Biology
A balanced diet is one that provides an adequate intake of energy and nutrients for maintenance of the body and therefore good health. A diet can easily be adequate for normal bodily functioning, yet may not be a balanced diet. An ideal human diet contains fat, protein, carbohydrates, vitamins, minerals, water and fibre all in correct proportions. These proportions vary for each individual because everyone has different metabolic rates and levels of activity.
Malnutrition results from an unbalanced diet, this can be due to an excess of some dietary components and lack of other components, not just a complete lack of food. Too much of one component can be as much harm to the body as too little. Deficiency diseases occur when there is a lack of a specific nutrient, although some diet related disorders are a result of eating an excess.
An adequate diet provides sufficient energy for the performance of metabolic work, although the energy food is in an unspecified form. A balanced diet provides all dietary requirements in the correct proportions. Ideally this would be 1/7 fat, 1/7 protein and 5/7 carbohydrate.
Energy is provided by carbohydrates, fats and proteins. Proteins are a provider of energy in an emergency, but are primarily used as building blocks for growth and repair of many body tissues. These energy providing compounds are needed in large quantities in our diet so are described as macronutrients.
We also need much smaller amounts of other nutrients, such as vitamins and minerals. Because much smaller quantities are needed for a balanced diet these are known as micronutrients. Despite the small quantities needed these are essential to provide a healthy diet as they have specific roles in metabolic reactions and as structural components.
Within the cells of our body, the nutrients ingested are converted to other compounds which are then...
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added: 10/18/2011
What is Gynecomastia? Definition Gynecomastia is a common disease of the male breast where there is a benign glandular enlargement of that breast at some time in the male's life. It usually consists of the appearance of a flat pad of glandular tissue beneath a nipple which becomes tender at the same time. The development may be unilateral or bilateral. There is rarely a continued growth of the breast tissue; ordinarily the process is of brief duration and stops short of the production of permanent enlargement of the breast. Causes A great number of patients who suffer from this disease have a disturbance in the proper ratio of androgen and estrogen levels. The normal ratio of the two hormones in plasma is approximately 100:1. "The etiology of gynecomastia in patients with a known documented cause appears to be related to increased estrogen stimulation, decreased testosterone levels, or some alteration of the estrogens and androgen so that the androgen-estrogen ratio is decreased"(Williams 373). From this information it was discovered that there is also a lower ratio of weaker adrenal androgens (delta 4-androstenedione and dehydroepiandrosterone) found in youths with this disease. It was once believed that there was an imbalance in the ratios of testosterone to estrogen or estradiol, but this is now know to be untrue. There are three areas the can be attributed to the cause of gynecomastia: physiologic, pathologic and pharmacologic. "Enlargement of the male breast can be a normal physiologic phenomenon at certain stages of life or the result of several pathologic states."(Isselbacher, 2037) In the case of physiologic gynecomastia the disease can occur in a newborn baby, at puberty or at any time in a man's life. In the newborn, transient enlargement of the breast is due to the action of maternal and/or placental estrogens. The enlargement usually disappears within a few weeks....
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added: 09/06/2011
Communication and Signaling in the Language of Birds Scientific research has revealed that throughout the living world, communication is just as important as it is to human beings. Countless living things lack the capacity for human speech, yet they employ entirely different methods in order to communicate with each other—and even with other species. Some of the most dramatic examples of this is displayed by birds. The astonishing behavior and ability to communicate that birds exhibit also totally invalidates the claims of the theory of evolution. All forms of life on Earth have been created with miraculous properties and astonishing abilities. The examination of just one single species is enough to reveal hundreds of proofs of God's magnificent creation. In one verse of the Qur'an, Allah reveals that: There is no creature crawling on the earth or flying creature, flying on its wings, who are not communities just like yourselves—We have not omitted anything from the Book—then they will be gathered to their Lord. (Qur'an, 6: 38) The birds to which this verse draws our attention notice are one of the living communities that we need to examine and reflect upon. There are roughly some 10,000 species of bird in the world, each of which possesses its own miraculous features. Wherever you may live, you can see a great number of these feathered creatures and can observe different and extraordinary properties in each and every one. With their attractive appearances, flawless flight mechanisms, expertise on the routes and timing of migrations, ability to build nests and altruistic behavior toward their young and to one another, birds possess countless proofs of the fact of creation. Their ability to communicate is another of these. Birds' Sense of Hearing For birds to display their talents in communicating by sound, song—and in the case of some birds, words— they require excellent hearing....
