Ch11 Ppt Lect

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