem

Spinalcord

Autonomicnuclei inspinal cord

BRAIN


Sympathetic Division (8.8)

• Preganglionic neurons

• From thoracic and superior lumbar segments of spinal cord

• Ganglionic neurons located:

1. Within sympathetic chain ganglia near spinal cord

2. In collateral ganglia within abdominopelvic cavity (celiac,

superior mesenteric, inferior mesenteric)

3. Within modified ganglion cells in adrenal medullae

• Affect target organs through release of hormones, epinephrine

and norepinephrine


Sympathetic nervous system ganglia location

Figure 8.8 11

PreganglionicNeurons

Ganglionic NeuronsTarget Organs

Sympathetic chain ganglia

Collateral ganglia

Adrenal medulla

Hormones

Nervoussignals

Visceral effectorsin abdomino-pelvic cavity

Organs and systems throughoutthe body

Visceral effectorsin thoracic cavity,head, body wall,and limbs

Hormones releasedinto circulation

Postganglionic fibers

Preganglionic fibersKEY


Sympathetic Division Axons and Neurotransmitters (8.8)

• Short preganglionic fibers (axons of

preganglionic neurons)

• Release acetylcholine (ACh)

• Long postganglionic fibers (axons of ganglionic

neurons)

• Release norepinephrine (NE)


Sympathetic Division – Functions (8.8)

• Produces "fight or flight" response, including:

1. Heightened mental alertness

2. Increased metabolic rate

3. Reduced digestive and urinary functions

4. Activation of energy reserves

5. Increased respiratory rate and dilation of respiratory passageways

6. Elevated heart rate and blood pressure

7. Activation of sweat glands


Parasympathetic Division (8.8)

• Preganglionic neurons

• From cranial nerves III, VII, IX, X, or sacral segments of spinal

cord

• Each typically synapses on 6 to 8 ganglionic neurons

• Ganglionic neurons found:

1. In terminal ganglia – near target organ; usually paired

2. In intramural ganglia – embedded in tissues of target organ;

usually in clusters

• Both preganglionic and postganglionic axon terminals

release acetylcholine


Parasympathetic nervous system ganglia location

Figure 8.8 22

PreganglionicNeurons

Sacral segments of spinal cord associated nuclei

Cranial nerve associated nuclei

III

VII

IX

X

Pelvicnerves

Ganglionic Neurons

Terminal ganglia

Ganglia close to targets

Intramuralganglia

Intramuralganglia

Target Organs

Intrinsic eye muscles(pupil and lens shape)

Nasal glands, tearglands, and submandibularand sublingual salivaryglands

Parotid salivaryglands

Visceral organsof neck,thoracic cavity,and most ofabdominal cavity

Visceral organs ininferior portion ofabdominopelviccavity

KEY

Preganglionic fibers

Postganglionic fibers


Parasympathetic Division – Functions (8.8)

• Regulates visceral function and energy conservation

• Known as the "rest and digest" system, causing:

1. Decreased metabolic rate

2. Decreased heart rate and blood pressure

3. Increased secretion by salivary and digestive glands

4. Increased motility and blood flow in digestive tract

5. Stimulation of urination and defecation


Module 8.8 Review

a. List general responses to increased sympathetic

activity and to parasympathetic activity.

b. Describe an intramural ganglion.

c. Starting in the spinal cord, trace the path of a

nerve impulse through the sympathetic ANS to its

target organ in the abdominopelvic cavity.


Innervation Patterns in the ANS (8.9)

• Both sympathetic and parasympathetic divisions

innervate many of same structures

• Sympathetic division

• Splanchnic nerves – bundles of preganglionic fibers on

way to collateral ganglia

• Sympathetic nerves – bundles of postganglionic fibers

innervating structures in thoracic cavity


Superiorcervicalsympatheticganglia

Postganglionicfibers to spinalnerves

Sympatheticchain gangliaT

Coccygealganglia (Co1)

fused together

PONS

Spinalcord

Splanchnicnerves

InferiorMesentericganglion

Sympathetic nerves

Autonomicplexus

Superior mesenteric ganglion

Celiac ganglion

Ovary

UterusPenisScrotum

Eye

Salivaryglands

Heart

Lung

Liver andgallbladder

Stomach

SpleenPancreas

LargeintestineSmallintestine

AdrenalmedullaKidney

Urinary bladder

Preganglionic neuronsGanglionic neurons

KEY

T1

L2 L2

T1

Innervation in the sympathetic nervous system

Figure 8.9 11


Innervation in the Parasympathetic Division (8.9)

• Vagus nerve

• Provides roughly 75 percent of all parasympathetic outflow

• Numerous branches intermingle with sympathetic fibers forming

plexuses

• Pelvic nerves

• Bundles of preganglionic fibers from sacral segment of spinal cord

• Innervate intramural ganglia in walls of kidneys, urinary bladder,

large intestine, and sex organs


Vagus nerve

Spinalcord

Autonomicplexuses

Pelvic nerves

Uterus Ovary

Penis

Scrotum

Terminal gangliaLacrimal glandEye

Salivary glands

Heart

LungsLiver andgallbladderStomachSpleenPancreas Large intestineSmall intestineRectum

Kidney

Urinary bladder

S2S3S4

III

VII

IX

X

PONS

Innervation in the parasympathetic nervous system

Figure 8.9 22


Module 8.9 Review

a. Define splanchnic nerves.

b. Which nerve carries the majority of the

parasympathetic outflow?

c. Describe sympathetic nerves.


Functional Characteristics of Sympathetic and Parasympathetic Divisions (8.10)

• Sympathetic

• Entire division quickly activated

• Parasympathetic

• Does not undergo division-wide activation

• Does not release neurotransmitters directly into

bloodstream


Anatomical characteristics of the sympathetic and parasympathetic divisions of the ANS

Figure 8.10 2 - 32 3–

Sympathetic

CNS

PNS

Adrenalmedulla

Bloodstream

Preganglionicneuron

Preganglionicfiber

Sympatheticganglion

Ganglionicneurons

Postganglionicfiber

NeurotransmittersKEY

AcetylcholineNorepinephrineEpinephrine

TARGET

Preganglionicneuron

Preganglionicfiber

Ganglionicneurons

Postganglionicfiber

Parasympathetic

CNS

PNS

Parasympatheticganglion

TARGET

Characteristic Sympathetic Division Characteristic Parasympathetic DivisionLocation of CNSvisceral motor neurons

Lateral gray horns of spinalsegments T1–L2

Location of CNSvisceral motor neurons

Brain stem and spinalsegments S2–S4

Location of PNS ganglia Near vertebral column (sympathetic chain ganglia)

Location of PNS ganglia Typically intramural

Preganglionic fibers Neurotransmitter

ShortACh

Preganglionic fibers Neurotransmitter

Relatively longACh

Postganglionic fibers Neurotransmitter

LongUsually norepinephrine (NE)

Postganglionic fibers Neurotransmitter

Relatively shortACh

General functions Stimulates metabolism;increases alertness; preparesfor emergency (“fight or flight”)

General functions Promotes relaxation, nutrientuptake, energy storage (“restand digest”)

or


Module 8.10 Review

a. What neurotransmitter is released by all

parasympathetic neurons?

b. Why is the parasympathetic division called the

anabolic system?

c. What physiological changes are typical in tense

(anxious) individuals?

powerpoint ® lecture slides prepared by betsy c. brantley valencia college c h a p t e r © 2013...

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