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Chapter 7 – Part 1 The Nervous System

Chapter 7 – Part 1 The Nervous System. Functions of the Nervous System. Sensory input – Gathering information To monitor changes occurring inside and outside the body Changes = stimuli Integration To process and interpret sensory input and decide if action is needed.

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Chapter 7 – Part 1 The Nervous System

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  1. Chapter 7 – Part 1The Nervous System

  2. Functions of the Nervous System • Sensory input – Gathering information • To monitor changes occurring inside and outside the body • Changes = stimuli • Integration • To process and interpret sensory input and decide if action is needed

  3. Functions of the Nervous System • Motor output • A response to integrated stimuli • The response activates muscles or glands

  4. Structural Classification of the Nervous System • Central nervous system (CNS) • Consist of the brain and spinal cord • Act as the integrating and command center • Interpret incoming sensory information and issue instructions

  5. Structural Classification of the Nervous System • Peripheral Nervous System (PNS) • Nerves outside the brain and spinal cord • These nerves serve as communication lines. • They link all parts of the body by carrying impulses from the sensory receptors to the CNS and from the CNS to the appropriate glands or muscles.

  6. Functional Classification of the Peripheral Nervous System • Sensory (Afferent) Division • Nerve fibers that carry information to the central nervous system • Keeps the CNS constantly informed of events going on both inside and outside the body.

  7. Functional Classification of the Peripheral Nervous System • Motor (Efferent) Division • Nerve fibers that carry impulses away fromthe central nervous system • These impulses activate muscles and glands; that is, they effect (bring about) a motor response.

  8. Functional Classification of the Peripheral Nervous System • Motor (Efferent) Division • Two subdivisions • Somatic Nervous System = Voluntary • Allows us to consciously control our skeletal muscles. • Autonomic Nervous System = Involuntary • Regulates the activity of the smooth and cardiac muscles and glands. • The ANC has two parts: The sympathetic and parasympathetic (Each typically brings about opposite effects)

  9. Organization of the Nervous System

  10. Nervous Tissue • Made up of two principal types of cells: • Supporting cells • Functions: Support, insulate, and protect • Not able to transmit nerve impulses • Never lose their ability to divide, whereas most neurons do. • Most brain tumors are formed by neuroglia cells. • Neurons • Are able to transmit nerve impulses

  11. Supporting Cells (Also Called Neuroglia) • Supporting cells of the CNS: • Astrocytes • Microglia • Ependymal • Oligodendrocytes • Supporting cells of the PNS: • Schwann cells • Satellite cells

  12. Nervous Tissue: Support Cells of the CNS (Neuroglia) • Astrocytes • Abundant, star- shaped cells • Brace neurons • Form a living barrier between capillaries and neurons • Help protect the neurons from harmful substances that might be in the blood. • Control the chemical environment of the brain • Pick up excess ions and recapture released neurotransmitters

  13. Nervous Tissue: Support Cells of the CNS • Microglia • Spider-like phagocytes • Dispose of debris (such as dead brain cells and bacteria) • Ependymal cells • Line cavities of the brain and spinal cord • Circulate cerebrospinal fluid

  14. Nervous Tissue: Support Cells of the CNS • Oligodendrocytes • Wrap their flat extensions tightly around the nerve fibers. • Produce myelin sheath (fatty insulating coverings) around nerve fibers in the CNS

  15. Nervous Tissue: Support Cells of the PNS • Satellite cells • Protect and cushion neuron cell bodies • Schwann cells • Form myelin sheath around nerve fibers in the PNS

  16. Nervous Tissue: Neurons • Neurons = Nerve Cells • Cells specialized to transmit messages • Major regions of neurons • Cell body– Nucleus and metabolic center of the cell • Processes – Fibers that extend from the cell body

  17. Neuron Anatomy • Cell Body • Nissl substance – Specialized rough ER • Neurofibrils – Intermediate cytoskeleton (filaments) that maintains cell shape

  18. Neuron Anatomy • Cell Body • Nucleus • Large nucleolus • Contains the usual organelles except for centrioles

  19. Neuron Anatomy • Extensions - Processes outside the cell body • Dendrites – Conduct impulses toward the cell body • Axons – Conduct impulses away from the cell body

  20. Processes or Extensions • Processes vary in length -From microscopic to 3-4 feet • The longest one in humans reach from the lumbar region of the spine to the big toe. • Neurons may have hundreds of the branching dendrites, depending on the neuron type. • Each neuron only has one axon.

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