Professionalism in Nursing an Example of the Topic Health Essays by

Professionalism in Nursing Abstract Nursing is gaining recognition as a profession. The nurse in all professional relationships, practices with compassion and respect for the inherent dignity, worth and, uniqueness of every individual, unrestricted by considerations of social or economic status, personal attributes, or the nature of health problems. Professionalism refers to professional character, spirit, or methods. It is a set of attributes, a way of life that implies responsibility and commitment. Each healthcare institution has specific standards and policies which are within the nursing educational program. Specific professional nursing values are stated in nursing code of ethics, in standards of nursing care practice and in the legal system itself. The professional nurse frequently assumes the roles of a leader who influences others to work together to accomplish a specific goal. Professionalism in Nursing Need essay sample on "Professionalism in Nursing" topic? We will write a custom essay sample specifically for you Proceed Our Customers Very Often Tell EssayLab professionals: Idon't want to write my essay. Because I don't have the time Essay writer professionals recommend: Essaylab.Com Can Provide You With The Winning Academic Essay A profession is generally distinguished from other kinds of occupations by its requirement of prolonged, specialized training to acquire a body of knowledge pertinent to the role to be performed, an orientation of the individual toward service, either to a community or to an organization, ongoing research, and code of ethics, autonomy, and professional organization. Nursing is an art of practice, based on theory driven, and scientifically based profession. The process of care, which occurs through partnership between the practitioners and patient, enables nurses to nurture human potential, enhance quality of life and assists to achieve optimal health. Nursing draws its knowledge and theory from nursing, basic, behavioral, and biological sciences (Mission, 2007). Leadership is a shared responsibility in which nurses form strong relationships that will result to excellent nursing practice. In order to support excellence in professional practice, humanism must be in the work environment to help nurses feel safe, respected and valued. The purpose of nursing leadership varies according to the level of application and includes (a) improving the health status of individuals or families, (b) increasing the effectiveness and level of satisfaction among professional colleagues, and (c) improving the attitudes of citizens and legislators toward the nursing profession and their expectations of it. Leadership has been characterized with different styles; one of the styles is autocratic. Also called an authoritarian leader. An authoritarian leader makes decision for the group. Their driving force is extrinsic, they desire rewards from others and are incapable of independent decision making. Autocratic style is effective and productivity is high. When urgent decisions are necessary, one must assume the responsibility for making decisions without being challenged. When we do not wish to participate in making decisions, the authoritarian style solves the problem and enables the individual or group to move on. Authority is one of the most important approaches towards influence as it monitors the behavior of any individuals of any organizations from the outside environment Simon, H.A. (1976). Authority is defined as the power to make decisions, which guides the actions of another, in other words, a typical relationship between superiors and subordinates. The superior constructs and communicates the orders to the subordinate with the expectations of its fulfillment. Simon discusses the four types of sanctions. Firstly, he informs us about the social sanctions, which is apparently the most essential of the sanctions. In a society an individual has certain social situational rules and if those rules are broken he or she suffers the embarrassment of insubordination. Secondly, are the psychological differences that play a crucial role in a relationship? Though the study of leadership is in a very primitive stage, there are some indications that there are certain personality types that lead and o thers follow. Third is sympathy, several conditions imply that this is an effective sanction. Formal sanctions follow which is based on the economic security and status. Therefore obedience would result in a higher position and higher salary. And finally, it is unwillingness, where the assigned task may displease the subordinates and they would prefer to be told what to do rather than do it on their own. In this the psychological aspects lies way beyond the consequences of an incorrect decision. Nurses deal with intimate and fundamental human events such as birth, death, and suffering. With this, they are responsible with the morality of their own actions when they face the many ethical issues. Nurses professional values are acquired during socialization into nursing from codes of ethics, nursing experiences, teachers and peers. As Professionals, codes of ethics were implemented to govern all professionals in their practice. It is a formal statement of a groups ideals and values. And a set of ethical principles that is shared by members of the group, it reflects their moral judgments over time, and serves as a standard and guidelines for their professional actions and informs the public of its commitment. This has higher requirements than legal standards and never lowers the legal standards of the profession. The nurses primary commitment is to the patient, whether an individual, family, group or community. Health is a fundamental right of every individual. Therefore, the nurses primary responsibility is to preserve health at all cost. Basic to nursing is knowledge and understanding of man. Standards of practice vary in different settings. Society is ever-changing and the nurse responds to changes. Respect for the rights and dignity of individuals is basic to the practice of the profession. Miltons (2007) study the following: For any discipline with a practice component, value priorities are reflection of choices on what it means to be a member of the discipline. For the recipients of professional nursing services, values reflect owning individual priorities for what is most important in living health and quality of life. In the context of healthcare, priority has been afforded to disciplinary practices whose values are consistent with those at normative, empirical sciences. Advocacy is needed for the nursing profession as well as for the public. Nurses who function responsibly as professional and public advocates are in an enviable position to effect change. Nurses are the advocates for their patients. They take appropriate steps to safeguard the patients rights and privileges. Advocacy role functions to inform, to support, and mediate. Nurses help to determine and implement desirable standards of nursing practice and nursing education. They participate actively in the development and growth of the nursing profession. They strive to secure equitable socio-economic and work conditions in nursing through appropriate legislation and other means. Nursing students also have legal responsibilities for their own actions and are liable for their own acts of negligence committed during the course of clinical experience. When performing duties within the levels of professional nursing, such as administering injections, they are legally held to the same standard of skill and competence as a registered professional nurse. In an influential article Charlotte Nath, B.S.N., Ed.D.; Rebecca Schmidt, D.O., F.A.C.P.; Erdogan Gunel, Ph.D. (2006) write about a study of medical schools and the role of professionalism being taught at each school. The study was conducted through a two-stage survey. The schools first were questioned about general activities related to the teaching of four essential elements of professionalism--subordinating one's self-interest to the interest of patients; adhering to high ethical and moral standards; responding to societal needs; and show clearly core humanistic values, such as empathy, integrity, altruism, and trustworthiness. The second survey instrument gathered more specific information about the format through which professionalism was taught and the goals of the curriculum. Todays health care arena poses complex ethical and moral dilemmas for both faculty and students of the health professions. The socialization process within various training programs contributes to the mol ding of and internalization of both personal and professional values specific to a particular discipline. Are those values standard across disciplines? Is professionalism a characteristic that a student brings to the field, or does he or she learns it in the socialization process inherent to the particular discipline? Is professionalism inherent to cultural and socioeconomic background? Is it the responsibility of health care educators to teach aspects of professionalism as part of the basic curriculum? Can professionalism be defined, taught, and measured? (p.825-834). According to UTHSCSA (2007), Faculty and preceptors, as role models for students, personify the qualities for professionalism. The objective of all nursing activities is to provide quality nursing care in the amount needed. Emphasis is placed not only in improving basic