introduction to nervous system.ppt
- 3. Composition of Nervous System Two main divisions 1) Central Nervous system (CNS) brain and spinal chord 2)Peripheral Nervous System (PNS) nerves
- 4. Remember from Homeostasis Message is received from sensory receptor along sensory neuron (afferent pathway) Messages reaches brain and is integrated (control center) Reaction command sent down efferent pathway along motor neuron (motor output)
- 5. Types of Motor Actions Somatic Happens in skeletal muscle voluntary Autonomic Happens in smooth and cardiac muscle Involuntary 2 parts Sympathetic and parasympathetic
- 6. Cells of the Nervous System Broken down into two groups 1) supporting cells 2) neurons
- 7. Examples of Neuroglia (supporting cells) 1) astrocytes – anchor neurons to capillaries 2) microglia – phagocytes (digest debris and dead cells) 3) Ependymal cells- ciliated; always on surface near spinal fluid; circulates fluid
- 8. One more Neuroglial cell (in CNS) 4)Oligodendrocytes – fatty; insulated nerve fibers Produce myelin sheath which surround and insulate the nerve fiber
- 9. In PNS Instead of oligodendrocytes, they have Schwann cells, which insulate the nerve fiber Satellite cells – form protective layer around nerve cell body
- 10. Neurons Specifically designed to transmit message (nerve impulse)
- 11. Parts of a Neuron 1)Cell Body- contains nucleus 2) fiber (process)- carries message to next neuron Toward cell body = dendrites Away from cell body = axon
- 12. Axonal Terminal As an axon ends, it branches into hundreds of synapses. Releases neurotransmitters to next neuron or muscle
- 13. Myelination of Neurons In CNS, the fatty covering is oligodendrocyte In PNS, fatty myelin forms Schwann cells, which increase transmission rate. Gaps between Schwann cells= Nodes of Ranvier