Chapter 17 - Napa Valley College Pages - Napa Valley ... 218...Lecture Presentation by Steven...

Lecture Presentation by

Steven Bassett

Southeast Community College

Chapter 17

The Nervous

System

The Autonomic

Nervous System

© 2015 Pearson Education, Inc.

Introduction

• The autonomic nervous system functions

outside of our conscious awareness

• The autonomic nervous system makes

routine adjustments in our body’s systems

• The autonomic nervous system:

• Regulates body temperature

• Coordinates cardiovascular, respiratory, digestive,

excretory, and reproductive functions


A Comparison of the Somatic and Autonomic Nervous Systems

• Autonomic Nervous System

• Axons innervate the visceral organs

• Has afferent and efferent neurons

• Afferent pathways originate in the visceral

receptors

• Somatic nervous system

• Axons innervate the skeletal muscles

• Has afferent and efferent neurons

• Afferent pathways originate in the skeletal

muscles


Sympathetic and Parasympathetic Subdivisions of the ANS

• The autonomic nervous system consists of

two major subdivisions

• Sympathetic division

• Also called the thoracolumbar division

• Most active during times of stress, exertion, or

emergency

• Parasympathetic division

• Also called the craniosacral division

• Most active during resting conditions


Figure 17.1 An Introduction to the Autonomic Nervous System (1 of 2)


Figure 17.1 An Introduction to the Autonomic Nervous System (2 of 2)


Sympathetic and Parasympathetic Subdivisions of the ANS

• The autonomic nervous system consists of

a third division (not commonly discussed)

• Enteric Nervous System

• Neurons located in the walls of the digestive tract

• Many visceral reflexes are initiated by the ENS


The Sympathetic Division

• Sympathetic division consists of:

• Preganglionic neurons between T1 and L2

• Neuronal cell bodies in ganglia near the

vertebral column

• Sympathetic chain ganglia

• Collateral ganglia

• Specialized neurons in the interior of the

suprarenal gland


Figure 17.2 Organization of the Sympathetic Division of the ANS


Sympathetic Division of ANS

Preganglionic

Neurons

Ganglionic Neurons Target Organs

KEY

Innervation by

postganglionic

fibers

Visceral effectorsin thoracic cavity,head, body wall,

and limbs

Visceral effectorsin abdominopelvic

cavity

Organs and systemsthroughout body

Sympatheticchain ganglia

(paired)

Collateralganglia

(unpaired)

Suprarenalmedullae(paired)

Through release of

hormones into

the circulation

Preganglionic fibers

Postganglionic fibers

Hormones released

into circulation

Lateral grayhorns of spinal

segmentsT1–L2


• Sympathetic Chain Ganglia

• Also called: paravertebral ganglia or lateral

ganglia

• Control effectors in the body wall, head, neck,

limbs, and thoracic cavity

• Preganglionic Neurons

• Cell bodies are in the lateral gray horns

• Axons enter the ventral roots



• Collateral Ganglia

• Also called prevertebral ganglia

• Neurons innervate effectors in the abdominopelvic

cavity

• Specialized Neurons

• Modified sympathetic ganglion in the suprarenal

gland

• Neurons release neurotransmitters that act like

hormones



• The Sympathetic Chain Ganglia

• The ventral root joins a dorsal root

• Forms a spinal nerve

• Passes through an intervertebral foramen

• White ramus branches off the spinal nerve


Figure 17.3a Sympathetic Pathways and Their General Functions


Sympathetic Chain Gangliaa

Spinal

nerve

Autonomic ganglion

of left sympathetic chain

Preganglionic

neuronAutonomic ganglion of

right sympathetic chain

Innervates

visceral

effectors via

spinal nerves

White

ramus

Ganglionic

neuron

Gray ramus

Sympathetic nerve

(postganglionic

fibers)

Innervates visceral

organs in thoraciccavity via

sympathetic nerves KEY

Preganglionic neurons

Postganglionic neurons

Major effects produced by sympathetic postganglionic

fibers in spinal nerves:

● Constriction of cutaneous blood vessels, reduction in

circulation to the skin and to most other organs in thebody wall

● Acceleration of blood flow to skeletal musclesand brain

● Stimulation of energy production and use by skeletal

muscle tissue

● Release of stored lipids from subcutaneousadipose tissue

● Stimulation of secretion by sweat glands● Stimulation of arrector pili● Dilation of the pupils and focusing for distant objects

Major effects produced by postganglionic fibers

entering the thoracic cavity in sympathetic nerves:

● Acceleration of heart rate and increasing the

strength of cardiac contractions

● Dilation of respiratory passageways


• Functions of Sympathetic Chain

• Decreases:

• Blood circulation to the skin

• Increases:

• Heart rate and blood circulation to skeletal muscles

• Stimulates:

• More energy production by skeletal muscles

• Arrector pili muscles and sweat glands

• The release of stored lipids

• Dilates:

• Pupils and respiratory tubes



• Anatomy of the Sympathetic Chain

• Cluster of ganglia that parallel the spinal cord

• Each sympathetic chain consists of:

• 3 cervical ganglia

• 11–12 thoracic ganglia

• 2–5 lumbar ganglia

• 4–5 sacral ganglia

• 1 coccygeal ganglion


Figure 17.4 Anatomical Distribution of Sympathetic Postganglionic Fibers

T4

T5

T6

T7

T8

T9

T10

T11

T12

L1

L2

T3

T2

T1

T4

T5

T6

T7

T8

T9

T10

T11

T12

L1

L2

T3

T2

T1

PONS

Sympathetic nerves

Cardiac and

pulmonary

plexuses

Celiac ganglion

Greater

splanchnic

nerve

Eye

Salivary

glands

Heart

Lung

Liver and

gallbladder

Stomach

Spleen

Pancreas

Large intestine

Small intestine

Superior

mesenteric

ganglion

Lesser

splanchnic

nerve

Suprarenal

medulla

Kidney

Inferior

mesenteric

ganglion

Lumbar

splanchnic nerves

Sacral

splanchnic

nerves

Urinary bladderScrotumPenisOvaryUterus

Coccygeal

ganglia (Co1)

fused together

(ganglion impar)

Spinal cord

L3

L4

L5

S1S2

S3S4

S5

L3

L4

L5

S1

S2

S3S4

S5

Sympathetic

chain ganglia


of spinal nerves

(innervating skin, blood

vessels, sweat glands,

arrector pili muscles,

adipose tissue)

Gray rami to

spinal nerves

Superior

Middle

Inferior

Cervical

sympathetic

ganglia

KEY





• Anatomy of the Sympathetic Chain

• Preganglionic and postganglionic neurons

• Cervical chain

• Only has postganglionic neurons

• Thoracic chain

• Has both preganglionic and postganglionic neurons

• Lumbar chain


• Sacral chain


• Coccygeal chain

• Has only postganglionic neurons



T4

T5

T6

T7

T8

T9

T10

T11

T12

L1

L2

T3

T2

T1

T4

T5

T6

T7

T8

T9

T10

T11

T12

L1

L2

T3

T2

T1

PONS

Sympathetic nerves

Cardiac and

pulmonary

plexuses

Celiac ganglion

Greater

splanchnic

nerve

Eye

Salivary

glands

Heart

Lung

Liver and

gallbladder

Stomach

Spleen

Pancreas

Large intestine

Small intestine

Superior

mesenteric

ganglion

Lesser

splanchnic

nerve

Suprarenal

medulla

Kidney

Inferior

mesenteric

ganglion

Lumbar

splanchnic nerves

Sacral

splanchnic

nerves


Coccygeal

ganglia (Co1)

fused together

(ganglion impar)

Spinal cord

L3

L4

L5

S1S2

S3S4

S5

L3

L4

L5

S1

S2

S3S4

S5

Sympathetic

chain ganglia


of spinal nerves




adipose tissue)

