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Nervous System
 

Nervous System

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    Nervous System Nervous System Presentation Transcript

    • PowerPoint Lecture Outlines to accompany Hole’s Human Anatomy and Physiology Eleventh Edition Shier  Butler  Lewis Chapter 11 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
    • Chapter 11 Nervous System II
      • Meninges
        • membranes surrounding CNS
        • protect CNS
        • three layers
          • dura mater – outer, tough
          • arachnoid mater – thin, weblike
          • pia mater – inner, very thin
    • Meninges of the Spinal Cord
    • Ventricles
      • interconnected cavities
      • within cerebral hemispheres and brain stem
      • continuous with central canal of spinal cord
      • filled with cerebrospinal fluid (CSF)
      • lateral ventricles
      • third ventricle
      • fourth ventricle
      • cerebral aqueduct
    • Cerebrospinal Fluid
      • secreted by choroid plexus
      • circulates in ventricles, central canal of spinal cord, and subarachnoid space
      • completely surrounds brain and spinal cord
      • clear liquid
      • nutritive and protective
      • helps maintain stable ion concentrations in CNS
    • Spinal Cord
      • slender column of nervous tissue continuous with brain
      • extends downward through vertebral canal
      • begins at level of foramen magnum and terminates near first and second lumbar
    • Cross Section of Spinal Cord
    • Functions of Spinal Cord
      • center for spinal reflexes
      • conduit for nerve impulses to and from the brain
    • Reflex Arcs Reflexes – automatic, subconscious responses to stimuli within or outside the body
    • Reflex Arcs
    • General Components of a Spinal Reflex
    • Reflex Behavior
      • example is the knee-jerk reflex
      • simple monosynaptic reflex
      • helps maintain an upright posture
    • Reflex Behavior
      • example is a withdrawal reflex
      • prevents or limits tissue damage
    • Reflex Arc
      • example crossed extensor reflex
      • crossing of sensory impulses within the reflex center
      • to produce an opposite effect
    • Tracts of the Spinal Cord
      • Ascending tracts conduct sensory impulses to the brain
      • Descending tracts conduct motor impulses from the brain to motor neurons reaching muscles and glands
    • Ascending Tracts
      • major ascending spinal cord tracts
        • fasciculus gracilis and fasciculus cuneatus
        • spinothalamic
          • lateral and anterior
        • spinocerebellar
          • posterior and anterior
    • Descending Tracts
      • major descending spinal cord tracts
        • corticospinal
          • lateral and anterior
        • reticulospinal
          • lateral, anterior and medial
        • rubrospinal
    • Nerve Tracts of the Spinal Cord
    • Brain
      • Functions
        • interprets sensations
        • determines perception
        • stores memory
        • reasoning
        • makes decisions
        • coordinates muscular movements
        • regulates visceral activities
        • determines personality
      • Major Parts
        • cerebrum
          • two hemispheres
        • basal nuclei
        • diencephalon
        • brainstem
        • cerebellum
    • Brain
    • Brain Development
      • Three Major Vesicles
      • Forebrain
      • Midbrain
      • Hindbrain
    • Brain Development
    • Structure of Cerebrum
      • corpus callosum
        • connects cerebral hemispheres
      • convolutions
        • bumps or gyri
      • sulci
        • grooves
      • longitudinal fissure
        • separates hemispheres
      • transverse fissure
        • separates cerebrum from cerebellum
    • Lobes of Cerebral Hemispheres
      • Frontal
      • Parietal
      • Temporal
      • Occipital
      • Insula
    • Functions of the Cerebrum
      • interpreting impulses
      • initiating voluntary movements
      • storing information as memory
      • retrieving stored information
      • reasoning
      • seat of intelligence and personality
    • Functional Regions of Cerebral Cortex Cerebral Cortex – thin layer of gray matter that constitutes the outermost portion of cerebrum; contains 75% of all neurons in nervous system
    • Sensory Areas
      • Cutaneous Sensory Area
        • parietal lobe
        • interprets sensations on skin
      • Visual Area
        • occipital lobe
        • interprets vision
      • Auditory Area
        • temporal lobe
        • interprets hearing
      • Sensory Area for Taste
        • near bases of the central sulci
        • Sensory Area for Smell
              • arise from centers deep within the cerebrum
    • Sensory Areas
    • Association Areas
      • regions that are not primary motor or primary sensory areas
      • widespread throughout the cerebral cortex
      • analyze and interpret sensory experiences
      • provide memory, reasoning, verbalization, judgment, emotions
    • Association Areas
      • Frontal Lobe Association Areas
        • concentrating
        • planning
        • complex problem solving
