Case 1 Marquis and Almandoz Can an ethical bank support...

EXPERIENCE HBR.ORG Case Study The Experts Christopher Marquis is an associate professor at Harvard Business School. Juan Almandoz is an assistant professor at lESE Business School, in Barcelona. Can an Ethical Bank Support Guns and Frac king? by Christopher Marquis and Juan Almandoz Ken LaRoe, chairman and CEO, First Green Bank A John Replogle, president and CEO, Seventh Generation | B | HBRs fictionalized case studies present B l dilemmas faced by leaders in real companies and offer solutions from experts. This one is based on the HBS Case Study First Green Bank: Bringing Bloom to Desert Landscapes (case no. 9-413-073), by Christopher Marquis and Juan Almandoz. It is available at HBR.org. s the founder and president of a new†¦show more content†¦Two other board members agreed with her about the gym, so Jay had scaled back those plans. Twin Debates Neitha had been the one to solicit the first problematic loan application. Shed been talking to the head of a Colorado engineering company that developed pumping sys124 Harvard Business Review April 2014 tems used in hydraulic fracturing—fracking—and wanted to expand into making the polymers, emulsions, and surfactants the industry relies on. These materials, the executive said, would be significantly less toxic than those currently in use. Though ambivalent about fracking in general, Neitha had recommended that the executive approach Rocky Mountain Green Bank. But on hearing about the opportunity, Neithas fellow directors were divided. One side touted the economic and employment smoking in public areas were a perfect example, he said: Many of them went into effect before the dangers of secondhand smoke had been proved. So if it looks bad, it is bad. Jay thought ruefully. Hoping for a more nuanced perspective. Jay went next to the pastor, the Reverend Clyde Dahlberg, who, to Jays surprise, advocated a completely evidence-based approach: Make two columns, one for adverse environmental impacts, one for the positives, he said In some ways, it was just the type of loan the bank needed: Field Force was a solid performer, a growing source of local jobs, and a good corporate citizen. benefits of fracking, while the other inmatter-of-factly. Figure out a way to

Evolution Of The Origin Of Man - 862 Words

First Draft Creationists say that teaching evolution in school would go against what they believe about the origins of man. But Evolution does not cover the origins of man, but how entire species have changed with time. US public schools should teach evolution as scientific fact because there is fossil evidence, bacterial evidence, and there is evidence hidden inside of the genes in all living things. Fossil’s from all over the world show evidence of evolution and change in entire species. Scientists have found fossils of ancient birds with DNA that is nearly the same as modern day birds. But the ancient birds had feathers and legs just like that of modern birds. But they also have teeth, clawed digits on their forelimbs, and a tailbone much like one from a reptile. From this scientists have put it together that birds had evolved from ancient reptiles, and that reptiles and birds are both closely related to each other even today. Philip D. Gingerich, an paleontologist and a professor at t he University of Michigan had found a fossil which he called Pakicetus. It was an ancient mammal found in Pakistan and Egypt whose ear bones show that it is a member in the whale family but it has a skull that looks like a dogs. Philip proposed that this was ancient ancestor of modern day whales. Later Hans Thewissen, a former student of Philip D. Gingerich found another fossil that was a slightly more recent form of Pakicetus that had webbed feet and legs built for walking or swimmingShow MoreRelatedAnthropology and Its Branches1728 Words   |  7 Pagesphysical anthropology, which is the study of human physical character, in both the past and present. Anthropology emerged as an independent science in the late 18th century, it developed two divisions: physical anthropology, which focuses on human Evolution and variation, using methods of Physiology, Anthropometry, Genetics, and Ecology; and cultural anthropology , which includes Archaeology, Ethnology, Social Anthropology, and Linguistics. Anthropology is a holistic subject that covers all facetsRead MoreThe Evolution of Evolution1188 Words   |  5 Pagescreation of humanity have rapidly changed since the discovery of evolution. Nevertheless, there was a time before the world did not know the theory of evolution and the theories demonstrated by Sir Charles Darwin. Before the evolution, there were people who were subjected to religious ideologies of how mankind was created, they believed that the upper class was known to be â€Å"divine creatures†. However, the introduction of evolution leads the theory to be the base of biology and changes the minds ofRead MoreThe Theory Of Evolution Of Creationism977 Words   |  4 PagesThe theory of evolution is at odds with the views of many religions, and many people want to allow a religious view of creationism to be taught in the public school system. The foundation of evolution is based upon the belief that the origin of all ordered complex systems, including living creatures, can be explained by natural laws without the initiation or intervention of God. A person who believes in the biblical model of creation is viewed by some non- believers as a naive, narrow-minded religiousRead More Human Evolution Essay1020 Words   |  5 PagesHuman Evolution   Ã‚  Ã‚  Ã‚  Ã‚  When people take a look at African history in general many topics and ideas come to mind. How the people of Africa lived, how they developed civilizations and cultures, and how their oral traditions came about are just a few examples. When I am trying to learn about different groups of people and different areas of the world I most likely start at the very beginning of their existence. Africa being the origin of man and the home for the majority of developments of early humansRead MoreDarwin s Theory Of Evolution Of Species1354 Words   |  6 Pagesdeeper and more impactful discussion; the origins of species. Prior to Darwin’s studies the discussion of the origin of man was dominated by creationism, or the belief that we derive from god, who created us all in his image. For the next thirty years, Darwin devoted himself to researching the long standing question â€Å"where did we come from?