nursing education, but increasingly on comprehensive nursing education, post-basic or advanced education, and overall planning for nursing service at state or national levels. Nurses acceptance of a leadership role in nursing affairs shows consideration of the cultural and social factors affecting the care of patients, the variety of clinical settings in which nurses serve. Each institutions foster high standards of nursing practice and to promote welfare and the professional advancement of nurses for better nursing care. The student will begin to realize that to practice nursing they should understand what is meant by professional nursing and how one may qualify to practice. The nursing student typically visualizes the various fields of nursing they want to enter into once they qualify to practice. Nurses are accountable for their own nursing practice. They are responsible for their personal and professional growth and development. They maintain or modify standards of practice within the reality of any given situation. Quality care is their goal. Respect for the rights and dignity of individuals is basic to the practice of profession. Recognizing the need for change and initiates, participates and supports activities to meet the health and social needs of the people. Nurses are aware that their nursing actions have professional, ethical, moral and legal dimensions. They strive to perform their work in the best interest of all concerned. References ACHE Code of Ethics (2007). Retrieved March 12, 2008 Charlotte Nath, B.S.N., Ed.D; Rebecca Schmidt, D.O., F.A.C.P.; Erdogan Gunel, Ph.D.(2006). Perceptions of Professionalism Vary Most with Educational Rank and Age, J. Dent Educ. 70(8): p. 825-834 Professional Issues in Nursing: Challenges and Opportunities, Retrieved March 13, 2008 Schroeter, Kathryn.(2007).The Nurse Ethicist. An Emerging Role in Advanced Practice,Vol.2, Issue 1, pp. 65-68. Milwaukee. UTHSCSA-School of Nursing (2007). Mission and Philosophy, Retrieved March 18, 2008 Simon, H.A. (1976). Administrative Organization: A study of decision-making process in Administrative organizations, 3rd Ed. Pp. 125-147.New York: Free Press

What the In-Crowd Wont Tell You About The Princeton Review College Essay

What the In-Crowd Won't Tell You About The Princeton Review College Essay the Princeton Review College Essay - Overview If you can just buy a single book, this is it. This book has a great deal of solid suggestions and great procedures to try. The books also provide lots of special, yet helpful devices. Still, they could benefit from a greater number of practice passages as well. The CARS Accelerator course is contained in their Classroom course, but it is also possible to take it like a stand-alone session. Quite simply, realize that at this point you have the ability to make your own rankings based on what is significant to you. You will understand what subjects you have to pay particularly close attention to in class as a way to improve! Provided that you meet the remainder of the application requirements below, you're going to be a shoo-in. The review is going to teach you whatever you will need to understand and then you are able to place your purchase confidently. Additionally, a customer may ask the writer to submit part of the job for review and, if needed, ask her or him to make corrections. After you locate a service you prefer, don't neglect to look at my review of it. Simply speaking, the service exists, so should you need to use it in order to find a top essay, that's reason enough. The schools have a chance to update their fire security data annually and will have their fire security ratings recalculated and published annually. A few of us took help from counsellors, and some people just got in. The regular time put in paying back these types of loans may be 21 decades. Most people compared financing packages, however we didn't try to find a faculty that was an extremely superior return on the investment. Whispered the Princeton Review College Essay Secrets If you're thinking that you will need a person to compose my essay at this time, you can just rely on our honest reviews. You are likely to love our work. In the MCAT p rep planet, there's a significant battle happening. There are likely to be a great deal of individuals reading this book. In many instances, the essay can make or break your opportunity to enter your dream school or maybe to win a lucrative scholarship. Now you can purchase genuine college essay online, one that is going to fit your financial plan and get your work done too. So should you need to employ college essay writer online, we're just the people that you will need to contact. While it's true that there are a few excellent writers in college some find it extremely tough to write. Princeton Review Graduate Essay Help The rising number of essay writing services is totally overwhelming. Writing is a present that comes naturally. Your essay rating will appear on every score report you send to colleges, no matter whether the school demands an essay. Boost your college essay to the peak of the pile! Who knew essay writing may be so tough. So for those who have an essay assigned that you will need help with, you can purchase essay online cheap from us. Completing the essay part of the SAT will help you become prepared to apply to any college. The essay section of the SAT is most likely the toughest to get ready for. Citations and extracts from several sources have to be formatted properly. Once you receive a task done from us you will return again if you need assistance with another one of your essays. Employing a writing service is the perfect method to have a well-written essay to use as a guideline to make sure the essays you write are hitting all the important points and are at the appropriate depth necessary for your academic grade. The supplemental essays are your opportunity to share critical details about yourself. The 30-Second Trick for the Princeton Review College Essay Friends and family will be speaking about colleges. In the evenings, students normally have a chance to learn more about the town or city. The instructors weren't professional and some were young college students which did not understand how to deal with any situation that wasn't scripted for them. Off-camera instructors will answer your questions during class, providing you the immediate clarification you requ ire, the same as in a conventional classroom. The Chronicles of the Princeton Review College Essay Culture is the thing that presents us with the sorts of valuable things that may fill a life. If at all possible visit the campus, permit yourself to get excited about this opportunity, and make every attempt to get a feeling of why Princeton is the excellent academic atmosphere for you! Regardless of what genre you would like Business Studies, Microeconomics, Business Management and Financial Accounting, we're here to serve your needs. Colleges want to get a feeling of maturity and introspectionpinpoint the transformation and demonstrate your private growth.

Free Choice Essay Topics

Free Choice Essay TopicsEssay topics are very important when you are writing a good Free Choice essay. It is very hard to think of anything or compose anything in the space allotted. Students with many life experiences can be tempted to write about those experiences when they are likely to be more successful when they take on more relaxed topics. The purpose of this article is to help you choose essay topics that are good for your Free Choice essay.You should first define what essay topics are. Essentially, an essay is a written communication between a student and the instructor. The essay must be cohesive and relevant. Essay topics are what you write in order to relate to the content of the course you are taking.The best essay topics can be one's own idea or someone else's. It is possible to use the same topic as another student. You will need to be careful to make sure the topic is relevant and does not address a similar subject matter. It is also helpful to choose topics that are appropriate to the writing style of the instructor. It can be difficult to write if you cannot correctly identify the purpose of the essay.By discussing the Free Choice is an intensive course. You will need to be familiar with all aspects of the program. This is especially true when the topics you choose to deal with subjects related to your work in class. If you need help when selecting topic material, a good resource is online discussions in discussion forums.There are several topics to consider. You can talk about a specific event that occurred within the course or life experience related to the course. When you take a free choice course, you are being taught a specific field of study.Choose topic areas that are broad but contain multiple choices. These could include occupations, hobbies, sports, areas of interest, organizations, or anything you can think of. They will allow you to compare courses and teach yourself. When you have a wide variety of topic choices, you are more lik ely to stay on task and focus.Once you have your topic selected, you can begin writing. The words are your tools. Write about how the topic applies to your life. By using detailed descriptions, you will come across as well informed and engaging.By reading through free choice essays, you will find that some students are able to write well about certain subjects. By choosing the proper essay topics, you can make the most of your free choice courses.

