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2/STRUCTURE AND FUNCTIONS OF CELLS OF THE NERVOUS SYSTEM TABLE OF CONTENTS TEACHING OBJECTIVES KEY TERMS LECTURE GUIDE Cells of the Nervous System Communication Within a Neuron Communication Between Neurons FULL CHAPTER RESOURCES MyPsychLab The Virtual Brain Lecture Launchers Activities Assignments Web Links PowerPoint Presentations Test Bank Accessing All Resources Handout Descriptions Handouts Copyright © 2014 Pearson Education, Inc. All Rights Reserved 1 TEACHING OBJECTIVES After completion of this chapter, the student should be able to: 1. Name and describe the parts of a neuron and explain their functions. 2. Describe the supporting cells of the central and peripheral nervous systems and describe and explain the importance of the blood–brain barrier. 3. Briefly describe the neural circuitry responsible for a withdrawal reflex and its inhibition by neurons in the brain. 4. Describe the measurement of the action potential and explain how the balance between the forces of diffusion and electrostatic pressure is responsible for the membrane potential. 5. Describe the role of ion channels in action potentials and explain the all-or-none law and the rate law. 6. Describe the structure of synapses, the release of the neurotransmitter, and the activation of postsynaptic receptors. 7. Describe postsynaptic potentials: the ionic movements that cause them, the processes that terminate them, and their integration. 8. Describe the role of autoreceptors and axoaxonic synapses in synaptic communication and describe the role of neuromodulators and hormones in nonsynaptic communication ▲ Return to Chapter 2: Table of Contents Copyright © 2014 Pearson Education, Inc. All Rights Reserved 2 KEY TERMS sensory neuron (20) motor neuron (20) interneuron (20) central nervous system (CNS) (21) peripheral nervous system (PNS) (21) soma (21) dendrite (21) synapse (21) axon (21) multipolar neuron (22) bipolar neuron (22) unipolar neuron (22) terminal button (22) neurotransmitter (22) membrane (23) cytoplasm (23) adenosine triphosphate (ATP) (23) nucleus (23) chromosome (23) deoxyribonucleic acid (DNA) (24) gene (24) cytoskeleton (24) enzyme (24) axoplasmic transport (24) microtubule (24) glia (24) astrocyte (24) phagocytosis (25) oligodendrocyte (25) myelin sheath (25) node of Ranvier (25) microglia (27) Schwann cell (27) blood–brain barrier (27) area postrema (28) electrode (30) microelectrode (30) membrane potential (30) oscilloscope (31) resting potential (31) depolarization (31) hyperpolarization (31) action potential (31) threshold of excitation (31) diffusion (32) electrolyte (32) ion (32) electrostatic pressure (32) intracellular fluid (32) extracellular fluid (32) sodium-potassium transporter (33) ion channel (34) voltage-dependent ion channel (35) all-or-none law (36) rate law (36) saltatory conduction (36) postsynaptic potential (38) binding site (38) ligand (38) dendritic spine (38) presynaptic membrane (38) postsynaptic membrane (38) synaptic cleft (38) synaptic vesicle (38) release zone (39) postsynaptic receptor (39) neurotransmitter-dependent ion channel (39) ionotropic receptor (40) metabotropic receptor (40) G protein (40) second messenger (40) excitatory postsynaptic potential (EPSP) (41) inhibitory postsynaptic potential (IPSP) (41) reuptake (42) enzymatic deactivation (42) acetylcholine (ACh) (42) acetylcholinesterase (AChE) (43) neural integration (43) autoreceptor (44) presynaptic inhibition (44) presynaptic facilitation (44) neuromodulator (45) peptide (45) hormone (45) endocrine gland (45) target cell (45) ▲ Return to Chapter 2: Table of Contents Copyright © 2014 Pearson Education, Inc. All Rights Reserved 3 LECTURE GUIDE I. Cells of the Nervous System (text p.21) Assignments 2.1 Vocabulary Crossword Puzzle Web Links 2.1 The Story of a Membrane 2.2 Glia the Forgotten Brain Cell 2.3 Millions and Billions of Cells: Types of Neurons 2.4 The Blood Brain Barrier 2.8 Biology Animations Assignments 2.1 Vocabulary Crossword Puzzle Handout Descriptions 2.1 Concept Maps 2.6 Things That You Need to Know about Neurons 2.7 How to Murder a Neuron Handouts 2.1 Concept Maps 2.2 Vocabulary Crossword Puzzle 2.6 Things That You Need to Know about Neurons 2.7 How to Murder a Neuron A. General organization of the nervous system 1. Types of neurons a. Sensory neurons detect changes in the internal or external environment b. Motor neurons control muscular contraction or glandular secretion c. Interneurons 1. Local 2. Relay 2. Divisions of the nervous system a. Central nervous system (CNS): the brain and the spinal cord b. Peripheral nervous system (PNS): the nerves outside the skull and spinal cord and the sensory organs B. Neurons 1. Basic structure (Figure 2.1, text p. 22) a. Soma (cell body) b. Dendrites 1. Synapse: the junction between the terminal buttons of one neuron and the somatic or dendritic membrane of the receiving cell c. Axon 1. Covered with myelin 2. Carries the action potential d. Classification of neurons (by axons and dendrites leaving the soma) 1. Multipolar (Figure 2.1, text p.22) 2. Bipolar (Figure 2.2, text p.22) 3. Unipolar (Figure 2.2, text p.22) e. Nerves (Figure 2.3, text p.23) 1. Bundles of axons f. Terminal buttons and synaptic connections (Figure 2.4, text p.23) 1. Site of neurotransmitter release 2. Internal structure (Figure 2.5, text p.24) a. Membrane 1. Boundary of cell 2. Contains proteins b. Cytoplasm 1. Jelly-like fluid containing organelles 2. Contains mitochondria a. Extract energy from nutrients b. Synthesize adenosine triphosphate (ATP) c. Contain