† Darwin became the first scientist to present a supported ar gument for evolution, with his crowned publication, â€Å"Origins of Species†, describing how all speciesRead MoreHow Charles Darwin Changed the World Forever1409 Words   |  6 PagesThere is one man in history who changed everything from the way we see everyday events in the world, and that man is Charles Darwin. Charles Darwin was a scientist who discovered the origin of life through a study on the Galapagos Islands. Before Darwin’s discovery, the world was looked upon as God’s playground where everything happened because of him. For example, if something bad happened to someone’s family like a disease it would be because they have angered God. Darwin lived during the dawnRead MoreThe Origin Of Life And Evolution1744 Words   |  7 Pageslast centuries. On the contrary, even though it is nearly 150 years since the Origin of Species (Charles Darwin, 1859), it seems paradoxical that there are still a great significant amount of people who maintain an a nti-darwian position on the origin of life and species. A poll done by Gallup Institute in 2004 showed that an approximate of 42% of Americans believe that humanity was created by God, 18% believe in an evolution directed by God, and only 26% of them support Darwin’s theory. In Great BritainRead MoreOn The Origin of Species by Charles Darwin915 Words   |  4 PagesHuman evolution has been of interest to people for quite some time. Even though in the publication of On The Origin of Species by Charles Darwin in 1859 human evolution was not specifically mentioned, only that light will be thrown on the origin of man and his history, Darwin did argue for the evolution of new species from older ones (1). Since then, interest in evolution, and especially human evolution, has been growing. An example of one of the first debates about human evolution is the debateRead MoreAnalysis Of Charles Darwin s The Origin Of Species Declared That Human Beings Developed Overtime From More Si mple Forms843 Words   |  4 PagesDarwin in his book On the Origin of Species declared that human beings developed overtime from more simple forms. Evolution suggested that the human species originated from ape-like creatures and gradually changed in structure. Essentially, given the changing patterns of weather and environment, the species had to acquire new skills and adapt to survive. Those that could not change were eliminated in a process that is known as Natural Selection (Larson 47). The Evolution theory, since its inceptionRead MoreHuman Evolution: How Humans Have Evolved800 Words   |  4 Pagesyears. Human evolution all started from our great ancestors, the chimpanzees. Human evolution started all in the continent of Africa. Due to global changes, evolution changed over time. Thus leading to the evolution of mankind. But man didnt just evolve from chimpanzees. There were a lot of scientific processes and different events that led up to final evolution of mankind. But wh at does it mean humans evolved from chimpanzees? Why is the human evolution such a small speck in the evolution graph of

Declaration Activity free essay sample

Jefferson chose to begin the Declaration with the words, â€Å"The unanimous Declaration of the thirteen united States of America. † Do you feel this was necessary? Why or why not? Could the 13 colonies have declared independence if they were not unanimous? Why or why not? Answers will vary. Most students might note that it was necessary for Jefferson to prove that the Continental Congress presented a united front to the world in order to prove that independence was the true goal of the colonies. Others may state that since each state provided signers to the document, it was obvious that all thirteen colonies accepted it. As to the question of whether the 13 colonies could have declared independence if they weren’t unanimous, answers will vary. Most students might state that independence would be difficult without the support of all thirteen colonies, but some might say independence without consensus was still possible. For instance, colonies that objected could be absorbed into Canada or find a way to peacefully co-exist with those that seceded. We will write a custom essay sample on Declaration Activity or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page 2. How does Jefferson explain the reason for a formal declaration of independence? Why do you think it was necessary for Jefferson to state the â€Å"causes which impel them to the separation†? Answers will vary. However, some students may note that other nations, such as France and the Netherlands, also had colonial interests in North America and may have been concerned if British colonists declared independence for groundless reasons. Also, because of Jefferson’s background as a lawyer, it might have also been true that he was building his case for independence before the world community, similar to what he might do if he were pleading a case before a jury. 3. Next, review the two sections of John Locke’s Two Treatises of Government. In your own words, how does Jefferson use Locke’s ideas in the preamble of the Declaration? Students will note similarities between Locke’s thoughts on natural rights and Jefferson’s mention of â€Å"inalienable rights, including â€Å"Life, Liberty, and the pursuit of Happiness. They may also note Jefferson’s view that â€Å"all men are created equal. † 4. According to Jefferson, what was the purpose of government? What does Jefferson suggest should happen whenever government becomes â€Å"destructive of the ends for which it was created? According to Jefferson, how do governments derive their