Gray rami to

spinal nerves

Superior

Middle

Inferior

Cervical

sympathetic

ganglia

KEY





• Splanchnic Nerves and Collateral Ganglia

• Splanchnic nerves are bundles of preganglionic

fibers

• Converge on collateral ganglia

• Innervates visceral tissue and organs



T4

T5

T6

T7

T8

T9

T10

T11

T12

L1

L2

T3

T2

T1

T4

T5

T6

T7

T8

T9

T10

T11

T12

L1

L2

T3

T2

T1

PONS

Sympathetic nerves

Cardiac and

pulmonary

plexuses

Celiac ganglion

Greater

splanchnic

nerve

Eye

Salivary

glands

Heart

Lung

Liver and

gallbladder

Stomach

Spleen

Pancreas

Large intestine

Small intestine

Superior

mesenteric

ganglion

Lesser

splanchnic

nerve

Suprarenal

medulla

Kidney

Inferior

mesenteric

ganglion

Lumbar

splanchnic nerves

Sacral

splanchnic

nerves


Coccygeal

ganglia (Co1)

fused together

(ganglion impar)

Spinal cord

L3

L4

L5

S1S2

S3S4

S5

L3

L4

L5

S1

S2

S3S4

S5

Sympathetic

chain ganglia


of spinal nerves




adipose tissue)

Gray rami to

spinal nerves

Superior

Middle

Inferior

Cervical

sympathetic

ganglia

KEY




Figure 17.3b Sympathetic Pathways and Their General Functions


Collateral Gangliab

Lateral gray horn

White

ramusSplanchnic nerve

(preganglionic

fibers)

Postganglionic

fibers

Collateral

ganglion

Innervates

visceral organs inabdominopelvic

cavity


of the collateral ganglia:

● Constriction of small arteries and reduction in the

flow of blood to visceral organs

● Decrease in the activity of digestive glands andorgans

● Stimulation of the release of glucose from glycogenreserves in the liver

● Stimulation of the release of lipids from adiposetissue

● Relaxation of the smooth muscle in the wall of the

urinary bladder

● Reduction of the rate of urine formation at thekidneys

● Control of some aspects of sexual function, such asejaculation in males


• Anatomy of the Collateral Ganglia

• There are three collateral ganglia

• Celiac ganglion

• Innervates stomach, duodenum, liver, gallbladder,

pancreas, spleen, and kidney

• Superior mesenteric ganglion

• Innervates small intestine and initial segments of

large intestine

• Inferior mesenteric ganglion

• Innervates terminal portions of large intestine, the

kidney, urinary bladder, and sex organs



T4

T5

T6

T7

T8

T9

T10

T11

T12

L1

L2

T3

T2

T1

T4

T5

T6

T7

T8

T9

T10

T11

T12

L1

L2

T3

T2

T1

PONS

Sympathetic nerves

Cardiac and

pulmonary

plexuses

Celiac ganglion

Greater

splanchnic

nerve

Eye

Salivary

glands

Heart

Lung

Liver and

gallbladder

Stomach

Spleen

Pancreas

Large intestine

Small intestine

Superior

mesenteric

ganglion

Lesser

splanchnic

nerve

Suprarenal

medulla

Kidney

Inferior

mesenteric

ganglion

Lumbar

splanchnic nerves

Sacral

splanchnic

nerves


Coccygeal

ganglia (Co1)

fused together

(ganglion impar)

Spinal cord

L3

L4

L5

S1S2

S3S4

S5

L3

L4

L5

S1

S2

S3S4

S5

Sympathetic

chain ganglia


of spinal nerves




adipose tissue)

Gray rami to

spinal nerves

Superior

Middle

Inferior

Cervical

sympathetic

ganglia

KEY




Figure 17.3b Sympathetic Pathways and Their General Functions


Collateral Gangliab

Lateral gray horn

White

ramusSplanchnic nerve

(preganglionic

fibers)

Postganglionic

fibers

Collateral

ganglion

Innervates

visceral organs inabdominopelvic

cavity


of the collateral ganglia:

● Constriction of small arteries and reduction in the

flow of blood to visceral organs

● Decrease in the activity of digestive glands andorgans

● Stimulation of the release of glucose from glycogenreserves in the liver

● Stimulation of the release of lipids from adiposetissue

● Relaxation of the smooth muscle in the wall of the

urinary bladder

● Reduction of the rate of urine formation at thekidneys

● Control of some aspects of sexual function, such asejaculation in males


• The Suprarenal Medullae

• Preganglionic fibers proceed to the suprarenal

medulla (medulla of adrenal glands)

