Ch11 Ppt Lect


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Ch11 Ppt Lect

  1. 1. Chapter 11- Nervous System II PowerPoint Presentation to accompany Hole’s Human Anatomy and Physiology, 10 th edition , edited by S.C. Wache for Biol2064.01
  2. 2.   You are responsible for the following figures and tables : Review Fig. 10.7. Differentiate CNS and PNS general tasks. Compare Fig. 11.5 - Structure of the CNS - the brain and spinal cord. Compare Tab. 11.9 and Fig. 11.29 - Components of the PNS Fig. 11.1 , 11.2 - meninges. Fig. 11.3, 11.4 - CSF. TB, blue box, p. 368 Clinical Applications 11.1 - Spinal tap. Fig. 11.6 - Structure of the spinal cord. Fig. 11.7 - Define 'reflex arc‘. Fig. 11.8, 11.9 - Examples: Knee-jerk reflex, withdrawal reflex. Tab. 11.2 - Study the parts of a reflex arc. Fig. 11.15, Tab. 11.7 - CNS/ Brain structure - Read p.388-391, endocrine functions. Fig. 11.16 - Note fissures, sulci, gyri. Fig. 11.17, 11.18 - Areas of the cerebrum. Tab. 11.5 - Functions of the cerebral lobes. Fig. 11.25. PNS / Cranial nerves . Fig. 11.26. The vagus nerve # X, is important. Fig. 11.6.- CNS/ Spinal cord structure. Fig. 11.29 - PNS/ Spinal nerves - (see table in the attached lecture handout). Fig. 11.35 - ANS innervates smooth muscle and glands. Fig. 11.40 - sympathetic / parasympathetic nerves (see diagram in the attached lecture).
  3. 5. <ul><li>The meninges are membranes that protect the brain and the spinal cord </li></ul><ul><li>Dura mater: outermost layer, composed of tough, white, dense connective tissue </li></ul><ul><li>Arachnoid mater: thin, weblike membrane, subarachnoid space contains the cerebrospinal fluid </li></ul><ul><li>Pia mater: thin membrane with nerves and blood vessels, attached to the brain and spinal cord </li></ul>Meninges
  4. 6. Ventricles <ul><li>The ventricles are a series of interconnected cavities </li></ul><ul><li>continuous with the central canal of the spinal cord which </li></ul><ul><li>transport the cerebrospinal fluid (CSF). </li></ul><ul><li>Lateral ventricles : first and second ventricles located in the cerebrum </li></ul><ul><li>Third ventricle: located in the midbrain, connected to the fourth ventricle via the cerebral aqueduct </li></ul><ul><li>Fourth ventricle: located in the brain stem </li></ul>
  5. 7. Cerebrospinal Fluid (CSF) <ul><li>CSF is a clear fluid with high Na + and glucose </li></ul><ul><li>and low K + concentration, compared to other body </li></ul><ul><li>fluids. </li></ul><ul><li>Choroid plexuses are specialized capillaries of the pia mater, secrete cerebrospinal fluid. </li></ul><ul><li>500 ml of CSF are secreted each day, but only 140 ml circulates, due to reabsorption through the arachnoid granulations. </li></ul>
  6. 9. Spinal Cord <ul><li>It begins where nervous tissue leaves the cranium at the foramen magnum . </li></ul><ul><li>It tapers to a point near the first and second lumbar vertebrae . Below this is the filum terminale and the cauda equina. </li></ul><ul><li>It consists of 31 segments each giving rise to a pair of spinal nerves. </li></ul><ul><li>The cervical and lumbar enlargements give off nerves to the upper and lower limbs respectively. </li></ul>
  7. 11. Note dorsal and ventral roots.