powers? Jefferson would note that the purpose of government was to protect the â€Å"inalienable rights† that man received from â€Å"their Creator. † In his view, if government became 2 â€Å"destructive,† it was the right of the citizens to â€Å"alter or abolish† that form of government and replace it with a better one. Jefferson believed that governments derived their power â€Å"from the consent of the governed. † In other words, the citizens of the nation permitted the government to rule. 5. Jefferson noted that â€Å"all men are created equal,† suggesting that this was â€Å"selfevident. Speculate as to w hat he meant by that statement. What sorts of conflicts and misconceptions may have stemmed from this statement? Answers will vary as to what Jefferson meant by the â€Å"all men are created equal† statement. Some students may note that Jefferson made this statement as a slave owner and had no intention of granting citizenship status or equality to his black slaves. Other students might speculate that Jefferson believed in a literal interpretation of this phrase and had no intention of granting equality or the right to vote to women. Also, students may note that some white men (if they were not property owners) did not have the right to vote. 6. Next, look at the list of grievances that Jefferson lists as reasons that the King has violated the natural rights of the colonists. Below, list the three grievances that you feel are the worst violations. Explain why you believe them to be important. Also, note that Jefferson points to King George III in his list of grievances despite the fact that Parliament passed the acts and approved the taxes that led to the colonists calling for independence. The King, on the other hand, was a monarch with limited power. Why would Jefferson blame the King for the problems leading to the Declaration? Explain your view. Answers will vary. Based on their study of the American Revolution and viewing of the series, many students may point to grievances that allowed the British military occupation of colonial cities (for example, the Boston Massacre), imposing taxes without consent (a grievance that is typically mentioned in textbooks), grievances that limit selfgovernment and possibly grievances that caused insurrections of Native Americans. Most students would probably note that it would be easier for the colonists to focus their anger on one individual, King George, than on the Parliament. His likeness was on colonial money, so he was known by all the colonists, while most members of Parliament were not known to the average colonist. Focusing anger and displeasure on one individual could provide a great psychological boost to the independence movement. 7. In the summer of 1776, Jefferson may not have recognized that his declaration would be studied and revered by generations. However, the Declaration has gained that status over time. Write a paragraph that explaining your view of why that has happened. If you do not feel that the Declaration is revered, explain why. Many students who feel that the Declaration is revered will probably note that Jefferson’s statements regarding fundamental rights are representative of our government’s foundation today. In addition, they may also note that the Declaration is displayed in a 3 similar manner (and in a similar location) as the Constitution of the United States and the Bill of Rights, thereby giving it the same status. Other students may note that the document helped unite various factions in the Continental Congress, paving the way for independence. Some students may note that in 21st Century America, the Declaration has no legal â€Å"force,† and therefore while it is an important historic document, its importance is significantly overstated. 8. The colonists had been fighting British soldiers for over a year before the Declaration was written and the formal declaration of war against Britain was announced. Why do you feel it took so long for the colonists to formally announce a declaration of war against the British? The length of time between the fighting at Lexington and Concord and the actual declaration of war probably occurred because most colonists (and many delegates to the Continental Congress) hoped for some sort of reconciliation with Britain. They felt that a declaration of war might antagonize the British and make reconciliation difficult, if not impossible. Answers will vary. 9. John Locke died in 1704, over 70 years before Jefferson wrote the Declaration of Independence. In your estimate, would Locke be happy with the way Jefferson used his Two Treatises to justify independence from Britain, which was Locke’s native country? Below, either write a fictitious letter from Locke to Jefferson critiquing his use of Two Treatises in the Declaration of Independence or a fictitious letter from Jefferson to Locke explaining how he adapted Locke’s theory in writing the Declaration. Answers will vary.

Outline of Chapter 2 Essay Example

Outline of Chapter 2 Essay chapter 2 chapter outline module 5 Neurons: The Basic Elements of Behavior The Structure of the Neuron How Neurons Fire Where Neurons Connect to One Another: Bridging the Gap Neurotransmitters: Multitalented Chemical Couriers module 6 module 7 The Brain The Nervous System and the Endocrine System: Communicating within the Body The Nervous System The Endocrine System: Of Chemicals and Glands Studying the Brain’s Structure and Functions: Spying on the Brain The Central Core: Our â€Å"Old Brain† The Limbic System: Beyond the Central Core The Cerebral Cortex: Our â€Å"New Brain† Neuroplasticity and the Brain The Specialization of the Hemispheres: Two Brains or One? Exploring Diversity: Human Diversity and the Brain Try It! Assessing Brain Lateralization The Split Brain: Exploring the Two Hemispheres Becoming an Informed Consumer of Psychology: Learning to Control Your Heart—and Mind—through Biofeedback Psychology on the Web The Case of . . . The Fallen Athlete Full Circle: Neuroscience and Behavior 46 The Deepest Cut Wendy Nissley carried her two-year-old daughter, Lacy, into