• Release neurotransmitters

• Epinephrine and norepinephrine

• Epinephrine is also called adrenaline

• Epinephrine accounts for 75–80% of the secretions

• These neurotransmitters generally cause changes

in the metabolic activities of cells



T4

T5

T6

T7

T8

T9

T10

T11

T12

L1

L2

T3

T2

T1

T4

T5

T6

T7

T8

T9

T10

T11

T12

L1

L2

T3

T2

T1

PONS

Sympathetic nerves

Cardiac and

pulmonary

plexuses

Celiac ganglion

Greater

splanchnic

nerve

Eye

Salivary

glands

Heart

Lung

Liver and

gallbladder

Stomach

Spleen

Pancreas

Large intestine

Small intestine

Superior

mesenteric

ganglion

Lesser

splanchnic

nerve

Suprarenal

medulla

Kidney

Inferior

mesenteric

ganglion

Lumbar

splanchnic nerves

Sacral

splanchnic

nerves


Coccygeal

ganglia (Co1)

fused together

(ganglion impar)

Spinal cord

L3

L4

L5

S1S2

S3S4

S5

L3

L4

L5

S1

S2

S3S4

S5

Sympathetic

chain ganglia


of spinal nerves




adipose tissue)

Gray rami to

spinal nerves

Superior

Middle

Inferior

Cervical

sympathetic

ganglia

KEY




Figure 17.3c Sympathetic Pathways and Their General Functions


c The Suprarenal Medullae

Major effect produced by preganglionic fibers

innervating the suprarenal medullae:

● Release of epinephrine and norepinephrine into

the general circulation

Preganglionic fibers Suprarenal

medullaeEndocrine cells

(specialized ganglionic

neurons)

Secrete

neurotransmittersinto generalcirculation


• Effects of Sympathetic Stimulation

• Increased alertness

• A feeling of energy and euphoria

• Increased cardiovascular activity

• Increased respiratory activity

• Increased muscle tone

• Increased mobilization of energy reserves



• Sympathetic Activation and Neurotransmitter

Release

• Sympathetic ganglion fibers release acetylcholine

at the synapse with ganglionic neurons

• These are cholinergic synapses

• The stimulation of ganglionic neurons causes the

release of norepinephrine at the neuroeffector

junction

• These terminals are adrenergic



• Sympathetic Activation and Neurotransmitter

Release

• Some ganglionic neurons release acetylcholine

• Especially at the neuroeffector junctions of skeletal

muscles


Figure 17.6 Sympathetic Postganglionic Nerve Endings


Ganglion

Preganglionic fiber(myelinated)

Ganglionic

neuron

Postganglionic fiber

(unmyelinated)

Varicosities

MitochondrionVesicles containing

norepinephrine

Schwann cell

cytoplasm

5 μm

Smooth muscle cells Varicosities


• Plasmalemma Receptors and Sympathetic

Function

• There are two classes of plasmalemma receptors

• Alpha receptors

• Stimulated by epinephrine

• Stimulated by norepinephrine

• Beta receptors

• Stimulated by epinephrine



• A Summary of the Sympathetic Division

• Consists of parallel chains on either side of the

spinal cord

• Preganglionic fibers are short and extend from

the spinal cord to the sympathetic chain

• Postganglionic fibers are long and extend from

the spinal cord to the body organs



• A Summary of the Sympathetic Division

• The sympathetic division shows considerable

divergence

• All preganglionic neurons release ACh / most

postganglionic neurons release norepinephrine

• The effector response depends on the presence of

either alpha receptors or beta receptors



T4

T5

T6

T7

T8

T9

T10

T11

T12

L1

L2

T3

T2

T1

T4

T5

T6

T7

T8

T9

T10

T11

T12

L1

L2

T3

T2

T1

PONS

Sympathetic nerves

Cardiac and

pulmonary

plexuses

Celiac ganglion

Greater

splanchnic

nerve

Eye

Salivary

glands

Heart

Lung

Liver and

gallbladder

Stomach

Spleen

Pancreas

Large intestine

Small intestine

Superior

mesenteric

ganglion

Lesser

splanchnic

nerve

Suprarenal

medulla

Kidney

Inferior

mesenteric

ganglion

Lumbar

splanchnic nerves

Sacral

splanchnic

nerves


Coccygeal

ganglia (Co1)

fused together

(ganglion impar)