      • Parietal Lobe Association Areas
        • understanding speech
        • choosing words to express thought
      • Temporal Lobe Association Areas
        • interpret complex sensory
        • experiences
        • store memories of visual scenes,
        • music, and complex patterns
      • Occipital Lobe Association Areas
        • analyze and combine visual images with other sensory experiences
    • Hemisphere Dominance
      • The left hemisphere is dominant is most individuals
      • Dominant hemisphere controls
        • speech
        • writing
        • reading
        • verbal skills
        • analytical skills
        • computational skills
      • Nondominant hemisphere controls
        • nonverbal tasks
        • motor tasks
        • understanding and interpreting musical and visual patterns
        • provides emotional and intuitive thought processes
    • Memory
      • Short Term
        • working memory
        • closed neuronal circuit
        • circuit is stimulated over and over
        • when impulse flow ceases, memory does also
          • unless it enters long-term memory via memory consolidation
      • Long Term
        • changes structure or function of neurons
        • enhances synaptic transmission
    • Motor Areas
      • Primary Motor Areas
        • frontal lobes
        • control voluntary muscles
      • Broca’s Area
        • anterior to primary motor cortex
        • usually in left hemisphere
        • controls muscles needed for speech
      • Frontal Eye Field
        • above Broca’s area
        • controls voluntary movements of eyes and eyelids
    • Motor Areas
    • Functions of the Cerebral Lobes
    • Basal Nuclei
      • masses of gray matter
      • deep within cerebral hemispheres
      • caudate nucleus , putamen , globus pallidus
      • produce dopamine
      • control certain muscular activities
        • primarily by inhibiting motor functions
    • Diencephalon
      • between cerebral hemispheres and above the brainstem
      • surrounds third ventricle
      • thalamus
      • hypothalamus
      • optic tracts
      • optic chiasma
      • infundibulum
      • posterior pituitary
      • mammillary bodies
      • pineal gland
    • Diencephalon
      • Thalamus
        • gateway for sensory impulses heading to cerebral cortex
        • receives all sensory impulses (except smell)
        • channels impulses to appropriate part of cerebral cortex for interpretation
      • Hypothalamus
        • maintains homeostasis by regulating visceral activities
        • links nervous and endocrine systems
    • Diencephalon
      • Consists of
        • portions of frontal lobe
        • portions of temporal lobe
        • hypothalamus
        • thalamus
        • basal nuclei
        • other deep nuclei
      • Functions
        • controls emotions
        • produces feelings
        • interprets sensory impulses
      Limbic System
    • Brain Stem
      • Three Parts
      • Midbrain
      • Pons
      • Medulla Oblongata
    • Midbrain
      • between diencephalon and pons
      • contains bundles of fibers that join lower parts of brainstem and spinal cord with higher part of brain
      • cerebral aqueduct
      • cerebral peduncles – bundles of nerve fibers
      • corpora quadrigemina – centers for visual and auditory reflexes
    • Pons
      • rounded bulge on underside of brainstem
      • between medulla oblongata and midbrain
      • helps regulate rate and depth of breathing
      • relays nerve impulses to and from medulla oblongata and cerebellum
    • Medulla Oblongata
      • enlarged continuation of spinal cord
      • conducts ascending and descending impulses between brain and spinal cord
      • contains cardiac, vasomotor, and respiratory control centers
      • contains various nonvital reflex control centers (coughing, sneezing, swallowing, vomiting)
    • Reticular Formation
      • complex network of nerve fibers scattered throughout the brain stem
      • extends into the diencephalon
      • connects to centers of hypothalamus, basal nuclei, cerebellum, and cerebrum
      • filters incoming sensory information
      • arouses cerebral cortex into state of wakefulness
    • Types of Sleep
      • Slow Wave
        • non-REM sleep
        • person is tired
        • decreasing activity of reticular system
        • restful
        • dreamless
        • reduced blood pressure and respiratory rate
        • ranges from light to heavy
        • alternates with REM sleep
      • Rapid Eye Movement (REM)
        • paradoxical sleep
        • some areas of brain active
        • heart and respiratory rates irregular
        • dreaming occurs
    • Cerebellum
      • inferior to occipital lobes
      • posterior to pons and medulla oblongata
      • two hemispheres
      • vermis connects hemispheres
      • cerebellar cortex – gray matter
      • arbor vitae – white matter
      • cerebellar peduncles – nerve fiber tracts
      • dentate nucleus – largest nucleus in cerebellum
      • integrates sensory information concerning position of body parts
      • coordinates skeletal muscle activity
