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Nervous System Communication

Explore the intricate network of nerve cells, learn about nerve impulses, and delve into the various systems in the nervous system. Discover how neurons transmit signals, the structure of nerve cells, and the function of neurotransmitters.

ronaldthompson
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Nervous System Communication

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  1. Nervous System Communication

  2. Kid ConcussionsIn The News

  3. Neurons • Nerve cells • Parts of neurons • Cell body • Long extensions • Message = nerve impulse

  4. Animal Nervous Systems • Sponges – no nervous system • Other animals all have neurons in systems

  5. Nerve Net • In all cnidarians • Interconnected nerve cells • No brain

  6. Ringlike Nervous System • In echinoderms • Ring with 5 radiating nerves

  7. Ladderlike Nervous System • In many Platyhelminthes • Some have distinct brain

  8. Annelid Nervous System • Segmental ganglia • Ganglia = aggregations of nervous tissue • Ventral nerve cord & brain

  9. Vertebrate Nervous System • Central nervous system • Brain & spinal cord • Peripheral nervous system • Nerves to & from CNS

  10. Nerve Cells • Cell body • Contains nucleus • Organelles necessary for cell • Axon • Long cell extension • May have myelin covering • Dendrites • Cell extensions • No myelin covering

  11. Sensory Neurons • Receive information • Transmit to the central nervous system

  12. Motor Neurons • Transmit commands away from CNS • To muscles & glands

  13. Interneurons • Located within brain & spinal cord • Integrate information • Axons may not be myelinated

  14. Neuroglia • Nerve support cells • Provide support, protection, & nutritional stability • Schwann cells • Found around axons • Produce myelin sheath

  15. Myelin Sheath • Insulates axon • Nodes of Ranvier • Uncovered areas

  16. Nerve Impulses • Electrical signals transmitted along membranes of nerves

  17. Resting Potential • Neuron is electrically charged at rest • Outside is positively charged • Inside is negatively charged

  18. Sodium-Potassium Pump • Proteins embedded within cell membrane • Moves sodium to the outside • Moves potassium to the inside • Maintains resting potential • Requires energy

  19. Action Potential • Nerve impulse is started by a stimulus • Stimuli cause movements of ions through membrane • Threshold potential • Sufficient stimulation to depolarize membrane • Action potential • Rapid reversal of membrane electric potential

  20. Nerve Transmission • Action potential at one point depolarizes next area • Depolarization moves in self-propagating wave

  21. Saltatory Conduction • Nerve impulse jumps & moves faster along myelinated axon

  22. Synapse • Area where nerve communicates • Transfers message • Another neuron • An effector

  23. Synaptic Cleft • Neurons do not touch other neurons or effector cells • Nerve impulse must cross gap

  24. Neurotransmitters • Organic molecules (> 60 different chemicals) • Transfer message across synaptic cleft • Attach to receptors on target cell

  25. Neuromuscular Junctions • Synapse between neuron & skeletal muscle • Neurotransmitter is acytylcholine

  26. Neuron to Neuron Connections • Uses many different neurotransmitters • Some cause different effects • Excitatory synapse – continuation of impulse • Inhibitory synapse – reduce ability to depolarize

  27. Integration of Nerve Impulses • Summed impulses determine if postsynaptic neuron will depolarize

  28. Human Nervous System • Central nervous system • Brain • Spinal cord • Peripheral nervous system • Brings messages to & from CNS • Somatic nervous system – voluntary • Autonomic nervous system - involuntary

  29. Central Nervous System • Integrates sensory & motor impulses

  30. Spinal Cord • Connects peripheral nervous system with brain • Receives information via spinal nerves • Includes reflex arcs

  31. CNS Protection - Meninges • Layers of membranes • Dura mater • Arachnoid • Pia mater

  32. Peripheral Nervous System • Sensory & motor impulses • Cranial nerves communicate directly with brain

  33. Spinal Nerves • Sensory & motor nerve fibers • Travel directly to spinal cord • Nerves are bundled to form mixed nerves

  34. Motor Neuron Systems • Somatic • Voluntary • Movements of skeletal muscles • Autonomic • Involuntary • Reflex = automatic response to nerve stimulation • Involuntary motor pathways

  35. Divisions of the Autonomic Nervous System • Parasympathetic • Prevails during periods of inactivity • Housekeeping • Sympathetic • “fight or flight” • Responds to stress • Prepares body for action • Parasympathetic & sympathetic together help to maintain homeostasis

  36. Psychoactive Drugs • Affect action of nervous system • Neurotransmitters • Specific parts of the brain • Some are abused

  37. Drug Addiction • Chronic use (or abuse) of psychoactive drugs • Person becomes physically dependant • Drug use tends to increase due to drug tolerance

  38. End Chapter 32

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