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The Nervous System

The Nervous System

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Bio30_u30a_ch13_00_notes Presentation Transcript

  • 1. Unit 30 ABiology 30 Nervous and Endocrine Systems Chapter 13 Nervous System
  • 2. Unit 30 ABiology 30 Nervous and Endocrine Systems Ch. 13 - Lesson 1 13.1 The Importance of the Nervous System (pp.406–10) 3
  • 3. Biology 30 Today’s ObjectivesToday you must be able to: 1. describe the general structure and function of a neuron and the myelin sheath. 2. identify the principal structures of the central and peripheral nervous systems.  Today we will also: 3. discuss the biological basis of the Parkinson’s disease, a neurological disease, and how this relates to treatment. 4
  • 4. Biology 30 Parkinson’s Disease A good reason to study the nervous system:  Do you recognize this face? o This is Michael J. Fox (A Canadian actor) o Michael was born in Edmonton, Alberta in 1961 o Michael is famous for many TV shows and movies in his younger days. o Now, Michael is commonly seen on TV promoting awareness for Parkinson’s disease. o He first started to show signs of the disease in 1990 5 while shooting the film “Doc Hollywood”.
  • 5. Biology 30 Parkinson’s Disease A good reason to study the nervous system: cont’d  What is parkinson’s disease? o Before we watch a video clip of Michael being interviewed by Katie Couric, I want you to keep these questions in mind. – What are the visible symptoms of Parkinson’s disease? – What part of the nervous system do you think is affected by this disease?Link: “Michael J. Fox Talks with Katie Couric” 6
  • 6. Biology 30 Parkinson’s Disease A good reason to study the nervous system: cont’d  What is Parkinson’s Disease? o It is a progressive degenerative nerve disorder that affects muscle activity. – The cells that degenerate and die belong to two areas of the brain: » substantia nigra (basal ganglia) – Normally, these cells secrete two chemicals (neurotransmitters) called: » dopamine » norepinephrine 7
  • 7. 13.1 The Importance ofBiology 30 the Nervous SystemWhat does the nervous system do for me?  Your nervous system undertakes many tasks, including, but not limited to, the following: o Processing information: – depth of breathing – condition of breathing muscles – amount of water in the respiratory tract – sensory information (temp., odour, light intensity, touch, etc.) o Memory: – happy times; sad times – hopes for the future (ambitions) 8
  • 8. 13.1 The Importance ofBiology 30 the Nervous System What does the nervous system do for me? (cont’d) o Emotions: – The chemical composition of our brain strongly influences how we feel. – The way our brain responds to external events in our lives will determine the chemical composition of our brain and thus set our mood.  In a nutshell, the nervous system allows us to respond to our external environment. 9
  • 9. Organization of theBiology 30 Nervous SystemThere are 2 main divisions of the nervous system:  The Central Nervous System (CNS): o Consists of the Brain and the Spinal Cord. o Acts as a coordinating center for incoming and outgoing information. 10
  • 10. Organization of theBiology 30 Nervous SystemThere are 2 main divisions of the nervous system: (cont’d)  The Peripheral Nervous System (PNS): o Consists of nerves carrying information between body organs and the CNS. o The PNS is further subdivided: – Somatic nerves: » Controls skeletal muscles, bones, and skin. » Consists of motor and sensory neurons. – Autonomic nerves: » Contains special motor nerves that control the internal organs of the body. 11
  • 11. Organization of theBiology 30 Nervous SystemThere are 2 main divisions of the nervous system: (cont’d)  The Peripheral Nervous System (PNS): (cont’d) – Autonomic nerves: (cont’d) » There are 2 divisions of the ANS: Sympathetic nervous system Parasympathetic nervous system 12
  • 12. Organization of theBiology 30 Nervous SystemNervous System:  This diagram shows the: o CNS o ANS – branch of the PNS  This diagram doesn’t show the: o Somatic nerves – branch of the PNS 13
  • 13. Organization of theBiology 30 Nervous SystemNervous System:  This diagram shows the: o Somatic nerves – branch of the PNS 14
  • 14. Organization of theBiology 30 Nervous SystemFigure 1, p.408 (Nelson)  The main divisions of the nervous system 15
  • 15. Anatomy of aBiology 30 Nerve CellCells of the Nervous System:  The Neuron: o The neuron is the functional unit of the nervous system. – Neurons are specialized cells that are able to conduct electrochemical impulses over substantial distances very quickly.  Glial Cells: o Non-conducting cells. o Important for structural support and metabolism of neurons. 16
  • 16. Anatomy of aBiology 30 Nerve CellAnatomy of a Nerve Cell:  Cell body: o contains the nucleus and is responsible for routine maintenance of the neuron.  Dendrite: o carries impulses towards the cell body.  Axon: o conducts nerve impulses away from the cell body. 17
  • 17. Anatomy of aBiology 30 Nerve CellFigure 2, p.409 (Nelson)  Structure of a neuron. The arrow shows the direction in which a nerve impulse travels. dendrites axon 18
  • 18. Anatomy of aBiology 30 Nerve CellAnatomy of a Nerve Cell: (cont’d)  Myelin Sheath: o glistening white coat of fatty protein. o acts as insulation for the neurons. – prevents the loss of charged ions from the neuron. (More on this in a couple of classes) o formed by special glial cells called Schwann cells.  Neurilemma: o found on all nerve fibres in the PNS. o a thin outer membrane, formed by Schwann cells, which surrounds the neuron. 19 o promotes regeneration of damaged axons.