  8. 12. <ul><li>Anterior median fissure and posterior median sulcus are grooves dividing the cord into right and left halves. </li></ul><ul><li>Gray butterfly is the inner gray matter consisting of interneurons. </li></ul><ul><li>Anterior and posterior horn are the wings. Between them is the lateral horn. </li></ul><ul><li>The gray commissure connects the wings. </li></ul><ul><li>The central canal contains CSF. </li></ul><ul><li>The white matter contains the myelinated nerve tracts. </li></ul>Spinal Cord
  9. 13. Reflex Arcs <ul><li>Definition: The simplest nerve pathway is a reflex arc </li></ul><ul><li>which is autonomically controlled. </li></ul><ul><li>Reflexes whose arcs pass through the spinal cord are spinal reflexes . </li></ul><ul><li>Reflexes are autonomic and subconscious . </li></ul><ul><li>They help maintain homeostasis by controlling heart rate, breathing rate, etc. </li></ul><ul><li>They carry out automatic actions such as swallowing, sneezing, coughing, vomiting. </li></ul>
  10. 14. Note the pathway that the impulse travels. neuron neuron neuron neuron
  11. 15. Parts of a Reflex Arc <ul><li>Receptor: sensitive to a specific change </li></ul><ul><li>Sensory neuron: transmits nerve impulse from the receptor to brain or spinal cord </li></ul><ul><li>Interneuron: processing, conducts impulse from sensory to motor neuron </li></ul><ul><li>Motor neuron : transmits nerve impulse from CNS out to effector (muscle or gland) </li></ul><ul><li>Effector : responds to stimulation and produces the reflex action </li></ul>
  12. 16. (Fig. 11.8) Note the pathway that the impulse travels. neuron neuron
  13. 17. Knee-jerk Reflex (Fig. 11.8) <ul><li>The knee-jerk or patellar tendon reflex is a monosynaptic reflex involving only two neurons. </li></ul><ul><li>Striking the patellar ligament pulls the quadriceps femoris group and activates stretch receptors. </li></ul><ul><li>The sensory neurons activate interneurons which transmit the impulse to a motor neuron . </li></ul><ul><li>The motor neuron innervates the quadriceps femoris which contracts, extending the leg . </li></ul>
  14. 18. Note the pathway that the impulse travels. neuron neuron neuron neuron
  15. 19. Withdrawal Reflex (Fig. 11.9) <ul><li>Occurs in response to touching something painful, </li></ul><ul><li>such as pricking the finger. </li></ul><ul><li>Sensory impulses are activated by pressure receptors in the skin and send a message to the spinal cord. </li></ul><ul><li>Interneurons are stimulated and synapse with motor neurons. </li></ul><ul><li>Motor neurons signal flexor muscles. </li></ul>
  16. 21. Crossed Extensor Reflex (Fig. 11.10) <ul><li>Occurs with the withdrawal reflex. This reflex </li></ul><ul><li>is due to interneurons within the reflex center </li></ul><ul><li>of the spinal cord. </li></ul><ul><li>Flexors are inhibited on the affected side (ipsilateral). </li></ul><ul><li>Extensors are stimulated on the opposite side (contralateral) allowing body weight to be supported. </li></ul>
  17. 22. Spinal Cord Nerve Tracts (Fig. 11.11) <ul><li>Spinal cord ascending and descending nerve </li></ul><ul><li>tracts: </li></ul><ul><li>Ascending and sensory - conduct impulses to the brain. </li></ul><ul><li>Anterior/Posterior spino-cerebellar tract </li></ul><ul><li>Anterior/ Lateral spino-thalamic tract </li></ul><ul><li>Medial reticulo-spinal tract </li></ul><ul><li>Descending and motor - conduct motor impulses from the brain to muscle and glands. </li></ul><ul><li>Anterior/ Lateral cortico-spinal tract </li></ul><ul><li>Anterior/ Lateral reticulo-spinal tract </li></ul>
  18. 23. Note decussation area.
  19. 25. <ul><li>Cerebral hemispheres : largest part </li></ul><ul><li>Corpus callosum: connects the hemispheres </li></ul><ul><li>Falx cerebri : dura mater separating the hemispheres </li></ul><ul><li>Gyri : convolutions or ridges in hemispheres </li></ul><ul><li>Sulci : shallow grooves between gyri </li></ul><ul><li>Fissures : deep grooves between gyri </li></ul>Cerebrum (Figure 11.15) Cerebral Lobes (Figure 11.16) <ul><li>Lobes: frontal, parietal, temporal, occipital </li></ul><ul><li>Insula: the lobe in the center of the cerebral hemisphere that is situated deeply between the lips of the sylvian fissure -- called also central lobe, island of Reil </li></ul>
  20. 26. Note the lobes, fissures and sulci.