their own genetic material d. Replicate independently of the rest of the cell c. Nucleus 1. Chromosomes a. Consist of long strands of DNA b. Contain genes, which code for proteins d. Proteins 1. Cytoskeleton 2. Enzymes 3. Microtubules a. Axoplasmic transport 1. Anterograde: cell to terminals 2. Retrograde: terminals to cells C. Supporting Cells 1. Glia: in the central nervous system a. Astrocytes (Figure 2.6, text p.25) 1. Control chemical composition around neurons 2. Processes wrap around neurons and blood vessels 3. Help nourish neurons a. Convert glucose from bloodstream to lactate, which is then used by neurons b. Store glycogen 4. Act as “glue” 5. Surround and isolate synapses 6. Remove debris via phagocytosis b. Oligodendrocytes (Figure 2.7, text p.37) 1. Produce the myelin sheath in the CNS (Figure 2.8, text p. 26) 2. Node of Ranvier: space between beads of myelin 3. One oligodendrocyte produces up to 50 myelin segments c. Microglia 1. Phagocytes 2. Protect brain from invading organisms – immune system function 2. Schwann Cells – peripheral nervous system a. Produce myelin in the PNS (Figure 2.8, text p. 26) 1. Each segment of myelin is one Schwann cell b. Chemical composition of myelin in PNS differs from that of the CNS D. The Blood–Brain Barrier (Figure 2.9, text p. 28) 1. Ehrlich’s experiment: injected blue dye into the blood; did not dye the CNS 2. Selectively permeable a. Active transport ferries many molecules into the CNS 3. More permeable in some areas, e.g. area postrema II. Communication Within A Neuron (text p. 28)\ MyPsychLab 2.1 Simulate: The Action Potential Lecture Launchers 2.1 Metaphors 2.2 Animations 2.3 Neuron Skits Activities 2.1 Measurement of the Speed of Axonal Transmission Assignments 2.1 Vocabulary Crossword Puzzle Web Links 2.8 Biology Animations 2.9 Resting Membrane Potential Handout Descriptions 2.3 Neuron Skits: Firing of a Neuron (for Lecture Launcher 2.3) Handouts 2.2 Vocabulary Crossword Puzzle 2.3 Neuron Skits: Firing of a Neuron (for Lecture Launcher 2.3) 2.5 Name Tags for Skits A. Neural Communication: An Overview 1. Withdrawal reflex (Figure 2.10, text p.29) 2. Inhibition of the withdrawal reflex (Figure 2.11, text p.30) B. Measuring Electrical Potentials of Axons 1. Squid giant axon a. Large enough to work with - diameter is 0.5mm b. Survives a day or two in a dish of seawater 2. Measuring electrical charge (Figure 2.12, text p.31) a. Electrode b. Microelectrode 1. A small electrode c. Place electrode in the seawater and the microelectrode in the axon (Figure 2.13, text p. 31) 3. Membrane potential a. Inside relative to outside b. Resting potential – 70 mV c. Depolarization 1. Reduction in size of the membrane potential d. Hyperpolarization 1. Increase in size of the membrane potential e. Action potential (Figure 2.14, text p.32) 1. Triggered at threshold of excitation C. The Membrane Potential: Balance of Two Forces (Figure 2.15, text p.33) 1. The force of diffusion a. Molecules distribute evenly throughout a medium b. Without barriers, molecules flow from areas of high concentration to areas of low concentration 2. The force of electrostatic pressure a. Electrolytes: molecules that split into two parts with opposing charges b. Ions 1. Cations – positive charge 2. Anions – negative charge c. Electrostatic pressure – force of attraction/repulsion 1. Opposites charges attract, like charges repels 3. Ions in the extracellular and intracellular fluid (Figure 2.15. text p. 33) a. Organic anions (A-) 1. Inside cell 2. Unable to pass through membrane b. Potassium ions (K+) 1. Concentrated inside 2. Diffusion pushes out 3. Electrostatic pushes in 4. Little net movement c. Chloride ions (Cl-) 1. Concentrated outside 2. Diffusion pushes in 3. Electrostatic pushes out 4. Little net movement d. Sodium ions (Na+) 1. Concentrated outside 2. Diffusion pushes in 3. Electrostatic pushes in 4. Sodium-potassium transporter (Figure 2.16, text p. 33) a. Uses energy b. Two K+ in; three Na+ out c. Helps keep concentration of Na+ low inside the neuron d. Membrane relatively impermeable to Na+ D. The Action Potential (MyPsychLab 2.1: Stimulate: The Action Potential) 1. Ion Channels (Figure 2.17, text p. 34) a. Proteins b. Form pores through the membrane that permit ions to enter or leave the cell 2. Sequence of events (Figure 2.18, text p.35) a. At threshold, voltage-dependent Na+ channels open and Na+ enters cell 1. Membrane potential moves from -70mV to +40mV b. Voltage dependent K+ channels begin to open and K+ leaves the cell c. Na+ channels close and become refractory at the peak of the action potential d. K+ continues to leave the cell until the membrane potential nears normal e. Na+ channels reset f. Membrane overshoots resting potential but returns to normal as K+ diffuses E. Conduction of the Action Potential (Figure 2.19, text p. 36; MyPsychLab 2.4: Explore the Virtual Brain: Neural Conduction) 1. All-or-none law a. Action potential either occurs, or does not occur b. Once initiated, it is transmitted to the end of the axon c. Always the same size (even when axon splits) 2. Rate law (Figure 2.20, text, p.36) a. Rate of firing is the basic element of information 3. Saltatory conduction (Figure 2.21, text p.37) a. Action potential moves passively under the myelin b. Action potential is regenerated at each node of Ranvier c. Advantages 1. The neuron expends less energy (ATP) to maintain ion balance 2. Faster conduction III. Communication Between Neurons (Text p.37; MyPsychLab 2.2 Simulate: Synapses) MyPsychLab 2.2 Simulate: Synapses 2.3 Simulate: Postsynaptic Potentials