1 / 52

Chapter 8

Chapter 8. The Central Nervous System. 8-1. Chapter 8 Outline CNS Embryonic Development Cerebrum Visualizing the Brain Functional Specializations of the Brain Learning & Memory Brain Structure & Function Spinal Cord Peripheral Nervous System. 8-2. CNS. 8-3. CNS.

vachel
Download Presentation

Chapter 8

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.

E N D

Presentation Transcript

  1. Chapter 8 The Central Nervous System 8-1

  2. Chapter 8 Outline • CNS • Embryonic Development • Cerebrum • Visualizing the Brain • Functional Specializations of the Brain • Learning & Memory • Brain Structure & Function • Spinal Cord • Peripheral Nervous System 8-2

  3. CNS 8-3

  4. CNS • Consists of brain & spinal cord • Receives input from sensory neurons • Directs activity of motor neurons • Association neurons integrate sensory & motor activity • Perform learning & memory Fig 8.1 8-4

  5. CNS continued • CNS composed of gray & white matter • Gray matter consists of neuron bodies & dendrites • White matter (myelin) consists of axon tracts • Adult brain weighs 1.5kg • Contains 200 billion neurons • Receives 20% of blood flow to body 8-5

  6. Embryonic Development 8-6

  7. Embryonic Development continued Fig 8.4 • Telencephalon grows disproportionately forming hemispheres of cerebrum • Ventricles & central canal are remnants of hollow part of neural tube • Contain cerebral spinal fluid (CSF) 8-10

  8. Cerebrum 8-11

  9. Cerebrum Fig 8.5 • Is largest part of brain (80% of mass) • Is responsible for higher mental functions 8-12

  10. Cerebrum continued • Its right & left hemispheres are interconnected by tract of the corpus callosum Fig 8.1 8-13

  11. Cerebral Cortex • Is highly convoluted • An elevated fold is called a gyrus (pl. gyri) • A depressed grove is called a sulcus (pl. sulci) Fig 8.5 8-14

  12. Cerebral Cortex continued • Each hemisphere has 5 lobes: frontal, parietal, temporal, occipital & insula Fig 8.5 8-15

  13. Cerebral Cortex continued Fig 8.5 • Frontal lobe is separated from parietal by central sulcus • Precentral gyrus of frontal lobe is involved in motor control • Postcentral gyrus of parietal lobe receives sensory info from areas controlled by precentral gyrus Fig 8.7 8-16

  14. Cerebral Cortex continued Fig 8.7 8-17

  15. Cerebral Cortex continued • Temporal lobe contains auditory centers; receives sensory info from cochlea • Also links & processes auditory & visual info Fig 8.5 8-18

  16. Cerebral Cortex continued • Occipital lobe is responsible for vision & coordination of eye movements Fig 8.5 8-19

  17. Cerebral Cortex continued • Insula plays role in memory encoding • Integrates sensory info with visceral responses • Coordinates cardiovascular response to stress Fig 8.5 Insula lobe (under frontal & temporal) 8-20

  18. Visualizing the Brain 8-21

  19. Functional Specializations of the Brain 8-28

  20. Basal Nuclei (basal ganglia) • Are distinct masses of cell bodies located deep inside cerebrum • Function in control of voluntary movement Fig 8.12 8-29

  21. Cerebral Lateralization • Refers to specialization of each hemisphere for certain functions • Each cerebral hemisphere controls movement on opposite side of body • & receives sensory info from opposite side of body • Hemispheres communicate thru the corpus callosum (Fig 8.1) 8-30

  22. Cerebral Lateralization continued • Left hemisphere possesses language & analytical abilities • Right hemisphere best at visuospatial tasks Fig 8.14 8-31

  23. Language • Language areas of brain known mostly from aphasias • = speech & language disorders due to brain damage • Broca’s area necessary for speech • Wernicke’s area involved in language comprehension Fig 8.15 8-32

  24. Emotion & Motivation • Originate largely in hypothalamus & limbic system (shown in blue on Fig 8.16) • Include aggression, fear, feeding, sex, & goal-directed behaviors Fig 8.16 8-33

  25. Learning & Memory 8-34

  26. Memory • Involves a number of regions in brain • Amnesia (memory loss) studies reveal separate short- & long-term memory systems 8-35

  27. Memory continued • Hippocampus is critical for acquiring new memories • & consolidating short- into long-term memory • Amygdala is crucial for fear memories • Storage of memory is in cerebral hemispheres • Higher order processing & planning occur in prefrontal cortex Fig 8.16 Prefrontal cortex 8-36