  • 19. Anatomy of aBiology 30 Nerve CellFigure 2, p.409 (Nelson)  Structure of a neuron. The arrow shows the direction in which a nerve impulse travels. dendrites Schwann myelin cell sheath axon 20
  • 20. Anatomy of aBiology 30 Nerve CellAnatomy of a Nerve Cell: (cont’d)  Node of Ranvier: o the areas between sections of myelin sheaths. o important for conduction of nerve impulses.  Synaptic End: o the end of the axon.  Synaptic Vesicle: o contain neurotransmitters, like dopamine. – chemicals that can activate, or inhibit, the firing of a post- synaptic neuron. 21
  • 21. Anatomy of aBiology 30 Nerve CellFigure 2, p.409 (Nelson)  Structure of a neuron. The arrow shows the direction in which a nerve impulse travels. dendrites node of Schwann myelin Ranvier sheath synaptic cell ends axon 22
  • 22. Anatomy of aBiology 30 Nerve CellAnatomy of a Nerve Cell: (cont’d)  Synapse: o the gap between the synaptic end of one neuron (presynaptic neuron) and a dendrite of another neuron (postsynaptic neuron). 23
  • 23. Anatomy of aBiology 30 Nerve CellTypes of Neurons:  There are 3 distinct types of neurons: o Sensory neurons: (afferent neurons) – Detect stimuli via sensory receptors (like taste buds) and transmit the stimulus to the CNS for processing. – Cell bodies of sensory neurons are located in clusters called ganglia located outside of the spinal cord. o Interneurons: – Link neurons to other neurons. – Located only within the CNS. 24
  • 24. Anatomy of aBiology 30 Nerve CellTypes of Neurons: (cont’d) o Motor Neurons: (efferent neurons) – Transmit impulses from the CNS to muscles, organs, or glands. » Muscles, organs, and glands are classified as effectors because they produce responses to the stimuli. 25
  • 25. Anatomy of aBiology 30 Nerve CellFigure 5, p.412 (Nelson)  3 Types of neurons. 26
  • 26. Biology 30 ActivityBuilding Neurons:  During this activity you will accomplish two tasks: 1. You will build, and label, a model of a neuron using pipe cleaners. 2. You will build a model of a neuron using: – 2 paper plates (cell body) – twine (for the axon) – yarn (for the dendrites) – small beads (for neurotransmitters) – large bead (representing an Action Potential) » more detail on this in a couple of classes. 27 – 3–4 plastic cups (synaptic ends)
  • 27. Biology 30 MicroscopeExamining Neurons:  If available, your teacher will make a microscope and slides of neurons available to you.  If not available, your teacher will find microscope images of neurons for you online. 28
  • 28. Biology 30 ClosureCan you: 1. describe the general structure and function of a neuron and the myelin sheath. 2. identify the principal structures of the central and peripheral nervous systems. 29
  • 29. Biology 30 AssignmentNelson (2007), p.410  Practice Questions #1–4Nelson (2007), p.414  Section 13.1 Question #6 30
  • 30. Unit 30 ABiology 30 Nervous and Endocrine Systems Ch. 13 - Lesson 2 13.1 The Importance of the Nervous System (pp.411–14) 31
  • 31. Biology 30 Today’s ObjectivesToday you must be able to: 1. describe, using an example, the organization of neurons into nerves. 2. describe, using an example, the composition and function of reflex arcs; e.g., the patellar reflex, the pupillary reflex 3. design and perform an experiment to investigate the physiology of reflex arcs 32
  • 32. Anatomy of aBiology 30 Nerve CellNerves:  Recall from last class: o There are 3 types of neurons: – Sensory, Interneurons, and Motor.  Within the CNS: o The CNS consists of mainly interneurons that highly interconnected. – This permits the complex processing that goes on in the brain. o The CNS does send output and receive input to and from the PNS. – This is done by motor (output) and sensory (input) 33 neurons.
  • 33. Anatomy of aBiology 30 Nerve CellNerves: (cont’d)  Within the PNS: o Neurons are typically organized into nerves, or nerve bundles. – Neurons that connect to similar parts of the body will be bundled, or grouped, together. – For example, » Sensory neurons that terminate in the left index finger will be bundled together. » They will connect to the spinal cord as a unified group. 34
  • 34. Anatomy of aBiology 30 Nerve CellFigure 3, p.410 (Nelson)  A Nerve 35
  • 35. Anatomy of aBiology 30 Nerve CellThe Nervous System: 36
  • 36. Biology 30 The Reflex ArcPonder the following questions:  Have you ever wondered why, or how, you respond so quickly when you accidently touch a hot surface?  Have you noticed that everyone reacts pretty much the same way? 37
  • 37. Biology 30 The Reflex ArcReflexes:  Reflexes allow you to respond to the environment without thinking. o This is very important, as you are able to react to a situation before your brain has time to process the information.  Reflexes are a survival mechanism. o When working properly, they should allow you to react to a situation in order to minimize damage to your body. 38
  • 38. Biology 30 The Reflex ArcThe Physiology of a Reflex Arc:  The Components: 1. A sensory receptor: – pain, pressure, photo/light, sound, temperature, etc. 2. A sensory neuron. 3. An interneuron. 4. A motor neuron. 5. An effector: – Usually a muscle of some type. 39
  • 39. Biology 30 The Reflex ArcThe Physiology of a Reflex Arc: (cont’d)  The Sequence of Events: 1. Sensory receptor: – A sensory receptor is stimulated by some external factor. (i.e., your finger touches a tack) 2. Sensory neuron: – The sensory receptor then sends an impulse down the sensory neuron towards the CNS (usually the spinal cord). 40
  • 40. Biology 30 The Reflex ArcThe Physiology of a Reflex Arc: (cont’d)  The Sequence of Events: (cont’d) 3. Interneuron: – In the CNS, the sensory neuron relays the impulse to an interneuron. – The interneuron will send the impulse: » to other interneurons sending the impulse up the CNS to the brain (for processing). » to a motor neuron. 4. Motor neuron: – An impulse travels down the motor neuron towards the effector (usually a muscle). 5. Effector: 41 – The muscle contracts.