  21. 28. cerebellum
  22. 29. Brain Areas and Their Functions (Tab. 11.5) visual association area / perceptions occipital lobes Wernicke’s speech comprehension area; primary auditory / hearing association area temporal lobe gustatory area parietal lobe / along lateral sulcus primary olfactory area, Broca’s speech motor area frontal lobe concerned autonomic functions , limbic system hypothalamus integrates neurons for short-term memory thalamus is part of the diencephalon short-term memory processing, limbic system (emotions and motivation) lateral ventricle hippocampus / internal frontal lobe areas Function Region of Brain
  23. 30. Cerebral Functions (Fig. 11.16)
  24. 32. <ul><li>Broca’s area : motor speech area </li></ul><ul><li>Frontal eye field : voluntary eye movements </li></ul><ul><li>Motor areas: primary motor areas contain pyramidal cells and contain synapses with descending spinal tracts. </li></ul><ul><li>Sensory Areas : contain synapses from ascending tracts </li></ul><ul><li>Association Areas : regions rich in interneurons that are neither motor or sensory, but interconnect with each other and other centers. </li></ul><ul><li>General interpretative area (Wernicke’s area): complex thought processing </li></ul>Cerebral Functions
  25. 33. Cerebral Lobes (Figure 11.18)
  26. 34. Fig. 11.18
  27. 35. <ul><li>Frontal lobes : motor areas for voluntary skeletal muscles, association areas </li></ul><ul><li>Parietal lobes : sensory areas of temperature, touch, pressure, pain, speech association </li></ul><ul><li>Temporal lobes: sensory area for hearing, sensory association areas </li></ul><ul><li>Occipital lobes : sensory area for vision, visual association area </li></ul>Cerebral Lobe Functions
  28. 36. Hemisphere Dominance <ul><li>Both hemispheres participate in basic functions. </li></ul><ul><li>One side is usually the dominant hemisphere for some functions. </li></ul><ul><li>For 90% of the population the left side is dominant for language-related activities of speech, writing, reading. </li></ul>
  29. 37. Coronal Cut - Left Cerebral Hemisphere (Fig.11.19)
  30. 38. Memory <ul><li>Short-term memory : patterns of synapses that change; </li></ul><ul><li>no permanent synapses formed. </li></ul><ul><li>Lateral ventricle hippocampus / internal frontal lobe areas : short-term memory processing. </li></ul><ul><li>Limbic system (emotions and motivation): thalamus integrates neurons for short-term memory </li></ul><ul><li>Long-term memory : </li></ul><ul><li>patterns of synapses that remain unchanged. </li></ul>
  31. 39. Basal Nuclei <ul><li>Basal Nuclei: masses of gray matter which consists of unmyelinated interneurons within the cerebral hemispheres </li></ul><ul><li>Hippocampus: a curved elongated ridge that is an important part of the limbic system , extends over the floor of the descending horn of each lateral ventricle of the brain, and consists of gray matter covered on the ventricular surface with white matter; </li></ul><ul><li>a region of the cerebral cortex that performs repeated stimulations to strengthen synapses. </li></ul><ul><li>Caudate nucleus, putamen, globus pallidus: </li></ul><ul><li>Relay motor impulses and produce the inhibitory neurotransmitter, dopamine </li></ul>
  32. 40. Diencephalon <ul><li>Thalamus : gateway for sensory impulses </li></ul><ul><li>Hypothalamus : controls anterior pituitary which, in turn, controls effector glands </li></ul><ul><li>Posterior and anterior pituitary gland (controls a variety of effector endocrine glands) attached to the hypothalamus via the infundibulum </li></ul><ul><li>Optic tract and optic chiasma ( cranial sensory nerve II ) </li></ul><ul><li>Mammillary bodies </li></ul><ul><li>Pineal gland releases melatonin which controls the biorhythm / circadian rhythm </li></ul>
  33. 41. Limbic System <ul><li>Composed of portions of the cerebral cortex, thalamus, hypothalamus, basal nuclei, and other deep nuclei </li></ul><ul><li>Controls emotional experiences </li></ul><ul><li>Produces feelings of fear, anger, pleasure </li></ul><ul><li>Interprets sensory impulses of smell / olfactory sense </li></ul>
