© 2012 pearson education, inc. figure 15-1 an overview of neural integration chapter 15chapter 16...

Figure 15-1 An Overview of Neural Integration

CHAPTER 15 CHAPTER 16

OVERVIEW OF NEURAL INTEGRATION

Sensoryprocessingcenters in

Sensorypathways

Generalsensory

receptors

Conscious andsubconsciousmotor centers

in brain

Motorpathways

SomaticNervous

System (SNS)

Skeletalmuscles

Memory, learning, andintelligence may

influence interpretationof sensory information

and nature of motoractivities

Higher-Order Functions

AutonomicNervous

System (ANS)

Visceral effectors(examples: smoothmuscles, glands,cardiac muscle,

adipocytes)

15-1 Sensory Information

• Sensory Receptors

• Specialized cells that monitor specific conditions

• In the body or external environment

• When stimulated, a receptor passes information to

the CNS

• In the form of action potentials along the axon of a

sensory neuron

• Sensory Pathways

• Deliver somatic and visceral sensory information to

their final destinations inside the CNS using:

• Nerves

• Nuclei

• Tracts

• Somatic Motor Portion of the Efferent Division

• Controls peripheral effectors

• Somatic Motor Commands

• Travel from motor centers in the brain along somatic

motor pathways of:

• Motor nuclei

• Tracts

• Nerves

• Somatic Nervous System (SNS)

• Motor neurons and pathways that control skeletal

muscles

15-2 Sensory Receptors

• General Senses

• Describe our sensitivity to:

• Temperature

• Pain

• Touch

• Pressure

• Vibration

• Proprioception

• Sensation

• The arriving information from these senses

• Perception

• Conscious awareness of a sensation

• Special Senses

• Olfaction (smell)

• Vision (sight)

• Gustation (taste)

• Equilibrium (balance)

• Hearing

• The Special Senses

• Are provided by special sensory receptors

• Special Sensory Receptors

• Are located in sense organs such as the eye or ear

• Are protected by surrounding tissues

• The Interpretation of Sensory Information

• Arriving stimulus reaches cortical neurons via labeled

• Takes many forms (modalities)

• Physical force (such as pressure)

• Dissolved chemical

• Sound

• Light

• The Interpretation of Sensory Information

• Sensations

• Taste, hearing, equilibrium, and vision provided by

specialized receptor cells

• Communicate with sensory neurons across chemical

synapses

• Adaptation

• Reduction in sensitivity of a constant stimulus

• Your nervous system quickly adapts to stimuli that

are painless and constant

15-3 Classifying Sensory Receptors

• Classifying Sensory Receptors

• Exteroceptors provide information about the external

environment

• Proprioceptors report the positions of skeletal

muscles and joints

• Interoceptors monitor visceral organs and functions

• Proprioceptors

• Provide a purely somatic sensation

• No proprioceptors in the visceral organs of the

thoracic and abdominopelvic cavities

• You cannot tell where your spleen, appendix, or

pancreas is at the moment

• General Sensory Receptors

• Are divided into four types by the nature of the

stimulus that excites them

1. Nociceptors (pain)

2. Thermoreceptors (temperature)

3. Mechanoreceptors (physical distortion)

4. Chemoreceptors (chemical concentration)

• Nociceptors (Pain Receptors)

• Are common

• In the superficial portions of the skin, in joint capsules

• Within the periostea of bones,around the walls of blood

vessels

• Carry sensations of fast pain, or prickling pain, such as

that caused by an injection or a deep cut

• Carry sensations of slow pain, or burning and aching

• Nociceptors

• May be sensitive to:

1. Temperature extremes

2. Mechanical damage

3. Dissolved chemicals, such as chemicals released by

injured cells

• Thermoreceptors

• Also called temperature receptors

• Conducted along the same pathways that carry pain

sensations

• Are free nerve endings located in:

• The dermis

• Skeletal muscles

• The liver

• The hypothalamus

• Mechanoreceptors

• Sensitive to stimuli that distort their plasma

membranes (Tactile, Baroreceptors,

Proprioceptors)

• Contain mechanically gated ion channels whose

gates open or close in response to:

• Stretching

• Compression

• Twisting

• Other distortions of the membrane

• Chemoreceptors

• Respond only to water-soluble and lipid-soluble

substances dissolved in surrounding fluid

• Receptors exhibit peripheral adaptation over period of

seconds

• Central adaptation may also occur

15-4 Sensory Pathways

• Somatic Sensory Pathways

• Carry sensory information from the skin and

musculature of the body wall, head, neck, and limbs

• Three major somatic sensory pathways

1. The spinothalamic pathway

2. The posterior column pathway

3. The spinocerebellar pathway

Figure 15-5 Somatic Sensory Pathways

SPINOTHALAMIC PATHWAY

KEYAxon of first-order neuron

Second-orderneuron

Third-orderneuron

Crude touch and pressure sensationsfrom right side of body

Anteriorspinothalamictract

Midbrain

Medullaoblongata

The anterior spinothalamictracts of the

spinothalamicpathway carry

crude touch and pressure sensa-

tions.

SPINOTHALAMIC PATHWAYKEY

Axon of first-order neuron

Second-orderneuron

Third-orderneuron

Pain and temperature sensationsfrom right side of body

Midbrain

Medullaoblongata

Spinalcord

Lateralspinothalamictract

The lateral spinothalamictracts of the

spinothalamicpathway carry pain

and temperaturesensations.

POSTERIOR COLUMN PATHWAY

Dorsal rootganglion

Medullaoblongata

Mediallemniscus

Midbrain

Nucleusgracilis and

nucleuscuneatus

Fasciculusgracilis and

fasciculuscuneatus

Fine-touch, vibration, pressure, andproprioception sensations from rightside of body

Ventral nucleiin thalamus

SPINOCEREBELLAR PATHWAY

Cerebellum

Spinocerebellarpathway

Posteriorspinocerebellartract

Anteriorspinocerebellartract

Medullaoblongata

Spinalcord

Proprioceptive input from Golgitendon organs, muscle spindles,and joint capsules

• Sensory Information

• Most somatic sensory information

• Is relayed to the thalamus for processing

• A small fraction of the arriving information

• Is projected to the cerebral cortex and reaches our

awareness

• Visceral Sensory Pathways

• Collected by interoceptors monitoring visceral tissues

and organs, primarily within the thoracic and

abdominopelvic cavities

• These interoceptors are not as numerous as in

somatic tissues

• Interoceptors include:

• Nociceptors

• Thermoreceptors

• Tactile receptors

• Baroreceptors

• Chemoreceptors

• Cranial Nerves V, VII, IX, and X

• Carry visceral sensory information from mouth, palate,

pharynx, larynx, trachea, esophagus, and associated

vessels and glands

15-5 Somatic Motor Pathways

• The Somatic Nervous System (SNS)

• Also called the somatic motor system

• Controls contractions of skeletal muscles (discussed

• The Autonomic Nervous System (ANS)

• Also called the visceral motor system

• Controls visceral effectors, such as smooth muscle,

cardiac muscle, and glands (Ch. 16)

• Somatic Motor Pathways

• Always involve at least two motor neurons

1. Upper motor neuron

2. Lower motor neuron

• Upper Motor Neuron

• Cell body lies in a CNS processing center

• Synapses on the lower motor neuron

• Innervates a single motor unit in a skeletal muscle

• Activity in upper motor neuron may facilitate or inhibit

lower motor neuron

• Lower Motor Neuron

• Cell body lies in a nucleus of the brain stem or spinal

• Triggers a contraction in innervated muscle

• Only axon of lower motor neuron extends outside CNS

• Destruction of or damage to lower motor neuron eliminates

voluntary and reflex control over innervated motor unit

• Levels of Processing and Motor Control

• Integrative centers in the brain

• Perform more elaborate processing

• As we move from medulla oblongata to cerebral cortex,

motor patterns become increasingly complex and

variable

• Primary motor cortex

• Most complex and variable motor activities are directed

by primary motor cortex of cerebral hemispheres

An Introduction to the ANS and Higher-Order Functions

• Somatic Nervous System (SNS)

• Operates under conscious control

• Seldom affects long-term survival

• SNS controls skeletal muscles

• Autonomic Nervous System (ANS)

• Operates without conscious instruction

• ANS controls visceral effectors

• Coordinates system functions

• Cardiovascular, respiratory, digestive, urinary, reproductive

Figure 16-1 An Overview of Neural Integration

CHAPTER 16CHAPTER 15

Higher-Order FunctionsConscious andsubconsciousmotor centers

in brain

Motorpathways

Memory, learning, andintelligence may

influence interpretationof sensory information

and nature of motoractivities

AutonomicNervous

System (ANS)