Lecture Launchers 2.2 Animations 2.3 Neuron Skits Assignments 2.1 Vocabulary Crossword Puzzle Web Links 2.5 The Synapse 2.6 Synaptic Transmission 2.7 Synaptic Transmission: A Four Step Process 2.8 Biology Animations 2.10 Synaptic Transmission Handout Descriptions 2.4 Neuron Skits: The Synapse 2.5 Name Tags for Skits Handouts 2.2 Vocabulary Crossword Puzzle 2.4 Neuron Skits: The Synapse 2.5 Name Tags for Skits A. Synaptic Transmission 1. The transfer of information from one neuron to another via a synapse 2. Relies on neurotransmitters a. Produce postsynaptic potentials b. Attach to receptor at a binding site c. Ligand is a chemical that attaches to a binding site d. Neurotransmitters are natural ligands B. Structure of Synapses 1. Types of synapses (Figure 2.22, text p.38) a) Axodendritic: on dendrite b) Axosomatic: on soma c) Axoaxonic: on axon 2. Structure (Figures 2.23, text p. 39 and Figure 2.24, text p. 40) a. Presynaptic membrane b. Postsynaptic membrane c. Synaptic cleft d. Synaptic vesicles: contain neurotransmitter e. Release zone: the location of neurotransmitter release f. Postsynaptic density: contains receptors and the proteins that hold them in place C. Release of Neurotransmitter (MyPsychLab 2.2 Simulate: Synapses) 1. Omega-structure (Figure 2.24, text p.40) a. Omega figures are synaptic vesicles fused with the membrane D. Activation of Receptors 1. Postsynaptic receptor 2. Neurotransmitter-dependent ion channels a. Ionotropic receptors (Figure 2.25, text p.40) 1. Ion channel 2. Neurotransmitter binding site b. Metabotropic receptors (Figure 2.26, text p.41) 1. Close to a G protein 2. Activation of G protein produces second messenger a. Opens ion channel b. Biochemical changes in other parts of the cell c. Turns genes on and off E. Postsynaptic Potentials (Figure 2.27, text p.41) 1. Excitatory postsynaptic potential (EPSP) 2. Inhibitory postsynaptic potential (IPSP) F. Termination of Postsynaptic Potentials 1. Reuptake (Figure 2.28, text p. 32) 2. Enzymatic deactivation a. Acetylcholine (ACh) by acetylcholinesterase (AChE) b. Myasthenia gravis 1. Muscular weakness 2. Physotigmine a. Inhibits AChE b. Treats symptoms of Myasthenia gravis 3. Caused by immune system attacking ACh receptors G. Effects of Postsynaptic Potentials: Neural Integration (Figure 2.29, text p.43; MyPsychLab 2.3 Simulate: Postsynaptic Potentials) 1. Combining of multiple signals 2. Performed by axon hillock 3. Neural inhibition does not always lead to behavioral inhibition H. Autoreceptors 1. Respond to the neurotransmitter released by the neuron that contains them 2. Generally inhibitory I. Axoaxonic Synapses 1. Alter amount of neurotransmitter released (Figure 2.30, text p. 44) 2. Presynaptic inhibition 3. Presynaptic facilitation J. Nonsynaptic Chemical Communication 1. Neuromodulators a. Modify large numbers of neurons near location of release b. Generally are peptides 2. Hormones a. Secreted by endocrine glands b. Distributed via bloodstream c. Target cells contain receptors for the hormone ▲ Return to Chapter 2: Table of Contents FULL CHAPTER RESOURCES MyPsychLab The Virtual Brain Lecture Launchers Activities Assignments Web Links PowerPoint Presentations Test Bank Accessing All Resources Handout Descriptions Handouts MyPsychLab MyPsychLab (www.mypsychlab.com) is an online homework, tutorial, and assessment program that truly engages students in learning. It helps students better prepare for class, quizzes, and exams—resulting in better performance in the course. It provides educators a dynamic set of tools for gauging individual and class performance. Customizable – MyPsychLab is customizable. Instructors choose what students’ course looks like. Homework, applications, and more can easily be turned off and off. Blackboard Single Sign-on - MyPsychLab can be used by itself or linked to any course management system. Blackboard single sign-on provides deep linking to all New MyPsychLab resources. Pearson eText and Chapter Audio – Like the printed text, students can highlight relevant passages and add notes. The Pearson eText can be accessed through laptops, iPads, and tablets. Download the free Pearson eText app to use on tablets. Students can also listen to their text with the Audio eText. Assignment Calendar & Gradebook – A drag and drop assignment calendar makes assigning and completing work easy. The automatically graded assessment provides instant feedback and flows into the gradebook, which can be used in the MyPsychLab or exported. Personalized Study Plan – Students’ personalized plans promote better critical thinking skills. The study plan organizes students’ study needs into sections, such as Remembering, Understanding, Applying, and Analyzing. MyPsychLab Margin Icons – Margin icons guide students from their reading material to relevant videos and simulations. MyPsychLab Margin Icons – Margin icons in the textbook guide students from their reading material to relevant videos and simulations. MyPsychLab Highlights for Chapter 2: MyPsychLab 2.1: Simulate: The Action Potential MyPsychLab 2.2: Simulate: Synapses MyPsychLab 2.3: Simulate: Postsynaptic Potentials MyPsychLab 2.4: Explore the Virtual Brain: Neural Conduction Virtual Brain The new MyPsychLab Brain is an interactive virtual brain designed to help students better understand neuroanatomy, physiology, and human behavior. Fifteen new modules bring to life many of the most difficult topics typically covered in the biopsychology course. Every module includes sections that explore relevant anatomy, physiological animations, and engaging case studies that bring behavioral