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The Nervous System Part 1

The Nervous System Part 1. “Organization of the Nervous System”. *The nervous system is the “wiring” that keeps the body connected and functioning. *Works with the endocrine system to keep the body in homeostatic balance.

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The Nervous System Part 1

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  1. The Nervous SystemPart 1 “Organization of the Nervous System”

  2. *The nervous system is the “wiring” that keeps the body connected and functioning. *Works with the endocrine system to keep the body in homeostatic balance. *The nervous system also enables us to learn, form memories and allow for critical and creative thinking in ways not fully understood. Parkinson’s and Alzheimer’s disease both affect the nervous system. Parkinson’s kills dopamine producing cells, so there is nothing to stop muscle contractions. Alzheimer's affects memory cells.

  3. Organization of the Nervous System • Central Nervous System (CNS) • Brain and spinal cord • makes decisions • made up of tracts of fibers • Peripheral Nervous System (PNS) • Cranial and spinal nerves • Relays info to and from the CNS • made up of Nerves

  4. Organization of the Peripheral Nervous System • Afferent Divisions (Sensory messages) • carries info towards the CNS • Efferent Divisions (Motor messages) • carries info away from the CNS

  5. Organization of the Peripheral Nervous System • Somatic Nervous System (SNS) Voluntary • Controls skeletal muscles • Somatic sensory division :(afferent) stimulus from muscle receptors to the CNS. • Somatic motor division: (efferent) response from CNS to skeletal muscles • Autonomic Nervous System (ANS) Involuntary • Controls smooth and cardiac muscles, glands • Visceral sensory division: (afferent) stimulus from organ receptors to CNS. • Visceral motor division: (efferent) response from CNS to organs • Sympathetic and parasympathic

  6. Divisions of Autonomic Nervous System • Involuntary part of the peripheral nervous system • Sympathetic Division • “Fight or flight” response • Takes over to deal with immediate threats • Parasympathetic Division • “Rest and repair” division • Coordinates normal resting activities

  7. The Nervous SystemPart 2 “Cells of the Nervous System”

  8. Cells of the Nervous System • Neurons (nerve cells) • Excitable cells that transmit signals • Neuroglia (glial cells) • Are support cells for the neurons • Sometimes called “nurse” cells

  9. Neurons Key Parts • No centrioles because amitotic • Soma or cell body -contains the nucleus • Nissl bodies - ribosomes to make neurotransmitters. • Dendrites(receptors) - receive signals • Axon - long arm extending away from cell body, transmits signal away from cell body to next neuron • Axons can have side branches called axon collaterals.

  10. Path of Nerve Impulse Dendrite  cell body  axon  synapse ------------------------------------------------------------------

  11. A. Multipolar Most neurons in brain and spinal cord are multipolar B. Bipolar Only one axon and dendrite Least numerous Found in eye, inner ear and nose C. Unipolar One end branches toward CNS while the other goes toward PNS Two processes form a long axon Carries both sensory and motor info. Structural Classification of Neurons

  12. TYPES OF GLIAL CELLS • Astrocytes • Microglia • Ependymal cells • Oligodendrocytes • Schwann cells • Satellite cells

  13. Astrocyte

  14. Astrocytes- ‘star cells’ • Found only in the CNS • Largest and most numerous type of glia • Bridge between capillaries and neurons • filter harmful substances and transport nutrients. • They form the blood-brain barrier (BBB)

  15. Microglia

  16. Microglia • Found in CNS • Small and stationary • Fight infection in brain tissue through phagocytosis.

  17. Ependymal cells

  18. Ependymal cells • Found only in CNS • Line fluid-filled cavities in the brain and spinal cord • Form Cerebrospinal fluid (CSF) • Cilia helps keep fluid circulating through brain and spinal cord.

  19. Myelin • Whitish fatty material that increases speed of conduction in an axon • Insulates nerve fiber axons • Myelinated fibers are called white matter • Non-myelinated fibers are called gray matter • Destroyed in individuals with multiple sclerosis

  20. Schwann Cells

  21. Schwann Cells • Found only in PNS • Form myelin sheaths around cells of the PNS. • Gaps between schwann cells are called nodes of ranvier.

  22. Oligodendrocytes

  23. Oligodendrocytes • Found only in CNS • Produce the fatty myelin sheath around the nerve fibers of CNS • Hold nerve fibers together

  24. Quick Check • What is the difference between neurons and glial cells? • What does myelin do? • Which glial cell makes myelin in the CNS?

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