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The Central Nervous System

The Central Nervous System. CNS. CNS: brain and spinal cord Necessary for the maintenance of homeostasis Contains 10 11 neurons Contains 10 14 synapses Responsible for everything we perceive, do, feel, and think. The Brain. BRAIN MATTER AND CEREBROSPINAL FLUID CEREBRUM

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The Central Nervous System

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  1. The Central Nervous System

  2. CNS • CNS: brain and spinal cord • Necessary for the maintenance of homeostasis • Contains 1011 neurons • Contains 1014 synapses • Responsible for everything we perceive, do, feel, and think

  3. The Brain • BRAIN MATTER AND CEREBROSPINAL FLUID • CEREBRUM • a- Cerebral hemispheres • a1- Lobes • a2- Basal ganglia (nuclei) • b- Brain stem • b1-Diencephalon • b1-1- Thalamus • b1-2- Hypothalamus • b2- Midbrain • b3- Pons • b4- Medulla oblongata • c- Limbic system • d- Reticular formation • CEREBELLUM

  4. Cerebrum • Five paired lobes within two hemispheres • Gray matter in cortex and in deeper cerebral nuclei • White matter inside • Higher functions are performed by the brain

  5. Brain matter • What is gray and white matter? • Gray matter: neurons and unmyelinated axons • White matter: myelinated axons

  6. Protection and Coverings • Cranial bones • Meninges - 3 layers: - Dura mater, Arachnoid, and pia mater • Between dura mater and arachnoid: subdural space • In between arachnoid and pia mater, in subarachnoid space: cerebro-spinal fluid (CSF)

  7. Meninges

  8. Meninges

  9. Meningitis

  10. CSF • Cushion the brain • Provide a constant IF environment • About 150 ml • Produced by the ependymal cells of the choroid plexus, in the ventricle • Resorbed by the arachnoid granulations • Continuously produced and continuously resorbed • Composition slightly different from plasma

  11. Cerebrospinal fluid circulation

  12. CSF circulation

  13. Hydrocephalus • A blockage of CSF circulation will trigger an accumulation of CSF in the ventricle • This will result in hydrocephalus

  14. Hydrocephalus

  15. Blood supply • CNS comprises 2% of body weight (3–4 pounds) • Receives 15% of blood supply • High metabolic rate • Brain uses 20% of oxygen consumed by body at rest • Brain uses 50% of glucose consumed by body at rest • Depends on blood flow for energy

  16. Energy supplies • Depends on aerobic glycolysis • Requires glucose and oxygen • No glycogen stores • Fatty acids not used for energy • Ketones used during extreme conditions

  17. The Brain • BRAIN MATTER AND CEREBROSPINAL FLUID • CEREBRUM • a- Cerebral hemispheres • a1- Lobes • a2- Basal ganglia (nuclei) • b- Brain stem • b1-Diencephalon • b1-1- Thalamus • b1-2- Hypothalamus • b2- Midbrain • b3- Pons • b4- Medulla oblongata • c- Limbic system • d- Reticular formation • CEREBELLUM

  18. Brain structure

  19. Cerebrum • Two hemispheres • Surface have gyri, grooves(sulci) and fissures • Two fissures: longitudinal (falx cerebri and cerebelli) and transverse (tentorium cerebelli) • Corpus callosum

  20. Cerebrum • Cerebral cortex - Lobes: 1 frontal, 1 parietal, 1 occipital, and 2 temporal and insula – surface is gray matter - Basal nuclei (or ganglia)- gray matter deep inside white matter.

  21. Frontal lobe • Voluntary motor control • Personality • Concentration, planning, decision making • Verbal communication

  22. Frontal lobe : Motor area

  23. Language • Broca’s aphasia: due to damage in the Broca’s area of the brain. Speech slow and poorly articulated • Wenicke’s aphasia: due to damages to Wernicke’s area produces a rapid speech without meaning. Comprehension destroyed

  24. Speech areas

  25. Parietal lobes • Sensory interpretations • Understanding speech • Formulating words to express thoughts and emotions • Interpretations of textures and shapes

  26. Sensory areas

  27. “Small brain”

  28. Temporal lobes • Interpretation of auditory sensations • Memory of auditory and visual experiences

  29. Occipital lobe • Perception of vision • Vision recognition • Focusing and eye movement

  30. Memory • Short and long term memory • Several regions of the brain involved, especially temporal lobe, hyppocampus • Short  long term memory: medial temporal lobe • Long term memory independent of temporal lobe • Memory acquisition possible due to synapse changes