How To Find A Top Rated Website For Essay Writing

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Essay Topics With Three Points of View

Essay Topics With Three Points of ViewWhen it comes to essay topics with three points of view, you can choose a more generic topic. You might find that there are fewer rules involved with this topic because the author doesn't have to worry about how exactly their topic is going to be chosen. In addition, the topic can be related to more than one person and this will also help the author in getting more responses.However, if the author knows how their topic is going to be written, they can come up with an excellent topic that is based on objective reasons or information. This is how you can actually find several different essay topics with three points of view. These are easy ways to get an idea how these topics work.When looking for essay topics with three points of view, the idea is to create a topic based on objective information. The third point of view has to be based on an opinion of the writer or author. This is not actually a bad idea when it comes to essay topics with three p oints of view because this topic will be based on facts and information. You won't have to worry about whether the topic is going to be controversial because there will be no real controversy involved in this topic.The first way to choose essay topics with three points of view is to know your objective. This is actually the topic that has to be based on objective facts. Your subject matter of this topic is going to be based on facts and information. This is a good way to select a topic with three points of view because the information will probably make sense.However, you can also choose to base your topics on opinions. These essays topics with three points of view will probably be based on the ideas of your audience. You will also need to be able to prove that the essay topics with three points of view are based on objective facts. In order to do this, you will need to put in facts that you can support the three points of view. In addition, you will also need to show why the inform ation is relevant to your subject matter. If you don't have any concrete arguments, you can go with opinion based topics with three points of view.You can really come up with topics with three points of view if you are passionate about the topic. This is an article for those who are new to essay topics with three points of view.

Extraction of metals and Alloys Essays

Extraction of metals and Alloys Essays Extraction of metals and Alloys Paper Extraction of metals and Alloys Paper An alloy is a mixture of metals, which may have different and improved qualities from metal elements, which make it. The percentage of elements in an alloy can be tailored to the application or purpose it is being made for. Usually an alloy is made of one metal (the base metal) with small amounts of other metals added. The other metals replace the position of the base metal in its structure. Extraction of Metals An element or a compound in nature inside the earths crust is called a mineral. They have a percentage of metal which can be extracted. This is called a metal ore. The most common metal ores are oxides and sulphides. Sulphides are the oldest ores. Oxides are formed when photosynthesis in plants release oxygen into the air. Metal ores are an infinite resource and once they are used, they are gone. Recycling helps this. Generally half of all metal is recycled through scrap metal facilities. The Reactivity Series (See appendix diagram 1) A metal that is under carbon in the Reactivity Series (zinc to silver) can be extracted from its ore by heating with carbon. Carbon is used as it is easily available and its cheap (coke and charcoal are both carbon). The metal is then reduced by the carbon. Hydrogen may be used to reduce other metals which are lower than it on the Reactivity Series. It is more expensive than carbon. It is only used for the extraction of tungsten. Gold and platinum are found naturally as elements and do not need to be reduced. Silver and copper are also naturally found. Extraction of Metals and Alloying Metal ores are found in the earth. They are rocks containing mineral or metal compounds or metals themselves and need to be extracted or removed from the rocks and the ground. To extract a metal from its ores you need to know its reactivity. The process involves a chemical reaction where the metal is separated from the other elements in the mineral. History of Metal Extraction Metals have been used by people for thousands of years. Gold and silver found in nature, were used for jewellery to show how wealthy people were. These two metals are too soft to be used as tools. The first useful metal discovered was bronze (the Bronze Age). Bronze was used a lot for tools and weapons in Asia and Africa from 4500 B.C. and in Britain from 2000 B.C. Bronze is not an element but an alloy of copper and tin. Ores of copper and tin can be reduced by heating with carbon. This would have happened as people lit wood fires in a place where tin and copper ore were. The burnt wood would have made the ores (copper and tin) into bronze. After the Bronze Age, coal fires were used to produce enough temperature for the extraction of iron (hence the Iron Age) The Iron Age began in Asia and Africa in 1100 B.C and in Britain in 500 B.C. Metals above carbon in the reactivity series can only be extracted by electrolysis. With the discovery of electricity in the nineteenth century, this allowed the extraction of more reactive metals. Aluminium has been extracted since around 1870. (3000 years since they found iron and 6000 years since they found bronze). Extraction of Aluminium Aluminium is the third most abundant (plentiful) element in the Earths crust. It is more abundant and the more expensive to produce compared with iron. This is because it takes a lot of electricity for the extraction process of electrolysis to happen. Around half of aluminium used is recycled. It takes less energy to recycle aluminuim than to extract it from its ore. Handling costs of aluminuim in the recycling process adds to this. Aluminium is high in the Reactivity Series and is resistant to corrosion as a thin layer of aluminium oxide on its surface protects it from corroding. Aluminuim has the ore called bauxite. Bauxite has aluminium oxide, water, iron and other things. The purified ore is called alumina (aluminium oxide). Alumina needs to be liquid or molten before the extraction method of electrolysis can happen. Alumina has a high melting point, so electrolysis cannot be done at this temperature. Alumina can dissolve in cryolite, which makes it have a lower melting point so electrolysis can be done at about 950oC. The main alloy of aluminium is Duralumin. Aluminuim is also used in titanium alloys. Duralumin is an alloy of aluminuim (94%), copper (4%) and magnesium (1%). There may also be small quantities of manganese and silicon in the alloy. Duralumin is a low density alloy that has a greater strength to weight ratio than aluminium. Duralumin is used for aircraft construction. Properties and Uses of Aluminuim Aluminium is strong and has a low density. It is also resistant to corrosion and can be easily bent into any shape. Aluminium is a good conductor of heat and electricity. It can be polished to achieve a highly reflective surface. Aluminuim can be used for making aircraft, lightweight vehicles, and ladders because it has a low density and it is strong. An alloy of aluminium, called Duralumin is used instead of pure aluminium because of its improved properties. Aluminium, as it is easy to shape and corrosion resistance, is a good material for making drink cans and roofing. Its also used for greenhouses and window frames because of its low density and resistance to rust. Aluminium is a good conductor of heat, so it can be used for boilers, cookers and cookware. As it is a good conductor of electricity, it is used for power cables and wire. Aluminium is highly reflective so its used in mirrors, reflectors and heat resistant clothes for fire fighters to use. Extracting Aluminium (See appendix diagram 2) A steel container is coated with carbon this is the negative electrode Electrolysis now begins. As aluminium is denser than the alumina and cryolite, it falls to the bottom where it is tapped off as pure liquid metal. Oxygen is removed from the positive carbon electrodes. Oxygen reacts with the carbon to form make carbon dioxide. Extraction of Iron Iron is extracted from its ore in a Blast Furnace. The ore is called Haematite. This is iron oxide. The iron ore has impurities in it, usually silica. Limestone is added to the iron ore which reacts with the silica which forms molten calcium silicate in the blast furnace. The calcium silicate floats on the liquid iron. Iron is low in the Reactivity Series, so iron ore is