neuroscience to life. At the end of each module, students can take an assessment that will help their measure their understanding. This hands-on experience engages students and helps make course content and terminology relevant. References throughout the text direct students to content in MyPsychLab, and a new feature at the end of each chapter directs students to MyPsychLab Brain modules. Virtual Brain Module applicable to Chapter 2, Structure and Functions of Cells of the Nervous System: Neural Conduction: This module reveals the key components of the neural communication system, as well as the processes of electrical intra-neural and chemical inter-nerual communication. See membrane potentials, synaptic communication, and neurotransmitters in action in detailed animations. Lecture Launchers Lecture Launcher 2.1 Metaphors Sometimes, it is helpful to take concepts that students are unfamiliar with and place them in a more familiar context. Remind the students that these are models and may not work the same as the real thing, but you can get past some cognitive barriers by making connections to the student’s current experience. A simplistic (and probably not entirely accurate) explanation If you are having trouble understanding Excitatory (EPSP) and Inhibitory (IPSP) Postsynaptic Potentials, you might find these explanations and metaphors helpful. Please remember that, like our model neuron, the following description is not how things really work, but it may help you to get a picture of the events that will then allow you to explore the information in more detail and revise and correct your understanding. Concentrations of various chemicals in and around the cell. The postsynaptic membrane has protein receptors in the membrane made of phospholipids (fat). Each receptor has a shape that fits at least one neurotransmitter molecule. Imagine a molecule of neurotransmitter floating through the extra cellular space in the synapse until it reaches one of these receptors. When the neurotransmitter gets close, it fits into the protein molecule like a key in a lock. This changes the shape of the protein molecule and sets off a change in the electrical potential of the cell. If the neurotransmitter is excitatory at that receptor, it will depolarize the cell membrane (make it more likely to transmit information) around the receptor site. You might think of this as dropping a stone into a still lake. The ripples move away from the receptor, getting weaker and weaker. At some point, a ripple will cross the cell body and move down the axonal hillock. If the receptor is close to the axonal hillock, the ripple will still be strong when it gets there. Axonal Hillock The axonal hillock is a small “hill” at the beginning of the axon. It is here that the decision is made to "fire.” The cell. The neuron “gun” is fired at the axonal hillock trigger. A small squeeze on the trigger will not fire the neuron. There will be a point when the trigger moves far enough to fire the neuron, and like a gun, once fired, it has to be reloaded. Postsynaptic Receptors Cells can be seen as a mini version of the world. Just as the cell seems to make decisions based on multiple inputs, in society we often make decisions based on information from a number of people. Imagine the axonal hillock as a meeting of 100 people - - (100 postsynaptic potentials). 1. The meeting is to decide whether to send a message encouraging another group of people to move to a different building (The goal is not important in this example). To make a decision, the meeting must have a Quorum of at least 50 people. Out of the people at the meeting, at least two-thirds must vote in favor of the action (be positive). 2. The meeting room has just a few people wandering around. (The resting potential) More people show up until there are 57 people in the room. The meeting begins. There is a vote on sending the message. Forty-five people vote for sending the message (EPSPs) and 12 vote against sending the message. Since the vote is more than 2/3 in favor, the message is sent. 3. The meeting room has just a few people wandering around. (The resting potential) More people show up until there are 45 people in the room. The meeting begins. There is a vote on sending the message. Forty people vote for sending the message (EPSPs) and five vote against sending the message. The vote is more than 2/3 in favor but there was not a quorum (not enough EPSPs) so the message is not sent. 4. The meeting room has just a few people wandering around. (The resting potential) More people show up until there are 57 people in the room. The meeting begins. There is a vote on sending the message. Twenty people vote for sending the message (EPSPs) and 37 vote against sending the message. Since the vote is not more than 2/3 in favor, the message is not sent. In these three situations, the number of excitatory and inhibitory potentials that reach the axonal hillock at the same time will be combined to determine whether or not the cell fires. Let’s look at several examples of meeting outcomes. Excitatory versus Inhibitory Postsynaptic Potential Excitatory influences in the nervous system make things more likely to happen Inhibitory influences in the nervous system make things less likely to happen Presynaptic versus Postsynaptic Terminal button of the axon Dendrite or cell body side of the synapse First, let’s look at the terms that discriminate an EPSP from an IPSP, excitatory and Inhibitory. Excitatory influences in the nervous system make things more likely to happen. Inhibitory influences in the nervous