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added: 12/18/2011
Acromegaly (Greek for "appendage enlargement") is a rare but very serious disease frequently referred to as "Gigantism" or "Giantism." It is the direct result of an overproduction and secretion of the adenohypophyseal growth hormone GH. True to its name, the disease is characterized by an enlargement of the organs, bones, and soft tissues, as well as a thickening of the skin and bodily membranes; and is frequently difficult to diagnose, as symptoms often do not appear until middle age. Typically the disease results in heart failure caused by an enlargement of the heart, organ failure due to pressure or thickening of the outer membrane of the organ, or brain hemorrhaging caused by a benign or malignant pituitary adenoma. To date, there are three known forms of the disease: Cushing's disease, Nelson Syndrome, and Prolactinoma. Each is characterized by different phenotypic attributes commonly linked by an enlargement of all or some particular body parts. Prolactinoma is the most frequently recognized form of giantism. It is characterized by an overall enlargement of the body, and was brought to public attention nearly twenty years ago by pro-wrestler and actor Andre the Giant, who later died of heart failure in the early 1990s. Nelson's disease and Cushing Syndrome are similar to each other, however there is now controversy as to whether these two diseases are even linked to Prolactinoma since they are not commonly characterized by an overall enlargement of the body, but rather an extreme overproduction of soft and fatty tissue. These diseases cause thickening of the bones, skin, and soft tissue, but often appear after the person has finished growing, making the patient appear overweight and unable to speak and move with fluidity since the tongue and hands are hindered. All three diseases tend to have the same outcome: organ failure or...
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added: 11/14/2011
Adrenoleukodystrophy The full name of ALD is Adrenoleukodystrophy. It is a rare X chromosome sex linked metabolic disorder that is characterized by the loss of myelin on nerve fibers within the brain. Myelin is the fatty covering on the nerve fibers. The disease causes the continued degeneration of the adrenal gland. The basic defect is that the impaired capacity to degrade very long chain fatty acids that are found in the blood plasma and tissues of the body. These fatty acids accumulate in the cerebral white matter of the brain and the adrenal glands. ALD only effects males. The symptoms of ALD may develop due to abnormal or a lack of microbodies that participate in the metabolism of fats called peroxisomes in the liver. This causes a disturbance of fatty acid metabolism and results in the abnormal accumulation of very long chain fatty acids. The exact enzyme deficiency that prevents the breakdown of VLCFAs is not known. ALD is an allelic mutation. The disease is caused by one mutation at the locus Xq28. The mutation causes deficient activity of the ligase enzyme. Diagnosis of the disease can be made from cultured skin fibroblasts or amniotic fluid cells. The disease is preventable through a combination of oleic and erucic acid (as used in Lorenzo's Oil) and a restricted diet lacking in very long fatty acids. More recently, some ALD patients have been experimentally treated with Glycerol Trioleate. Continued research is being done to determine the effectiveness and safeness of these substances. For those that are identified with the disease prenatally or soon after birth, this is a successful treatment. Those that take the prescribed dose of the oil and are restricted in their diet appropriately can live otherwise normal lives. The Myelin Project is the research project dedicated to the cure of this disease and others related...
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added: 10/04/2011
Hydroponics: Advantages of Producing Crops Through Use of Hydroponics HYDROPONICS derives its name from the Greek HYDRO-PONOS meaning water/labor. Literally, "Hydroponics" means "Water Work." There is no soil in a hydroponic garden. No organic matter is present so nourishment (Nutrient) is not available to the plants in the same was as it is in a soil garden. Instead, nutrients are added to the water. So, as plants are watered, they are also fed. There are many ways to feed and water plants. The method chosen becomes a "Hydroponic System." Common systems are: Hand watered, recirculating system (With a submersible water pump), gravity fed from a nutrient tank into pots or trays, or a wick system. A common question is, "What can be grown in hydroponics?" Surprisingly to some, anything that can be grown in soil can be grown in a hydroponic system! Flowers, herbs, vegetables, fruit trees, vines, and ornamental shrubs. Everything from Aloe Vera to Zucchinis can be grown in this unique system. There are many advantages to using a hydroponic system for growing plants. The most obvious of these advantages is that it is easier to control the plant growing environment. Some others are restricted supply of suitable water, lack of suitable soil, high labor cost of traditional cultivation, high cost of sterilizing soil, and there is a greater reliability and predictability of plant production. In addition, It's easy! Depending on what is being grown, most of the time hydroponic plants require less attention than soil-grown crops. Because of this, it can relieve some people of the added responsibility that soil-grown plants require. As one can see, there are many advantages to this system of growing plants. Since its origination, thousands of companies have sprung up dealing solely with hydroponics and hydroponic equipment. Maybe someday, when man inhabits outer-space,...
