1. The Central Nervous System
Chapter 9, part A
The Central Nervous System

2. About this Chapter Emergent properties of the nervous system
Anatomy and functions of the CNS
Divisions of the brain and what each controls
Integration of complex pathways for behavior
Language, memory and others

3. Evolution of the Nervous System
Nerve net – jellyfish
Simple brain & nerve cord – flatworm
Brain & nerve cord with ganglia – earthworm
Increasing forebrain – fish, bird & human
Olfactory – fish
Complex behavior – birds
Reasoning & cognition – humans

4. Evolution of the Nervous System
Figure 9-1: Evolution of the nervous system

5. Embryonic Development of Nervous System
Neural plate to neural tube
Neural crest–PNS
Anterior forms brain
Forebrain
Midbrain
Hindbrain
Hollow ventricles
Spinal cord
Figure 9-2: The embryonic nervous system develops into a hollow tube

6. Embryonic Development of Nervous System
Figure 9-3 a-c: The neural tube specializes into the six major regions of the nervous system.

7. Central Nervous System: Overview
Brain
Spinal cord
Figure 9-4a: ANATOMY SUMMARY: The Central Nervous System

8. Protecting the Brain Hair, skin, cranium Venous sinus blood Meninges
Drua mater
Arachnoid membrane
Pia mater
Cerebrospinal fluid
Figure 9-4b, c: ANATOMY SUMMARY: The Central Nervous System

9. Cerebrospinal Fluid From coracoid plexus
Fills ventricles & subarachnoid
Fluid pillow floats brain
Exchange transport
From blood
To brain tissue

10. Cerebrospinal Fluid
Figure 9-5: ANATOMY SUMMARY: Cerebrospinal Fluid

11. Blood Brain Barrier Extensive capillaries & sinuses
Tight junctions: limit permeability
Astrocyte foot processes: secrete paracrines
Protects brain: hormones & circulating chemicals
Many glucose transporters
Figure 9-6: The blood-brain barrier

12. Spinal Cord Regions Cervical Thoracic Lumbar Sacral
Figure 9-4a: ANATOMY SUMMARY: The Central Nervous System

13. Spinal Cord Organization
Gray matter: mostly cell bodies
Dendrites & terminals
Spinal reflex integrating center
White matter
Bundles of myelinated axons
Ascending tracts – sensory
Descending tracts – motor
Dorsal roots
Ventral roots

14. Spinal Cord Organization
Figure 9-7: Specialization in the spinal cord

15. Brain Overview Trillion interneurons fill the brain
Up to 200,000 synapses each
Brain divisions
Cerebrum
Diencephalons
Midbrain
Cerebellum
Pons
Medulla oblongata

16. Brain Overview
Figure 9-9b, c: ANATOMY SUMMARY: The Brain

17. Brain Stem Overview: Midbrain, Pons & Medulla
Many cranial nerves enter
Pyramids – nerve tracts crossover
Midbrain – eye movement control
Pons – breathing, signal relay
Medulla – involuntary functions
Examples: Blood pressure, vomiting
Reticular formation:
Network in brain stem
Arousal, sleep, pain, & muscle tone

18. Brain Stem Overview: Midbrain, Pons & Medulla
Figure 9-9d: ANATOMY SUMMARY: The Brain

19. Cranial Nerves
Table 9-1: The Cranial Nerves