reduced into iron metal by heating with coke. How the Blast Furnace Works (See appendix Diagram 3) Hot air is blasted into the Blast Furnace which creates the carbon or coke to ignite. The temperature is about 2000oC. Carbon dioxide reacts with the carbon and makes carbon monoxide. This reduces iron in the ore into iron metal. Iron then drops to the bottom as liquid iron and is tapped off as needed. Properties and Uses of Iron Iron is a magnetic metal. Iron from a Blast Furnace contains around 5% carbon which comes from the coke in the furnace. It is put into molds called pigs, and the iron is then called cast iron or pig iron. It is very brittle and cracks easily, but it has a good resistance to corrosion compared to pure iron or steel. Cast iron is used for manhole covers and for engine blocks for petrol and diesel engines. Carbon is removed from molten cast iron by bubbling air through it. The air reacts with the carbon before it reacts with the iron because its more reactive (the carbon). Pure iron with the carbon removed is called wrought iron. This metal is easily shaped and is used for ornamental metal work like gates. The iron in the Blast Furnace is made into steel for use in construction. Alloys containing Iron The iron alloys are steel, manganese steel and stainless steel. Steel is a fixture of iron and carbon. The percentage of carbon may vary from 0.1% to 1.5% giving steels different properties. Steel is inexpensive and strong and easily shaped. It can be used on the construction of bridges, buildings, ships and vehicles. More than half of the steel is recycled. Steel will need a protective coat, like paint or it will rust. Rusting reverses the process that happens in a Blast Furnace. Manganese steel is an alloy of iron. Its iron (84%) and manganese (15%) and carbon (1%). It is very hard and is used for railway points and dredging equipment. Stainless steel is an alloy of iron. It is iron (80%) and chromium (15%), nickel (4%) and carbon (1%). Stainless steel is very strong, hard and resists corrosion. It is used in cookware, cutlery and industrial chemical plants. Corrosion of Iron and Steel When iron is exposed to air it will return to its oxide. This is called rusting or corroding. This process needs both oxygen and water, salt or acid will make corroding faster. You can prevent rust by coating the surface so the air doesnt come into contact with it. It can also be protected by a more reactive metal (See the Reactivity Series in the appendix diagram 1). Iron and steel are mostly protected by paint, plastic coating or metal plating. Zinc plating is called galvanizing. Chromium plating is used for wheels and bumpers of cars to give a polished surface. Sacrificial protection is used for ships, under water pipelines and oil rigs. Extraction of Copper Copper is sometimes found as a native metal. Copper ore can be reduced by causing it to react with carbon. The most common way is by heating copper sulphide ore which breaks down. The impure copper that results is called blister copper. Around half of all copper is recycled each year. Pure copper is needed for good electrical conductivity. Pure copper is made from the extraction method of electrolysis. Extraction of Copper Purification (see appendix diagram 4) The impure copper, when electricity is put through the cell, copper dissolves at the anode into solution. Copper forms at the cathode by reduction. Copper ions move from the anode to the cathode. The anode gets smaller and the cathode gets bigger. This is called the redox reaction. The impurities dissolve and fall to the bottom as sludge, which can have silver and platinum in it which can be taken out. Properties and Uses of Copper Copper is an excellent conductor of electricity and heat. It is soft and easy to shape. Copper is also corrosion resistant. It can be used for electrical wiring (so can aluminium) Copper is also used in cookware, but is not very common. It is used in gas pipes as it is easily bent for the application for it is ideal to use. Copper is used for water pipes for the same reason as why it is used for gas pipes. Copper is below hydrogen in the Reactivity Series (See the Reactivity Series in the appendix diagram 1), so it does not react with water. Lead was always used in plumbing in the past, but is being replaced with copper because of the lead going into the water which is toxic. Copper is mixed with other metals to form alloys, mainly zinc for brass and tin for bronze. Alloys containing copper include brass, bronze, cupro-nickel and duralumin. Brass is an alloy of copper (70%) and zinc is (30%). Brass is harder and less expensive than copper and can be used for musical instruments, screws and other fixtures or ornamental objects that need to be corrosion resistant. Bronze is an alloy of copper (90%) and tin (10%). Bronze is harder and stronger and rust resistant. Bronze is used for casting objects and bearings (e.g. wheel bearings). Cupro-nickel is an alloy of copper (70%) and nickel (30%). It is easily shaped and it is rust resistant and is used to make silver coins e.g. 5c, 10c, 20c, and the 50c pieces. Silver coins have not contained real silver since 1947. Alloys containing Lead The main alloy of lead is solder. Solder is an alloy of lead (70%) and tin (30%). Half of the lead and tin used each year is recycled. Solder has a low melting point and is stronger than lead or tin. Solder is used for connections in electrical wiring and plumbing. Properties and Uses of Lead People have used lead as long ago as 5000B.C. Lead is a shiny metal that is corrosion resistant and very dense and soft. It is toxic if absorbed by the body. Lead is rarely found in nature and it is a heavy metal. It has a low melting point and is flexible. It conducts electricity. Lead is able to be shaped into many things from water pipes to coins and stained glass windows. It also is used in car batteries and TVs and computers. It is also used for making wheelchairs, lift trucks, baggage loaders, golf carts and submarines. Lead is also used to absorb radiation around x-rays and nuclear equipment. Its also used in computer screens to again absorb radiation. It also absorbs sound. Leads used as a shield around electrical cables. Alloys of Titanium Titanium is mixed with aluminium (5%) and vanadium (5%). Titanium is expensive and is only used where its properties are needed. Its properties are its low density, hardness and rust resistance. Titanium alloys are used in special parts of aircraft and ship construction and chemical plants and hip joint replacements. The mined minerals are sent to mills to be separated from one another using electrical and magnetic techniques. To obtain pure, white titanium dioxide, the minerals are reacted with chlorine then burned in oxygen. Producing pure titanium metal is only done overseas, where mineral sands are reacted with other chemicals and then heated Properties and Uses of Titanium Titanium is a newish metal which started to be commercially produced in the 1940s. It is lightweight, strong and rust resistant. Titanium is a silver white metal and is soft when alloyed with other metals. It has a high melting point. It is non toxic and has many uses. Titanium is used to make aircraft engines, spacecraft, missiles, cars, sports equipment, watches, and general industrial equipment. Being non-toxic, it can be used for pacemakers, artificial joints and bone pins. Alloys and Recent Developments In recent times, the development of alloys has flourished because of further research and development of metals and characterising metals and the implementation of new materials and processes. Using previous philosophy of how metals are extracted and alloyed and advancing on these techniques which include using the modern top-down method that eliminates design constraints in the earlier manufacturing process. The discovery of high strength steels for new applications is a recent development. This means that the steels are stronger, tougher and even have a higher rust resistance when alloyed. New alloys of stainless steel have also been developed and the metal can now be used for new applications previously unavailable, especially in aviation. High temperature metallic materials can now be used in casting alloys in the wrought processing of alloy sheet technology. Also new super-alloys are being produced that can take higher temperatures using new chemistry processes. Alloys have in recent times needed to be lighter and also retain their strength for use in modern applications. Another recent development is the production of alloys is called Al-Li, which has great corrosion prevention compounds. Researchers are now developing fatigue resistant alloys to reduce failures of components and less maintenance. Lastly, low cost methods have been found, including single hearth melt, laser deposition and casting for titanium alloying has been discovered.