  • 41. Biology 30 Reflex ArcsInvestigation 13.1, p.436 (Nelson)  Your teacher will now pass out the worksheet, “Investigation 13.1: Reflex Arcs”.  You will be assigned into groups of 2–3.  Procedure: o Read through each step of the investigation carefully. (Ask for clarification) o Do Parts 1 – 4 – Record observations on your worksheet. 42
  • 42. Biology 30 Reflex ArcsInvestigation 13.1, p.436 (Nelson)  Procedure: (cont’d) o Do Part 5: – Develop a brief experimental design keeping manipulated, responding, and controlled variables in mind. – Carry out your procedure. o Answer all Analysis and Evaluation questions. 43
  • 43. Chapter 13 Unit 30 A Biology Biology 30 Nervous and Endocrine Systems Nervous System13.1 Summary The Importance of the Nervous System
  • 44. Biology 30 ClosureCan you: 1. describe, using an example, the organization of neurons into nerves. 2. describe, using an example, the composition and function of reflex arcs; e.g., the patellar reflex, the pupillary reflex 3. design and perform an experiment to investigate the physiology of reflex arcs 45
  • 45. Biology 30 AssignmentNelson (2007), p.414  Section 13.1 Questions #1–3 46
  • 46. Unit 30 ABiology 30 Nervous and Endocrine Systems Ch. 13 - Lesson 3 13.2 Electrochemical Impulse (pp.415–8) 47
  • 47. Biology 30 Today’s ObjectivesToday you must be able to: 1. explain the formation and transmission of an action potential. 48
  • 48. 13.2 ElectrochemicalBiology 30 ImpulseA little History:  1900: o A German physiologist (Julius Bernstein) suggested that nerve impulses were an electrochemical message created by the movement of ions through the neuron membrane.  1939: o Researchers at Columbia University (K.S. Cole & H.J. Curtis) came up with an experiment to prove this German physiologist correct. 49
  • 49. 13.2 ElectrochemicalBiology 30 ImpulseA little History: (cont’d)  The Experiment: o They conducted their experiment on a large neuron of a squid. o Researchers placed a tiny electrode inside the axon and found the following: – The resting membrane had a potential of –70 mV. – When the neuron became excited, the potential on the inside of the neuron became +40 mV. » This reversal of potential is what we now call an action potential (AP). – A few milliseconds after an action potential occurred the potential on the inside of the neuron went back to 50 –70 mV (the resting potential).
  • 50. 13.2 ElectrochemicalBiology 30 ImpulseFigure 1, p.415 (Nelson)  The Experiment: 51
  • 51. Biology 30 The Resting PotentialWhat gives plasma membranes this potential?  This potential is setup by concentrating potassium ions (K+) and sodium ions (Na+) across the nerve cell’s membrane. o K+ is concentrated on the inside of the cell. o Na+ is concentrated on the outside of the cell.  The potential changes from –70 mV to +40 mV when: o K+ moves out of the cell (facilitated diffusion). o Na+ moves into the cell (facilitated diffusion). 52
  • 52. Biology 30 The Resting PotentialFigure 2, p.415 (Nelson)  Ion distribution and movement. 53
  • 53. Biology 30 The Resting PotentialCell Membrane Properties:  Recall: o Cell membranes are selectively permeable. – The neuron’s cell membrane is impermeable to both potassium and sodium ions. o Entities like potassium and sodium must, initially, be moved across the cell membrane by active transport. – This is accomplished by the sodium-potassium pump. » This is an active process requiring energy in the form of ATP. – The Na-K pump is responsible for setting up the resting membrane potential of –70 mV. 54
  • 54. Biology 30 The Resting PotentialFigure 3, p.416 (Nelson)  The Na-K pump 55
  • 55. Biology 30 The Resting PotentialCell Membrane Properties: (cont’d)  Recall: (cont’d) o Since the membrane is impermeable to both Na+ and K+ ions, these ions cannot move down their concentration gradients without help. – The movement of these ions is facilitated by the opening of gated ion channels. – When open the specific ion can move down it’s concentration gradient (hence, facilitated diffusion). – Each gated ion channel is matched to a specific type of ion. » For example, K+ channels only allow K+ ions to flow through them. 56
  • 56. Biology 30 The Resting PotentialFigure 3, p.416 (Nelson)  Gated Ion Channels 57
  • 57. Biology 30 The Resting PotentialCell Membrane Properties: (cont’d)  What would happen if the membrane wasn’t impermeable to Na+ and K+ ions? o The K+ and Na+ ions being pumped across the membrane by the Na-K pump would simply diffuse back down their concentration gradients so that their concentrations would be equal on both sides of the membrane. – Thus, there would be no membrane potential. 58
  • 58. Biology 30 The Action PotentialThe Phases:  Polarized Membrane: o The resting membrane is polarized to –70 mV. o This is due to the unequal distribution of the positively charged sodium and potassium ions inside and outside of the neuron.  Depolarization: o The diffusion of Na+ into the nerve cell when Na+ gates open. o This results in a charge reversal (+40 mV). 59
  • 59. Biology 30 The Action PotentialThe Phases: (cont’d)  Repolarization: o The process of restoring the membrane back to the resting potential of –70 mV. o How repolarization happens: – When the membrane potential becomes positive, the sodium channels close and the potassium channels open. » Na+ ions stop diffusing » K+ ions begin to slowly diffuse out of the neuron. 60
