Download Sensory Pathways

Figure 15-1 An Overview of Neural Integration
OVERVIEW OF NEURAL INTEGRATION
CHAPTER 15
Sensory
processing
centers in
brain
Sensory
pathways
CHAPTER 16
Conscious and
subconscious
motor centers
in brain
Motor
pathways
Somatic
Nervous
System (SNS)
General
sensory
receptors
© 2012 Pearson Education, Inc.
Skeletal
muscles
Higher-Order Functions
Memory, learning, and
intelligence may
influence interpretation
of sensory information
and nature of motor
activities
Autonomic
Nervous
System (ANS)
Visceral effectors
(examples: smooth
muscles, 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
© 2012 Pearson Education, Inc.
15-1 Sensory Information
• Sensory Pathways
• Deliver somatic and visceral sensory information to
their final destinations inside the CNS using:
• Nerves
• Nuclei
• Tracts
© 2012 Pearson Education, Inc.
15-1 Sensory Information
• 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
© 2012 Pearson Education, Inc.
15-1 Sensory Information
• Somatic Nervous System (SNS)
• Motor neurons and pathways that control skeletal
muscles
© 2012 Pearson Education, Inc.
15-2 Sensory Receptors
• General Senses
• Describe our sensitivity to:
• Temperature
• Pain
• Touch
• Pressure
• Vibration
• Proprioception
© 2012 Pearson Education, Inc.
15-2 Sensory Receptors
• Sensation
• The arriving information from these senses
• Perception
• Conscious awareness of a sensation
© 2012 Pearson Education, Inc.
15-2 Sensory Receptors
• Special Senses
• Olfaction (smell)
• Vision (sight)
• Gustation (taste)
• Equilibrium (balance)
• Hearing
© 2012 Pearson Education, Inc.
15-2 Sensory Receptors
• 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
© 2012 Pearson Education, Inc.
15-2 Sensory Receptors
• The Interpretation of Sensory Information
• Arriving stimulus reaches cortical neurons via labeled
line
• Takes many forms (modalities)
• Physical force (such as pressure)
• Dissolved chemical
• Sound
• Light
© 2012 Pearson Education, Inc.
15-2 Sensory Receptors
• The Interpretation of Sensory Information
• Sensations
• Taste, hearing, equilibrium, and vision provided by
specialized receptor cells
• Communicate with sensory neurons across chemical
synapses
© 2012 Pearson Education, Inc.
15-2 Sensory Receptors
• Adaptation
• Reduction in sensitivity of a constant stimulus
• Your nervous system quickly adapts to stimuli that
are painless and constant
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
15-3 Classifying Sensory Receptors
• 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
© 2012 Pearson Education, Inc.
15-3 Classifying Sensory Receptors
• 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)
© 2012 Pearson Education, Inc.
15-3 Classifying Sensory Receptors
• 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
pain
© 2012 Pearson Education, Inc.
15-3 Classifying Sensory Receptors
• Nociceptors
•
May be sensitive to:
1. Temperature extremes
2. Mechanical damage
3. Dissolved chemicals, such as chemicals released by
injured cells
© 2012 Pearson Education, Inc.
15-3 Classifying Sensory Receptors
• 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
© 2012 Pearson Education, Inc.
15-3 Classifying Sensory Receptors
• 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
© 2012 Pearson Education, Inc.
15-3 Classifying Sensory Receptors
• 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
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
Figure 15-5 Somatic Sensory Pathways
SPINOTHALAMIC PATHWAY
KEY
Axon of firstorder neuron
Second-order
neuron
Third-order
neuron
Midbrain
The anterior
spinothalamic
tracts of the
spinothalamic
pathway carry
crude touch and
pressure sensations.
Medulla
oblongata
Anterior
spinothalamic
tract
Crude touch and pressure sensations
from right side of body
© 2012 Pearson Education, Inc.
Figure 15-5 Somatic Sensory Pathways
SPINOTHALAMIC PATHWAY
KEY
Axon of firstorder neuron
Second-order
neuron
Third-order
neuron
Midbrain
Medulla
oblongata
Spinal
cord
The lateral
spinothalamic
tracts of the
spinothalamic
pathway carry pain
and temperature
sensations.
Lateral
spinothalamic
tract
Pain and temperature sensations
from right side of body
© 2012 Pearson Education, Inc.
Figure 15-5 Somatic Sensory Pathways
POSTERIOR COLUMN PATHWAY
Ventral nuclei
in thalamus
Midbrain
Nucleus
gracilis and
nucleus
cuneatus
Medial
lemniscus
Medulla
oblongata
Fasciculus
gracilis and
fasciculus
cuneatus
Dorsal root
ganglion
Fine-touch, vibration, pressure, and
proprioception sensations from right
side of body
© 2012 Pearson Education, Inc.