      • maintains posture
    • Major Parts of the Brain
    • Peripheral Nervous System
      • Cranial nerves arising from the brain
        • Somatic fibers connecting to the skin and skeletal muscles
        • Autonomic fibers connecting to viscera
      • Spinal nerves arising from the spinal cord
        • Somatic fibers connecting to the skin and skeletal muscles
        • Autonomic fibers connecting to viscera
    • Nervous System Subdivisions
    • Structure of a Peripheral Nerve
    • Nerve Fiber Classification
      • Sensory Nerves – conduct impulses into brain or spinal cord
      • Motor Nerves – conduct impulses to muscles or glands
      • Mixed Nerves – contain both sensory nerve fibers and motor nerve fibers; most nerves
    • Nerve Fiber Classification
      • General somatic efferent fibers
        • carry motor impulses from CNS to skeletal muscles
      • General visceral efferent fibers
        • carry motor impulses away from CNS to smooth muscles and glands
      • General somatic afferent fibers
        • carry sensory impulses to CNS from skin and skeletal muscles
      • General visceral afferent fibers
        • carry sensory impulses to CNS from blood vessels and internal organs
    • Nerve Fiber Classification
      • Special somatic efferent fibers
        • carry motor impulses from brain to muscles used in chewing, swallowing, speaking, and forming facial expressions
      • Special visceral afferent fibers
        • carry sensory impulses to brain from olfactory and taste receptors
      • Special somatic afferent fibers
        • carry sensory impulses to brain from receptors of sight, hearing, and equilibrium
    • Cranial Nerves
    • Cranial Nerves I and II
      • Olfactory (I)
        • sensory
        • fibers transmit impulses associated with smell
      • Optic (II)
        • sensory
        • fibers transmit impulses associated with vision
    • Cranial Nerves III and IV
      • Trochlear (IV)
        • some sensory
          • proprioreceptors
        • primarily motor
        • motor impulses to muscles that move the eyes
      • Oculomotor (III)
        • some sensory
          • proprioreceptors
        • primarily motor
        • motor impulses to muscles that
          • raise eyelids
          • move the eyes
          • focus lens
          • adjust light entering eye
    • Cranial Nerve V
      • Trigeminal (V)
        • mixed
        • opthalmic division
          • sensory from surface of eyes, tear glands, scalp, forehead, and upper eyelids
        • maxillary division
          • sensory from upper teeth, upper gum, upper lip, palate, and skin of face
        • mandibular division
          • sensory from scalp, skin of jaw, lower teeth, lower gum, and lower lip
          • motor to muscles of mastication and muscles in floor of mouth
    • Cranial Nerves VI and VII
      • Abducens (VI)
        • primarily motor
        • motor impulses to muscles that move the eyes
        • some sensory with proprioreceptors
      • Facial (VII)
        • mixed
        • sensory from taste receptors
        • motor to muscles of facial expression, tear glands, and salivary glands
    • Cranial Nerves VIII and IX
      • Vestibulocochlear (VIII)
        • sensory
        • vestibular branch
          • sensory from equilibrium receptors of ear
        • cochlear branch
          • sensory from hearing receptors
      • Glossopharyngeal (IX)
        • mixed
        • sensory from pharynx, tonsils, tongue, and carotid arteries
        • motor to salivary glands and muscles of pharynx
    • Cranial Nerve X
      • Vagus (X)
        • mixed
        • somatic motor to muscles of speech and swallowing
        • autonomic motor to viscera of thorax and abdomen
        • sensory from pharynx, larynx, esophagus, and viscera of thorax and abdomen
    • Cranial Nerves XI and XII
      • Accessory (XI)
        • primarily motor
        • cranial branch
          • motor to muscles of soft palate, pharynx, and larynx
        • spinal branch
          • motor to muscles of neck, and back; some proprioreceptor
      • Hypoglossal (XII)
        • primarily motor
        • motor to muscles of the tongue; some proprioreceptor
    • Functions of Cranial Nerves
    • Spinal Nerves
      • mixed nerves
      • 31 pairs
        • 8 cervical
          • (C1 to C8)
        • 12 thoracic
          • (T1 to T12)
        • 5 lumbar
          • (L1 to L5)
        • 5 sacral
          • (S1 to S5)
        • 1 coccygeal
          • (Co)
    • Spinal Nerves
      • Dorsal root (posterior or sensory root)
        • axons of sensory neurons in the dorsal root ganglion
      • Dorsal root ganglion
        • cell bodies of sensory neurons whose axons conduct impulses inward from peripheral body parts
    • Dermatome
      • an area of skin that the sensory nerve fibers of a particular spinal nerve innervate
    • Spinal Nerves
      • Ventral root (anterior or motor root)
        • axons of motor neurons whose cell bodies are in spinal cord
      • Spinal nerve
        • union of ventral root and dorsal root
