The Central Nervous System

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

7. 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)

8. Meninges

9. Meninges

10. Meningitis

11. 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

13. Cerebrospinal fluid circulation

14. CSF circulation

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

16. Hydrocephalus

17. 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

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

19. 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

20. Brain structure

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

22. 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.

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

24. Frontal lobe : Motor area

25. 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

26. Speech areas

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

28. Sensory areas

29. “Small brain”

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

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

32. 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

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

36. Basal 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

39. 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

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. 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

42. Hypothalamus

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. 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

45. Midbrain

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. 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

48. Pons

49. 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

50. 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