  • 60. Biology 30 The Action PotentialThe Phases: (cont’d)  Hyperpolarization: o When the inside of the neuron membrane has a greater negative charge than the resting membrane (< –70 mV). o This occurs because the potassium channels are slow to close. – This allows for more K+ to diffuse out of the cell creating a larger negative potential. 61
  • 61. Biology 30 The Action PotentialThe Phases: (cont’d)  Refractory Period: o The recovery time required before a neuron can produce another action potential (AP). o During this time, the Na-K pump is working to restore the membrane back to it’s resting membrane potential (–70 mV) by: – moving Na+ back outside of the neuron and – moving K+ back inside the neuron. o This can last between 1 to 10 ms (milliseconds). 62
  • 62. Biology 30 The Action PotentialFigure 4, p.417 (Nelson)  The phases of an action potential. 63
  • 63. Biology 30 The Action PotentialMovement of the Action Potential:  Now the question becomes, “How does the action potential move along the neuron?” o In fact, the AP does not move. o Instead, AP’s occur in succession along the neuron. – This looks like a “wave” of depolarization. – Like “domino’s” falling in succession. 64
  • 64. Biology 30 The Action PotentialMovement of the Action Potential: (cont’d)  The sequence of events: 1. The first AP is generated as Na+ ions rush in through the opened sodium channels. – This creates a local increase in the Na+ concentration. 2. The Na+ ions inside the neuron now move down their concentration gradient to adjacent areas of lower Na+ concentration. – This influx of Na+ ions to adjacent areas inside of the neuron creates an electrical disturbance. » This disturbance causes sodium channels in this adjacent area to open. 65
  • 65. Biology 30 The Action PotentialMovement of the Action Potential: (cont’d)  The sequence of events: (cont’d) 3. Now, a new AP is generated in this adjacent area as Na+ ions rush into the neuron. 4. Steps 1 – 3 repeat over and over as new AP’s are created ‘down-stream’. 66
  • 66. Biology 30 The Action PotentialFigure 6, p.418 (Nelson)  Successive APs along an axon. 67
  • 67. Biology 30 The Action PotentialMovement of the Action Potential: (cont’d)  Can an AP move backwards? No! o Recall: – Shortly after the Na+ channels open, the following phases occur: » the K+ channels open (repolarization). » then the Na-K pump needs to reset the concentration gradients (the refractory period). – While this is going on no new AP’s can be initiated. 68
  • 68. Biology 30 The Action PotentialSpeeding up Impulse Transmission:  Imagine the following: o Two students are asked to race down the hallway with the following task: – Student 1: » Open every locker door on your way down the hall. – Student 2: » Open every 10th locker door on your way down the hall. o Who wins the race? – Ans: Student 2 69
  • 69. Biology 30 The Action PotentialSpeeding up Impulse Transmission: (cont’d)  Saltatory Conduction: o Definition: – The generation of APs only at nodes of Ranvier in myelinated axons, resulting in the rapid transmission of nerve impulses. o Recall: – Specialized Schwann cells wrap around axons creating ‘bare’ areas on the axon called nodes of Ranvier. » These ‘bare’ areas are full of sodium and potassium channels. » Since these areas are well spaced out, the Na+ ions flow very quickly from node to node creating APs as they open sodium channels. (Remember: Step 2) 70
  • 70. Biology 30 The Action PotentialFigure 7, p.418 (Nelson)  Saltatory conduction. 71
  • 71. Biology 30 ClosureCan you: 1. explain the formation and transmission of an action potential. 72
  • 72. Biology 30 AssignmentNelson (2007), p.418  Practice #1–4Nelson (2007), p.425  Section 13.2 Questions #1–5 73
  • 73. Unit 30 ABiology 30 Nervous and Endocrine Systems Ch. 13 - Lesson 4 13.2 Electrochemical Impulse Threshold Levels & Synaptic Transmission (pp.418–21) 74
  • 74. Biology 30 Today’s ObjectivesToday you must be able to: 1. explain the all-or-none response and intensity of response. 2. describe the transmission of a signal across a synapse. 3. describe the main chemicals and transmitters involved, i.e., norepinephrine, acetylcholine and cholinesterase. 75
  • 75. Threshold Levels and theBiology 30 All-or-None ResponseThreshold Level:  Definition: o The minimum level of a stimulus to produce a response.  Let’s look at a classic experiment to explore threshold levels. o A single neuron leading to a muscle is isolated and a mild electrical shock is applied to the neuron. 76
  • 76. Threshold Levels and theBiology 30 All-or-None ResponseFigure 8, p.419 (Nelson)  The setup of the classic experiment. 77
  • 77. Threshold Levels and theBiology 30 All-or-None ResponseThreshold Level: (cont’d)  The Observations: 1. A stimuli of less than 2 mV did not produce any muscle contraction. 2. A stimuli of 2 mV, or more, caused the muscles to contract with a force of 3 N.  The Conclusions: o A stimuli of less than 2 mV did not reach the threshold for this particular neuron. – Different neurons can have different threshold levels. o All stimuli of 2 mV, or more, caused the same magnitude of force in the muscle. – This is why it is called the all-or-none response. – An AP either occurs, or doesn’t occur, there is nothing in the 78 middle.