Biology Aqa

16. 8 – Genetic fingerprinting43 Section 9. 1 – Sensory Reception †¢ A stimulus is a detectable change in the internal or external environment of an organism that produces a response. The ability to respond to a stimulus increases an organism’s chances of survival. †¢ Receptors transfer the energy of a stimulus into a form that can be processed by the organism and leads to a response. †¢ The response is carried out by â€Å"effectors† which can include cells, tissues, organs and systems. Taxis – A simple response that’s direction is determined by the direction of the stimulus An organism can respond directly to a change in the environment by moving its body either: 1. Toward the stimulus (positive taxis) 2. Away from the stimulus (negative taxis) Kinesis – Results in an increase of random movements †¢ Organism does not move towards/away from the stimulus †¢ The more intense the stimulus the more rapid the movements †¢ Kinesis is important when the stimulus is less directional such as heat or humidity Tropism – a growth movement of part of a plant in response to a directional stimulus Positive phototropism – shoots/leaves Positive Geotropism – roots Section 9. 2 – Nervous Control Nervous organisation The nervous system can be thought of as having two main divisions: . The central nervous system (CNS) – brain and spinal cord 2. The peripheral nervous system (PNS) – Made up of pairs of nerves that originate either from the brain or the spinal cord The peripheral nervous system This is divided into: †¢ Sensory neurons which carry impulses away from receptors to the CNS †¢ Motor neurons which carry nervous impulses from the CNS to effectors The spinal cord is a column of nervous tissue A reflex – involuntary response to a stimulus (you do stop to consider an alternative) The pathway of neurons involved in a reflex is called a reflex arc. Reflex arcs contain just 3 neurons: 1. A sensory neuron 2. An intermediate neuron 3. A motor neuron There are several stages of a reflex arc: 1. Stimulus 2. Receptor 3. Sensory neuron 4. Synapse 5. Coordinator (intermediate neuron) 6. Synapse 7. Motor neuron 8. Effecter 9. Response Importance of the reflex arc †¢ Involuntary – does not require the decision making power of the brains †¢ Brain can override the response if necessary †¢ Protects the body from harmful stimuli Effective from birth – does not need to be learnt †¢ Short pathway – fewer synapses Synapses – slow Neurons – fast Section 9. 3 – Control of heart rate The Autonomic nervous system Controls subconscious activities of muscles and glands Has two main divisions: The sympathetic nervous system – Speeds up activities and thus allows us to cope with stressful situations (fight or flight r esponse) The parasympathetic nervous system – Inhibits effects and slows down activities. This allows energy to be conserved. Controls under normal resting conditions The two divisions are antagonistic meaning that their effects oppose one another Control of heart rate Changes of the heart rate are controlled by a region of the brain called the medulla oblongata which has two main divisions One division is connected to the sinoatrial node through the sympathetic nervous system The other is connected to the sinoatrial node via the parasympathetic nervous system Control by chemoreceptors Chemoreceptors are found in the wall of the carotid arteries and detect hanges in pH as a result of CO2 concentration When CO2 concentration in the blood is too low, chemoreceptors detect the drop in pH and send impulses to the section of the medulla oblongata responsible for increasing heart rate This section then increases the number of impulses sent to the S. A node via the sympathetic nervous system This results in an increase in heart rate which then causes blood pH to return to normal. Control by pressure receptors Pressure receptors occur in the wall of the carotid arteries and the aorta When blood pressure is too high – impulses are sent to the medulla oblongata which then sends impulses to the S. A node via the parasympathetic nervous system decreasing the heart rate When blood pressure is too low – impulses are sent to the medulla oblongata which then sends impulses to the S. A node via the sympathetic nervous system, increasing the heart rate Section 9. 4 – Role of receptors Features of sensory reception A sensory receptor will: †¢ Only respond to a specific type of stimulus (e. g. light, pressure, etc) †¢ Produce a generator potential by acting as a transducer. This means that it can convert the information to a form that the human body can interpret. This is achieved by using the energy of a stimulus into a nerve impulse called a generator potential. Structure and function of a pacinian corpuscle Responds to mechanical pressure Occurs in ligaments and joints so that it is possible to tell which direction a joint is changing The neuron of a pacinian corpuscle is in the centre of layers of tissue, each separated by gel The sensory neuron of a pacinian corpuscle has stretch-mediated sodium channels in its plasma membrane †¢ During its resting state, stretch-mediated sodium channels are too narrow to allow sodium through. The corpuscle therefore has a resting potential †¢ When pressure is applied, the membrane of the neuron is stretched causing sodium channels to widen therefore allowing sodium to diffuse into the neuron †¢ The influx of sodium ions cause a change in the polarity of the neuron, creating a resting potential †¢ The generator potential creates a action potential which moves along the neuron Receptors working together in the eye Different receptors respond to a different intensity of a stimulus Light receptors of the eye are found in the retina (the inner most layer) The light receptors in the eye can are of two types, rod and cone cells. Both receptors convert light energy into a nervous impulse and are therefore acting as transducers Rod cells Cannot distinguish between different wavelengths Many rod cells are connected to the same neuron and so can function at low light intensities. A threshold must be reached in the bipolar cells to which they are attached to and so since they can all contribute to reaching this threshold, they will function at lower light intensities Rod cells breakdown the pigment rhodopsin to generate an action potential. Rhodopsin is easily broken down in low light intensity Since more that one rod cell is connected to the same neuron, only one impulse will be generated. It is impossible for the brain to determine which rod cells were stimulate to begin with and so it is not possible to determine exactly the source of light This results in rod cells having a relatively poor visual acuity and so are not very effective in distinguishing between two points close together Cone cells There are three types of cone cells, each of which respond to a different avelength The colour interpreted depends of the proportion of each type of cone cell stimulated Cone cells are connected only to one bipolar cells, this means that they cannot combine to reach a threshold. As a result of this a high light intensity is required to create a generator potential Cone cells breakdown the pigment iodopsin to create a generator potential Iodopsin can only be broken down by a high light intensity Since cone cells are connected to a single bipolar cell, when two adjacent cells are stimulated, two separate nervous impulses will be sent to the brain. This means that it is easier to determine the source of the light. As a result, cone cells are responsible for higher visual acuity since they allow you to better distinguish between two points Light is concentrated by a lens to the centre of the eye called the fovea. This region receives a high light intensity and therefore has more cone cells. The peripheries of the eye receive a low light intensity and therefore consist mainly of rod cells. Section 10. 