O. R. 12 at Johns Hopkins Hospital to have half of her brain removed. Lacy suffers from a rare malformation of the brain, known as hemimegalencephaly, in which one hemisphere grows larger than the other. The condition causes seizures, and Lacy was having so many—up to forty in a day—that at an age when other toddlers were trying out sentences, she could produce only a few language-like sounds. As long as Lacy’s malformed right hemisphere was attached to the rest of her brain, it would prevent her left hemisphere from functioning normally. We will write a custom essay sample on Outline of Chapter 2 specifically for you for only $16.38 $13.9/page Order now We will write a custom essay sample on Outline of Chapter 2 specifically for you FOR ONLY $16.38 $13.9/page Hire Writer We will write a custom essay sample on Outline of Chapter 2 specifically for you FOR ONLY $16.38 $13.9/page Hire Writer So Lacy’s parents had brought her to Johns Hopkins for a hemispherectomy, which is probably the most radical procedure in neurosurgery. (Kenneally, 2006, p. 36) neuroscience and behavior It took nearly a day, but the surgery to remove half of Lacy’s brain was a success. Within a few months, Lacy was crawling and beginning to speak. Although the long-term effects of the radical operation are still unclear, it brought substantial improvement to Lacy’s life. The ability of surgeons to identify and remove damaged portions of the brain is little short of miraculous. The greater miracle, though, is the brain itself. An organ roughly half the size of a loaf of bread, the brain controls our behavior through every waking and sleeping moment. Our movements, thoughts, hopes, aspirations, dreams—our very awareness that we are human—all depend on the brain and the nerves that extend throughout the body, constituting the nervous system. Because of the importance of the nervous system in controlling behavior, and because humans at their most basic level are biological beings, many researchers in psychology and other fields as diverse as computer science, zoology, and medicine have made the biological underpinnings of behavior their specialty. These experts collectively are called neuroscientists (Beatty, 2000; Posner DiGirolamo, 2000; Gazzaniga, Ivry, Mangun, 2002; Cartwright, 2006). Psychologists who specialize in considering the ways in which the biological structures and functions of the body affect behavior are known as Behavioral neuroscientists Psychologists who specialize in behavioral neuroscientists (or biopsychologists). They seek to answer sevconsidering the ways in which the eral key questions: How does the brain control the voluntary and involunbiological structures and functions tary functioning of the body? How does the brain communicate with other of the body affect behavior. parts of the body? What is the physical structure of the brain, and how does this structure affect behavior? Are psychological disorders caused by biological factors, and how can such disorders be treated? As you consider the biological processes that we’ll discuss in this chapter, it is important to keep in mind why behavioral neuroscience is an essential part of psychology: our understanding of human behavior requires knowledge of the brain and other parts of the nervous system. Biological factors are central to our sensory experiences, states of consciousness, motivation and emotion, development throughout the life span, and physical and psychological health. Furthermore, advances in behavioral neuroscience have led to the creation of drugs and other treatments for psychological and physical disorders. In short, we cannot understand behavior without understanding our biological makeup (Plomin, 2003a; Compagni Manderscheid, 2006; Plomin et al. , 2008). 47 looking ahe ad module 5 Neurons The Basic Elements of Behavior learning outcomes 5. 1 Explain the structure of a neuron. The nervous system is the pathway for the instructions that permit our bodies to carry out everyday activities such as scratching an itch as well as more remarkable skills like climbing to the top of Mount Everest. Here we will look at the structure and function of neurons, the cells that make up the nervous system, including the brain. 5. 2 Describe how neurons fire. 5. 3 Summarize how messages travel from one neuron to another. 5. 4 Identify neurotransmitters. The Structure of the Neuron LO 1 Playing the piano, driving a car, or hitting a tennis ball depend, at one level, on exact muscle coordination. But if we consider how the muscles can be activated so precisely, we see that there are more fundamental processes involved. For the muscles to produce the complex movements that make up any meaningful physical activity, the brain has to provide the right messages to them and coordinate those messages. Such messages—as well as those which enable us to think, remember, and experience emotion—are passed through specialized cells called neurons. Neurons Nerve cells, the basic Neurons, or nerve cells, are the basic elements of the nervous system. Their elements of the nervous system. uantity is staggering—perhaps as many as 1 trillion neurons throughout Dendrites A cluster of fibers at the body are involved in the control of behavior (Boahen, 2005). one end of the neuron that receives messages from other neurons. Although there are several types of neurons, they all have a similar strucAxon The part of the neuron that ture, as illustrated in Figure 1. In contrast to most other cells, however, carries messages destined for other neurons have a distinctive feature: the ability to communicate with other neurons. cells and transmit information across relatively long distances. Many of the body’s neurons receive signals from the environment or relay the nervous system’s messages to muscles and other target cells, but the vast majority of neurons communicate only with other neurons in the elaborate information system that regulates behavior. As you can see in Figure 1, a neuron has a cell body with a cluster of fibers called dendrites at one end. Those fibers, which look