Download Chapter 14

Anatomy and Physiology, Sixth Edition
Rod R. Seeley
Idaho State University
Trent D. Stephens
Idaho State University
Philip Tate
Phoenix College
Chapter 14
Lecture Outline*
*See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes.
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Chapter 14
Integration of
Nervous System Functions
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Sensation
• Senses: Means by which brain receives
information about environment and body
– General: Distributed over large part of body
• Somatic: Touch, pressure, temperature, proprioception, pain
• Visceral: Internal organs and consist mostly of pain and
pressure
– Special senses: Smell, taste, sight, hearing, balance
• Sensation or perception: Conscious awareness of
stimuli received by sensory receptors
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Types of Sensory Receptors
• Mechanoreceptors: Compression, bending,
stretching of cells
• Chemoreceptors: Smell and taste
• Thermoreceptors: Temperature
• Photoreceptors: Light as vision
• Nociceptors: Pain
• Exteroreceptors: Associated with skin
• Visceroreceptors: Associated with organs
• Proprioceptors: Associated with joints, tendons
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Sensory Nerve Endings
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Free nerve endings: Cold receptors and warm
Merkel’s disk: Light touch, superficial pressure
Hair follicle receptor: Light touch, bending of hair
Pacinian corpuscle: Deep cutaneous pressure,
vibration and proprioception
Meissner’s corpuscle: Two-point discrimination
Ruffini’s end organ: Continuous touch or pressure
Muscle spindle: Proprioception as to muscle
stretch and control of muscle tone
Golgi tendon organ: Important in muscle
contraction and tendon stretch proprioception
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Sensory Nerve Endings in Skin
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Two-Point Discrimination
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Muscle Spindle and
Golgi Tendon Organ
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Responses of Sensory Receptors
• Receptor: Interaction of stimulus with sensory
receptor produces a local potential
– Primary: Have axons that conduct action potential in
response to receptor potential
– Secondary: Have no axons and receptor potentials
produced do not result in action potentials but cause
release of neurotransmitters
• Accommodation or adaptation: Decreased
sensitivity to a continued stimulus
• Proprioceptors
– Tonic: Example is know where little finger is without
looking
– Phasic: Example is you know where hand is as it moves
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Sensory Nerve Tracts
• Transmit action
potentials from
periphery to brain
• Each pathway
involved with specific
modalities
• First half of word
indicates origin,
second half indicates
termination
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Spinothalamic System
• Conveys cutaneous
sensory information to
brain
• Unable to localize source
of stimulus
• Divisions
– Lateral for pain and
temperature
– Anterior for light touch,
pressure, tickle, itch
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Dorsal-Column/
Medial-Lemniscal System
• Carries sensations of
– Two-point
discrimination
– Proprioception
– Pressure
– Vibration
• Tracts
– Fasciculus gracilis
– Fasciculus cuneatus
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Spinocerebellar System
• Carry proprioceptive
information to cerebellum
• Actual movements can be
monitored and compared
to cerebral information
representing intended
movement
• Tracts
– Posterior
– Anterior
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Sensory Areas of Cerebral Cortex
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Pain
• Types
– Referred: Sensation in one
region of body that is not
source of stimulus
– Phantom: Occurs in people
who have appendage
amputated or structure
removed as tooth
– Chronic: Not a response to
immediate direct tissue
injury
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Somatic Sensory Cortex
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Primary Motor Cortex
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Descending Spinal Pathways
• Direct
– Control muscle tone and
conscious skilled
movements
– Direct synapse of upper
motor neurons of cerebral
cortex with lower motor
neurons in brainstem or
spinal cord
– Tracts
• Corticospinal
• Lateral
• Anterior corticobulbar
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Descending Spinal Pathways
• Indirect
– Synapse in some
intermediate nucleus
rather than directly
with lower motor
neurons
– Tracts
• Rubrospinal
• Vestibulospinal
• Reticulospinal
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Cerebellar Comparator Function
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Speech
• Speech area normally in left cerebral cortex
– Wernicke’s area: Sensory speech
– Broca’s area: Motor speech
• Aphasia: Absent or defective speech or language
comprehension
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Brain Waves and Sleep
• Electroencephalogram (EEG): Record of brain’s electrical activity
• Brain wave patterns
– Alpha: Resting state with eyes closed
– Beta: During intense mental activity
– Theta: Occur in children but also in adults experiencing frustration or brain
disorders
– Delta: Occur in deep sleep, infancy, and severe brain disorders
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Memory
• Sensory
– Very short-term retention of
sensory input
• Short-term
– Information retained for few
seconds to minutes
• Long-term
– Explicit or declarative
• Retention of facts
• Accessed by hippocampus
and amygdaloid (emotional)
– Implicit or procedural
• Development of skills as
riding a bicycle
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Long-Term Potentiation
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General CNS Disorders
• Infections
– Encephalitis: Inflammation of the brain
– Rabies: Viral disease transmitted by bite of infected
animal
– Multiple sclerosis: Possibly involves autoimmune
response to viral infection
• Other disorders
– Stroke: CVA or cerebrovascular accident caused by
hemorrhage, thrombosis, embolism
– Aneurysm: Dilation or ballooning of an artery
– Alzheimer’s disease: Severe type of dementia
– Epilepsy: Group of brain disorders that have seizures
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Effects of Aging on Nervous
System
• Gradual decline in sensory and motor
function
• Reflexes slow
• Size and weight of brain decrease
– Decreased short-term memory in most people
– Long-term memory unaffected or improved
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