1. 9 Unit 1 Chapter 9

2. 9 Unit 1 Brain- Neurons enclosed in skull Spinal cord– connects to brain & enclosed in spinal cavity Nerves- bundles of neuronal axons Cranial emerge from brain; spinal nerves- emerge from spinal cord Ganglia- groups of cell bodies outside brain & spinal cord Enteric plexuses- networks in digestive tract Sensory receptors- monitor changes in internal or external environments

3. Figure 9.1

4. 9 Unit 1 Sensory Receptors & afferent nerves Carry information into brain & spinal cord Integration- information processing Perception = awareness of sensory input Carry by short interneurons Motor activity- efferent nerves Signals to glands and muscles (effectors)

5. 9 Unit 1 Central Nervous System (CNS) Peripheral Nervous System (PNS) Subdivided: Somatic (SNS) & Autonomic (ANS) nervous systems Also INPUT-Afferent or Sensory division OUTPUT- Efferent or Motor division

6. Figure 9.2

7. 9 Unit 1 Neuron= nerve cell Specialized for signal carrying & information processing Neuroglia cells-support, nourish & protect neurons Neuroglia critical for homeostasis of interstitial fluid around neurons

8. 9 Unit 1 Cell body- nucleus, cytoplasm with typical organelles Dendrites- highly branched input structures emerging from cell body Axon- conducts away from cell body toward another neuron or effector Axon terminals -at end of axon with synaptic bulbs

9. Figure 9.3

10. 9 Unit 1 Axons covered with a myelin sheath Many layered lipid & protein creating insulations Increases speed of nerve conduction. Nodes of Ravier= gaps in the myelin Some diseases destroy myelin- E.g. multiple sclerosis & Tay-Sachs

11. 9 Unit 1 White matter- primarily myelinated axons Gray matter- cell bodies, dendrites, unmyelinated axons, axon terminals & neuroglia Spinal cord gray matter is centrally located Gray matter in brain covers surface of cerebrum & cerebellum – cortex

12. 9 Unit 1 Make-up ~ half the volume of CNS Cells smaller than neurons Can multiply and divide and fill in brain areas Do not conduct nerve impulses

13. 9 Unit 1 Astrocytes- blood brain barrier Oligodendrocytes- myelin in CNS microglia - defense Ependymal cells- CSF production Schwann- PNS cell support Satellite cells- in PNS ganglia