Visceral effectors(examples: smooth

muscle, glands,cardiac muscle,

adipocytes)

Sensoryprocessingcenters in

Sensorypathways

Generalsensory

receptors

SomaticNervous

System (SNS)

Skeletalmuscles

OVERVIEW OF NEURAL INTEGRATION

16-1 Autonomic Nervous System

• Organization of the ANS

• Visceral motor neurons

• In brain stem and spinal cord, are known as

preganglionic neurons

• Preganglionic fibers

• Axons of preganglionic neurons

• Leave CNS and synapse on ganglionic neurons

16-1 Autonomic Nervous System

• Visceral Motor Neurons

• Autonomic ganglia

• Contain many ganglionic neurons

• Ganglionic neurons innervate visceral effectors

• Such as cardiac muscle, smooth muscle, glands,

and adipose tissue

• Postganglionic fibers

• Axons of ganglionic neurons

Figure 16-2a The Organization of the Somatic and Autonomic Nervous Systems

Somatic nervous system

Somaticmotor nucleiof spinal cord

SPINALCORD

Lowermotor

neurons

Skeletalmuscle

Somatic motornuclei of brain

Upper motorneurons in

primary motorcortex

Figure 16-2b The Organization of the Somatic and Autonomic Nervous Systems

Autonomic nervous system

Smoothmuscle

Cardiacmuscle

Adipocytes

Glands

Visceral Effectors

Preganglionicneuron

Autonomicganglia

Ganglionicneurons

Preganglionicneurons

Autonomicnuclei inbrain stem

SPINALCORD

Autonomicnuclei inspinal cord

Visceral motornuclei in

hypothalamus

16-1 Divisions of the ANS

• The Autonomic Nervous System

• Operates largely outside our awareness

• Has two divisions

1. Sympathetic division

• Increases alertness, metabolic rate, and muscular

abilities

2. Parasympathetic division

• Reduces metabolic rate and promotes digestion

• Sympathetic Division

• “Kicks in” only during exertion, stress, or

emergency

• “Fight or flight”

• Parasympathetic Division

• Controls during resting conditions

• “Rest and digest”

• Sympathetic and Parasympathetic Division

1. Most often, these two divisions have opposing effects

• If the sympathetic division causes excitation, the

parasympathetic causes inhibition

2. The two divisions may also work independently

• Only one division innervates some structures

3. The two divisions may work together, with each

controlling one stage of a complex process

• Preganglionic fibers (thoracic and superior lumbar;

thoracolumbar) synapse in ganglia near spinal cord

• Preganglionic fibers are short

• Postganglionic fibers are long

• Prepares body for crisis, producing a “fight or flight”

response

• Stimulates tissue metabolism

• Increases alertness

• Seven Responses to Increased Sympathetic Activity

1. Heightened mental alertness

2. Increased metabolic rate

3. Reduced digestive and urinary functions

4. Energy reserves activated

5. Increased respiratory rate and respiratory passageways dilate

6. Increased heart rate and blood pressure

7. Sweat glands activated

• Preganglionic fibers originate in brain stem and sacral

segments of spinal cord; craniosacral

• Synapse in ganglia close to (or within) target organs

• Preganglionic fibers are long

• Postganglionic fibers are short

• Parasympathetic division stimulates visceral activity

• Conserves energy and promotes sedentary activities

• Five Responses to Increased Parasympathetic

Activity

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. Urination and defecation stimulation

Figure 16-5 The Distribution of Sympathetic Innervation

Preganglionic neuronsGanglionic neurons

Gray rami tospinal nerves

Cervicalsympathetic

ganglia

Superior

Middle

Inferior

Sympathetic nerves

Cardiac andpulmonary plexuses(see Figure 16-10)

Salivaryglands

Coccygealganglia (Co1)

fused together

Superiormesenteric

ganglion

Splanchnicnerves

Uterus Ovary

Greatersplanchnicnerve

Celiac ganglion

Inferiormesentericganglion

Penis Scrotum Urinary bladder

Liver and gallbladder

Stomach

SpleenPancreas

Largeintestine

Smallintestine

AdrenalmedullaKidney

Spinal cord

Sympatheticchain ganglia

Postganglionic fibersto spinal nerves

(innervating skin,blood vessels,sweat glands,

arrector pili muscles,adipose tissue)

