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Chapter 40

Chapter 40. Neural Regulation. Nerve nets Radially symmetrical invertebrates Nerve cells scattered throughout the body. Hydra’s nerve net. Radial nervous systems Radially symmetrical invertebrates Nerve ring and nerves that extend to various parts of the body. Bilateral nervous systems

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Chapter 40

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  1. Chapter 40 Neural Regulation

  2. Nerve nets • Radially symmetrical invertebrates • Nerve cells scattered throughout the body

  3. Hydra’s nerve net

  4. Radial nervous systems • Radially symmetrical invertebrates • Nerve ring and nerves that extend to various parts of the body

  5. Bilateral nervous systems • Bilaterally symmetrical animals • Nerve cells form nerves, nerve cords, ganglia, and brain • Sense organs concentrated in the head region

  6. Bilateral nervous systems • Wide range of responses • Increased number of association neurons • More complex synaptic contacts permit a planarian flatworms

  7. Planarian flatworms • Cerebral ganglia • Two solid ventral nerve cords connected by transverse nerves

  8. Ladder-type nervous system in flatworms

  9. Annelids and arthropods • Ventral nerve cord • Numerous ganglia • Cerebral ganglia of arthropods have specialized regions • Cephalopod mollusks • Complex nervous systems • Neurons in a central region

  10. Annelid and arthropod nervous systems

  11. Evolutionary trends • Increased numbers and concentration of nerve cells • Specialization of function • Increased number of association neurons • More complex synaptic contacts • Formation of a head

  12. Vertebrate nervous system • Central nervous system (CNS) • Brain • Dorsal, tubular spinal cord • Peripheral nervous system (PNS) • Sensory receptors • Nerves

  13. Vertebrate brain development • Brain and spinal cord arise from the neural tube • Anterior end of the tube differentiates into • Forebrain • Midbrain • Hindbrain

  14. Early development of the vertebrate nervous system

  15. Section through the human brain

  16. Hindbrain subdivides into • Metencephalon • Myelencephalon

  17. Myelencephalon develops into the medulla • Vital centers • Other reflex centers • Fourth ventricle • Communicates with the central canal of the spinal cord

  18. Metencephalon gives rise to the cerebellum • Muscle tone • Posture • Equilibrium • Pons • Connects various parts of the brain

  19. Midbrain • Largest part of the brain in fishes and amphibians • Main association area, linking sensory input and motor output • Center for visual and auditory reflexes in reptiles, birds, and mammals

  20. Brain stem • Medulla • Pons • Midbrain

  21. Forebrain differentiates to form the diencephalon and telencephalon • Diencephalon develops into the thalamus and hypothalamus • Thalamus • Relay center for motor and sensory information

  22. Hypothalamus • Controls autonomic functions • Links nervous and endocrine systems • Controls temperature, appetite, and fluid balance • Emotional and sexual responses

  23. Telencephalon develops into the cerebrum and olfactory bulbs • Cerebrum • Divided into right and left hemispheres • In fishes and amphibians, integrates sensory information

  24. In birds, the corpus striatum controls complex behavior patterns, such as flying and singing • In mammals, the neocortex accounts for a large part of the cerebral cortex

  25. Human brain and spinal cord • Protected by bone and three meninges • Dura mater • Arachnoid • Pia mater • Cushioned by cerebrospinal fluid (CSF)

  26. Spinal cord • Transmits impulses to and from the brain • Controls many reflex actions • Gray matter contains nuclei that serve as reflex centers

  27. Structure of the spinal cord

  28. Ascending tracts • Transmit information to the brain • Descending tracts • Transmit information from the brain

  29. Withdrawal reflex • Sensory receptors • Sensory neurons • Interneurons • Motor neurons • Effectors

  30. Reflex action

  31. Human cerebral cortex • Gray matter • Forms folds or convolutions • Fissures • Deep furrows between the folds

  32. Cerebrum • Sensory areas • Receive incoming sensory information • Motor areas • Control voluntary movement

  33. Association areas • Link sensory and motor areas • Learning • Language • Thought • Judgment

  34. The cerebrum consists of lobes • Frontal lobes • Parietal lobes • Temporal lobes • Occipital lobes

  35. Human brain

  36. White matter of the cerebrum • Lies beneath the cerebral cortex • Corpus callosum • Large band of white matter • Connects right and left hemispheres

  37. Basal ganglia • Cluster of nuclei within the white matter • Important centers for motor function

  38. Sleep–wake pattern • Regulated by the hypothalamus and brain stem

  39. Alpha wave patterns • Relaxed states • Beta wave patterns • Accompany heightened mental activity

  40. Theta and delta waves • Slower frequency • Higher-amplitude • Non-REM sleep

  41. EEGs showing electrical activity in the brain

  42. Reticular activating system (RAS) • Arousal system • Neurons filter sensory input • Selects which information is transmitted to the cerebrum

  43. Non-REM sleep • Electrical activity of the cerebral cortex slows • Metabolic rate slows • REM sleep • Dreaming

  44. Suprachiasmatic nucleus • Main biological clock • Receives information about light and dark • Transmits it to other nuclei that regulate sleep

  45. Limbic system • Emotional aspects of behavior • Motivation • Sexual behavior • Autonomic responses • Biological rhythms

  46. Hippocampus • Categorizes information • Consolidated memories • Amygdala • Evaluates incoming information • Signals danger

  47. Learning • Acquiring information as a result of experience • Memory • Information is encoded, stored, and retrieved

  48. Implicit memory • Unconscious memory for perceptual and motor skills • Explicit memory • Factual memory of people, places, or objects

  49. Short-term memory • Recall information for a few minutes • Information can be transferred to long-term memory

  50. Synaptic plasticity • Ability of the nervous system to modify synapses during learning and remembering • Long-term memory storage • Gene activation • Long-term functional changes at synapses

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