like the twisted Remember that Dendrites branches of a tree, receive messages from other neurons. On the opposite Detect messages from other of the cell body is a long, slim, tubelike extension called an axon. The axon neurons; Axons carry signals carries messages received by the dendrites to other neurons. The axon is conAway from the cell body. siderably longer than the rest of the neuron. Although most axons are several s tudy aler t 48 Chapter 2 neuroscience and behavior Dendrites Terminal buttons Cell body M o ec vem tric ent of al i mpu lse el Myelin sheath Axon (inside myelin sheath) Figure 1 The primary components of the specialized cell called the neuron, the basic element of the nervous system (Van De Graaff, 2000). A neuron, like most types of cells in the body, has a cell body and a nucleus, but it also contains structures that carry messages: the dendrites, which receive messages from other neurons, and the axon, which carries messages to other neurons or body cells. In this neuron, as in most neurons, the axon is protected by the sausagelike myelin sheath. What advantages does the treelike structure of the neuron provide? millimeters in length, some are as long as three feet. A xons end in small bulges called terminal buttons, which send messages to other neurons. The messages that travel through a neuron are electrical in nature. Although there are exceptions, those electrical messages, or impulses, generally move across neurons in one direction only, as if they were traveling on a one-way street. Impulses follow a route that begins with the dendrites, continues into the cell body, and leads ultimately along the tubelike extension, the axon, to adjacent neurons. To prevent messages from short-circuiting one another, axons must be insulated in some fashion (just as electrical wires must be insulated). Most axons are insulated by a myelin sheath, a protective coating of fat and protein that wraps around the axon like links of sausage. Terminal buttons Small bulges at the end of the axons that send messages to other neurons. Myelin sheath A protective coat of fat and protein that wraps around the axon. All-or-none law The rule that neurons are either on or off. Resting state The state in which there is a negative electrical charge of about 70 millivolts within a neuron. s tudy aler t Think of a neuron as a sausage, and the myelin sheath as the case around it. LO 2 How Neurons Fire Like a gun, neurons either fire—that is, transmit an electrical impulse along the axon—or don’t fire. There is no in-between stage, just as pulling harder on a gun trigger doesn’t make the bullet travel faster. Similarly, neurons follow an all-or-none law: they are either on or off, with nothing in between the on state and the off state. Once there is enough force to pull the trigger, a neuron fires. Before a neuron is triggered—that is, when it is in a resting state—it has a negative electrical charge of about 70 millivolts. When a message arrives at a neuron, gates along the cell membrane open briefly to allow positively charged ions to rush in at rates as high as 100 million ions per second. The sudden arrival of these positive ions causes the charge within the nearby part of the cell to change momentarily from negative to positive. When the positive charge reaches a critical level, the â€Å"trigger† is pulled, and an electrical impulse, known as an action potential, travels along the axon of the neuron (see Figure 2). psych 2. 0 www. mhhe. com/psychlife Neurons 49 Module 5 neurons: the basic elements of behavior Figure 2 Movement of the action potential across the axon. Just before Time 1, positively charged ions enter the cell membrane, changing the charge in the nearby part of the neuron from negative to positive and triggering an action potential. The action potential travels along the axon, as illustrated in the changes occurring from Time 1 to Time 3 (from top to bottom in this drawing). Immediately after the action potential has passed through a section of the axon, positive ions are pumped out, restoring the charge in that section to negative. Time 1 Voltage Time 2 ++ +++ – – – – – – Time 3 Voltage Voltage Positive charge Negative charge Direction of impulse Action potential An electric nerve impulse that travels through a neuron when it is set off by a â€Å"trigger,† changing the neuron’s charge from negative to positive. Mirror neurons Neurons that fire when a person enacts a particular behavior and also when a person views others’ behavior. The action potential moves from one end of the axon to the other like a flame moving along a fuse. Just after an action potential has occurred, a neuron cannot fire again immediately no matter how much stimulation it receives. It is as if the gun has to be reloaded after each shot. Eventually, though, the neuron is ready to fire once again. Neurons differ not only in terms of how quickly an impulse moves along the axon but also in their potential rate of firing. Some neurons are capable of firing as many as a thousand times per second; others fire at much slower rates. The intensity of a stimulus determines how much of a neuron’s potential firing rate is reached. A strong stimulus, such as a bright light or a loud sound, leads to a higher rate of firing than a less intense stimulus does. Thus, even though all impulses move at the same strength or speed through a particular axon—because of the all-or-none law—there is variation in the frequency of impulses, providing a mechanism by which we can distinguish the tickle of a feather from the weight of someone standing on our toes. Although all neurons operate through the firing of action potentials, there is significant specialization among different types of neurons. For example, in the last decade, neuroscientists have discovered the existence of mirror neurons, neurons that fire not only when a person enacts a particular behavior, but also when a person simply observes another individual carrying out the same behavior (Lepage Theoret, 2007; Schulte-Ruther et al. , 2007). 