  • 78. Threshold Levels and theBiology 30 All-or-None ResponseThreshold Level: (cont’d)  The question now becomes, “How can we differentiate between warm and hot objects?” o Different intensities of stimuli can be detected in two ways: 1. The nerves can send impulses at different frequencies. » Warm objects placed on your hand cause neurons to fire at a slow rate. » When a hot object is placed on your hand, the neurons fire at a faster rate. 79
  • 79. Threshold Levels and theBiology 30 All-or-None ResponseThreshold Level: (cont’d) o Different intensities of stimuli can be detected in two ways: (cont’d) 2. Different neurons can have different threshold levels. » A glass rod at 40 °C may cause a single neuron to reach threshold level. » However, a glass rod at 50 °C may cause two or more neurons to reach threshold level. The second neuron would have a higher threshold level than the first. » The greater the number of impulses reaching the brain, the greater the intensity of the response. 80
  • 80. Biology 30 Synaptic TransmissionSynapse:  Definition: o A region between neurons, or between neurons and effectors; also known as the synaptic cleft.  The synapse is very small (20 nm).  Nerve transmission is slow across the synapse. o This is due to the diffusion of neurotransmitters across the synapse. (A relatively slow process) 81
  • 81. Biology 30 Synaptic TransmissionSynapse: (cont’d)  Synapses rarely involve just two neurons. 82
  • 82. Biology 30 Synaptic TransmissionSynapse: (cont’d)  Presynaptic neurons: o Contain many synaptic vesicles. – Synaptic vesicles contain neurotransmitters (chemical messengers) o Release the neurotransmitters when an AP reaches the synaptic end. – The neurotransmitters diffuse across the synapse to trigger receptors on postsynaptic neurons (or effectors). 83
  • 83. Biology 30 Synaptic TransmissionSynapse: (cont’d)  Postsynaptic neurons: o Contain many membrane receptors for neurotransmitters. – There are two types of membrane receptors: » Excitatory – open up sodium channels to help initiate an AP. » Inhibitory – open up potassium channels to inhibit an AP. 84
  • 84. Biology 30 Synaptic TransmissionFigure 10, p.420 (Nelson)  A Synapse 85
  • 85. Biology 30 NeurotransmittersCommon Neurotransmitters:  Acetylcholine: o Can act as an excitatory neurotransmitter. – Opens up sodium gates and allows Na+ ions to rush into the neuron. – If enough Na+ ions rush in, the membrane will depolarize and an AP will move down the neuron. o After an AP has been generated, the acetylcholine must be removed. – If not, no further APs would be possible, as the postsynaptic end would not be allowed to repolarize. o Acetylcholine is destroyed by it’s enzyme cholinesterase. 86
  • 86. Biology 30 NeurotransmittersCommon Neurotransmitters: (cont’d)  Acetylcholine: (cont’d) o Can act as an inhibitory neurotransmitter. – Opens up potassium gates and allows K+ ions to rush into the neuron. – If enough K+ ions rush in, the membrane will become hyperpolarized and it will become more difficult for an AP to occur. o Other details: – Acetylcholine is commonly excitatory to skeletal muscles causing muscular contractions. – It functions both in the PNS and CNS. 87
  • 87. Biology 30 NeurotransmittersCommon Neurotransmitters: (cont’d)  Norepinephrine: o Can be both excitatory and inhibitory. o Acts in both the PNS and CNS. o Responsible mainly for wakefulness / alertness.  Dopamine: o Generally excitatory. o Acts in both the PNS and CNS. o Responsible for voluntary movement and emotions. – Recall: Parkinson’s disease (lack of dopamine) 88
  • 88. Biology 30 NeurotransmittersCommon Neurotransmitters: (cont’d)  Serotonin: o Generally inhibitory. o Acts in the CNS only. o Responsible mainly for sleep.  GABA: o Generally excitatory. o Acts in both the PNS and CNS. o Responsible for motor behavior. 89
  • 89. Biology 30 NeurotransmittersSummation:  Recall: o There are many presynaptic neurons at most synapses.  How is the creation of an AP on a postsynaptic neuron controlled? o Let’s take a look a figure 11 on p.422 (Nelson) 90
  • 90. Biology 30 NeurotransmittersFigure 11, p.422 (Nelson)  Summation 91
  • 91. Biology 30 NeurotransmittersSummation: (cont’d)  Excitatory Neurons: o Looking at the diagram, both presynaptic neurons A and B are excitatory. o Independently neither neuron can trigger an AP in the postsynaptic neuron (D). – The amount of excitatory neurotransmitters released by either A or B does not open enough sodium channels in neuron D for neuron D to reach its threshold. 92
  • 92. Biology 30 NeurotransmittersSummation: (cont’d)  Excitatory Neurons: (cont’d) o However, when both presynaptic neurons A and B release their neurotransmitters at the same time, they do cause an AP in neuron D. – This is essentially summation. 93
  • 93. Biology 30 NeurotransmittersSummation: (cont’d)  Inhibitory Neurons: o Summation can include inhibitory neurons as well. o These presynaptic neurons release neurotransmitters than open potassium channels instead. – This causes the postsynaptic neuron (D) to hyperpolarize instead. – Hyperpolarization of a neurons membrane makes it more difficult for an AP to occur. » However, it is not impossible. 94
  • 94. Chapter 13 Unit 30 A Biology Biology 30 Nervous and Endocrine Systems Nervous System13.2 Summary Electromagnetic Impulse• Nerves conduct electrochemical impulses from the dendrites along the axon to the end plates of the neuron.• Active transport and diffusion of sodium and potassium ions establish a polarized membrane.• An action potential is caused by the inflow of sodium ions.• Nerve cells exhibit an all-or-none response.• Neurotransmitters allow the nerve message to move across synapses.