1 – Coordination Body systems cannot work in isolation and must therefore be integrated in a coordinated fashion. Principles of coordination In mammals, there are two main forms of coordination: 1. The nervous system – Uses nerve cells that can pass electrical impulses along their length. The result is the secretion of chemicals by the target cells called neurotransmitters. The response is quick, yet short lived and only acts on a localised region of the body. 2. The hormonal system – Chemicals are transported in the blood plasma which then reach target certain cells, thus stimulating them to carry out a function. The responses due to secretion of hormones often act over a longer period of time, yet are slower to act. Chemical mediators Nervous and hormonal forms of communication are only useful at coordinating the activities of the whole organism. At the cellular level they are complimented by chemical mediators. Chemical mediators are secreted by individual cells and affect other cells in the immediate vicinity. A common example of this type of coordination is the inflammation of certain tissues when they are damaged or exposed to foreign agents. Two examples of chemical mediators are: 1. Histamine – Stored in white blood cells and is secreted due to the presence of antigens. Histamine causes dilation of blood vessels, increased permeability of capillaries and therefore swelling the infected area. 2. Prostaglandins – Found in cell membranes and cause dilation of small arteries and arterioles. They release due to injuries and increase the permeability of capillaries. They also affect blood pressure and neurotransmitters. In doing so they relieve pain. Hormonal system |Nervous system | |Communication by chemicals |Communication by nervous impulses | Transmission takes place in the blood |Transmission is by neurons | |Transmission is generally slow |Transmission is very rapid | |Hormones travel to all areas of the body, but target only |Nerve impulses travel to specific areas of the body | |certain tissues/organs | | |Response is widespread |Response is localised | |Effect may be permanent/long lasting/ irreversible |Effect is temporary and reversible | Plant growth factors Plants respond to external stimuli by means of plant growth factors (plant hormones) Plant growth factors: †¢ Exert their influence by affecting growth †¢ Are not produced by a particular organ, but are instead produced by all cells †¢ affect the tissues that actually produce them, rather than other tissues in a different area of the plant. One plant hormone called indoleacetic acid (IAA) causes plant cells to elongate Control of tropisms by IAA IAA is used to ensure that plant shoots grow towards a light source. 1. Cells in the tip of the shoot produce IAA, which is then transported down the shoot. 2. The IAA is initial transported to all sides as it begins to move down the shoot 3. Light causes the movement of IAA from the light side to the shaded side of the shoot. 4. A greater concentration of IAA builds up on the shaded side of the shoot 5. The cells on the shaded side elongate more due to the higher concentration of IAA 6. The shaded side of the root therefore grows faster, causing the shoot to bend towards the source of light IAA can also effect the bending of roots towards gravity. However in this case it slows down growth rather than speeds it up. IAA decreases root growth and increases shoot growth Section 10. 2 – Neurons Specialised cells adapted to rapidly carry electrochemical changes (nerve impulses) from part of the body to another Neuron structure Cell body †¢ Nucleus †¢ Large amounts of rough endoplasmic reticulum to produce neurotransmitters Dendrons †¢ Extensions of the cell body sub-divided into dendrites †¢ Carry nervous impulses to the cell body Axon †¢ A single long fibre that carries nerve impulses away from the cell body Schwann cell †¢ Surrounds the axon †¢ Protection/electrical insulation/phagocytosis. Can remove cell debris and are associated with nerve regeneration. Myelin sheath †¢ Made up from the Schwann membrane which produces myelin (a lipid) †¢ Some neurons are unmyelinated and carry slower nerve impulses Nodes of Ranvier †¢ The gaps between myelinated areas †¢ 2 – 3 micrometers long and occur every 1 – 3mm Sensory Neuron †¢ Transmit impulses from a receptor to an intermediate neuron or motor neuron †¢ One Dendron towards the cell body, one axon away from the cell body Motor neuron †¢ Transmit impulses from the sensory/intermediate neuron to an effector †¢ Long axon, many short dendrites Intermediate neuron †¢ Transmit impulses between neurons †¢ Numerous short processes Section 10. 3 – The nerve impulse A nerve impulse is not an electrical current! It is a self-propagating wave of electrical disturbance that travels along the surface of an axon membrane. Nerve impulse – temporary reversal of the electrical p. d across an axon membrane The reversal is between two states The resting potential no nerve impulse transmitted The action potential – nerve impulse transmitted Resting potential †¢ Sodium/potassium are not lipid soluble and cannot cross the plasma membrane. Transported via intrinsic proteins – ion channels †¢ Some intrinsic proteins actively transport potassium ions into the axon and sodium ions out. This is called the sodium potassium pump. Sodium potassium pump 3 sodium ions pumped out for every 2 potassium ions pump in †¢ Most gated potassium channels remain open – potassium ions move out of the axon down their chemical gradient †¢ Most gated sodium channels remain closed The action potential †¢ Temporary reversal of the charge of the membrane from (-65mV to +65mV). When the p. d is +65mV the axon is said to be depolarised †¢ Occurs because the ion channels open/close depending upon the voltage across the membrane †¢ When the generator potential is reached, sodium ion channels open and potassium close, allowing sodium to flood into the axon. Sodium being positively charged causes the axon to become more positive in charge The passage of an action potential along an unmyelinated axon †¢ Stimulus – some voltage – gated ion channels open, sodium ions move in down electrochemical gradient †¢ Causes more sodium channels to open †¢ When the action potential reaches ~ +40mV sodium channels close †¢ Voltage – gated potassium channels open and begin repolarisation of the axon Hyper – polarisation †¢ The inside of the axon becomes more negative than usual due to an â€Å"overshoot† in potassium ions moving out of the axon. †¢ Potassium channels close †¢ Sodium potassium pump re-established the -65mV resting potential Section 10. 5 – The speed of a nerve impulse Factors affecting speed 1. The myelin sheath – Prevents the action potential forming in myelinated areas of the axon. The action potential jumps from one node of Ranvier to another (salutatory conduction) – this increases the speed of the impulse as less action potentials need to occur 2. The greater the diameter of the axon the greater the speed of conductance – due to less leakage of ions from the axon 3. Temperature – Higher temperature, faster nerve impulse. Energy for active transport comes from respiration. Respiration like the sodium potassium pump is controlled by enzymes. Refractory period After an action potential, sodium voltage-gated channels are closed and sodium cannot move into the axon. It is therefore impossible during this time for a further action potential to be generated. This time period, called the refractory period serves two purposes: It ensures that an action potential can only be propagated in one direction – An action potential can only move from an active region to a resting region. It produces discrete impulses – A new action potential cannot be generated directly after the first. It ensures action potentials are separated from one another. It limits the number of action potentials – action potentials are separated from one another, therefore there is a limited amount that can pass along a neuron in a given time. All or nothing principle Nervous impulses are all or nothing responses A stimulus must exceed a certain threshold value to trigger an action potential A stimulus that exceeds the threshold value by a significant amount, will produce the same strength of action potential as if it has only just overcome the threshold value A stimulus can therefore only produce one action potential An organism can perceive different types of stimulus in two ways: The number of impulses in a given time (larger stimulus, more impulses per second) Having neurons with different threshold values – depending on which neurons are sending impulses, and how frequently impulses are sent, the brain can interpret the strength of the stimulus Section 10. 