Spinal cord

L3

L4

L5

S1S2

S3S4

S5

L3

L4

L5

S1

S2

S3S4

S5

Sympathetic

chain ganglia


of spinal nerves




adipose tissue)

Gray rami to

spinal nerves

Superior

Middle

Inferior

Cervical

sympathetic

ganglia

KEY




The Parasympathetic Division

• Parasympathetic Division

• Preganglionic neurons are in the brain stem and

sacral segments

• Preganglionic neurons do not diverge as much as

the sympathetic division

• Therefore, the parasympathetic division is more

localized and specific as compared to the

sympathetic division

• Postganglionic neurons are near (terminal) the

target organ or within (intramural) the target organ



• Organization and Anatomy of the

Parasympathetic Division

• Preganglionic fibers leave the brain via:

• CN III (to the intrinsic eye muscles, pupil, and lens)

• CN VII (to the tear glands and salivary glands)

• CN IX (to the parotid salivary glands)

• CN X (to the visceral organs of the thoracic cavity

and abdominal cavity)

• Preganglionic fibers leave the sacral region via:

• Pelvic nerves (to the visceral organs in the inferior

portion of the abdominopelvic cavity


Figure 17.7 Organization of the Parasympathetic Division of the ANS


Ciliary ganglion

N III

N VII

N IX

Nuclei in

brain stemIntrinsic eye muscles(pupil and lens shape)

Target Organs

Nasal glands, tear

glands, and saliveryglands

Pterygopalatine

and submandibularganglia

Otic ganglion Parotid salivary gland

Intramural

ganglia

Visceral organs

of neck,

thoracic cavity,and most of

abdominal cavity

N X

Preganglionic Neurons Ganglionic Neurons

Pelvic

nerves Intramural

ganglia

Nuclei in

spinal cord

segments

S2-S4

Visceral organs in

interior portion of

abdominopelvic cavityPreganglionic fibers


KEY

Parasympathetic Division of ANS

Figure 17.8 Anatomical Distribution of the Parasympathetic Output

Pterygopalatine ganglion

Lacrimal

gland

Eye

Salivary

glands

Ciliary ganglion

Submandibular

ganglion

Otic ganglion

N III

N VII

N IX

N X (Vagus)Heart

Lungs

Autonomic plexusesLiver and

gallbladder

Stomach

Spleen

Pancreas

Large intestine

Small intestine

Rectum

Kidney

Pelvic

nerves

Uterus Ovary Penis Scrotum Urinary bladder

Spinal

cord

PONS

(see Figure 17.9 )

S2

S3

S4



KEY



• General Functions of the Parasympathetic Division

• Parasympathetic stimulation generally results in:

• Relaxation

• Food processing

• Energy absorption

• Major effects of parasympathetic stimulation

• Pupil constriction

• Secretion of digestive enzymes from:

• Salivary glands, gastric glands, duodenal glands,

pancreas, and liver



• General Functions of the Parasympathetic Division

• Major effects of parasympathetic stimulation

(continued)

• Secretion of hormones that promote nutrient

absorption

• Increased smooth muscle activity of the digestive

system

• Stimulation and coordination of defecation

• Contraction of the urinary bladder

• Constriction of respiratory passages

• Reduced heart rate

• Sexual arousal



• Parasympathetic Activation and Neurotransmitter

Release

• All preganglionic and postganglionic fibers release

ACh at their synapses and neuroeffector junctions

• Most parasympathetic stimulations are short lived

• This is due to the immediate breakdown of ACh by

acetylcholinesterase

• Any diffused ACh will be deactivated by

cholinesterase

• Thus, parasympathetic stimulations are very

localized



• Plasmalemma Receptors and Responses

• Two types of ACh receptors are found on the

postsynaptic plasmalemmae:

• Nicotinic receptors

• Respond to nicotine

• Found on surfaces of parasympathetic and

sympathetic ganglionic neurons

• Muscarinic receptors

• Respond to muscarine

• Found on surfaces of parasympathetic cholinergic

neuroeffector junctions



• A Summary of the Parasympathetic Division

• Involves CN III, CN VII, CN IX, and CN X

• Involves sacral segments S2 to S4

• All parasympathetic neurons are cholinergic

• Release of ACh stimulates nicotinic receptors on

ganglionic neurons

• Effect is always excitatory

• Release of ACh on neuroeffector junctions

stimulates muscarinic receptors

• Effect can be excitatory or inhibitory



• A Summary of the Parasympathetic Division

(continued)

• Parasympathetic stimulation are usually brief

• Parasympathetic stimulation is localized

• Parasympathetic nerves innervate

• Head, thoracic, abdominal, and pelvic organs


Relationships between the Sympathetic and Parasympathetic Divisions

• Sympathetic

• Widespread effect on visceral organs

• Parasympathetic

• Modifies the activity of structures innervated by

specific cranial nerves and pelvic nerves

• Most vital organs are innervated by both the

sympathetic and parasympathetic nerves

• This is known as dual innervation

• The two often oppose (antagonistic) each other



• Anatomy of Dual Innervation

• Head region

• The parasympathetic fibers accompany the

sympathetic fibers to the target organ

• Thoracic and abdominopelvic regions

• The parasympathetic and sympathetic fibers

mingle together forming plexuses

• Cardiac, pulmonary, esophageal, celiac, inferior

mesenteric, and hypogastric plexus


Figure 17.9a The Peripheral Autonomic Plexuses


Trachea

Left vagus nerve

Right vagus nerve

Aortic arch

Thoracic

spinal

nerves

Esophagus

Splanchnic

nerves

Diaphragm

Celiac trunk

Superior mesenteric

artery

Inferior mesenteric

artery

Cardiac plexus

Pulmonary plexus

Thoracic sympathetic

chain ganglia

Esophageal plexus

Celiac plexus and

ganglion

Superior mesenteric

ganglion

Inferior mesenteric

plexus and ganglion

Hypogastric plexus

Pelvic sympathetic

chain

This is a diagrammatic view of the distribution of ANS plexuses

in the thoracic cavity (cardiac, esophageal, and pulmonary

plexuses) and the abdominopelvic cavity (celiac, inferior

mesenteric, and hypogastric plexuses).

a

Autonomic Plexuses

and Ganglia


• A Comparison of the Sympathetic and

Parasympathetic Divisions

• Compare the length of the preganglionic fibers

• Compare the length of the postganglionic fibers

• Compare the location of the ganglia

• Compare the neurotransmitter released

• Compare the degree of divergence


Figure 17.10 A Comparison of the Sympathetic and Parasympathetic Divisions.


Sympathetic

ganglion

Preganglionic

neuron

Preganglionic

fiber

Ganglionic

neurons

Circulatory

system Postganglionic

fiberParasympathetic

ganglion

Neurotransmitters

Acetylcholine

Norepinephrine

Epinephrine

KEY

TARGET

CNS

PNS

Sympathetic Parasympathetic

or

Table 17.1 A Comparison of the Sympathetic and Parasympathetic Divisions of the ANS


Visceral Reflexes

• Provide autonomic motor responses to:

• Modify or facilitate higher centers

• All visceral reflexes are polysynaptic

• Reflexes can be:

• Long reflexes

• Short reflexes


Visceral Reflexes

• Long Reflexes

• Visceral sensory neurons go to the CNS via the

dorsal roots

• There are interneurons within the CNS

• Information is “interpreted” in the spinal cord or

brain

• ANS sends motor commands to the visceral

organs


Visceral Reflexes

• Short Reflexes

• Sensory nerve impulses go to the ganglionic

neurons

• Motor commands are distributed by the

postganglionic fibers

• Impulses bypass the CNS


Figure 17.11 Visceral Reflexes


Receptors

in peripheral

tissue

Afferent

(sensory)

fibers

Stimulus

Long

reflex

Short

reflex

CENTRAL NERVOUS

SYSTEM

Processing center

in spinal cord

(or brain)

Preganglionic

neuron

Autonomic ganglion

(sympathetic or

parasympathetic)

Postganglionic

neuron

Peripheral

effectorResponse

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