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Chapter 21 Nervous Systems

Chapter 21 Nervous Systems. It’s all about communication!. Think what’s involved in touching your finger to your nose… How do you do it?. 3. Nerve : Latin nervus sinew, nerve 4. What requires a nervous system?. 6. 6. 6. 5. 6.

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Chapter 21 Nervous Systems

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  1. Chapter 21 Nervous Systems It’s all about communication! Think what’s involved in touching your finger to your nose… How do you do it? 3

  2. Nerve: Latin nervus sinew, nerve4 What requires a nervous system? 6 6 6 5 6 Think what’s involved in licking a lollipop… How do you do it?

  3. Nervous Systems42 Make it possible for animals to know and react to the world around them… An action requires a stimulus that causes the organism to respond Stimuli may be internal or external

  4. Neuron Function • Neurons • Respond to Stimuli • Conduct impulses • Release chemical signals 2 Neurons carry messages from one cell to another

  5. Cell Body Nucleus and Organelles Dendrites(Receiver) Receive stimuli and transmit signal to cell body Axon(Transmitter) Carries impulsesaway from cell body Synapse (Junction) Axon meets Dendrite to pass on the message Synaptic Terminal Bulb-like extension of axon where it meets target cell Neuron Structure 1

  6. Sensory Systems - Input • Sensory Neurons have receptors that • Collect Information • Pass message to other cells • Stimuli include • Heat • Light • Pressure • Temperature See p. 548 for picture of skin receptors And p. 550 for an explanation of sight 10 What’s a stimulus?

  7. Motor Systems - Output … allow the organism to react to stimuli Effector: muscles and glands that do the response • Voluntary: requires a conscious decision • Involuntary: automatic response to stimulus Complex reactions may require many neurons and both voluntary and involuntary responses Think about running… P. 551

  8. Neuron Organization 3 Types of Neurons • Motor (Efferent) Neuron Transmit signal from CNS to muscles or glands (effectors) • Sensory Neurons From environment to CNS • Interneuron Between CNS neurons – most common type CNS = Central Nervous System • Brain and spinal cord PNS = Peripheral Nervous System • Sensory and motor neurons that connect to the CNS • 12 pairs of cranial nerves and 31 pairs of spinal nerves Where is the CNS? 1

  9. Sensory input Integration Sensory neuron Sensory receptor Motor neuron Interneuron Motor output Brain and spinal cord Effector Peripheral nervous system (PNS) Central nervous system (CNS)

  10. The Vertebrate Nervous System 1. Control responses to environment 2. Control internal organs 29 P. 553 Both 1 and 2 7

  11. Sympathetic division Parasympathetic division Brain Eye Constricts pupil Dilates pupil Salivary glands Stimulates saliva production Inhibits saliva production Relaxes bronchi Constricts bronchi Lung Accelerates heart Slows heart Adrenal gland Heart Spinal cord Stimulates epinephrine and norepinephrine release Liver Stomach Pan-creas Stimulate glucose release Stimulates stomach, pancreas, and intestines Inhibits stomach, pancreas, and intestines Intestines Bladder Inhibits urination Stimulates urination Promotes ejaculation and vaginal contractions Promotes erection of genitalia Genitalia Figure 27.10

  12. 1 The Central Nervous System Functions of the CNS • Connect sensory and motor functions of the PNS • Coordinates body functions such as endocrine system • Memory and learning 1.5 kg (~3.3 lbs) – 100 billion neurons Cerebrum 31 CNS = Brain + Spinal Cord

  13. 28 Spinal Cord and Vertebrae 20 Single Vertebra 20 Vertebrae of Tursops truncatus Lower part of a human spinal cord 19

  14. Meninges Cranium Cerebrospinal Fluid 18 Around the Brain What is the function of each part?

  15. Brain43 CEREBRUM: Holds our memories, and controls how we respond to sensory signals CEREBELLUM: Coordinates all of your movement and muscles MEDULLA: Controls our breathing and heartbeat; coughing, sneezing, swallowing, etc.; autonomic reflexes BRAIN STEM: Sends all of the decisions that the brain makes to the rest of the body.