6/10. 7 – Structure and function of the synapse / Transmission across a synapse A synapse occurs where a dendrite of one neuron connects to the axon of another Structure of a synapse Synapses use neurotransmitters to send impulses between neurons The gap between two neurons is called the synaptic cleft The neuron that produces neurotransmitters is called the presynaptic neuron The axon of the presynaptic neuron ends in a presynaptic knob The presynaptic knob consists of many mitochondria and endoplasmic reticulum These organelles are required to produce neurotransmitters which are stored in synaptic vesicles Synaptic vesicles can fuse with the presynaptic membrane releases the neurotransmitter Functions of synapses †¢ A single impulse from neuron can be transmitted to several other neurons at a synapse. This means that one impulse can create a number of simultaneous responses †¢ A number of different impulses can be combined at a synapse. This means that several responses can be combined to give on single response Neurotransmitters are made in the presynaptic cleft only When an action potential reaches the presynaptic knob, it causes vesicles containing the neurotransmitter to fuse with the presynaptic membrane The neurotransmitter will the diffuse across the synaptic cleft The neurotransmitter then bind with receptors on the postsynaptic membrane, in doing so generating a new action potential in the postsynaptic neuron Features of synapses Unidirectionality Impulses can only be sent from the presynaptic membrane to the postsynaptic membrane Summation †¢ Spatial summation Different presynaptic neurons together will release enough neurotransmitter to exceed the threshold value to form an action potential †¢ Temporal summation – One neuron releasing neurotransmitter many times over a short period. Eventually the neurotransmitter will accumulate so as to overcome the threshold value of the postsynaptic membrane. Therefore generating a new action potential Inhibition Some postsynaptic membranes have protein channels that can allow chloride ions to diffuse into the axon making it more negative than usual at resting potential. This type of hyperpolarisation inhibits the postsynaptic neuron from generating a new action potential. The importance of these inhibitory synapses is that it allows for nervous impulses to be controlled and stopped if necessary Transmission across a synapse When the neurotransmitter across a synapse is the chemical acetylcholine it is called a cholinergic synapse Acetylcholine is made up of acetyl (ethanoic acid) and choline Cholinergic synapses are more common in vertebrates Cholinergic synapses occur in the central nervous system and at neuromuscular junctions 1. When an action potential reaches the presynaptic knob, calcium channels open allow calcium to diffuse into the presynaptic knob 2. The influx of calcium ions causes presynaptic vesciles containing acetylcholine to fuse with the presynaptic membrane, releasing the neurotransmitter into the synaptic cleft 3. Acetylcholine diffuses across the cleft and fuses with receptor sites on sodium channels found on the presynaptic membrane. When they do so, the sodium channels open, allowing sodium ions to diffuse along their concentration gradient into the postsynaptic knob. 4. The influx of sodium ions, generates a new action potential in the postsynaptic neuron 5. Acetylcholinesterase hydrolyses acetylcholine back into the acetyl and choline which will the diffuse back across the synaptic cleft into the presynaptic neuron. In this way acetylcholine can be recycles and reused and also is prevented from continuously generating new action potentials on the postsynaptic neuron. 6. ATP is released by mitochondria, providing energy to recombine acetyl and choline. Sodium channels on the postsynaptic membrane are now closed due to the absence of acetylcholine attached to receptor sites. Section 11. 1 – Structure of skeletal muscle There are three types of muscle in the body: Cardiac muscle which is found only in the heart Smooth muscle which is found in the walls of blood vessels Skeletal muscle which is attached to bone and is the only type of muscle under conscious control Muscles are made up of many muscle fibres called myofibrils If the cells of muscles were joined together from the end of one cell to another, the point between cells would be a point of weakness Because of this, the muscle cells are fused together into muscle fibres Cells of the same myofibrils share the same nuclei as well as cytoplasm (sarcosplasm). Within the sacroplasm are many mitochondria as well as endoplasmic reticulum Microscopic structure of skeletal muscle Myofibrils are made up of two types of protein filament Actin – thinner, consists of two strands twisted around each other Myosin – thicker and is made up of long rod shaped fibres with bulbous heads projecting outwards Myofibrils have coloured bands The isotropic (I) bands appears lighter since it consists only of actin (no overlap) The anisotropic (A) bands are darker since this is where acting and myosin overlap The H zone is the region in the centre of the sarcomere that is lighter in colour since there is only myosin The z line lies at the centre of the I bands Types of muscle fibre Slow-twitch fibres – Contract more slowly, less powerful. Adapted for endurance/aerobic respiration so less lactic acid forms Adaptations include: Large store of myoglobin, Supply of glycogen, Rich supply of blood vessels, Numerous mitochondria Fast-twitch – Contracts more rapidly with more power but only for a short period of time. Adapted for intense exercise by: Having hicker and more numerous myosin filaments, having a high concentration of enzymes used for anaerobic respiration, a large store of phosphocreatine to provide phosphate to make ATP Neuromuscular junctions Many neuromuscular junctions are spread through the muscle for simultaneous contraction Each muscle fibre has one motor neuron associated with it. The muscle fibre and the neuron make up one motor unit When only a small force is needed only a few motor units are stimulated When a nerve impulse reaches the neuromuscular junction, the synaptic vesicles join with the presynaptic membrane and release acetylcholine which diffuses across to the postsynaptic membrane and stimulates it to allow sodium ions to enter. The acetylcholine is then broken down by Acetylcholinesterase and then diffuses back into the presynaptic neuron. Section 11. 