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added: 02/16/2012
Charles Darwin in his book, On the Origin of Species, presents us with a theory of natural selection. This theory is his attempt at an explanation on how the world and its species came to be the way that we know them now. Darwin writes on how through a process of millions of years, through the effects of man and the effects of nature, species have had a trial and error experiment ongoing. It is through these trials that the natural world has developed beneficial anomalies that at times seem too great to be the work of chance. Darwin writes on how a species will adapt to its surrounding given enough time. When an animal gains a genetic edge over its competitors, be they of the same species or of another genus altogether, the animal has increased its chance of either procreation or adaptation. When this animal has this beneficial variance, the advantage becomes his and because of this, the trait is then passed on to the animals offspring. The theory of natural selection is not limited to inheritable and beneficial variations of a species. It also relies a great deal on the population growth and death of a species. For a species to continue to exist it must make sure of a few things. It must first produce more offspring than survive. If this is not done then the species is obviously going to die off. It is also important for the species to propagate at such a rate as to allow for variance, for it is variance that will ultimately allow the animal to exist comfortably in his surroundings. In his studies, Darwin was led to understand that "…the species of the larger genera in each country would oftener present varieties, than the species of the smaller genera;" (p. 55)....
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added: 02/08/2012
"Biotechnology involves any technique that uses living organisms or parts there of to make or modify products, to improve plants or animals or to develop micro organisms for specific uses" In the past century humans have been lucky enough to stumble upon one of the basic building blocks of organisms, DNA. In recent years scientists have been able to develop ways in which they can manipulate, alter, and transfer DNA in forms that can help improve our lives. One way in which DNA research has been used to improve our lifestyle, is by engineering the deoxyribonucleic acid into ways which can alter food supplies to make them bigger, taste better, resistant to pests and even make them have a greater concentration of nutrients. Of course this is great news to the human population, but there are still a few disadvantages. With all the good news these altered crops provide for humans, concerns are still among people. These concerns include; whether or not these alterations will affect humans in a negative way, and what impact they will have on the environment. Although no one can know for sure., the effects of these genetically engineered crops are probably overstated. Bioengineered crops could play a significant role in increasing crop production which will allow the world to feed more people and do it using less land. A recent study on bioengineered crops concluded that these crops are safe and can improve production dramatically. Those opposing the genetically altered crops state that "when altered DNA molecules are introduced into a living organism in the filed, the full range of their effects cannot be predicted or known before commercialization (over)." In the near future, shoppers will be able to find foods that last longer, taste better and are more nutritious than the foods currently eaten. And an even...
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added: 01/19/2012
Anti-Cloning Research: To those against it, cloning presents as much a moral problem as a technical problem. For them, cloning is an affront to religious sensibilities; it seems like "playing God," and interfering with the natural process. There are, of course, more logical objections, regarding susceptibility to disease, expense, and diversity. Others are worried about the abuses of cloning. Cloning appears to be a powerful force that can be exploited to produce horrendous results. Their basic objections to cloning research are outlined here. Cloning may reduce genetic variability, Producing many clones runs the risk of creating a population that is entirely the same. This population would be susceptible to the same diseases, and one disease could devastate the entire population. One can easily picture humans being wiped out be a single virus, however, less drastic, but more probable events could occur from a lack of genetic diversity. For example, if a large percentage of an nation's cattle are identical clones, a virus, such as a particular strain of mad cow disease, could effect the entire population. The result could be catastrophic food shortages in that nation. Cloning may cause people to settle for the best existing animals, not allowing for improvement of the species. In this way, cloning could potentially interfere with natural evolution. Cloning is currently an expensive process. Cloning requires large amounts of money and biological expertise. Ian Wilmut and his associates required 277 tries before producing Dolly. A new cloning technique has recently been developed which is far more reliable. However, even this technique has 2-3% success rate. There is a risk of disease transfer between transgenic animals and the animal from which the transgenes were derived. If an animal producing drugs in its milk becomes infected by a virus, the animal may transmit the virus to a patient using the drug. Any...