  16. Functional Areas of the Brain Cerebrum Sensory Reception Muscle Control P. 555 Speech Visual Association Planning & Problem Solving Reading FRONTAL LOBE: Language and emotions. PARIETAL LOBE: Sense of touch as well as how we use our hands OCCIPITAL LOBE: Vision TEMPORAL LOBE: Hearing and organization Hearing Speech Smell and Taste Medulla Cerebellum Left Hemisphere of Brain: Verbal & Analytical Functions Right Hemisphere of Brain: Imaginative/Creative Thinking 22

  17. Human Cerebral Cortex Right Left Sensory and Motor Control Regions of the Human Cerebral Cortex 32

  18. Cells of the Nervous System 22

  19. Glial Cells2 • >50% of nervous system weight • 10-50x as many as neurons • Support neurons with nutrients and growth factors • Fill in space and coat CNS and brain blood cells • Schwann cells form myelin sheath on vertebrate axons Insect glial cell nucleus 3980x Astrocytic neuroglia cell 345x Astrocytic neuroglia cell 870x

  20. 1 Axons in Detail Nerve = Bundle of axons

  21. 8 Speeding Transmission Schwann Cells (p. 557) • Wrap an axon in Myelin Sheath • ~10x speed of transmission to 120 m/s Myelin Sheath Node of Ranvier Schwann Cell Axon Nucleus 9 Node of Ranvier • Space between Schwann Cells • Messages jump between nodes

  22. Ganglia: interconnected networks of neurons in the PNS Nuclei: interconnected networks of neurons in the CNS Lamina: layered functional groups in CNS Organized Networks 36 Vertebrate Ganglia Caterpillar Ganglia 37

  23. What’s a Potential? Polarization/Potential: charge across a membrane (+ on one side, - on the other) • Along the axon, maintained by active transport • Measured in volts 11 Red balls are Na+. Where is the charge most positive?

  24. Net + outside the cell Maintained by active transport by a Na+/K+ Pump Nerve Cell Body Axon K+ Na+ Cl- Inside Axon Na+ Cl- K+ Outside Axon Outside Inside Resting Potential12 When the neuron is not transmitting a signal

  25. Signal Transmission: The Action Potential The nerve signal involvesdepolarization of a small portion of the cell membrane. (flipping the charge around) 13 Threshold Voltage Change in potential is “all or nothing” once the threshold has been passed (Like computer bits)

  26. Na+ Na+ Na/K Pump Na/K Pump K+ K+ Recovery 12 14 Recovery

  27. Each depolarization triggers a depolarization in the next section of membrane. Remember that the refractory period keeps the AP moving in one direction only. Action Potential Transmission 15 Think of it like a message passed down a chain of people

  28. ElectroEncephaloGraph: detects electrical activity in the brain Positron Emission Tomography: measures radioactive decay – what parts of the brain are most active EEGs and PETs 33

  29. At the end of the Axon The message is carried to the next cell via a neurotransmitter. After use, the neurotransmitter is degraded. Synaptic Vesicles Axon Synapse Neurotransmitter Target Cell Dendrites Receptor 16 Synapse = junction between a neuron and another cell

  30. 1Synthesisand storage of neurotransmitter molecules in synaptic vesicles. 5 Return of neurotransmitters to neuron. 4 Inactivation by enzyme digestion or diffusion of neurotransmitters. 3Bindingof neurotransmitters at receptor sites on target cell (post synaptic membrane) 2Releaseof neurotransmitter molecules into synaptic cleft. 25 Synapse = junction between a neuron and another cell

  31. The Action Potential starts up again through the opening of ion channels in the target cell which depolarize the membrane. 14 Read on P. 564-565 about different types of neurotransmitters.

  32. Synapses in Action2 Synapses get stronger with lots of use shown by 1. More neurotransmitter released 2. Synapse shape changed to make it more efficient 3. Rate of neurotransmitter uptake/release changed to change stimulus length 4. More receptors for neurotransmitter made There are also electrical synapses that don’t use neurotransmitters!

  33. Depressants Alcohol Barbituates Lower nervous system activity by inhibiting synaptic transmission or directly affecting cells Stimulant Caffeine Nicotine Amphetamine Cocaine Mimic neurotransmitters in the body, amplifying the impulses Drugs as Neurotransmitters39 Psychoactive Drug:no nutritional value affects the psychological process Drugs can alter the way your nervous system works… Don’t damage your hardware! Why are they addictive?

  34. Neural Integration43 One Neuron – LOTS of data input!

  35. Sensory receptor Sensory input Integration Effector Motor output PNS CNS Visual Summary 27.1

  36. Nervous System Integration38 Neural Integration: • Many different inputs to CNS • Combine inhibitory and excitatory inputs so produce a specific response Threshold reached: Signal sent More stimulus counters inhibition: Signal sent Inhibition Counters Stimulus: No signal sent

  37. Reflex Arcs Faster response because the stimulus doesn’t pass through the brain 27

  38. Evolution of Nervous Systems43 More examples on P. 569 Nerve Net = evenly distributed nerve cells; signals pass through whole animal Simple animals, like jellyfish and hydra use a nerve net More complicated animals like planaria and insects have ganglia, nerve cords and simple brains

  39. Vertebrates have central and peripheral nervous systems. 1

  40. Ancestral Vertebrate Brain43 3 Specialized Regions 1. Hindbrain–reflexes • Cerebellum: movement coordination 2. Midbrain–relay center 3. Forebrain–processing • Cerebrum: learning and memory – Gets much bigger with evolution • Thalamus: sensory input • Hypothalamus: regulation of homeostasis; endocrine

  41. Developments in the Vertebrate Brain See P. 571 Size Complexity Specialization 43

  42. Adaptations in Nervous Systems Pufferfish venom blocks sodium channels which prevents depolarization.40 This fish has a 1 amino acid difference from other animals that protects their channels. Torpedo fish – synapses evolved to produce a protective electric charge.41 Like any other trait, changes in the genes that produce nervous system adaptations that help the organism are passed on!