  • 95. Biology 30 ClosureCan you: 1. explain the all-or-none response and intensity of response. 2. describe the transmission of a signal across a synapse. 3. describe the main chemicals and transmitters involved, i.e., norepinephrine, acetylcholine and cholinesterase. 96
  • 96. Biology 30 AssignmentNelson (2007), p.420  Practice #5–7Nelson (2007), p.425  Section 13.2 Questions #6 & 7 97
  • 97. Unit 30 ABiology 30 Nervous and Endocrine Systems Ch. 13 - Lesson 5 13.3 The Central Nervous System The Brain (pp.426–32) 98
  • 98. Biology 30 Today’s ObjectivesToday you must be able to: 1. identify the principal structures of the central nervous system and explain their functions in regulating the voluntary (somatic) and involuntary (autonomic) systems of the human organism; i.e., cerebral hemispheres and lobes, cerebellum, pons, medulla oblongata, hypothalamus, & spinal cord. 99
  • 99. Brain Structure and Biology 30 FunctionBrain Protection:The skull:  Supports the structures of the face.  Protects the brain from injury. Unit A - Nervous and Endocrine 100 Systems
  • 100. Brain Structure and Biology 30 FunctionBrain Protection: - cont’dThe Meninges:  Made up of 3 membranes that wrap around the brain. odura matter – outer membrane oarachnoid – contains blood vessels – subarachnoid space contains cerebrospinal fluid (CSF) opia matter – directly on top of the brain 101
  • 101. Brain Structure and Biology 30 Function The Meninges: (Diagram) Unit A - Nervous and Endocrine Systems 102
  • 102. Brain Structure and Biology 30 FunctionBrain Protection: - cont’dCerebrospinal Fluid (CSF):  The brain is also cushioned by CSF between the arachnoid and pia matter layers.  CSF also acts as a transport medium. o It transports nutrients to the brain cells, and wastes away from the brain cells to the blood.  There are four chambers in brain (ventricles) also filled with CSF. Unit A - Nervous and Endocrine 103 Systems
  • 103. Brain Structure andBiology 30 Function Unit A - Nervous and Endocrine Systems 104
  • 104. Brain Structure and Biology 30 FunctionStructures of the Brain:2 Hemispheres:  The right hemisphere controls left side of the body  The left hemisphere controls right side of the body Unit A - Nervous and Endocrine 105 Systems
  • 105. Brain Structure andBiology 30 Function Unit A - Nervous and Endocrine 106 Systems
  • 106. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’d2 Hemispheres: - cont’d  The left hemisphere is associated with the following tasks: o logical o symbolic o sequential Unit A - Nervous and Endocrine 107 Systems
  • 107. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’d2 Hemispheres: - cont’d  A structure called the corpus callosum connects the two hemispheres. o It allows the two hemispheres to communicate with each other. o Thus, the two hemispheres are never really working in isolation from each other. o If damaged physically, or by disease, very interesting observations can be made. Unit A - Nervous and Endocrine 108 Systems
  • 108. Brain Structure and Biology 30 FunctionCorpus callosum damaged: (Diagram) Because the right hemi- sphere is responsible for facial recognition. Who does she see & why? Unit A - Nervous and Endocrine 109 Systems
  • 109. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’dThere are 3 major divisions:  Hindbrain (medulla oblongata, cerebellum, & pons)  Midbrain (reticular formation)  Forebrain (cerebrum, thalamus, hypothalamus, pituitary gland, pineal gland, and basal ganglia)There are 12 cranial nerve pairs that extend from the brain. (Bonus material)  most are mixed nerves (motor and sensory)  except olfactory and optic nerves (sensory only110 )
  • 110. Brain Structure and Biology 30 FunctionCranial nerves: Unit A - Nervous and Endocrine Systems 111
  • 111. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’d1. Hindbrain:  Medulla oblongata: o Control of body functions like heart rate and breathing rate. o Destruction = death  Cerebellum: o Co-ordinating body movements o Balance Unit A - Nervous and Endocrine 112 Systems
  • 112. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’d1. Hindbrain: cont’d  Pons: o Relays nerve impulses between hindbrain and forebrain. Unit A - Nervous and Endocrine 113 Systems
  • 113. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’d1. Hindbrain: - cont’d Pons Medulla oblongata Cerebellum Unit A - Nervous and Endocrine Systems 114
  • 114. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’d2. Midbrain:  Reticular formation: o Activates forebrain to analyze sensory information. o Selects which information is to be analyzed by forebrain. o Is not a single structure, but rather links various structures together. Unit A - Nervous and Endocrine 115 Systems
  • 115. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’d2. Midbrain: - cont’d Reticular formation Unit A - Nervous and Endocrine Systems 116
  • 116. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’d3. Forebrain:  Thalamus: o “Gate-keeper” of the cerebral cortex o All sensory information passes through thalamus o Consciousness (awareness)  Hypothalamus: o Monitors and regulates temperature and water levels in blood o Co-ordinating center for internal organs (e.g., thirst, hunger, rage, sex drive, and satiety) 117
  • 117. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’d3. Forebrain: - cont’d Thalamus Hypothalamus Unit A - Nervous and Endocrine Systems 118
  • 118. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’d3. Forebrain: - cont’d  Pituitary gland: o Master gland (controls all other glands) o Link to the endocrine system Unit A - Nervous and Endocrine 119 Systems
  • 119. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’d3. Forebrain: - cont’d Pituitary gland Unit A - Nervous and Endocrine Systems 120