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added: 11/24/2011
Purpose - The purpose of this lab is to use a chemical titration to measure and them calculate the rate of conversion of hydrogen peroxide (H2O2) to water and oxygen gas using the enzyme catalase. Hypothesis - The rate of enzymatically-catalyzed reactions can be determined by taking time reactions at different time intervals. When the rates are plotted on a graph, the rate of the reaction is the slope of the linear portion of the curve. To determine a rate, any two points on the straight-line portion of the curve is picked out. Divided the difference in the amount of product formed between these two points by the difference in time between them. The result will be the rate of the reaction. I believe that the reactions rate will be that highest during the first interval (0-10 seconds) because there are larger amounts of substrate molecules than enzyme molecules, but as times increase the lower the reaction rate because there will be more product molecules as result of the chemical reactions between the enzyme and the substrate. Materials: •ring stand •double clamp •2 burettes •beakers •test tube •1.5% hydrogen peroxide (H2O2) •distilled water •liver •potassium permanganate (KMnO4) •graduate cylinders •1.0% sulfuric acid (H2SO4) Procedure: See handout Observations: See handout Analysis - My hypothesis proved to be correct. The reaction rate was the highest during the intervals of (0-10 seconds) and also at the beginning of 10-30 seconds because there is a large amount of substrate molecules in comparison to the number of enzyme molecules and there will be a maximal number of collisions between the enzymes and the substrate. As the number in seconds increased the reaction rate decreased. The lowest reaction rate was during the last interval (120-180 seconds). As the number of substrate molecules decreased and the number of product molecules (O2) increases the number of collisions between the substrate decreases. Eventually, the enzyme will...
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added: 01/06/2012
An occasional patient will ask: "Are x-rays safe?" Others will ask about the amount of radiation. As a radiologist you have a responsibility to give a reasonably honest and understandable answer to the patient. You can certainly explain that diagnostic x-rays are safe. There are no data to indicate otherwise. There is evidence that suggest that such low doses may actually reduce the chance of cancer.1 The question about amount is difficult to answer in an understandable way. First, because it is a rare x-ray unit that has a meter to measure the radiation to the patient and second, because scientific units for radiation dose are not understood. This article is to help you explain radiation to patients in words that they understand. In addition, I present evidence from various human studies to show that low level radiation, comparable to that from a radiograph, may be beneficial and even reduce cancer. Explaining radiation dose to a patient using the BERT concept Answering your patient's question about the amount of radiation would be easy if you knew the effective dose. However, it is unlikely the patient would be satisfied if your answer was "the mammogram will give you an effective dose of about 1 millisievert (mSv)." She probably would understand if you converted the effective dose into the amount of time it would take her to accumulate the same effective dose from background radiation. Since the average background rate in the U.S. is about 3 mSv per year, the answer in this case would be about four months. It is likely that she would understand and be satisfied with your answer. This method of explaining radiation is called Background Equivalent Radiation Time or BERT.2,3 The idea is to convert the effective dose from the exposure to the time in days, weeks, months or years...
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added: 01/03/2012
The origins of man is an extremely controversial issue within today's society. Scientists have a host of different theories pertaining to man's inhabitance of earth. Many disagreements arise between scientists who have different beliefs pertaining to where and how mankind arose. One such argument is the conflict involving the theory of evolution versus the theory of creation. After extensive scientific research, it is apparent that the theory of evolution is correct. Evolution is the theory that life arose by natural processes at an early stage of the earth's history and that complex organisms developed from simpler organisms by a process of slow change (Coren 209). It's the idea that new species arise from older species after thousands of years of gradual chemical, environmental, and genetic change (Coren 142). Evolution can also be described as the complex processes by which living organisms originated on earth and have been diversified and modified through sustained changes in form and function ("Evolution"). Scientists, looking for an explanation to the origin of man and other organisms created this evolutionism theory, which also presented answers to the many asked questions dealing with similarities between species. Unlike the theory of creation, which states that the complexity of life and different species can only be explained in terms of a supernatural creator or god who placed life on earth, the theory of evolution has a plethora of evidence proving it to be true ("Creation"). There are several different types of observations that support the theory of organic evolution as an explanation for the similarities and the differences among species. One such observation is in the geologic record. The geologic record is the rock scheme found within the earth's outer crust. By means of radioactive dating, the ages of rocks in many places on earth have been determined. It's a...