system make things less likely to happen. How does the axonal hillock know how far is far enough to fire the neuron? Here is another metaphor. It does a little basic math. Addition and subtraction. If the ripple of potential is excitatory, when it reaches the axonal hillock it will be added to other excitatory potentials that arrive at about the same time. If the sum of the potentials is great enough, the axonal hillock will send an action potential down the axon. If the ripple is inhibitory, it changes the cell potentials by making the cell less likely to fire or by subtracting from the potentials arriving at about the same time. In general, the farther away from the axonal hillock the stimulated receptor is – the less of a depolarization will occur because the postsynaptic potential fades as it moves away from the receptor. What about situations where not all the postsynaptic potentials reach the axonal hillock at exactly the same time? Which is going to be the most disruptive? (Have the most influence on communication.) 1. One person talking during a class or 10 people talking during a class at the same time? 2. Ten people distributed over a large classroom and talking during a class or the same ten people sitting together and talking during a class? 3. Ten people each talking for one minute at different times in a one-hour class, or the same ten people talking for one minute at the same time? Each of these represents a different situation at the cell membrane. If one receptor is stimulated by an excitatory transmitter, it is not likely to create a large enough change in the neuron potential to cause the cell to fire. Multiple stimulations, even if at different locations, are more likely to be successful in depolarizing the membrane and firing the cell. More is better. Even if multiple receptors are stimulated; if they are closer together, they have a greater effect as the depolarization from one enhances that of the others. This is referred to as spatial summation. Together is better. Neurotransmitters take time to float across the synapse. Not all will reach the receptors at the same time. If it takes too long, the effect of the early neurotransmitters will be almost gone before the other arrives Lecture Launcher 2.2 Animations Since the process of transmission takes place over time, students may be confused while looking at still diagrams. The Internet is a great place to find animations that focuse on the level of detail that you wish to emphasize. Projecting these animations during a lecture and making them available for further examination online can help students to catch on the way that a potential travels along the neuron and the changes that take place at a single point over time. YouTube is an outstanding resource for many animations, although the links tend not to be particularly stable. It is also imperative to screen the videos before using them in class. Lecture Launcher 2.3 Neuron Skits Scientific courses often miss activities that students find both entertaining and useful learning activities. One of these is “Role Playing.” Choose students who are outgoing and willing to volunteer to stand in front of the class. Give them the instruction sheets the class before they will be doing the activity so that they can prepare their character. (Handout 2.2 or 2.3) Before the next class, have the students come a few minutes early to discuss their interaction. You may wish to project an image of a synapse at the front of the room or suggest that class members turn to an appropriate illustration in their text. During the class, have the students go through the activity. Ask the class to identify the “actors” and pin appropriate signs on them. Allow the class to act as directors, revising the action. Encourage discussion of the difference between the model as portrayed by the actors and the interactions within the nervous system. Have class members assist in figuring out what each element should do with the actors following class instructions. Have the actors try literally to interpret what they are being told to do. (If the class suggests that the neurotransmitter should go through the cell membrane before the vesicle attaches to it, the vesicle membrane should keep tightly closed - they have not been told to let go or to merge with the presynaptic membrane - and the presynaptic membrane should not let the neurotransmitter through.) When the correct steps have been figured out, have the actors go through the process one or two times correctly before joining the class. Handouts Handout 2.3 Neuron Skits: Firing of a Neuron Handout 2.4 Neuron Skits: The Synapse Activities Activity 2.1 Measurement of the Speed of Axonal Transmission Equipment Stopwatch or watch with second hand Tape Measure (Optional) Calculator It would be very difficult to measure the speed of transmission through an axon in a classroom if a single axon were used, but an estimate of the speed of transmission can be easily calculated in a class activity, and the larger the class, the better. Scientists often use multiple measurements of rapidly occurring phenomena and then divide by the number of measurements. Begin by having the class estimate the distance that an impulse must travel to go from a person’s shoulder to the hand on the same side. (Having a tape measure available is useful, but not necessary.) Multiply this by the number of students in the class. This is the distance the signal must travel. Have students stand. (Moving to the outside of the room works best but may not be possible for a large lecture class.) Each student