  34. 42. Brain Stem-Midbrain <ul><li>Connects brain stem and spinal cord with the CNS </li></ul><ul><li>Cerebral peduncles : motor and sensory pathways </li></ul><ul><li>Red nucleus : posture reflexes </li></ul><ul><li>Corpora quadrigemina </li></ul><ul><ul><li>Superior colliculi: visual reflexes </li></ul></ul><ul><ul><li>Inferior colliculi: auditory reflexes </li></ul></ul>
  35. 43. Fig. 11.20 midbrain Medulla oblongata
  36. 44. Brain Stem-dorsal view (Fig. 11.20)
  37. 45. Brain Stem <ul><li>Midbrain: the middle division of the three primary divisions of the adult brain that includes a ventral part with the cerebral peduncles and a dorsal part with the corpora quadrigemina and that surrounds the aqueduct of Sylvius connecting the third and fourth ventricles </li></ul><ul><li>Pons: sensory impulses relayed to brain, works with the medulla oblongata </li></ul><ul><li>Medulla Oblongata: ascending and descending tracts pass through; contains the cardiac center which controls heart rate; contains the vasomotor center which controls blood pressure; contains the respiratory center which controls rate, rhythm, depth of breathing; </li></ul><ul><li>corticospinal tract: any of four columns of motor fibers of which two run on each side of the spinal cord and which are continuations of the pyramids of the medulla oblongata : PYRAMIDAL TRACT : a : LATERAL CORTICOSPINAL TRACT </li></ul><ul><li>b : VENTRAL CORTICOSPINAL TRACT </li></ul>
  38. 46. <ul><li>Reticular Formation (shown in green) : </li></ul><ul><li>Extends from the superior portion of the spinal cord into the diencephalon </li></ul><ul><li>Activates the cerebral cortex into a state of wakefulness </li></ul><ul><li>Filters incoming sensory impulses and regulates motor activities </li></ul>
  39. 47. Cerebellum <ul><li>Integrates sensory information concerning positions of body parts, coordination of skeletal muscle activity, maintain posture </li></ul><ul><li>Two lateral hemispheres separated by the falx cerebelli , a layer of dura mater; the Vermis connects the hemispheres </li></ul><ul><li>Cerebellar cortex : gray matter on outside </li></ul><ul><li>Arbor vitae : treelike pattern of white matter </li></ul><ul><li>Cerebellar peduncles: - inferior </li></ul><ul><ul><li>- middle </li></ul></ul><ul><ul><li> - superior </li></ul></ul>
  40. 48. Fig. 11.22 Arbor vitae- ‘ tree of life’
  41. 49. Peripheral Nervous System <ul><li>Cranial nerves and spinal nerves: </li></ul><ul><li>Somatic Nervous System : nerves that connect CNS to skin and skeletal muscles </li></ul><ul><li>Autonomic Nervous System : nerves that connect CNS to viscera, smooth muscle nad glands. </li></ul>
  42. 50. Fig. 11.24 Epineurium : outer layer of connective tissue Perineurium : sleeve of looser connective tissue surrounding a fascicle Endoneurium : loose connective tissue surrounding each nerve fibers
  43. 51. <ul><li>Twelve pairs of nerves which originate from brain stem and cerebrum </li></ul><ul><li>Pass through foramen magnum in the skull </li></ul><ul><li>Mixed nerves and special senses; some motor nerves </li></ul>
  44. 52. Cranial Nerves <ul><li>I: Olfactory : sense of smell </li></ul><ul><li>II: Optic : sense of vision </li></ul><ul><li>III: Oculomotor : eye movement, focusing </li></ul><ul><li>IV: Trochlear : eye movement </li></ul><ul><li>V: Trigeminal : mixed nerve - ophthalmic: sensory: accessory eye structures </li></ul><ul><ul><li> - maxillary: sensory: teeth, gum, lip, face </li></ul></ul><ul><ul><li> - mandibular: sensory: scalp, jaw, teeth, lip </li></ul></ul><ul><li>VI: Abducens : eye movement </li></ul><ul><li>VII: Facial : mixed: taste, facial expression </li></ul><ul><li>VIII: Vestibulocochlear - vestibular branch: sense of equilibrium </li></ul><ul><ul><li>- cochlear branch: sense of hearing </li></ul></ul><ul><li>IX: Glosspharyngeal : mixed: pharynx </li></ul><ul><li>X: Vagus: mixed: speech, swallowing, autonomic nervous system to viscera </li></ul><ul><li>XI: Accessory : - cranial branch: motor to pharynx and larynx </li></ul><ul><ul><li> - spinal branch: motor to neck and back </li></ul></ul><ul><li>XII: Hypoglossal : tongue movement </li></ul>