  28. Brain Structures & their Functions 8-40

  29. Thalamus & Epithalamus • Are located at base of cerebral hemispheres • Thalamus is relay center thru which all sensory info (except olfactory) passes to cerebrum • & plays role in level of arousal • Epithalamus contains choroid plexus which secretes CSF • Also contains pineal gland which secretes melatonin • Involved in sleep cycle & seasonal reproduction Fig 8.20 8-41

  30. Hypothalamus Fig 8.21 • Is most important structure for homeostasis • Contains neural centers for hunger, thirst, body temperature • Regulates sleep, emotions, sexual arousal, anger, fear, pain, & pleasure • Controls hormone release from anterior pituitary • Produces ADH & oxytocin • Coordinates sympathetic & parasympathetic actions 8-42

  31. Pituitary Gland Fig 8.21 • Is divided into anterior & posterior lobes • Posterior pituitary stores & releases ADH (vasopressin) & oxytocin • Both made in hypothalamus & transported to pituitary • Hypothalamus produces releasing & inhibitinghormones that control anteriorpituitary hormones 8-43

  32. Circadian Rhythms • Are body's daily rhythms • Regulated by SCN (suprachiasmatic nucleus) of hypothalamus • The master clock • Adjusted daily by light from eyes • Controls pineal gland secretion of melatonin which regulates circadian rhythms 8-44

  33. Midbrain • Contains: • Superiorcolliculi -- involved in visual reflexes • Inferiorcolliculi -- relays for auditory info 8-45

  34. Midbrain continued • Rednucleus & substantianigra -- involved in motor coordination • S. nigra dopamine neurons degenerate in Parkinson’s • Mesolimbic dopamine neurons are involved in reward & addiction Fig 8.22 8-46

  35. Hindbrain • Contains pons, cerebellum & medulla Fig 8.20 cerebellum pons medulla 8-47

  36. Hindbrain - Pons Fig 8.23 • Contains several nuclei of cranial nerves • & 2 important respiratory control centers • Apneustic & pneumotaxic centers 8-48

  37. Hindbrain - Cerebellum • 2nd largest structure in brain • Receives input from proprioceptors (joint, tendon, & muscle receptors) • Involved in coordinating movements & motor learning Fig 8.20 cerebellum 8-49

  38. Hindbrain - Medulla Fig 8.23 • Contains all tracts that pass between brain & spinal cord • & many nuclei of cranial nerves • & several crucial centers for breathing & cardiovascular systems 8-50

  39. Reticular Formation Fig 8.23 • Is complex network of nuclei & fibers spanning medulla, pons, midbrain, thalamus, & hypothalamus • Functions as reticularactivatingsystem • Sets level of arousal of cerebral cortex to incoming sensory information 8-51

  40. Spinal Cord 8-52

  41. Spinal Cord Tracts • Sensory info from body travels to brain in ascending spinal tracts • Motor activity from brain travels to body in descending tracts 8-53

  42. Ascending Spinal Tracts • Ascending sensory tracts decussate (cross) so that brain hemispheres receive info from opposite side of body • Same for most motor tracts from brain Fig 8.24 8-54

  43. Descending Spinal Tracts • Are divided into 2 major groups: • Pyramidal or corticospinal tracts descend directly without synaptic interruption from cerebral cortex to spinal cord • Function in control of fine movements Fig 8.25 8-55

  44. Descending Spinal Tracts • Reticulospinal or extrapyramidal tracts descend with many synapses • Influence movement indirectly Fig 8.25 8-56

  45. Peripheral Nervous System 8-57

  46. Peripheral Nervous System (PNS) • Consists of nerves that exit from CNS & spinal cord, & their ganglia (= collection of cell bodies outside CNS) 8-58

  47. Cranial Nerves • Consist of 12 pairs of nerves • 2 pairs arise from neurons in forebrain • 10 pairs arise from midbrain & hindbrain neurons • Most are mixed nerves containing both sensory & motor fibers 8-59

  48. Spinal Nerves • Are mixed nerves that separate next to spinal cord into dorsal & ventral roots • Dorsal root composed of sensory fibers • Ventral root composed of motor fibers Fig 8.28 8-60

  49. Spinal Nerves continued • There are 31 pairs: • 8 cervical, • 12 thoracic, • 5 lumbar, • 5 sacral, & • 1 coccygeal Fig 8.27 8-61

  50. Reflex Arc • Is a simple sensory input, motor output circuit involving only peripheral nerves & spinal cord • Sometimes arc has an association neuron between sensory & motor neuron Fig 8.28 8-62

More Related