places his or her right hand on the right shoulder of the next person. The instructor begins the action by squeezing the shoulder of the first student in line while keeping track of the time. The students each squeeze the shoulder of the next person as soon as he or she feels a squeeze. The last person needs to indicate that he or she has felt the squeeze so that the instructor can stop timing. You may need to run through the action a few times to get the estimate to stabilize. Divide the number of seconds from start to finish by the distance and the number of students to get an estimate of transmission time. (See Rozin & Jonides [1977] and Hamilton and Knox [1996].) Activity 2.2 How to Murder a Neuron An understanding of the fragile nature of a single neuron can be represented by having the students explore the manner in which a neuron can be damaged. This handout gives some suggestions in an informal manner. Have the students pair up to decide what could happen that would result in the different types of neural damage. Handout Handout 2.7 How to Murder a Neuron Assignments 2.1 Vocabulary Crossword Puzzle Part of the assignment will require that the student knows the terminology used in describing the nervous system. I have created a crossword puzzle for this assignment. Crosswords provide cues in the length of the words and in letters determined from easier clues. This can be used as an assignment, a test, or an in class activity done in small groups of two to five students. See Handout 2.2: Vocabulary Crossword Puzzle ACROSS 2. EXOCYTOSIS – the process by which neurotransmitters are secreted 5. AXON – the long, thin, cylindrical structure that conveys information from the soma of a neuron to its terminal buttons 7. NUCLEUS – a structure of a cell, containing the nucleolus and chromosomes 12. DNA – deoxyribonucleic acid is commonly referred to as _____ 15. UNIPOLAR – a neuron with one axon and many dendrites attached to its soma is referred to as _____ 20. NEUROTRANSMITTER – a chemical that is released by a terminal button DOWN 1. GENE – the functional unit of the chromosome 3. 4. 6. 8. 9. 10. 11. 13. 14. 16. 17. 18. 19. SYNAPSE – the space between the terminal button of an axon and the membrane of another neuron MITOCHONDRIA – an organelle that is responsible for extracting energy from nutrients MRNA – a macromolecule that delivers genetic information concerning the synthesis of a protein from a portion of a chromosome to a ribosome SOMA – the cell body of a neuron ENZYME – a molecule that controls a chemical reaction RANVIER – a naked portion of a myelinated axon is called a node of _____ CHROMOSOME – a strand of DNA that carries genetic information CYTOPLASM – the viscous, semiliquid substance contained in the interior of a cell RIBOSOME – a cytoplasmic structure that serves as the site of production of proteins translated from mRNA LYSOSOME – an organelle that contains enzymes that break down waste products MONOPOLAR – a neuron with one divided axon attached to its soma is referred to as ____ MYELIN – a sheath that surrounds and insulates axons ATP – a molecule of prime importance to cellular metabolism Web Links 2.1 The Story of a Membrane http://www.concord.org/~barbara/workbench_web/unitIII_mini/cf_membranes/about_pores .html Structure of the plasma membrane proteins, lipids, and sugars at work in a single pore 2.2 Glia: The Forgotten Brain Cell http://faculty.washington.edu/chudler/glia.html 2.3 Millions and Billions of Cells: Types of Neurons http://faculty.washington.edu/chudler/cells.html 2.4 The Blood Brain Barrier http://faculty.washington.edu/chudler/bbb.html An intuitive description of the structure and function of the blood brain barrier. 2.5 The Synapse http://faculty.washington.edu/chudler/synapse.html 2.6 Synaptic Transmission http://www.youtube.com/user/llkeeley?feature=mhee A set of animations showing the basics of neurotransmission using the neuromuscular junction as a model. This also shows the effect of insecticides on the activity of the neuromuscular junctions. 2.7 Synaptic Transmission: A Four Step Process http://www.williams.edu/imput/synapse/pages/about.html Requires QuickTime for Animations 2.8 Biology Animations http://highered.mcgrawhill.com/sites/0072437316/student_view0/chapter45/animations.html Chemical Synapse (478.0K) Membrane-Bound Receptors, G Proteins, and Ca2+ Channels (825.0K) Voltage Gated Channels and the Action Potential (1276.0K) Sodium-Potassium Exchange (1103.0K) Function of the Neuromuscular Junction (699.0K) Action Potential Propagation in an Unmyelinated Axon (366.0K) Animations with voiceover 2.9 Resting Membrane Potential http://bcs.whfreeman.com/thelifewire/content/chp44/4401s.swf The “step through” function makes this animation particularly useful for lecture. 