  31. The Brain • BRAIN MATTER AND CEREBROSPINAL FLUID • CEREBRUM • a- Cerebral hemispheres • a1- Lobes • a2- Basal ganglia (nuclei) • b- Brain stem • b1-Diencephalon • b1-1- Thalamus • b1-2- Hypothalamus • b2- Midbrain • b3- Pons • b4- Medulla oblongata • c- Limbic system • d- Reticular formation • CEREBELLUM

  32. Basal Nuclei • Mass of neurons located deep into the white matter • Help control of voluntary movement

  33. Basal Nuclei

  34. The Brain • BRAIN MATTER AND CEREBROSPINAL FLUID • CEREBRUM • a- Cerebral hemispheres • a1- Lobes • a2- Basal ganglia (nuclei) • b- Brain stem • b1-Diencephalon • b1-1- Thalamus • b1-2- Hypothalamus • b2- Midbrain • b3- Pons • b4- Medulla oblongata • c- Limbic system • d- Reticular formation • CEREBELLUM

  35. Diencephalon

  36. Diencephalon • Thalamus:4/5 of diencephalon • Below lateral ventricles • Relay center through which sensory informations (except smell) pass, on the way to the cortex • Many nuclei

  37. The Brain • BRAIN MATTER AND CEREBROSPINAL FLUID • CEREBRUM • a- Cerebral hemispheres • a1- Lobes • a2- Basal ganglia (nuclei) • b- Brain stem • b1-Diencephalon • b1-1- Thalamus • b1-2- Hypothalamus • b2- Midbrain • b3- Pons • b4- Medulla oblongata • c- Limbic system • d- Reticular formation • CEREBELLUM

  38. Diencephalon: Hypothalamus and pituitary gland • Below thalamus • Neural centers for many functions: - hunger, thirst, body temperature regulation - controls pituitary gland - contribute to sleep regulation, emotions (fear, anger, pain, pleasure..), sexual arousal

  39. Hypothalamus

  40. The Brain • BRAIN MATTER AND CEREBROSPINAL FLUID • CEREBRUM • a- Cerebral hemispheres • a1- Lobes • a2- Basal ganglia (nuclei) • b- Brain stem • b1-Diencephalon • b1-1- Thalamus • b1-2- Hypothalamus • b2- Midbrain • b3- Pons • b4- Medulla oblongata • c- Limbic system • d- Reticular formation • CEREBELLUM

  41. Midbrain • Between diencephalon and pons • Several nuclei: - corpora quadrigemina: visual and auditory reflexes - red nucleus: motor coordination - nigrostriatal system (from substancia nigra- basal ganglia) motor coordination (involved in Parkinson’s disease) - cerebral peduncles: ascending and descending fiber tracts

  42. Midbrain

  43. The Brain • BRAIN MATTER AND CEREBROSPINAL FLUID • CEREBRUM • a- Cerebral hemispheres • a1- Lobes • a2- Basal ganglia (nuclei) • b- Brain stem • b1-Diencephalon • b1-1- Thalamus • b1-2- Hypothalamus • b2- Midbrain • b3- Pons • b4- Medulla oblongata • c- Limbic system • d- Reticular formation • CEREBELLUM

  44. Pons • Between midbrain and medulla oblongata • Several nuclei associated with cranial nerves (V, VI, VII, and VIII) • Respiratory centers: apneustic and pneumotaxic centers • Communicates with cerebellum and medulla oblongata, and midbrain

  45. Pons

  46. The Brain • BRAIN MATTER AND CEREBROSPINAL FLUID • CEREBRUM • a- Cerebral hemispheres • a1- Lobes • a2- Basal ganglia (nuclei) • b- Brain stem • b1-Diencephalon • b1-1- Thalamus • b1-2- Hypothalamus • b2- Midbrain • b3- Pons • b4- Medulla oblongata • c- Limbic system • d- Reticular formation • CEREBELLUM

  47. Medulla oblongata • Between pons and spinal cors • Numerous nuclei controlling cranial nerves (VIII,IX,X,XI, and XII), and vital functions: vasomotor, cardiac, respiratory, sneezing, swallowing centers • Passageway for sensory and motor fibers • Fibers “decussate” or cross over

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