Figure 15-5 Somatic Sensory Pathways
SPINOCEREBELLAR PATHWAY
PONS
Cerebellum
Medulla
oblongata
Spinocerebellar
pathway
Spinal
cord
Posterior
spinocerebellar
tract
Anterior
spinocerebellar
tract
Proprioceptive input from Golgi
tendon organs, muscle spindles,
and joint capsules
© 2012 Pearson Education, Inc.
15-4 Sensory Pathways
• 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
© 2012 Pearson Education, Inc.
15-4 Sensory Pathways
• 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
© 2012 Pearson Education, Inc.
15-4 Sensory Pathways
• Visceral Sensory Pathways
• Interoceptors include:
• Nociceptors
• Thermoreceptors
• Tactile receptors
• Baroreceptors
• Chemoreceptors
© 2012 Pearson Education, Inc.
15-4 Sensory Pathways
• Visceral Sensory Pathways
• Cranial Nerves V, VII, IX, and X
• Carry visceral sensory information from mouth, palate,
pharynx, larynx, trachea, esophagus, and associated
vessels and glands
© 2012 Pearson Education, Inc.
15-5 Somatic Motor Pathways
• The Somatic Nervous System (SNS)
• Also called the somatic motor system
• Controls contractions of skeletal muscles (discussed
next)
• The Autonomic Nervous System (ANS)
• Also called the visceral motor system
• Controls visceral effectors, such as smooth muscle,
cardiac muscle, and glands (Ch. 16)
© 2012 Pearson Education, Inc.
15-5 Somatic Motor Pathways
• Somatic Motor Pathways
•
Always involve at least two motor neurons
1. Upper motor neuron
2. Lower motor neuron
© 2012 Pearson Education, Inc.
15-5 Somatic Motor Pathways
• 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
© 2012 Pearson Education, Inc.
15-5 Somatic Motor Pathways
• Lower Motor Neuron
• Cell body lies in a nucleus of the brain stem or spinal
cord
• 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
© 2012 Pearson Education, Inc.
15-5 Somatic Motor Pathways
• 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
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
Figure 16-1 An Overview of Neural Integration
OVERVIEW OF NEURAL INTEGRATION
CHAPTER 16
CHAPTER 15
Sensory
processing
centers in
brain
Sensory
pathways
Conscious and
subconscious
motor centers
in brain
© 2012 Pearson Education, Inc.
Memory, learning, and
intelligence may
influence interpretation
of sensory information
and nature of motor
activities
Motor
pathways
Somatic
Nervous
System (SNS)
General
sensory
receptors
Higher-Order Functions
Skeletal
muscles
Autonomic
Nervous
System (ANS)
Visceral effectors
(examples: smooth
muscle, glands,
cardiac muscle,
adipocytes)
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
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
Figure 16-2a The Organization of the Somatic and Autonomic Nervous Systems
Upper motor
neurons in
primary motor
cortex
BRAIN
Somatic motor
nuclei of brain
stem
Skeletal
muscle
Lower
motor
neurons
SPINAL
CORD
Somatic
motor nuclei
of spinal cord
Skeletal
muscle
Somatic nervous system
© 2012 Pearson Education, Inc.
Figure 16-2b The Organization of the Somatic and Autonomic Nervous Systems
Visceral motor
nuclei in
hypothalamus
BRAIN
Preganglionic
neuron
Visceral Effectors
Smooth
muscle
Glands
Cardiac
muscle
Autonomic
ganglia
Ganglionic
neurons
Adipocytes
Preganglionic
neurons
Autonomic
nuclei in
brain stem
SPINAL
CORD
Autonomic
nuclei in
spinal cord
Autonomic nervous system
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
16-1 Divisions of the ANS
• Sympathetic Division
• “Kicks in” only during exertion, stress, or
emergency
• “Fight or flight”
• Parasympathetic Division
• Controls during resting conditions
• “Rest and digest”
© 2012 Pearson Education, Inc.
16-1 Divisions of the ANS
• 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
© 2012 Pearson Education, Inc.
16-1 Divisions of the ANS
• Sympathetic Division
• 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
© 2012 Pearson Education, Inc.
16-1 Divisions of the ANS
• 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
© 2012 Pearson Education, Inc.
16-1 Divisions of the ANS
• Parasympathetic Division
• 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
© 2012 Pearson Education, Inc.
16-1 Divisions of the ANS
• 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
© 2012 Pearson Education, Inc.
Figure 16-5 The Distribution of Sympathetic Innervation
PONS
Superior
Cervical
sympathetic
ganglia
Middle
Inferior
T1
Gray rami to
spinal nerves
KEY
Preganglionic neurons
Ganglionic neurons
© 2012 Pearson Education, Inc.