2 contraction of skeletal muscle During muscle contract, actin and myosin slide past each other; hence its name the sliding filament mechanism Evidence for the sliding filament mechanism When a muscle contract, the following changes occur to the sarcomere: The I band becomes narrower The z lines move close to one another The h band becomes narrower The a band does not change as this band is determined by the width of the myosin Myosin is made up of two different types of protein 1. A fibrous protein arranged into the filament called the tail 2. A globular protein that forms a head at each end Actin is a globular proteins thats molecules are arranged into two chains that twist around each other in a helical manner Tropomyosin forms long thin stands that s wound around the actin molecule The process of muscle contraction has a three main stages: Stimulation, contraction and relaxation Muscle stimulation When an action potential reaches the neuromuscular junctions, Calcium ion channels open and calcium ions move into the synaptic knob The Calcium ions cause the synaptic vesicles to move to the presynaptic membrane and fuse with it releasing acetylcholine Acetylcholine diffuses across the synaptic cleft and binds with receptors on the sodium voltage gated channels on the postsynaptic membrane causing it to depolarise Muscle contraction The action potential movies through the fibres by travelling through T – tubules that branch through the sarcoplasm The action potential moves through the tubules until it reach the sarcoplasmic reticulum The action potential opens calcium ions in the sarcoplasmic reticulum Calcium ions diffuse out into the muscle Calcium ions cause tropomyosin to change shape and so that the binding sites on the actin filament are exposed An ADP molecule that is attached to the myosin heads allows it to form a cross bridge with actin by binding with the receptor site Once the cross bridge is formed, the myosin head changes shape and slides the actin across. In doing so it loses the ADP An ATP molecule attaches to the myosin head and thus causes it to detach Calcium ions activate the enzyme ATPase which hydrolyses ATP and releases energy that allows the myosin head to resume its original shape. The myosin head now has a new ADP molecule that will allow it to bind with a new receptor site somewhere along the actin filament Muscle relaxation When the muscle is not being stimulated, the sarcoplasmic reticulum actively transport calcium ions back into it The lack of calcium ions means that tropomyosin can establish its original position, covering the myosin head binding sites Energy supply Energy is needed for the movement of myosin heads and the active transport of calcium ions ATP often needs to be generated anaerobically Phosphocreatine provides inorganic phosphate molecules to combine with ADP to form ATP Section 12. 1 – Principle of homeostasis The maintenance of a constant internal environment By maintaining a relatively constant environment (of the tissue fluid) for their cells, organisms can limit the external changed these cells experience thereby giving the organisms a degree of independence. What is homeostasis? Maintaining the volume, chemical make up and other factors of blood and tissue fluid within restricted limits There are continuous fluctuations; however, they occur around a set point Homeostasis is the ability to return to that set point thus maintaining equilibrium The importance of homeostasis Enzymes and other proteins are sensitive to changes in pH and temperature Water potential of blood and tissue fluid should be kept constant to ensure cells do not burst or shrink due to a net movement of water (osmosis) Maintaining a constant blood glucose concentration ensures that the water potential of the blood remains the same Independence of the external environment – a wider geographical range and therefore a greater chance of finding food shelter, etc Mammals – homeostasis allows them to tolerate a wide range of conditions Control mechanisms The set point is monitored by: 1. Receptor 2. Controller brain analyses and records information from a number of different sources and decides on the best course of action 3. Effector – brings about the change to return to set point 4. Feedback loop – informing the receptor of the changes in the system brought about by the effector Section 12. 2 Thermoregulation Mechanisms of heat loss and gain Production of heat – Metabolism of food during respiration Gain of heat from the environment – Conduction, convection (surrounding air/fluid), Radiation (electromagnetic waves particularly infrared) Mechanisms for losing heat Evaporation of water Conduction – to ground/solid Convection convection (to surrounding air/fluid), Radiation Endotherms derive most heat energy from metabolic activities Ectotherms – obtain most heat from the external environment Regulation of body temperature in Ectotherms Body temp fluctuates with the environment Controlled by exposure to the sun Shelter to the sun/burrows at night/obtains heat from the ground and very little from respiration. Can sometimes change colour to alter heat that is radiated Regulation of body temperature in Endotherms Most heat gained through internal metabolic activities Temperature range 35 – 44 oC – Compromise between higher temperature where enzymes work more rapidly and the amount of energy needed (hence food) to maintain that temperature Conserving and gaining heat in response to a cold environment Long term adaptations: Small SA:V ration Therefore mammals and birds in cold environments are relatively large Smaller extremities (e. g. ears) thick fur, feathers or fat reserves to insulate the body Rapid changes: Vasoconstriction – reducing the diameter of arteries/arterioles Shivering – in voluntary rapid movements and contractions that produce he energy from respiration Raising hair – enables a thick layer of still air to build up which acts as a good insulator. Behavioural mechanisms – bathing in the sun Decreased sweating Loss of heat in response to a warm environment Long term adaptations: Large SA:V ratio so smaller animals are found in warmer climates Larger extremities Light coloured fur to reflect heat Vasodilation – Arterioles increase in diameter, more blood reaches capillaries, more heat is therefore radiated away Increased sweating – Heat energy is required to evaporate sweat (water). Energy for this comes from the body. Therefore, removes heat energy to evaporate water Lower body hair – Hair erector muscles relax. Hairs flatten, reduces the insulating layer of air, so more heat can be lost to the environment Behavioural mechanisms – seeking shade, burrows, etc Control of body temperature Mechanisms to control body temperature are coordinated by the hypothalamus in the brain The hypothalamus has a thermoregulatory centre divided into two parts: A heat gain centre which is activated by a fall in body temperature And a heat loss centre which is activated by an increase in temperature The hypothalamus measures the temperature of blood passing through it Thermoreceptors in the skin also measure the temperature Impulses sent to the hypothalamus are sent via the autonomic nervous system The core temperature in the blood is more important that the temperature stimulating skin Thermoreceptors Section 12. 3/12/4 – Hormones and the regulations of blood glucose/Diabetes and its control Hormones are produced by glands (endocrine glands) which secrete the hormones into the blood The hormones are carried in the blood plasma to the target cells to which they act. The target cells have complementary receptors on the cell surface membrane Hormones are affective in small quantities set have widespread and long-lasting affects Some hormones work via the secondary messenger model: 1. The hormone (the first messenger) binds to receptors on the cell surface membrane, forming a hormone-receptor complex 2. The hormone-receptor complex activates an enzyme inside the cell that produces a secondary messenger chemical 3. The secondary messenger acts within the cell produces and a series of changes Both glucagon and adrenaline work by the secondary messenger model Adrenaline as a secondary messenger 1. The hormone adrenaline forms a hormone-receptor complex and therefore activates an enzyme inside the cell membrane 2. The activated enzyme the converts ATP to cyclic AMP which acts as the secondary messenger.