50 Chapter 2 neuroscience and behavior Mirror neurons may help explain how (and why) humans have the capacity to understand others’ intentions. Specifically, mirror neurons may fire when we view others’ behavior, helping us to predict what their goals are and what hey may do next (Oberman, Pineda, Ramachandran, 2007; Triesch, Jasso, Deak, 2007). Mirror neurons may help explain how (and why) humans have the capacity to understand others’ intentions. LO 3 Where Neurons Connect to One Another: Bridging the Gap Synapse The space between two If you have looked inside a computer, you’ve seen that each part is physically connected to another part. In con trast, evolution has produced a neural transmission system that at some points has no need for a structural connection between its components. Instead, a chemical connection bridges the gap, known as a synapse, between two neurons (see Figure 3). The synapse is the space between two neurons where the axon of a sending neuron 1 Neurotransmitters are produced and stored in the axon. neurons where the axon of a sending neuron communicates with the dendrites of a receiving neuron by using chemical messages. 2 If an action potential arrives, the axon releases neurotransmitters. 3 Neurotransmitters travel across the synapse to receptor sites on another neuron’s dendrite. Axon Axon Synapse Dendrite Synapse Neurotransmitter Neurotransmitter Synapse Receptor site Receptor site 4 When a neurotransmitter fits into a receptor site, it delivers an excitatory or inhibitory message. If enough excitatory messages are delivered, the neuron will fire. A Neurotransmitter Dendrite B Figure 3 (A) A synapse is the junction between an axon and a dendrite. The gap between the axon and the dendrite is bridged by chemicals called neurotransmitters (Mader, 2000). (B) Just as the pieces of a jigsaw puzzle can fit in only one specific location in a puzzle, each kind of neurotransmitter has a distinctive configuration that allows it to fit into a specific type of receptor cell (Johnson, 2000). Why is it advantageous for axons and dendrites to be linked by temporary chemical bridges rather than by the hard wiring typical of a radio connection or telephone hookup? Module 5 neurons: the basic elements of behavior 51 communicates with the dendrites of a receiving neuron by using chemical messages (Fanselow Poulos, 2005; Dean Dresbach, 2006). carry messages across the synapse to When a nerve impulse comes to the end of the axon and reaches a terminal the dendrite (and sometimes the cell button, the terminal button releases a chemical courier called a neurotransbody) of a receiver neuron. mitter. Neurotransmitters are chemicals that carry messages across the Excitatory messages Chemical synapse to a dendrite (and sometimes the cell body) of a receiving neuron. messages that make it more likely that a receiving neuron will fire and an The chemical mode of message transmission that occurs between neurons is action potential will travel down its axon. strikingly different from the means by which communication occurs inside Inhibitory messages Chemical neurons: although messages travel in electrical form within a neuron, they messages that prevent or decrease the move between neurons through a chemical transmission system. ikelihood that a receiving neuron will fire. There are several types of neurotransmitters, and not all neurons are Reuptake The reabsorption of capable of receiving the chemical message carried by a particular neuneurotransmitters by a terminal button. rotransmitter. In the same way that a jigsaw puzzle piece can fit in only one specific location in a puzzle, e ach kind of neurotransmitter has a distinctive configuration that allows it to fit into a specific type of receptor site on the receiving neuron (see Figure 3B). It is only when a neurotransmitter fits precisely into a receptor site that successful chemical communication is possible. If a neurotransmitter does fit into a site on the receiving neuron, the chemical message it delivers is basically one of two types: excitatory or inhibitory. Excitatory messages make it more likely that a receiving neuron will fire and an action potential will travel down its axon. Inhibitory messages, in contrast, do just the opposite; they provide chemical information that prevents or decreases the likelihood that the receiving neuron will fire. Because the dendrites of a neuron receive both excitatory and inhibitory messages simultaneously, the neuron must integrate the messages by using a kind of chemical calculator. Put simply, if the excitatory messages (â€Å"fire! †) outnumber psych 2. 0 the inhibitory ones (â€Å"don’t fire! †), the neuron fires. In contrast, if the inhibitory www. mhhe. com/psychlife messages outnumber the excitatory ones, nothing happens, and the neuron remains in its resting state (Mel, 2002; Flavell et al. , 2006). If neurotransmitters remained at the site of the synapse, receiving neurons would be awash in a continual chemical bath, producing constant stimulation or constant inhibition of the receiving neurons—and effective communication across the synapse would no longer be possible. To solve this problem, neurotransmitters are either deactivated by enzymes or—more commonly— reabsorbed by the terminal button in an example of chemical recycling called reuptake. Like a vacuum cleaner sucking up dust, neurons reabsorb the neurotransmitters that are now clogging the synapse. All this activity Messages Traveling between Neurons occurs at lightning speed (Helmuth, 2000; Holt Jahn, 2004). Neurotransmitters Chemicals that LO 4 Neurotransmitters: Multitalented Chemical Couriers Neurotransmitters are a particularly important link between the nervous system and behavior. Not only are they important for maintaining vital brain and body functions, a deficiency or an excess of a neurotransmitter can produce severe behavior disorders. More than a hundred chemicals have been found to act as neurotransmitters, and neuroscientists believe that more may ultimately be identified (Penney, 2000; Schmidt, 2006). Neurotransmitters vary significantly in terms