2.10 Synaptic Transmission http://bcs.whfreeman.com/thelifewire/content/chp44/4403s.swf The “step through” function makes this animation particularly useful for lecture. PowerPoint Presentations Two sets of standard lecture PowerPoint slides—comprehensive and brief, prepared by Grant McLaren, Ph.D., Edinboro University of Pennsylvania, are also offered and include detailed outlines of key points for each chapter supported by selected visuals from the textbook. Both sets of PowerPoint slides are available for download at the Instructor’s Resource Center at www.pearsonhighered.com/irc (ISBN 020594034X). Test Bank Written by Paul Wellman, Texas A&M University. This resource contains questions that target key concepts. Each chapter has approximately 100 questions, including multiple choice, true/false, short answer, and essay—each with an answer justification, page references, difficulty rating, and type designation. All questions are correlated to both chapter learning objectives and APA learning objectives. The Test Bank is also available in Pearson MyTest (ISBN 0205940374), a powerful online assessment software program. Instructors can easily create and print quizzes and exams as well as author new questions online for maximum flexibility. Both the Test Bank and MyTest are available online at www.pearsonhighered.com/irc (ISBN 0205940366). Accessing all Resources for Foundations of Behavioral Neuroscience, Ninth Edition: For a list of all student resources available with Foundations of Behavioral Neuroscience, go to www.mypearsonstore.com, enter the text ISBN (0205940242) and check out the “Everything That Goes With It” section under the book cover. For access to the instructor supplements for Foundations of Behavioral Neuroscience, Ninth Edition, simply go to http://pearsonhighered.com/irc and follow the directions to register (or log in if you already have a Pearson user name and password). Once you have registered and your status as an instructor is verified, you will be e-mailed a login name and password. Use your login name and password to access the catalogue. Click on the “online catalogue” link, click on “psychology” followed by “introductory psychology” and then the Carlson Foundations of Behavioral Neuroscience, Ninth Edition text. Under the description of each supplement is a link that allows you to download and save the supplement to your desktop. For technical support for any of your Pearson products, you and your students can contact http://247.pearsoned.com. Handout Descriptions 2.1 Concept Maps These maps may assist students in organizing the material in this chapter. You can make these maps available to the students or encourage them to construct their own maps. 2.2 Vocabulary Crossword Puzzle 2.3 Neuron Skits: Firing of a Neuron Script for Student Role Playing Activity (Lecture Launcher 2.3) 2.4 Neuron Skits: The Synapse Script for Student Role Playing Activity (Lecture Launcher 2.3) 2.5 Name Tags for Skits Name tags to be used with scripts for Student Role Playing Activity (Lecture Launcher 2.3) 2.6 Things That You Need to Know About Neurons A few basic facts about neurons 2.7 How to Murder a Neuron To be used with Activity 2.2 ▲ Return to Chapter 2: Table of Contents Handouts Handout 2.1: Concept Maps Name: Section: Date: Handout 2.2: Vocabulary Crossword Puzzle The Neuron Do not include spaces when the answer includes more than one word. Across 2. The process by which neurotransmitters are secreted. 5. The long, thin, cylindrical structure that conveys information from the soma of a neuron to its terminal buttons. 7. A structure of a cell, containing the nucleolus and chromosomes. 12. Deoxyribonucleic acid is commonly referred to as: 15. A neuron with one axon and many dendrites attached to its soma is referred to as: 20. A chemical that is released by a terminal button. Down 1. The functional unit of the chromosome. 3. The space between the terminal button of an axon and the membrane of another neuron. 4. An organelle that is responsible for extracting energy from nutrients. 6. A macromolecule that delivers genetic information concerning the synthesis of a protein from a portion of a chromosome to a ribosome. 8. The cell body of a neuron. 9. A molecule that controls a chemical reaction. 10. A naked portion of a myelinated axon is called a node of: 11. A strand of DNA that carries genetic information. 13. The viscous, semiliquid substance contained in the interior of a cell. 14. A cytoplasmic structure that serves as the site of production of proteins translated from mRNA. 16. An organelle that contains enzymes that break down waste products. 17. A neuron with one divided axon attached to its soma is referred to as: 18. A sheath that surrounds and insulates axons. 19. A molecule of prime importance to cellular energy metabolism Puzzle created with Puzzlemaker at DiscoverySchool.com Handout 2.3 Neuron Skit: Firing of a Neuron THE CHARACTERS The presynaptic membrane on the terminal button (two to four people, arms outstretched, holding hands.) The vesicle (three people holding hands on the inside of the presynaptic membrane) A molecule of neurotransmitter (inside the circle made by the vesicle arms) The dendrite (Two people, one hand on each shoulder of “the receptor”) The receptor (Stands between the dendrite membranes – arms out) The action potentials for the presynaptic and postsynaptic neurons. (One at the back of the classroom near one aisle. The second action potential is standing behind the barrier formed by the receptor and two dendrite membrane sections.) THE SETTING The synaptic gap between two neurons THE ACTION The action potential The action potential runs down the aisle (Axon) yelling “Fire! Fire!” When it reaches the vesicle, it helps the vesicle over to the membrane. The vesicle The vesicle opens at one grasped hand, as does the presynaptic membrane. The vesicle joins hands with the membrane to become part of the presynaptic membrane. The neurotransmitter The neurotransmitter wanders out and meanders around, eventually finding the receptor. The receptor The receptor and neurotransmitter grasp hands for a moment. The receptor turns tells and the other parts of the membrane that something exciting has happened. The second action potential The second action potential moves away from the receptor up the opposite aisle (axon) The neurotransmitter The neurotransmitter lets go and