    • Cervical Plexuses Nerve plexus – complex networks formed by anterior branches of spinal nerves; fibers of various spinal nerves are sorted and recombined
      • Cervical Plexus
        • formed by anterior branches of C1-C4
        • lies deep in the neck
        • supply muscles and skin of the neck
        • C3 – C5 contribute to phrenic nerves
    • Brachial Plexuses
      • C5-T1
      • lies deep within shoulders
      • musculocutaneous nerves
        • supply muscles of anterior arms and skin of forearms
      • ulnar and median nerves
        • supply muscles of forearms and hands
        • supply skin of hands
      • radial nerves
        • supply posterior muscles of arms and skin of forearms and hands
      • axillary nerves
        • supply muscles and skin of anterior, lateral, and posterior arms
    • Lumbosacral Plexuses
      • T12 – S5
      • extend from lumbar region into pelvic cavity
      • obturator nerves
        • supply motor impulses to adductors of thighs
      • femoral nerves
        • supply motor impulses to muscles of anterior thigh and sensory impulses from skin of thighs and legs
      • sciatic nerves
        • supply muscles and skin of thighs, legs, and feet
    • Plexuses
    • Autonomic Nervous System
      • functions without conscious effort
      • controls visceral activities
      • regulates smooth muscle, cardiac muscle, and glands
      • efferent fibers typically lead to ganglia outside CNS
      • Two Divisions
        • sympathetic – prepares body for fight or flight situations
        • parasympathetic – prepares body for resting and digesting activities
    • Autonomic Nerve Fibers
      • all are neurons are motor (efferent)
      • preganglionic fibers
        • axons of preganglionic neurons
        • neuron cell bodies in CNS
      • postganglionic fibers
        • axons of postganglionic neurons
        • neuron cell bodies in ganglia
    • Sympathetic Division
      • thoracolumbar divison – location of preganglionic neurons
      • preganglionic fibers leave spinal nerves through white rami and enter paravertebral ganglia
      • paraverterbral ganglia and fibers that connect them make up the sympathetic trunk
    • Sympathetic Division
      • postganglionic fibers extend from sympathetic ganglia to visceral organs
      • postganglionic fibers usually pass through gray rami and return to a spinal nerve before proceeding to an effector
      • Exception: preganglionic fibers to adrenal medulla do not synapse with postganglionic neurons
    • Sympathetic Division
    • Parasympathetic Division
      • craniosacral division – location of preganglionic neurons
      • ganglia are near or within various organs
        • terminal ganglia
      • short postganglionic fibers
        • continue to specific muscles or glands
      • preganglionic fibers of the head are included in nerves III, VII, and IX
      • preganglionic fibers of thorax and abdomen are parts of nerve X
    • Parasympathetic Division
    • Autonomic Neurotransmitters
      • Cholinergic Fibers
        • release acetylcholine
        • preganglionic sympathetic and parasympathetic fibers
        • postganglionic parasympathetic fibers
      • Adrenergic Fibers
        • release norepinephrine
        • most postganglionic sympathetic fibers
    • Actions of Autonomic Neurotransmitters
      • depend on receptors in the membrane
      • Cholinergic receptors
        • bind to acetlycholine
        • muscarinic
          • excitatory
          • slow
        • nicotinic
          • excitatory
          • rapid
      • Adrenergic Receptors
        • bind to epinephrine and norepinephrine
        • alpha and beta
          • both elicit different responses on various effectors
    • Insert figure 11.39 Actions of Autonomic Neurotransmitters
    • Control of Autonomic Activity
      • Controlled largely by CNS
      • Medulla oblongata regulates cardiac, vasomotor and respiratory activities
      • Hypothalamus regulates visceral functions, such as body temperature, hunger, thirst, and water and electrolyte balance
      • Limbic system and cerebral cortex control emotional responses
    • Life-Span Changes
      • Brain cells begin to die before birth
      • Over average lifetime, brain shrinks 10%
      • Most cell death occurs in temporal lobes
      • By age 90, frontal cortex has lost half its neurons
      • Number of dendritic branches decreases
      • Decreased levels of neurotransmitters
      • Fading memory
      • Slowed responses and reflexes
      • Increased risk of falling
      • Changes in sleep patterns that result in fewer sleeping hours
    • Clinical Application Cerebral Injuries and Abnormalities
      • Concussion
        • brain jarred against cranium
        • loss of consciousness
        • temporary loss of memory
        • mental cloudiness
        • headache
        • recovery usually complete
      • Cerebral Palsy
        • motor impairment at birth
        • caused by blocked cerebral blood vessels during development
        • seizures
        • learning disabilities
      • Cerebrovascular Accident
        • stroke
        • sudden interruption in blood flow
        • brain tissues die