  • 120. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’d3. Forebrain: - cont’d  Pineal gland: o More important in lower animals o Detects body temperature and exposure to sun o It is a regressive structure o Secretes melatonin – Induces sleep in humans – Stimulated by darkness – Inhibited by daylight o What impact does this have on Canadians? (Especially those in the far north) 121
  • 121. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’d3. Forebrain: - cont’d Pineal gland Unit A - Nervous and Endocrine Systems 122
  • 122. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’d3. Forebrain: - cont’d  Basal ganglia: o Located deep within the cerebrum o Associated with the following functions: – Motor control (posture & voluntary movement) – Cognition (the process of thought) – Emotions – Learning Unit A - Nervous and Endocrine 123 Systems
  • 123. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’d3. Forebrain:  Basal ganglia: Unit A - Nervous and Endocrine Systems 124
  • 124. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’d3. Forebrain: - cont’d  Cerebrum (Cerebral cortex): o Most prominent part of the brain o Occupies approx. 1.35 L of space (largest of all animals) o Has a mass of approx. 3 lbs. o The cerebrum is separated into 4 lobes – Each lobe is separated by a deep fissure called a ‘sulcus’ o The 4 lobes are: 1. Frontal 3. Occipital 2. Parietal 4. Temporal 125
  • 125. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’d3. Forebrain: - cont’d  Cerebrum (Cerebral cortex): cont’d o Frontal lobe: – Motor control (movement, speech, etc.) » The basal ganglia are imbedded within the frontal lobe – Intellectual activities – Personality Unit A - Nervous and Endocrine 126 Systems
  • 126. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’d3. Forebrain: - cont’d  Cerebrum (Cerebral cortex): - cont’d o Occipital lobe: – Sensory areas interpret visual information (optic nerve) o Temporal lobe: – Sensory areas interpret vision and hearing information – Interpreting speech – Association areas linked with memory Unit A - Nervous and Endocrine 127 Systems
  • 127. Brain Structure and Biology 30 FunctionStructures of the Brain: - cont’d3. Forebrain: - cont’d  Cerebrum (Cerebral cortex): - cont’d o Parietal lobe: – Sensory areas for touch and temperature awareness – Emotions Unit A - Nervous and Endocrine 128 Systems
  • 128. Brain Structure andBiology 30 Function3. Forebrain: - cont’d 129
  • 129. Brain Structure and Biology 30 FunctionStructures of the Brain: - Parietal lobe cont’d Occipital lobe3. Forebrain: - cont’d  Cerebrum Frontal lobe Temporal lobe Unit A - Nervous and Endocrine Systems 130
  • 130. Biology 30 Parkinson’s DiseaseMichael J. Fox: - cont’dNow we will view another video on Parkinson’s disease.  Afterwards, we will discuss how this relates to what we have learned today.  Make sure you identify the brain structure that is mostly responsible for the symptoms of Parkinson’s disease. Link: “Understanding Parkinson’s Disease” 131
  • 131. Biology 30 Parkinson’s DiseaseMichael J. Fox: - cont’dFollow up questions to the video, “Understanding Parkinson’s Disease”.  What was the brain structure responsible for the symptoms of Parkinson’s disease? o Basal ganglia  What are the symptoms of Parkinson’s disease? o Trembling hand, stiffness of limbs, depression, etc. Unit A - Nervous and Endocrine 132 Systems
  • 132. Biology 30 Parkinson’s DiseaseMichael J. Fox: - cont’dMore follow up questions to the video, “Understanding Parkinson’s Disease”.  What is the physiological problem with the neurons? o The pre-synaptic axons are not producing or secreting enough dopamine.  Parkinson’s disease is treated by taking drugs like Levodopa. What would be the physiological effect of Levodopa on the body? o It is converted into dopamine in the brain. 133
  • 133. Biology 30 Parkinson’s DiseaseMichael J. Fox: - cont’dMore follow up questions to the video, “Understanding Parkinson’s Disease”.  There are other types of drugs, like Mirapex ®, that stimulate dopamine receptors to function with lower levels of dopamine. Unit A - Nervous and Endocrine 134 Systems
  • 134. Biology 30 The Brain13.3 The Central Nervous System:  Review of the Brain: o Watch Mr. Woods DEMO the making of your ‘thinking’ cap. o Procedure: – Make your ‘thinking’ cap. – Outline the 4 lobes of the cerebrum on your cap. – Label each lobe. – Write down 1 function of each lobe within the outlined area. » For the temporal lobe, write down the function on both sides of your cap. 135
  • 135. Biology 30 The Brain13.3 The Central Nervous System:  Review of the Brain: o As we watch the following video, I want you to do the following: – Point to the areas of your brain. – This is a good time to wear your ‘thinking’ caps.Link: “Pinky & the Brain” 136
  • 136. Chapter 13 Unit 30 A Biology Biology 30 Nervous and Endocrine Systems Nervous System13.3 Summary The Central Nervous System
  • 137. Biology 30 ClosureCan you: 1. identify the principal structures of the central nervous system and explain their functions in regulating the voluntary (somatic) and involuntary (autonomic) systems of the human organism; i.e., cerebral hemispheres and lobes, cerebellum, pons, medulla oblongata, hypothalamus, & spinal cord. 138
  • 138. Biology 30 AssignmentNelson (2007), p.430  Case Study Questions #1–3Nelson (2007), p.432  Section 13.3 Questions #1–5 139
  • 139. Unit 30 ABiology 30 Nervous and Endocrine Systems Ch. 13 - Lesson 6 13.3 The Central Nervous System The Spine 13.4 The Peripheral Nervous System (pp.433–5) 140
  • 140. Biology 30 Today’s ObjectivesToday you must be able to: 1. identify the principal structures of the central nervous system and explain their functions in regulating the voluntary (somatic) and involuntary (autonomic) systems of the human organism; i.e., cerebral hemispheres and lobes, cerebellum, pons, medulla oblongata, hypothalamus, & spinal cord. 141
  • 141. Biology 30 The Spinal CordRecall:  The spinal cord is part of the Central Nervous System (CNS).  The spinal cord represents the connection point where the Peripheral Nervous System (PNS) connects to the CNS. 142
