1. Central Nervous System
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

2. Glial Cells 90% of CNS composed of glia Five types of glial cells
Astrocyte—numerous functions
Ependymal cells—line cavities
Microglia—phagocytes
Oligodendrocytes—form myelin
Schwann cells (located in PNS)—form myelin

3. Glial Cells

4. Astrocytes Remove neurotransmitter from synaptic cleft
Maintain normal electrolyte composition of spinal fluid in CNS
Protect neurons against toxic substances

5. Microglia Protect CNS from foreign matter through phagocytosis
Bacteria
Dead or injured cells

6. CNS: Physical Support

7. Cerebrospinal Fluid (CSF)
Extracellular fluid of the CNS
Secreted by ependymal cells
Functions
Cushions brain
Maintains stable fluid environment

8. CSF Production Total volume of CSF = 125–150 mL
Recycled three times a day

9. Blood Supply to the CNS 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

10. Stroke Caused by decreased blood supply
Occlusion (blockage, closing) of cerebral blood vessel
Hemorrhage from cerebral blood vessel

11. Blood-Brain Barrier Capillaries Blood-brain barrier
Sites of exchange between blood and interstitial (space between structures) fluid
Blood-brain barrier
Special anatomy of CNS capillaries which limit exchange

12. CNS: Gray and White Matter

13. CNS: Gray and White Matter
Figure 9.5b–c

14. II. Spinal Cord Cylinder of nerve tissue Continuous with brain
Surrounded by vertebral column
Origin of spinal nerves (31 pairs)

15. Spinal Cord

16. Spinal Cord: Cross Section

17. Brain

18. Brain: Midsagittal View
Cerebrum
Forebrain
Corpus
callosum
Thalamus
Diencephalon
Hypothalamus
Pituitary gland
Cerebellum
Midbrain
Brainstem
Pons
Spinal cord
Medulla oblongata
(c)
Midsagittal section

19. Functional Areas of Cerebrum
Primary motor cortex
(voluntary movement)
Central sulcus
Premotor cortex
(coordinates
voluntary
movements)
Primary somatosensory
cortex (somesthetic sensations
and proprioception)
Sensory association
areas (integration of
sensory information)
Prefrontal
association
areas (idea and
plan for voluntary
movement, thoughts,
personality)
Visual association
areas (higher vision
processing)
Primary visual cortex
(vision)
Broca’s area
(speech formation)
Wernicke’s area
(language
comprehension)
Olfactory cortex
(smell)
Limbic association
cortex (emotions,
learning, and memory)
Auditory
association
areas
Primary auditory
cortex (hearing)

20. Topographical Organization: Motor

21. Topographical Organization: Sensory

22. Automatic patterned response to a stimulus
Reflexes
Automatic patterned response to a stimulus
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

23. Reflex Arc

24. Stretch Reflex

25. Withdrawal and Crossed-Extensor Reflexes