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Nervous System

Nervous System. 3 Functions of the Nervous System (SIM). 1. Sensory input—gathering information monitor changes inside and outside the body changes = stimuli sensory receptors responsible for input 2. Integration decide if and what action is needed 3. Motor Output a response

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Nervous System

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  1. Nervous System

  2. 3 Functions of the Nervous System (SIM) 1. Sensory input—gathering information • monitor changes inside and outside the body • changes = stimuli • sensory receptors responsible for input 2. Integration • decide if and what action is needed 3. Motor Output • a response • activates muscles or glands (effectors)

  3. Functions of the Nervous System Figure 7.1

  4. Organization of the Nervous System Figure 7.2

  5. Structural Classification of the Nervous System 2 Main Divisions • Central nervous system (CNS) • Brain • Spinal cord 2. Peripheral nervous system (PNS) • Spinal nerves (to and from spinal cord) • Cranial nerves (to and from brain)

  6. Functional Classification of the Peripheral Nervous System • Sensory (afferent) division • carry information to the central nervous system • Keep the body informed of internal and external environment • Motor (efferent) division • carry impulses away from the central nervous system • Cause some sort of effect

  7. Functional Classification ofthe Peripheral Nervous System • Two subdivisions of the Motor (efferent) division • Somatic nervous system = voluntary Skeletal muscles (except reflexes) • Autonomic nervous system = involuntary smooth muscle, cardiac muscle, glands

  8. Functional Classification ofthe Peripheral Nervous System Two subdivisions of the Autonomic nervous system 1. Sympathetic • Concerned with processes involving expending energy. • Active during times of extreme stress, emotion, and exercise. • Parasympathetic • Concerned with conservation of energy • Can dominate sympathetic system. Books says antagonistic, but they are more complimentary

  9. Nervous Tissue: 2 Main Types of Cells 1. Neurons carry messages (impulses) 2. Supporting cells or neuroglia

  10. Nervous Tissue: Neurons specialized to transmit messages • structures may differ, but all neurons have: PARTS: 1. Cell body • contains transparent nucleus • large conspicuous nucleolus • metabolic center of the cell

  11. Nervous Tissue: Neurons 2 Types of Processes • fibers that extend from the cell body • Dendrites—conduct impulses toward the cell body • Axons—conduct impulses away from the cell body

  12. Nervous Tissue: Neurons Figure 7.4

  13. Axon Terminals- axon ends • contain vesicles with neurotransmitters • do not touch dendrite of next neuron OR muscle • Synaptic cleft—gap between adjacent neurons • Synapse—junction between nerves

  14. Nervous Tissue: Neurons • Myelin sheath—whitish, fatty material covering axons • Schwann cells—produce myelin sheaths in jelly roll–like fashion • Nodes of Ranvier—gaps in myelin sheath along the axon

  15. Neurons Figure 7.4

  16. Functional Classification of Neurons • Sensory (afferent) neurons • Carry impulses from the sensory receptors to the CNS • Cutaneous sense organs • Heat, cold, pressure, pain • Proprioceptors—detect stretch or tension (found in muscles, tendons and joints) • Motor (efferent) neurons • Carry impulses from the central nervous system to viscera, muscles, or glands

  17. Functional Classification of Neurons • Interneurons (association neurons) • Found in neural pathways in the central nervous system • Connect sensory and motor neurons • Receptors • Specialized dendritic endings • Simple: cutaneous receptors (pain, touch) • Complex: special sense organs (eye, nose)

  18. Figure 7.6

  19. 6 Types of Support Cells 1. Astrocytes (CNS) • star-shaped cells • Most abundant of the glial cells Mainly function between neurons and capillaries • Bridging the two • Communication between the two • Barrier between the two • Control the chemical environment of the brain (taking in extra K+ or neurotransmitters)

  20. Nervous Tissue: Support Cells 2. Microglia (CNS) • Spiderlike phagocytes (phago- eat) • Dispose of debris (dead brain cells and bacteria)

  21. Nervous Tissue: Support Cells 3. Ependymal cells (CNS) • Line cavities of the brain and spinal cord • Ciliated cuboidal epithelial cells • Circulate cerebrospinal fluid • Help in production of cerebrospinal fluid

  22. Nervous Tissue: Support Cells 4. Oligodendrocytes (CNS) • Wrap around nerve fibers in the central nervous system • Produce myelin sheaths in CNS 5. Schwann cells (PNS) • Form myelin sheath in the PNS

  23. Nervous Tissue: Support Cells 6. Satellite cells (PNS) • Protect neuron cell bodies by providing cushion

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