  • 142. Biology 30 The Spinal CordAnatomy:  The spinal cord is surrounded by vertebrae. o The vertebrae provide protection against physical trauma.  The vertebrae is separated by intervertebral disks composed of cartilage. 143
  • 143. Biology 30 The Spinal CordAnatomy: (cont’d)  The spinal cord is made up of two types of nerve tissue: o Grey matter: – Non-myelinated nerve fibres. – The grey matter is made up of interneurons only. o White matter: – Myelinated nerve fibres. – Both motor and sensory nerves are present. » Dorsal root: Nerve tract made up of sensory neurons. » Ventral root: Nerve tract made up of motor neurons. 144
  • 144. Biology 30 The Spinal CordFigure 1, p.426 (Nelson)  Anatomy of the spinal cord: 145
  • 145. 13.4 The PeripheralBiology 30 Nervous SystemGeneral Composition:  Consists of: o Sensory neurons: – Relays information from stimulus receptors to the CNS. o Motor neurons: – Runs from the CNS to effectors (muscles or organs).  The PNS has two distinct divisions: o The Sensory-Somatic System o The Autonomic Nervous System 146
  • 146. 13.4 The PeripheralBiology 30 Nervous SystemFigure 1, p.433 (Nelson)  The PNS: 147
  • 147. The Sensory-SomaticBiology 30 SystemIn General:  Relays sensory information about the external environment to the CNS.  A response from the CNS (the spine or the brain) is relayed back to an effector muscle.  The sensory-somatic system is considered to be under voluntary (somatic) control. o For the most part, you can control your muscles in response to an external stimulus. o The only exception is the reflex arc. 148
  • 148. The Sensory-SomaticBiology 30 SystemFigure 5, p.412 (Nelson)  The Sensory-Somatic System: 149
  • 149. The AutonomicBiology 30 Nervous SystemIn General:  Relays sensory information about the internal environment to the CNS.  A response from the CNS (the brain) is relayed back to an effector (smooth muscle, cardiac muscle, internal organs, or glands).  The autonomic nervous system is considered to be under involuntary control. o For example, – If your blood oxygen levels fall below normal, the autonomic nerves acts to restore oxygen levels by 150 increasing breathing and heart rates.
  • 150. The AutonomicBiology 30 Nervous SystemThe ANS is made up of two distinct units:  The Sympathetic Nervous System (SNS): o Prepares the body for stress. – Increases heart rate. – Causes the release of epinephrine from the adrenal glands. – Increases release of glucose from the liver. – Dilates the pupils. – Decreases peristalsis in the digestive tract. – Increases blood flow to the skin. – Relaxes the bladder’s sphincter. o Releases epinephrine (a neurotransmitter) onto the effector. 151
  • 151. The AutonomicBiology 30 Nervous System The ANS is made up of two distinct units: ( cont’d)  The Parasympathetic Nervous System (PSNS): o Restores the body back to normal. – Decreases heart rate. – Glucose is stored in the liver. – Constricts the pupils. – Increases peristalsis in the digestive tract. – Decreases blood flow to the skin. – Constricts the bladder’s sphincter. o Releases acetylcholine and nitric oxide (neurotransmitters) onto the effector. 152
  • 152. The Autonomic Biology 30 Nervous SystemFigure 2, p.434 (Nelson)  The ANS of the PNS: 153
  • 153. Chapter 13 Unit 30 A Biology Biology 30 Nervous and Endocrine Systems Nervous System13.4 Summary The Peripheral Nervous System• The peripheral nervous system is made up of the sensory-somatic and the autonomic nervous systems. Together they sense and respond to external and internal stimuli.• The autonomic nervous system consists of the sympathetic and parasympathetic systems. The sympathetic system prepares the body for stress; the parasympathetic system returns the body to a resting state.
  • 154. Chapter 13 Unit 30 A Biology Biology 30 Nervous and Endocrine Systems Nervous SystemChapter 13 Summary: OutcomesKnowledge• describe a neuron and myelin sheath, explaining the formation and transmission of an action potential and the transmission of a signal across a synapse and the main chemicals and transmitters involved (13.1, 13.2)• identify structures of the central and peripheral nervous systems and explain their functions in regulating the voluntary (somatic) and involuntary (autonomic) systems, (13.1, 13.3, 13.4)• describe the organization of neurons into nerves and simple reflex arcs (13.1)
  • 155. Chapter 13 Unit 30 A Biology Biology 30 Nervous and Endocrine Systems Nervous SystemChapter 13 Summary: OutcomesSTS• explain that scientific knowledge and theories develop through hypotheses, collection of experimental evidence and by providing explanations (13.1)• explain that scientific investigation includes analyzing evidence and providing explanations based on scientific theories and concepts (13.2)• explain that the goal of technology is to provide solutions to practical problems (13.3)
  • 156. Chapter 13 Unit 30 A Biology Biology 30 Nervous and Endocrine Systems Nervous SystemChapter 13 Summary: OutcomesSkills• conduct investigations and record data by: investigating the physiology of reflex arcs (13.1); observing neurons and synapses (13.3); and observing a mammalian brain and identifying structures (13.3)• analyze data and apply concepts (13.1, 13.3)• work as members of a team (all)
  • 157. Unit 30 ABiologyBiology 30 Nervous and Endocrine SystemsGeneral OutcomesIn this unit, you will• explain how the nervous system controls physiological processes• explain how the endocrine system contributes to homeostasis
  • 158. Biology 30 ClosureCan you: 1. identify the principal structures of the central nervous system and explain their functions in regulating the voluntary (somatic) and involuntary (autonomic) systems of the human organism; i.e., cerebral hemispheres and lobes, cerebellum, pons, medulla oblongata, hypothalamus, & spinal cord. 159
  • 159. Biology 30 AssignmentNelson (2007), p.435  Section 13.4 Questions #1,2,4,5Nelson (2007), pp.441–3  Chapter 13 REVIEW #1–11, 12–20 160