wanders around for a few more moments before returning to the presynaptic membrane. The membrane The membrane opens and the neurotransmitter moves inside Handout 2.4 Neuron Skit: Synapse This is a rough guide for the possible interaction between these characters. Actors should feel free to improvise, and observers should feel free to comment on and correct the action. THE CHARACTERS: Tranella (a neurotransmitter) Agie Agonist (An agonist) Auntie Agonist (An antagonist) Reggie Receptor (one of the postsynaptic receptors in the synapse) Soma (The cell body – Played by remaining class members) THE SETTING: You are in the synapse of a sensory neuron. THE ACTION Reggie Receptor and Soma (Reggie Receptor is hanging out on the postsynaptic membrane. He is bored, waiting for something stimulating to happen.) Tranella, Agie, and Auntie Agonist: (Tranella, Agie, and Auntie Agonist are wandering around the synaptic gap looking for Reggie.) Auntie Agonist and Reggie Receptor and Soma (Auntie Agonist finds Reggie first. They grasp hands. She begins telling him that there is nothing of any importance going on and that he doesn’t need to do anything. She should be as “antagonistic” as possible.) Auntie wanders off, to be replaced by Agie. Agie and Reggie Receptor and Soma (Agie Tells Reggie about what is going on around him, but she waits for a moment or two before she comments on what she sees most of the time. He passes on the information to the waiting cell body -The class). Agie leaves, and Tranella moves closer to Reggie Tranella and Reggie Receptor and Soma (Tranella tells him about things that she is aware of and he passes the information on to Soma.) Tranella (a neurotransmitter) 37 Agie Agonist (An agonist) Auntie Agonist (An antagonist) Reggie Receptor (a postsynaptic receptor) Presynaptic Membrane on the terminal button Vesicle membrane A molecule of neurotransmitter Dendrite Membrane The Receptor The Action Potential Handout 2.6 Things That You Need to Know About Neurons. Water and Ions The body is 2/3 water. Water molecules tend to be more positive on one side and negative on the other. Ions are repelled by the charged sides of water. (Making them hydrophobic) A small percentage of water molecules pull apart to form ions (O 2 - (2 extra electrons) H+) Sodium Chloride (NaCl) separates to form ions when dissolved in water. Chemicals in and Around the Cell. ORGANIC MOLECULES ION INTRACELLULAR EXTRACELLULAR (Sea Water) (Blood) 400 10 20 Sodium (Na+) 50 460 440 Chloride (Cl+) 40 540 560 Calcium (Ca2+) 0.1 10 10 Many Few Few Potassium (K+) Organic Ions - protein, amino acids, & nucleic acids etc. (anions -) Amino Group Carboxylic Acid Some organic molecules are made up chiefly of carbon and hydrogen arranged in chains. These are not charged and do not interact with water molecules... The Cell Cells are essentially bags of water floating in water. Phospholipids have a charged phosphorous containing group at one end and can interact with water (hydrophilic) and the other end cannot (hydrophobic) making the molecule (amphipathic – likes both). When exposed to water the molecules line up. (Form a membrane.) Membranes are 25 to 60% protein. Proteins are built using RNA as a pattern to link amino acids. Protein molecules span the thickness of the membrane. They form hydrophilic channels and pumps. Some are anchored, others float. Neurons are very small The membrane of a neuron is so thin that it cannot be seen under a light microscope. It is thinner than a wavelength of light. Seven nanometers or 10-9 meters. Each neuron uses a the same neurotransmitter/s at all its synapses (In most cases) Transmission speed is dependent on several factors: 1. Size/Diameter of the cell 2. Myelinization The myelin cells are made up of a large percentage of lipid (fat). The information flows in only one direction, unless forced. Transmission changes the electrical difference between the interior and exterior of the cell. Transmission is “all-or-nothing” Vesicles use calcium to merge with the membrane and release intracellular material to the outside. (This is also related to how the cell grows.) The membrane can also pinch in to bring extra cellular material inside. (Cell retraction) Handout 2.7 How to Murder a Neuron TECHNIQUE WHAT HAPPENS ACCOMPLISHED Reduce Blood Supply (Ischemia) Reduce Glucose in blood Heart Attack Arteriosclerosis Thrombosis or embolism Starvation Insulin overdose Reduce blood supply Reduce oxygen intake through lungs Heart Attack Arteriosclerosis Thrombosis or embolism Drowning Carbon monoxide poisoning Squish it Reduce space inside of skull through: Reduction of skull capacity Increase in fluid in the cerebrospinal system Increase amount of blood inside of skull Crush skull Insert something into skull that takes up space Hydrocephaly Hematoma Use the skull to stop a brain that is moving at high speed Poison it Absorb toxins which destroy internal structures Bind to receptor sites and stimulate cells till they die (Neurotoxins) Heavy Metals Mercury Lead Arsenic Cut it Remove axon Remove dendrites Remove synapse remove cell or groups of cells Gun shot wound or other projectile entering brain or nervous system Surgery Infect it Bacterial infections Viral infections Syphilis Rabies Mumps Herpes Chicken Pox Mutate it Genetic Disorders Down's Syndrome Huntington's Chorea Starve it Suffocate it NOTES Cells that are without oxygen may release excessive glutamate (See neurotoxins) Over stimulate it Epilepsy Grand mal seizures Expose it Remove myelin Multiple sclerosis Amyotrophic lateral sclerosis Attack it Immune Disorders