1 / 80

Anatomy and Physiology Chapter 11 Nervous System II

Anatomy and Physiology 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. Chapter 11 Nervous System II. Dura Mater. outermost layer

Télécharger la présentation

Anatomy and Physiology Chapter 11 Nervous System II

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.


Presentation Transcript

  1. Anatomy and Physiology Chapter 11 Nervous System II

  2. Meninges • membranes surrounding CNS • protect CNS • three layers • dura mater – outer, tough • arachnoid mater – thin, weblike • pia mater – inner, very thin Chapter 11Nervous System II

  3. Dura Mater • outermost layer • made of tough, white dense connective tissue • contains many blood vessels and nerves • attaches to inside of cranial cavity • some areas split into two layers which venous blood flows through

  4. strong tubular sheath that surrounds the spinal cord • sheath is separated from spinal cord by an epidermal space which contains blood vessels, loose connective tissue, and adipose tissue

  5. Arachnoid Mater • thin weblike membrane between dura and pia maters • lacks blood vessels • subarachnoid space between arachnoid and pia maters • contains cerebrospinal fluid (clear and watery)

  6. Pia Mater • attached to brain and spinal cord • contains many nerves and blood vessels that nourish underlying cells

  7. Meninges of the Spinal Cord

  8. Ventricles and Cerebrospinal Fluid • Ventricles are interconnected cavities filled with cerebrospinal fluid (CSF) • CSF completely surrounds the brain and spinal cord providing protection • CSF helps maintain a stable ionic concentration • CSF provides a pathway to blood for waste

  9. Ventricles

  10. Cerebrospinal Fluid

  11. Spinal Cord

  12. Cross Section of Spinal Cord

  13. Spinal Cord • Slender column of nerve fibers • Continuous with brain • Extends down through vertebral canal • Tapers and terminates near the disk between 1st and 2nd lumbar vetebrae • Fibers extend downward to become spinal nerves at the remaining lumbar and sacral levels – filum terminale

  14. Structure of the Spinal Cord • 31 segments each of which gives rise to a pair of spinal nerves • Cervical enlargement – supplies nerves to upper limbs • Lumbar enlargement – supplies nerves to lower limbs

  15. Functions of the Spinal Cord • Conduit for nerve impulse to and from the brain • Center for spinal reflexes • Nerve tracts and nerves spinal provide for 2 way communication between the brain and body parts outside the brain

  16. Ascending tracts conduct sensory impulses to the brain • Descending tracts Conduct motor impulses from the brain to muscles and glands • Nerve fibers in the tracts are axons

  17. Ascending Tracts

  18. Descending Tracts

  19. Reflex Arcs • Simple nerve pathways that carry out reflexes • Pathway: Receptor  sensory neuron  interneurons in CNS  motor neurons  effectors (muscles & glands)  • Spinal reflexes have reflex arcs that pass through the spinal cord

  20. Reflex Behavior • Automatic and subconscious responses to stimuli inside or outside the body • Help maintain homeostasis by controlling many involuntary processes: heart rate, breathing rate, blood pressure and digestion • Also control involuntary actions: swallowing, sneezing, coughing and vomiting • Ex: patellar tendon reflex, withdrawal reflex

  21. Reflex Behavior • example is the knee-jerk reflex • simple monosynaptic reflex • helps maintain an upright posture

  22. Reflex Behavior • example is a withdrawal reflex • prevents or limits tissue damage

  23. Brain Major Parts • cerebrum • two hemispheres • basal nuclei (ganglia) • diencephalon • brainstem • cerebellum

  24. Brain- General functions • Largest and most complex part of NS • Has about one hundred billion multipolar neurons and innumerable nerve fibers • Responsible for sensations and perceptions • Issues motor commands and coordinates muscular movements

  25. Regulates visceral activities • Responsible for reasoning and memory • Provides characteristics of personality

  26. Brain

  27. Brain Development • Forms during early embryonic stage • Begins as neural tube with 3 cavities (vesicles) that gives rise to the CNS • Walls of the tube give rise to various regions of the brain, brain stem, and spinal cord

  28. Brain Development Three Major Vesicles • Forebrain • Midbrain • Hindbrain

  29. Brain Development

  30. Structure of the Cerebrum • Largest part of the mature brain • Consists of 2 large masses called cerebral hemispheres • Corpus callosum (bridge of nerve fibers) connects the 2 hemispheres • Convolutions (ridges) separated by grooves found on the surface • Sulcus – shallow groove • Fissure –deep groove

  31. Lobes of the cerebral hemisphere are named after the skull bones they are under: frontal lobe, parietal lobe, temporal lobe, occipital lobe, and insula • Thin layer of gray matter (cerebral cortex) makes up the outermost portion and has about 75% of all nerve cell bodies in NS

  32. Mass of white matter ( myelinated nerve fibers) under the cerebral cortex Some pass between hemispheres Some carry sensory or motor impulses

  33. Structure of Cerebrum

  34. Lobes of Cerebral Hemispheres • Frontal • Parietal • Temporal • Occipital • Insula

  35. Functions of the Cerebral Lobes

  36. Functions of the Cerebrum • Regions of the cerebral cortex perform specific functions • Primary motor areas – Fig 11.16 Pg 391 send impulses that cross from one side of the brain to the other within the brain stem • Sensory Areas – Fig 11.16 Pg 391 interpret impulses from sensory receptors

  37. 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

  38. Sensory Areas • Cutaneous Sensory Area • parietal lobe • interprets sensations on skin • Sensory Area for Taste • near bases of the central sulci • Sensory Area for Smell • arise from centers deep within the cerebrum • Visual Area • occipital lobe • interprets vision • Auditory Area • temporal lobe • interprets hearing

  39. Sensory & Motor Areas

  40. Association Areas – interconnect with each other and with other brain structures - occupy anterior portions of frontal lobes and widespread in the lateral portions of the parietal, temporal, and occipital lobes

  41. 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

  42. General interpretive area – primary role in complex thought processing - located where the parietal, temporal, and occipital association areas join near the posterior end of the lateral sulcus

  43. Hemisphere Dominance • Both hemispheres participate in basic functions such as receiving and interpreting sensory impulses, controlling skeletal muscles on the opposite side of the body, and storing memory • Most people have a dominant hemisphere for language related activities, and skills requiring verbal, analytical, and computational skills

  44. 90% of people are left hemisphere dominant, some are right dominant, and some are equally dominant • Broca’s area on one side controls speech – usually the left side • Nondominant hemisphere specializes in nonverbal functions • Nerve fibers in the corpus callosum connect the hemispheres and transfer information

  45. Hemisphere Dominance • The left hemisphere is dominant is most individuals • Nondominant hemisphere controls • nonverbal tasks • motor tasks • understanding and interpreting musical and visual patterns • provides emotional and intuitive thought processes • Dominant hemisphere controls • speech • writing • reading • verbal skills • analytical skills • computational skills

  46. 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 • 10 billion neurons can form 60 trillion synapses allowing limitless number of memories

  47. Major Parts of the Brain

  48. Basal Nuclei (ganglia) • masses of gray matter • deep within cerebral hemispheres • produces dopamine • controls certain muscular activities primarily by inhibiting motor functions

More Related