  43. Literature Cited 1. The Online Biology Book. http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookNERV.html 2. www.denniskunkel.com with permission 3. www.personalizedpersonals.com/ members/meetingmating.htm 4. Mirriam Webster Dictionary Online: http://www.m-w.com/cgi-bin/dictionary 5. www.summacare.com/members/ complimentary.asp 6. www.pfizer.com/brain/ dlgame.html 7. www.rsdrx.com/ Anatomy%20Sketches.htm 8. http://www.keck.ucsf.edu/classes/physio126/EM-neuronal-components.html 9. http://www.albany.net/~tjc/9/myelin2.jpg 10. Mechanoreceptor: http://soma.npa.uiuc.edu/courses/physl341/Lec8.html 11. Measuring Potential: cas.bellarmine.edu/tietjen/HumanBioogy/ bills_nerve_pix.htm 12. Resting Potential: http://www.csus.edu/indiv/a/averyw/bio11/lectures/nervous/sld012.htm 13. AP Membrane diagram: http://www.zoology.ubc.ca/~auld/bio350/lectures/action_potential.html 14. Liebaert, Richard. Interactive Study Partner for Biology, Fifth Edition by Campbell, Reece & Mitchell.

  44. Literature Cited, cont. 15. Action Potential Movement: psychology.unn.ac.uk/andrew/ PY013/BBBrp_ap.htm 16. Synapse:www.neurogen.com/glossary.htm 17. Vertebrate brain evolution: bio.calpoly.edu/BioSci/Courses/ BIO/BIO414/Intro/I07.html 18. Bared brain: www.furman.edu/~einstein/general/ neurodemo/brain.htm 19. Spinal Cord:www.keck.ucsf.edu/classes/physio126/ spinal-cord.html 20. Single Vertebra: www.stoppingpain.com/ vertebralc.htm 21. Tursiops Vertebrae:http://lionfish.ims.usm.edu/~musweb/seatrout/bufeo/Tursiops_truncatus_spond_pictures.html 22. Brain Structure and Function:www.sciencebob.com/lab/ bodyzone/brain.html 23. Neuron 2: http://www.enchantedlearning.com/subjects/anatomy/brain/Neuron.shtml 24. Brain Schematic/Functions: www.wramc.amedd.army.mil/departments/ aasc/brain.htm 25. http://homepage.psy.utexas.edu/homepage/Class/Psy301/Salinas/sec2/Brain/transparencies03.html 26. Autonomic Nervous System: www.driesen.com/ autonomic_nervous_system.htm 27. Reflex Arc: www.esb.utexas.edu/zoo314k/ lectures8-16.htm 28. Brain Cartoon 2: kuoi.asui.uidaho.edu/ ~kamikaze/dg.html 29. Brain Cartoon:www.artstudiollc.com/ trivia3.htm 30. Brain MRI: www.mypacs.net/about.htm 31. user.shikoku.ne.jp/tobrains/ brain/brain-e.html 32. http://www.math.tu-dresden.de/~belov/brain/motorcor2.gif, http://www.math.tu-dresden.de/~belov/brain/sensory2.gif. - Brown & Benchmark Introductory Psychology Electronic Image Bank. 1995 33. http://psg275.bham.ac.uk/bbs/symon-fac.htm 34. http://info.med.yale.edu/neurobio/mccormick/seminar/figure1.htm 35. http://www.memory.ucla.edu/home.htm 36. marlin.life.utsa.edu/ Default.html 37. http://microscopy.bio-rad.com/galleryimages/image9.htm 38. http://www.arts.uwaterloo.ca/~cellard/teaching/PSYC261/neuro3/sld001.htm 39. http://www.abortionfacts.com/contraceptives/contraceptives.asp 40. www.dhushara.com/book/ med/zombie.htm 41. www.oceanlight.com/html/ lesser_electric_ray.html 42. Larson, Gary. The PreHistory of the Far Side: A 10th Anniversary Exhibit. Andrews and McMeel, Kansas City. 1980. 43. Bioshow: for Biology: Concepts and Connections, Second Edition. Campbell, Mitchell, and Reece

  45. Heat Light touch Pain Cold (Hair) Light touch Epidermis Dermis Nerve Touch Strong pressure Skin Receptors43 Figure 27.16

  46. Smell Receptors43

  47. Taste Receptors43

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