16-2 The Sympathetic Division

• Sympathetic Activation

• Change activities of tissues and organs by:

• Releasing NE at peripheral synapses

• Target specific effectors, smooth muscle fibers in

blood vessels of skin

• Are activated in reflexes

• Do not involve other visceral effectors

• Sympathetic Activation

• Changes activities of tissues and organs by:

• Distributing E and NE throughout body in bloodstream

• Entire division responds (sympathetic activation)

• Are controlled by sympathetic centers in

hypothalamus

• Effects are not limited to peripheral tissues

• Alters CNS activity

• Changes Caused by Sympathetic Activation

• Increased alertness

• Feelings of energy and euphoria

• Change in breathing

• Elevation in muscle tone

• Mobilization of energy reserves

Figure 16-8 The Distribution of Parasympathetic Innervation

N X (Vagus)

Otic ganglion

Ciliary ganglion

Pterygopalatine ganglion

Submandibular ganglion

Lacrimal gland

Salivary glands

Figure 16-8 The Distribution of Parasympathetic Innervation

Liver andgallbladder

Stomach

Spleen

Pancreas

LargeintestineSmallintestineRectum

Kidney

Uterus Ovary Penis Scrotum

Urinary bladder

Spinalcord

Pelvicnerves

Autonomic plexuses(see Figure 16-10)

16-4 The Parasympathetic Division

• Parasympathetic Activation

• Centers on relaxation, food processing, and

energy absorption

• Localized effects, last a few seconds at most

• Major Effects of Parasympathetic Division

• Constriction of the pupils

• (To restrict the amount of light that enters the eyes)

• And focusing of the lenses of the eyes on nearby objects

• Secretion by digestive glands

• Including salivary glands, gastric glands, duodenal

glands, intestinal glands, the pancreas (exocrine and

endocrine), and the liver

• Secretion of hormones

• That promote the absorption and utilization of nutrients

by peripheral cells

• Changes in blood flow and glandular activity

• Associated with sexual arousal

• Increase in smooth muscle activity

• Along the digestive tract

• Stimulation and coordination of defecation

• Contraction of the urinary bladder during urination

• Constriction of the respiratory passageways

• Reduction in heart rate and in the force of contraction

16-6 Dual Innervation

• Widespread impact

• Reaches organs and tissues throughout body

• Innervates only specific visceral structures

• Sympathetic and Parasympathetic Division

• Most vital organs receive instructions from both

sympathetic and parasympathetic divisions

• Two divisions commonly have opposing effects

Figure 16-9 Summary: The Anatomical Differences between the Sympathetic and Parasympathetic Divisions

KEYNeurotransmitters

Epinephrine

Norepinephrine

Acetylcholine

Parasympatheticganglion

TARGET

Circulatorysystem

Sympatheticganglion

Postganglionicfiber

Ganglionicneurons

Preganglionicneuron

Preganglionicfiber

Sympathetic Parasympathetic

16-7 Visceral Reflexes Regulate the ANS

• Higher Levels of Autonomic Control

• Simple reflexes from spinal cord provide rapid and automatic responses

• Complex reflexes coordinated in medulla oblongata

• Contains centers and nuclei involved in:

• Salivation

• Swallowing

• Digestive secretions

• Peristalsis

• Urinary function

• Regulated by hypothalamus

Figure 16-12 A Comparison of Somatic and Autonomic Function

CentralNervousSystem

PeripheralNervousSystem SNS ANS

Cerebral cortex

Thalamus

Somatic sensory

Hypothalamus

Limbicsystem

Visceralsensory

Relay and processing centers in brain stem

Somaticreflexes

Longreflexes

Lower motorneuron

PreganglionicneuronSensory

pathways

Shortreflexes

Ganglionicneuron

Skeletalmuscles

Sensoryreceptors

Visceraleffectors

Figure 16-13 Memory Storage

Sensoryinput

Repetitionpromotesretention

Consolidation

Permanent loss dueto neural fatigue,shock, interferenceby other stimuli

Temporary loss

Permanent loss

• Cerebral cortex (fact memory)• Cerebral cortex and cerebellar cortex (skill memory)

Short-termMemory

Long-term Memory

SecondaryMemory

TertiaryMemory

© 2012 pearson education, inc. figure 15-1 an overview of neural integration chapter 15chapter 16...

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