  45. 53. Spinal Nerves <ul><li>Thirty-one pairs of 2-inch long mixed nerves which </li></ul><ul><li>originate from the spinal cord and provide communication </li></ul><ul><li>between the spinal cord and the peripheral nerves which </li></ul><ul><li>transport impulses to the periphery of the human </li></ul><ul><li>body. </li></ul><ul><li>AM-PS: </li></ul><ul><li>Ventral ( a nterior) root : m otor </li></ul><ul><li>Dorsal ( p osterior) root : s ensory; dorsal root ganglion = cell bodies of sensory nerves </li></ul>
  46. 54. <ul><li>Cervical nerves: 8 pairs, C1-C8 </li></ul><ul><li>Thoracic nerves: 12 pairs, T1-T12 </li></ul><ul><li>Lumbar nerves: 5 pairs, L1-L5 </li></ul><ul><li>Sacral nerves: 5 pairs, S1-S5 </li></ul><ul><li>Coccygeal nerves: 1 pair, C0 </li></ul>Fig. 11.30
  47. 55. Plexuses <ul><li>Cervical : first four cervical nerves [C1-C4] </li></ul><ul><li>Brachial : lower four cervical nerves and first thoracic nerve [C5-C8 and T1] </li></ul><ul><li>Lumbosacral : last thoracic nerve and lumbar, sacral, and coccygeal nerves [T12-S5] </li></ul>PNS - Autonomic Nervous System <ul><li>Functions independently, involuntary / subconscious control </li></ul><ul><li>Controls visceral activities by regulating smooth and cardiac muscles and glands </li></ul><ul><li>Regulates heart rate, blood pressure, breathing, body temperature and other homeostatic mechanisms </li></ul><ul><li>Responds to stress </li></ul>
  48. 56. Note : nerve cells are neurons. Note the spelling !!! Also note the pathway that the impulse travels !
  49. 57. Sympathetic Division of Motor Nerves Fig. 11.37 – note the dorsal and ventral roots.
  50. 58. Fig. 11.36 – note the meninges, dorsal and ventral roots. Note that the spinal nerves are mixed function nerves [AM-PS].
  51. 59. Parasympathetic Division of Motor Nerves <ul><li>Fibers arise from brain stem and sacral spinal cord. </li></ul><ul><li>The vagus nerve (X) carries 75% of the parasympathetic fibers. </li></ul><ul><li>Fibers travel to terminal ganglia close to viscera. </li></ul><ul><li>Postganglionic fibers travel to specific muscles or glands. </li></ul>
  52. 60. Neurotransmitters (Tab. 11.10) <ul><li>Acetylcholine functions to maintain homeostasis. </li></ul><ul><li>Preganglionic fibers are cholinergic and secrete acetylcholine : </li></ul><ul><li>Preganglionic sympathetic fibers of the ANS arise from the thoracic and lumbar regions of the spinal cord. </li></ul><ul><li>Preganglionic parasympathetic fibers of the ANS arise from the brain and sacral region of the spinal cord. </li></ul><ul><li>Postganglionic parasympathetic and sympathetic fibers of sweat glands are also </li></ul><ul><li>cholinergic . </li></ul><ul><li>Norepinephrine and epinephrine function to </li></ul><ul><li>respond to stress </li></ul><ul><li>All other postganglionic sympathetic fibers are adrenergic and secrete norepinephrine </li></ul>
  53. 61. Fig. 11.38 – ANS preganglionic sympathetic fibers arise from the thoracic and lumbar regions of the spinal cord.
  54. 62. Fig. 11.40 – ANS preganglionic parasympathetic fibers arise from the brain and sacral region of the spinal cord.
  55. 63. Neurotransmitter Receptors <ul><li>Acetylcholine binds to two cholinergic receptors: </li></ul><ul><ul><li>muscarinic receptors: effector cells at parasympathetic postganglionic terminals </li></ul></ul><ul><ul><li>nicotinic receptors: synapses between pre- and postganglionic fibers and at neuromuscular junctions of skeletal muscles </li></ul></ul><ul><li>Epinephrine and norepinephrine bind to two adrenergic receptors: </li></ul><ul><li>- alpha and beta receptors, which give different </li></ul><ul><li> responses at the target organ </li></ul>
  56. 64. Fig. 11.40 – note that most sympathetic fibers in the thoracic and lumbar regions are adrenergic and secrete norepinephrine / epinephrine
  57. 65. <ul><li>Programmed cell death ( apoptosis ) begins at birth and is a natural control point within the cell cycle (G o , G 1 , S, G 2 , mitosis/meiosis, apoptosis or G o ). </li></ul><ul><li>Loss of neurons does not always mean loss of function. </li></ul><ul><li>Signs of aging: fading memory, slowed responses and reflexes, and other changes. </li></ul>Life-Span Changes