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Nervous System

Nervous System. Ch 9. Pre. And Suf. Quiz Thursday. Ax- axle gangli- swelling Dendr- tree lemm- peel/rind Funi-small cord or fiber moto- moving Mening- membrane peri-around Plex- interweave sens- feeling Syn- together ventr- belly/stomach. What is the nervous system?.

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Nervous System

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  1. Nervous System Ch 9

  2. Pre. And Suf. Quiz Thursday • Ax- axle gangli- swelling • Dendr- tree lemm- peel/rind • Funi-small cord or fiber moto- moving • Mening- membrane peri-around • Plex- interweave sens- feeling • Syn- together ventr- belly/stomach

  3. What is the nervous system? • A system of nerves and supporting tissues that create the • Senses (Sight, Hearing, etc..) • Thought • Muscle Movement • Feelings

  4. What is the job of the nervous system? • Sensory function: Detect changes in and out of the body. • Motor function: Effect Muscles & glands. • Integrative function: To connect the Sensory and Motor function. Produces thought.

  5. What are the two major parts of the nervous system and what are they composed of? • Central nervous system: Brain and Spinal chord • Peripheral nervous system: All other nerves Vs.

  6. Parts of the Peripheral Nervous System (PNS) The NS In Action • Somatic Nervous System • Called Voluntary Nervous System • Autonomic Nervous System • Involuntary Nervous System • 2 Major Branches • Sympathetic • Fight or flight • Liver: glycogen to glucose, Bronchi dilate, Adrenaline increases, Heart rate and breathing increase • Parasympathetic • Calms body down. Decreases Heart and breathing, increases digestion. Parasympathetic vs. SympatheticNervous System Autonomic Nervous System in Action

  7. What is nervous tissue? • Neurons: or nerve cells. Conduct the impulses. • Neuroglial/ Glial cells: nurse cells to neurons. Protect, feed, speed up the signal. May be the cause of Alzheimer's and Parkinson's. • Schwann Cells: form myelin sheath

  8. What are the parts of a nerve? • Axon • Dendrite • Cell Body • Nucleus • Myelin • Node of Ranvier

  9. What are the types of nerve cells? • Unipolar: used in ganglia. Nucleus is off to the side. • Bipolar: used in eyes, nose, and ears. Nucleus is in the middle. • Multipolar: used in brain and spinal cord. Nucleus is within the dendrites.

  10. Nerve Cell • Cell body: cytoplasm, organelles: mitochondria, lysosomes, golgi apparatus, and Nucleus. • Dendrites: pick up the nerve signal. • Axon: Long, may be branched carry nerve signals Away. Review of A Neuron

  11. Do nerve cells reproduce once mature? • No. That is the problem. They can grow axon ends, but once the nucleus is damaged that nerve will not grow back.

  12. What are Neuroglial Cells? • Schwann cells: wrap around axon and speeds up nerve signals. Mainly fat called Myelin. Can’t carry nerve signal so the charge jumps over them at the nodes of Ranvier. = Grey Matter • Astrocytes: Structural support & feed • Microglial Cells: Phagocytize invaders & broken cell parts

  13. What difference does it make if a nerve has Schwann cells or not? • Nerves that have a large diameter and are myelinated are super-fast: 120m/s • Nerves with a small diameter that are unmyelinated are slow: 0.5m/s

  14. How do nerves communicate? • Through Neurotransmitters: chemical signals sent from the Axon terminals of the nerve. • Nerves communicate through electrical signals. • These electrical signals are created through action and resting potentials.

  15. How is an action potential reached? Action Potential Explained • Change in nerve membrane permeability. Na+ rushes in the nerve is depolarized (loses its charge). • K+ then rushes out which repolarizes the nerve cell. • 1/1000 of a second. Both steps together are the action potential. • Active transport soon reestablishes the resting potential. Action Potential

  16. So… How does a nerve signal reach resting potential? • Nerve has a slightly negative charge inside and a slightly positive charge outside at rest. = Polarized See fig 7.9 • K+ ions are inside, Na+ ions outside. Negative charge can’t diffuse through the membrane. • Active transport is used to push Na+ out and K+ in. More + leave than enter= neg. charge inside.

  17. What do muscles and nerves have in common? • All or none response. The nerve impulse is either conducted or not. The intensity of the signal does not change.

  18. How is an action potential sent? • Write one paragraph explaining it without looking in your notes. • Someone or someone's will be chosen to read their explanations to the class.

  19. How are Neurotransmitters released? • Action potential causes Ca+ ions to enter the terminal end of the axon. • Synaptic vesicles then fuse with the membrane. • Contents are released into the synaptic cleft. • Neurotransmitters are decomposed and the vesicles retreat to be refilled.

  20. How do Neurotransmitters Communicate? Neurotransmitter Actions NIH Worksheet Group Work: Summarize how you think the neuron works. NIH Neurotransmitters

  21. What is a Synapse? • The junction between two communicating nerves. • Presynaptic neuron to the synaptic cleft to the Postsynaptic neuron

  22. Synaptic Cleft

  23. If a drug like procaine decreased the membrane permeability to Na+ ions, what would be the effect? • Impulses from one nerve can not pass to the next region. The action potential can’t be reached. Used by doctors as a local anesthetic.

  24. What kind of neurotransmitters cross the synaptic cleft? • Acetylcholine: Muscles • Epinephrine/ Adrenaline: Fight or Flight • Norepinephrine: almost the same as epinephrine but has no effect on the heart. • Dopamine: brain functions: not working= schizophrenia and Parkinson's • Seratonin: suppresses pain impulses

  25. Need a review? Hit the button.Go through each of them EXCEPT the second one.

  26. How does a reflex work? • Reflex Arc • Stimulus Receptor end of a Sensory neuron  Interneuron (reflex center, often the spinal cord)  Motor neuron  Effector (Muscle being moved)Response Reflex Arc

  27. Can you control a reflex? • No. Reflexes are automatic & unconscious. • Anesthesiologists will often use this information to test if the medicine is working.

  28. Reflex Lab

  29. Some neurons are Sensory Receptors • Naked Nerve Endings=Pain • Meissner’s Corpuscles= Touch • Pacinian Corpuscles= Deep Touch • Many Others: Figure 7.7 Factoid: Your funny bone is really your Ulnar nerve (close to the surface of your body.)

  30. What do other neurons do? • Mirror Neurons in the Brain PBS Special: 2005 14 minutes On Mirror Neurons

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