T1
Figure 16-5 The Distribution of Sympathetic Innervation
Eye
PONS
Salivary
glands
Sympathetic nerves
Heart
Cardiac and
pulmonary plexuses
(see Figure 16-10)
T1
KEY
Preganglionic neurons
Ganglionic neurons
© 2012 Pearson Education, Inc.
Lung
Figure 16-5 The Distribution of Sympathetic Innervation
T1
Greater
splanchnic
nerve
KEY
Preganglionic neurons
Ganglionic neurons
Celiac ganglion
Superior
mesenteric
ganglion
Liver and
gallbladder
Stomach
Splanchnic
nerves
Spleen
Pancreas
Inferior
mesenteric
ganglion
L2
Large
intestine
Small
intestine
Adrenal
medulla
Kidney
Coccygeal
ganglia (Co1)
fused together
© 2012 Pearson Education, Inc.
Uterus Ovary
Penis Scrotum Urinary bladder
Figure 16-5 The Distribution of Sympathetic Innervation
Postganglionic fibers
to spinal nerves
(innervating skin,
blood vessels,
sweat glands,
arrector pili muscles,
adipose tissue)
Sympathetic
chain ganglia
L2
Spinal cord
KEY
Preganglionic neurons
Ganglionic neurons
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
16-2 The Sympathetic Division
• 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
© 2012 Pearson Education, Inc.
16-2 The Sympathetic Division
• Changes Caused by Sympathetic Activation
• Increased alertness
• Feelings of energy and euphoria
• Change in breathing
• Elevation in muscle tone
• Mobilization of energy reserves
© 2012 Pearson Education, Inc.
Figure 16-8 The Distribution of Parasympathetic Innervation
Pterygopalatine ganglion
N III
Lacrimal gland
Eye
Ciliary ganglion
PONS
N VII
N IX
Submandibular
ganglion
Salivary glands
Otic ganglion
N X (Vagus)
Heart
KEY
Preganglionic neurons
Ganglionic neurons
© 2012 Pearson Education, Inc.
Lungs
Figure 16-8 The Distribution of Parasympathetic Innervation
KEY
Preganglionic neurons
Ganglionic neurons
Lungs
Autonomic plexuses
(see Figure 16-10)
Liver and
gallbladder
Stomach
Spleen
Pancreas
Large
intestine
Small
intestine
Rectum
Pelvic
nerves
Spinal
cord
Kidney
S2
S3
S4
Uterus Ovary
© 2012 Pearson Education, Inc.
Penis
Scrotum
Urinary bladder
16-4 The Parasympathetic Division
• Parasympathetic Activation
• Centers on relaxation, food processing, and
energy absorption
• Localized effects, last a few seconds at most
© 2012 Pearson Education, Inc.
16-4 The Parasympathetic Division
• 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
© 2012 Pearson Education, Inc.
16-4 The Parasympathetic Division
• Major Effects of Parasympathetic Division
• 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
© 2012 Pearson Education, Inc.
16-4 The Parasympathetic Division
• Major Effects of Parasympathetic Division
• 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
© 2012 Pearson Education, Inc.
16-6 Dual Innervation
• Sympathetic Division
• Widespread impact
• Reaches organs and tissues throughout body
• Parasympathetic Division
• 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
© 2012 Pearson Education, Inc.
Figure 16-9 Summary: The Anatomical Differences between the Sympathetic and Parasympathetic Divisions
Sympathetic
CNS
Parasympathetic
Preganglionic
neuron
PNS
Preganglionic
fiber
Sympathetic
ganglion
KEY
Neurotransmitters
Acetylcholine
Norepinephrine
or
Epinephrine
Ganglionic
neurons
Circulatory
system
Postganglionic
fiber
TARGET
© 2012 Pearson Education, Inc.
Parasympathetic
ganglion
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
© 2012 Pearson Education, Inc.
Figure 16-12 A Comparison of Somatic and Autonomic Function
Central
Nervous
System
Cerebral cortex
Limbic
system
Thalamus
Hypothalamus
Somatic sensory
Visceral
sensory
Relay and processing centers in brain stem
Long
reflexes
Somatic
reflexes
Peripheral
Nervous
SNS
System
Lower motor
neuron
Sensory
pathways
Preganglionic
neuron
ANS
Short
reflexes
Ganglionic
neuron
Skeletal
muscles
© 2012 Pearson Education, Inc.
Sensory
receptors
Visceral
effectors
Figure 16-13 Memory Storage
Repetition
promotes
retention
Sensory
input
Short-term
Memory
Long-term Memory
Consolidation
Secondary
Memory
Tertiary
Memory
• Cerebral cortex (fact memory)
• Cerebral cortex and cerebellar
cortex (skill memory)
Temporary loss
Permanent loss due
to neural fatigue,
shock, interference
by other stimuli
© 2012 Pearson Education, Inc.
Permanent loss