PowerPoint Lecture Outlines to accompany Hole’s Human Anatomy and Physiology Eleventh Edition Shier w Butler w Lewis Chapter Copyright © The McGraw-Hill Companies, Inc.
Download ReportTranscript PowerPoint Lecture Outlines to accompany Hole’s Human Anatomy and Physiology Eleventh Edition Shier w Butler w Lewis Chapter Copyright © The McGraw-Hill Companies, Inc.
PowerPoint Lecture Outlines to accompany Hole’s Human Anatomy and Physiology Eleventh Edition Shier w Butler w Lewis Chapter 11 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 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 2 Meninges of the Spinal Cord 3 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 4 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 5 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 6 Cross Section of Spinal Cord 7 Functions of Spinal Cord • center for spinal reflexes • conduit for nerve impulses to and from the brain 8 Reflex Arcs Reflexes – automatic, subconscious responses to stimuli within or outside the body 9 Reflex Arcs 10 General Components of a Spinal Reflex 11 Reflex Behavior • example is the knee-jerk reflex • simple monosynaptic reflex • helps maintain an upright posture 12 Reflex Behavior • example is a withdrawal reflex • prevents or limits tissue damage 13 Reflex Arc • example crossed extensor reflex • crossing of sensory impulses within the reflex center to produce an opposite effect 14 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 15 Ascending Tracts • major ascending spinal cord tracts • fasciculus gracilis and fasciculus cuneatus • spinothalamic • lateral and anterior • spinocerebellar • posterior and anterior 16 Descending Tracts • major descending spinal cord tracts • corticospinal • lateral and anterior • reticulospinal • lateral, anterior and medial • rubrospinal 17 Nerve Tracts of the Spinal Cord 18 Brain Functions Major Parts • interprets sensations • cerebrum • two hemispheres • determines perception • basal nuclei • stores memory • diencephalon • reasoning • brainstem • makes decisions • cerebellum • coordinates muscular movements • regulates visceral activities • determines personality 19 Brain 20 Brain Development Three Major Vesicles 1. Forebrain 2. Midbrain 3. Hindbrain 21 Brain Development 22 Structure of Cerebrum • corpus callosum • connects cerebral hemispheres • convolutions • bumps or gyri • sulci • grooves • longitudinal fissure • separates hemispheres • transverse fissure • separates cerebrum from cerebellum 23 Lobes of Cerebral Hemispheres • Frontal • Parietal • Temporal • Occipital • Insula 24 Functions of the Cerebrum • interpreting impulses • initiating voluntary movements • storing information as memory • retrieving stored information • reasoning • seat of intelligence and personality 25 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 26 Sensory Areas • Cutaneous Sensory Area • parietal lobe • interprets sensations on skin • Visual Area • occipital lobe • interprets vision • Auditory Area • Sensory Area for Taste • near bases of the central sulci • Sensory Area for Smell • arise from centers deep within the cerebrum • temporal lobe • interprets hearing 27 Sensory Areas 28 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 29 Association Areas Frontal Lobe Association Areas • concentrating • planning • complex problem solving Temporal Lobe Association Areas • interpret complex sensory experiences • store memories of visual scenes, music, and complex patterns Parietal Lobe Association Areas • understanding speech • choosing words to express thought Occipital Lobe Association Areas • analyze and combine visual images with other sensory experiences 30 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 31 Memory Short Term • working memory • closed neuronal circuit • circuit is stimulated over and over • when impulse flow ceases, memory does also • unless it enters longterm memory via memory consolidation Long Term • changes structure or function of neurons • enhances synaptic transmission 32 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 33 Motor Areas 34 Functions of the Cerebral Lobes 35 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 36 Diencephalon • between cerebral hemispheres and above the brainstem • surrounds third ventricle • thalamus • hypothalamus • optic tracts • optic chiasma • infundibulum • posterior pituitary • mammillary bodies • pineal gland 37 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 38 Diencephalon Limbic System 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 39 Brain Stem Three Parts 1. Midbrain 2. Pons 3. Medulla Oblongata 40 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 41 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 42 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) 43 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 44 Types of Sleep Slow Wave Rapid Eye Movement (REM) • non-REM sleep • paradoxical sleep • person is tired • some areas of brain active • decreasing activity of • heart and respiratory rates reticular system irregular • restful • dreaming occurs • dreamless • reduced blood pressure and respiratory rate • ranges from light to heavy • alternates with REM sleep 45 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 46 Major Parts of the Brain 47 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 48 Nervous System Subdivisions 49 Structure of a Peripheral Nerve 50 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 51 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 52 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 53 Cranial Nerves 54 Cranial Nerves I and II Olfactory (I) • sensory • fibers transmit impulses associated with smell Optic (II) • sensory • fibers transmit impulses associated with vision 55 Cranial Nerves III and IV Oculomotor (III) • some sensory • proprioreceptors • primarily motor • motor impulses to muscles that • raise eyelids • move the eyes • focus lens •adjust light entering eye Trochlear (IV) • some sensory • proprioreceptors • primarily motor • motor impulses to muscles that move the eyes 56 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 57 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 58 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 59 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 60 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 61 Functions of Cranial Nerves 62 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) 63 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 64 Dermatome • an area of skin that the sensory nerve fibers of a particular spinal nerve innervate 65 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 66 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 67 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 68 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 69 Plexuses 70 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 71 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 72 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 73 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 74 Sympathetic Division 75 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 76 Parasympathetic Division 77 Autonomic Neurotransmitters Cholinergic Fibers • release acetylcholine • preganglionic sympathetic and parasympathetic fibers • postganglionic parasympathetic fibers Adrenergic Fibers • release norepinephrine • most postganglionic sympathetic fibers 78 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 79 Actions of Autonomic Insert figure 11.39 Neurotransmitters 80 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 81 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 82 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 83