of how strong their concentration must be to trigger a neuron to fire. Furthermore, the effects of a particular neurotransmitter vary, depending on the area of the nervous system in 52 Chapter 2 neuroscience and behavior Dopamine Pathways Name Acetylcholine (ACh) Location Brain, spinal cord, peripheral nervous system, especially some organs of the parasympathetic nervous system Brain, spinal cord Brain, spinal cord Effect Excitatory in brain and autonomic nervous system; inhibitory elsewhere Function Muscle movement, cognitive functioning Glutamate Gamma-amino butyric acid (GABA) Excitatory Main inhibitory neurotransmitter Memory Eating, aggression, sleeping Serotonin Pathways Dopamine (DA) Brain Inhibitory or excitatory Muscle disorders, mental disorders, Parkinson’s disease Sleeping, eating, mood, pain, depression Pain suppression, pleasurable feelings, appetities, placebos Serotonin Brain, spinal cord Inhibitory Endorphins Brain, spinal cord Primarily inhibitory, except in hippocampus Figure 4 Some major neurotransmitters. which it is produced. The same neurotransmitter, then, can act as an excitatory message to a neuron located in one part of the brain and can inhibit firing in neurons located in another part. (The major neurotransmitters and their effects are described in Figure 4. ) One of the most common neurotransmitters is acetylcholine (or ACh, its chemical symbol), which is found throughout the nervous system. ACh is Michael J. Fox, who suffers from Parkinson’s disease, like Muhammad Ali, has become a strong advocate for research into the disorder. The pair is seen here asking Congress for additional funds for Parkinson’s research. Module 5 neurons: the basic elements of behavior 53 involved in our every move, because—among other things—it transmits messages relating to our skeletal muscles. ACh is also involved in memory capabilities, and diminished production of ACh may be related to Alzheimer’s disease (Mohapel et al. , 2005). Another major neurotransmitter is dopamine (DA), which is involved in movement, attention, and learning. The discovery that certain drugs can have a significant effect on dopamine release has led to the development of effective treatments for a wide variety of physical and mental ailments. For instance, Parkinson’s disease, from which actor Michael J. Fox suffers, is caused by a deficiency of dopamine in the brain. Techniques for increasing the production of dopamine in From the perspective of . . . A Health Care Provider How might your understanding of the nervous system help you explain the symptoms of Parkinson’s disease to a patient with the disorder? Parkinson’s patients are proving effective (Kaasinen Rinne, 2002; Willis, 2005; Iversen Iversen, 2007). In other instances, over production of dopamine produces negative consequences. For example, researchers have hypothesized that schizophrenia and some other severe mental disturbances are affected or perhaps even caused by the presence of unusually high levels of dopamine. Drugs that block the reception of dopamine reduce the symptoms displayed by some people diagnosed with schizophrenia (Baumeister Francis, 2002; Bolonna Kerwin, 2005; Olijslagers, Werkman, McCreary, 2006). recap Explain the structure of a neuron.  ¦ A neuron has a cell body (which contains a nucleus) with a cluster of fibers called dendrites, which receive messages from other neurons. On the opposite end of the cell body is a tubelike extension, an axon, which ends in a small bulge called a terminal button. Terminal buttons send messages to other neurons. (p. 48) message to fire, it releases an action potential, an electrical charge that travels through the axon. Neurons operate according to an all-ornone law: Either they are at rest, or an action potential is moving through them. There is no in-between state. p. 49) Summarize how messages travel from one neuron to another.  ¦ Once a neuron fires, nerve impulses are carried to other neurons through the production of chemical substances, neurotransmitters, that actually bridge the gaps—known as synapses—between neurons. Neurotransmitters Describe how neurons fire.  ¦ Most axons are insulated by a coating called the myelin sheath. When a neuron receives a 54 Chapter 2 neuroscience and behavior may be either excitatory, telling other neurons to fire, or inhibitory, preventing or decreasing the likelihood of other neurons firing. (p. 52) Identify neurotransmitters. Neurotransmitters are an important link between the nervous system and behavior. Common neurotransmitters include the following: acetylcholine, which transmits messages relating to our muscles and is involved in memory capabilities; glutamate, which plays a role in memory; gamma-amino butyric acid (GABA), which moderates behaviors from eating to aggression; dopamine, which is involved in movement, attention, and learning; serotonin, which is associated with the regulation of sleep, eating, mood, and pain; and endorphins, which seem to be involved in the brain’s effort to deal with pain and elevate mood. p. 53) evaluate 1. The is the fundamental element of the nervous system. and send messages through their 2. Neurons receive informatio n through their . 3. Just as electrical wires have an outer coating, axons are insulated by a coating called the . 4. The gap between two neurons is bridged by a chemical connection called a 5. Endorphins are one kind of , the chemical â€Å"messengers† between neurons. . rethink How might psychologists use drugs that mimic the effects of neurotransmitters to treat psychological disorders? Answers to Evaluate Questions 1. neuron; 2. dendrites, axons; 3. yelin sheath; 4. synapse; 5. neurotransmitter key terms Behavioral neuroscientists (or biopsychologists) p. 47 Neurons p. 48 Dendrites p. 48 Axon p. 48 Terminal buttons p. 49 Myelin sheath p. 49 All-or-none law p. 49 Resting state p. 49 Module 5 neurons: the basic elements of behavior Action potential p. 50 Mirror neurons p. 50 Synapse p. 51 Neurotransmitters p. 52 Excitatory messages p. 52 Inhibitory messages p. 52 Reuptake p. 52 55 module 6 The Nervous System and the Endocrine System Communicating within the Body learning ou tcomes 6. 