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Chapter 34

Chapter 34. Neural Control. Nervous System. Functions (Neurons) Sensory input Detect & receive Internal or external Integration Process & interpret Motor output Muscles & glands. Nerve Pathway. Nervous System Types. Nerve Net Cnidarians Sensory neurons in epidermis

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Chapter 34

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  1. Chapter 34 Neural Control

  2. Nervous System • Functions (Neurons) • Sensory input • Detect & receive • Internal or external • Integration • Process & interpret • Motor output • Muscles & glands

  3. Nerve Pathway

  4. Nervous System Types • Nerve Net • Cnidarians • Sensory neurons in epidermis • Motor neurons in all tissues

  5. Nervous System Types • Ladder-Like • Plathyhelminthes • Long nerves • Ganglia (“brain”) • Integration

  6. Nervous System Types • Advanced Invertebrates • More advanced • Cephalized • Brain • Ventral nerve cord • Branching nerves

  7. Nervous System Types • Vertebrate • More advanced • Many more neurons • 1 million in insects • Vertebrates 1,000-1 billion more! • Two divisions • Central nervous system • Peripheral nervous system

  8. Nerve Cells • Neuron • Primary cell type • Conducts impulses • Neuroglial • Support/nourish neuron • Non-excitatory • 9:1 ratio

  9. Neuroglial Cells—CNS

  10. Neuroglial Cells—PNS

  11. Neurons • Characteristics • Excitable • Longevity • High Metabolic Rate • Sometimes Large • Amitotic • May Regenerate

  12. Neurons • Sensory (afferent) • Detects stimuli • Carry signal to CNS • Interneuron (association) • Transmit between neurons in CNS • Motor (efferent) • Carry signal to muscle or gland

  13. Neurons • Axon • Soma • Dendrite • Myelin sheath • Axon terminal • Synapse

  14. Neurons • Myelin Sheath • Insulating • Myelinated transmit faster

  15. Neurons • Synapse • Chemical • Electrical

  16. Neurotransmitters • Acetylcholine • Most common • Neuromuscular junction • Norepinephrine • Involuntary functions • Dopamine • Many functions • Behavior & mental ability • Serotonin • Mood • Sleep

  17. Nerve Impulse • Resting potential • Na+ higher outside of cell • K+ higher inside of cell

  18. Nerve Impulse

  19. Nerve Impulse

  20. Nerve Impulse • Sodium gates open • Sodium moves into cell • Action potential starts • Potassium gates open • Potassium moves out of cell • Electrical charges across membrane switch • “Wave” of charge moves along axon

  21. Nerve Impulse • Myelinated axons transmit signal faster

  22. Nerve Impulse • All-or-nothing • Refractory period • Cannot respond to signal

  23. Central Nervous System • Brain & spinal cord • White matter—myelinated • Grey matter—unmyelinated • Meninges • Cerebrospinal fluid

  24. Central Nervous System • Brain • Alligator—0.003% body weight • Sperm whale—0.06% • Rat—0.5% • Human—2%

  25. Brain • Cerebrum • Integrates & analyzes • Frontal lobe—motor control • Parietal lobe—sensory from body • Occipital lobe—vision • Temporal lobe—hearing, emotions

  26. Brain • Thalamus • Relay station • Memories, emotions • Hypothalamus • Homeostasis • Sleep, sex, thirst, etc. • Medulla Oblongata • Heart rate, breathing, blood pressure • Involuntary muscle contractions

  27. Brain • Pons • Fine-tune breathing • Hearing/sight reflexes • Cerebellum • Coordinate movement • Gordon • Weebles

  28. Brain • Limbic System • Learning • Memory • Fear & pleasure • Facial expressions

  29. Peripheral Nervous System • Cranial & spinal nerves

  30. Peripheral Nervous System • 12 pairs Cranial Nerves • 31 pairs Spinal Nerves

  31. Peripheral Nervous System • Somatic • Sensory signals to skeletal muscle • Synapses in brain or spinal cord • Reflexes

  32. Peripheral Nervous System • Reflex arc

  33. Peripheral Nervous System • Autonomic • Involuntary • Cardiac muscle • Smooth muscle • Glands

  34. Autonomic Nervous System • Sympathetic • “Fight or flight” • Excitement • Exercise • Emergency • Embarassment • Parasympathetic • “Rest & digest” • Digestion • Defecation • Diuresis

  35. Autonomic Nervous System

  36. Autonomic Nervous System

  37. Autonomic Nervous System

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