1 Explain how the structures f the nervous system are linked together. The complexity of the nervous system is astounding. Estimates of the number of connections between neurons within the brain fall in the neighborhood of 10 quadrillion—a 1 followed by 16 zeros. Furthermore, connections among neurons are not the only means of communication within the body; as we’ll see, the endocrine system, which secretes chemical messages that circulate through the blood, also communicates messages that influence behavior and many aspects of biological functioning (Kandel, Schwartz, Jessell, 2000; Forlenza Baum, 2004; Boahen, 2005). . 2 Describe the operation of the endocrine system and how it affects behavior. Central nervous system (CNS) The part of the nervous system that includes the brain and spinal cord. Spinal cord A bundle of neurons LO 1 The Nervous System that leaves the brain and runs down the length of the back and is the main means of transmitting messages b etween the brain and the body. The human nervous system has both logic and elegance. We turn now to a discussion of its basic structures. Central and Peripheral Nervous Systems As you can see from the schematic representation in Figure 1, the nervous system is divided into two main parts: the central nervous system and the peripheral nervous system. The central nervous system (CNS) is composed of the brain and spinal cord. The spinal cord, which is about the thickness of a pencil, contains a bundle of neurons that leaves the brain and runs down the length of the back (see Figure 2). As you can see in Figure 1, the spinal cord is the primary means for transmitting messages between the brain and the rest of the body. 56 Chapter 2 euroscience and behavior The Nervous System Consists of the brain and the neurons extending throughout the body Peripheral Nervous System Made up of long axons and dendrites, it contains all parts of the nervous system other than the brain and spinal cord Central Nervous System Consists of the brain and spinal cord Somatic Division (voluntary) Specializes in the control of voluntary movements and the communication of information to a nd from the sense organs Autonomic Division (involuntary) Concerned with the parts of the body that function involuntarily without our awareness Brain An organ roughly half the size of a loaf of bread that constantly controls behavior Spinal Cord A bundle of nerves that leaves the brain and runs down the length of the back; transmits messages between the brain and the body Sympathetic Division Acts to prepare the body in stressful emergency situations, engaging resources to respond to a threat Parasympathetic Division Acts to calm the body after an emergency situation has engaged the sympathetic division; provides a means for the body to maintain storage of energy sources Figure 1 A schematic diagram of the relationship of the parts of the nervous system. However, the spinal cord is not just a communication channel. It also Reflex An automatic, involuntary controls some simple behaviors on its own, without any help from the response to an incoming stimulus. brain. An example is the way the knee jerks forward when it is tapped with a rubber hammer. This behavior is a type of reflex, an automatic, involuntary response to an incoming stimulus. A reflex is also at work when psych 2. 0 you touch a hot stove and immediately withdraw your hand. Although the www. mhhe. com/psychlife brain eventually analyzes and reacts to the situation (â€Å"Ouch—hot stove— pull away! ), the initial withdrawal is directed only by neurons in the spinal cord. Three kinds of neurons are involved in reflexes. Sensory (afferent) neurons transmit information from the perimeter of the body to the central nervous system. Motor (efferent) neurons communicate information from the nervous system to muscles and glands. Interneurons connect sensory and mot or neurons, carrying messages between the two. Organization of the Nervous System Module 6 the nervous system and the endocrine system 57 Central Nervous System Brain Spinal cord Peripheral Nervous System Spinal nerves Figure 2 The central nervous system, consisting of the brain and spinal cord, and the peripheral nervous system. Sensory (afferent) neurons Neurons that transmit information from the perimeter of the body to the central nervous system. Motor (efferent) neurons Neurons that communicate information from the nervous system to muscles and glands. Interneurons Neurons that connect sensory and motor neurons, carrying messages between the two. Peripheral nervous system The part As suggested by its name, the peripheral nervous system branches out from the spinal cord and brain and reaches the extremities of the body. Made up of neurons with long axons and dendrites, the peripheral nervous system encompasses all the parts of the nervous system other than the brain and spinal cord. There are two major divisions— the somatic division and the autonomic division— both of which connect the central nervous system with the sense organs, muscles, glands, and other organs. The somatic division specializes in the control of voluntary movements—such as the motion of the eyes to read this sentence or those of the hand to turn this page—and the communication of information to and from the sense organs. On the other hand, the autonomic division controls the parts of the body that keep us alive—the heart, blood vessels, glands, lungs, and other organs that function involuntarily without our awareness. As you are reading at this moment, the autonomic division of the peripheral nervous system is pumping blood through your body, pushing your lungs in and out, and overseeing the digestion of your last meal. Activating the Divisions of the Autonomic Nervous System The autonomic division plays a particularly crucial role during emergencies. Suppose that as you are reading in bed you suddenly sense that someone is outside your bedroom window. As you look up, you see the glint of an object that might