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added: 10/30/2011
The issue of bio-ethics presents a myriad of new dilemmas; all of which have arisen in the recent past, and must be addressed in the near future. The majority of these questions stem from the introduction of new, genetically-engineered organisms. These organisms, or at least many of them, are created in laboratories, by gene splicing, swapping, etc. and essentially, these scientists are playing god, creating biological entities as they want them. This is the main source of the controversy. In more developed countries where genetically engineered disputes may ensue, the trend is total protection through patents and other regulatory and monitoring agencies. These problems come about from identification of the new bio-engineered organisms, and this approach allows the industries and entrepreneurs to recover the enormous costs involved in the research and development of genetic engineering. It promotes the development of products to benefit society, and it allows access for a larger genetic bank for analyses, experimentation, and investigation. There is a second side to this coin-it means that the researchers can assert an excessive price to their 'product' while eliminating any competition for a given period of time. It allows for copies of living things to be made easily and inexpensively. This happens outside the United States, where strict regulations are not in continuity with those pirating compact discs in Japan, bottling Coca Cola in India, etc. No countries spend any monetary amount comparable to the over 300 million dollars to run the patent and trademark office, as the U.S. does. Another observation can be made that because of the time involved and the cost that the free flow of information is inhibited between researchers. These arguments all take place under the umbrella that "Life forces can be controlled by ownership." Many countries take the view that these genetic products are not intellectual...
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added: 01/24/2012
Water is essential to life itself, with out water life on earth would not exist. Water is a major component of cells, typically forming between 70 and 95% of the mass of the cell. This means that we are made from approximately 80% water by mass and some soft bodied creatures such as jellyfish are made of up to 96% water. Water also provides an environment for organisms to live in, 75% of the earth is covered in water. Water itself is a simple molecule made up of 2 hydrogen atoms and one oxygen atom, H20. The hydrogen and oxygen atoms are bonded covalently as shown in the diagram of water's electron structure. Water is not a linear molecule, the two hydrogen atoms form a bond with the oxygen at the angle of 104.5o. Diagram of water's electron structure Covalent bonds are formed by sharing electrons in the outer orbits of the quantum shells. In the case of water however the large number of protons in the oxygen nucleus have a stronger attraction for these shared electrons than the comparatively tiny hydrogen nuclei. This pulls the electrons slightly closer to the oxygen nucleus and away from the hydrogen so that the oxygen develops a slight negative charge and the hydrogen's a slight positive charge. This makes the molecules slightly polar. Diagram of water molecule showing slight charges This slight charge means that when water molecules are close together the positively charged hydrogen atoms are attracted to the negatively charged oxygen atoms of another water molecule to form a weak hydrogen bond. The bonds are weak individually but the sheer number of them means that the total force keeping the molecules together is considerable. Diagram of water molecules forming hydrogen bonds Water is an unusual substance, mostly due to it's hydrogen bonds, it's properties allow it to act as...
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added: 01/07/2012
The plasma membrane is the boundary of life; this selectively permeable membrane allows the cell to maintain a unique internal environment and to control the movement of materials into and out of the cell. The phospholipid bilayer (fluid mosiac model) with specific membrane proteins accounts for he selective permeability of the membrane and passive and active transport mechanisms. Membrane phospholipids are amphipathic. Cell membranes are phospholipid bilayers with the hydrophobic hydrocarbon tails in the center and the hydrophilic heads facing the aqueous solution on both sides of the membrane. The phospholipid bilayer also called the fluid mosiac model has proteins embedded in the phospholipid bilayer with their hydrophilic regions extending out into the aqueous environment. Membranes are held together by weak hydrophobic interactions that allow the lipids and some of the proteins to drift laterally. Phospholipids with unsaturated hydrocarbon tails maintain membrane fluidity at lower temperatures. The steroid cholesterol restricts movement of phospholipids, therefore, reducing fluidity at warmer temperatures. Cholesterol also prevents the close packing of lipids and thus enhances fluidity at lower temperatures. The plasma membrane permits regular exchange of nutrients, waste products, oxygen, and inorganic ions. Membranes are selectively permeable which means that they allow some substances to cross more easily than others. Hydrophobic molecules, such as hydrocarbons, can dissolve in and cross through a membrane. Very small polar molecules, including water, can cross a plasma membrane easily. Ions and polar molecules may move across the plasma membrane with the aid of transport proteins, which may provide a hydrophilic channel or may physically bind and transport a specific molecule. The selectively permeability of a membrane depends on both the discriminating barrier of the lipid bilayer and the specific transport proteins built into the membrane. The structure of membranes is directly related to the transport of materials across a membrane. Diffusion...
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added: 02/13/2012
This lab deals with the process of genetic exchange in prokaryotes. There are three main mechanisms of genetic exchange which include transformation, transduction, and conjugation. In transformation, DNA is released from cells in the surrounding environment which is then incorporated into the recipient cells DNA. In transduction, DNA is transferred through a virus to the recipient. In conjugation, genetic exchange occurs through direct contact with another cell and the plasmid is transferred from the donor to recipient. Plasmids are circular modules of double-stranded DNA which are beneficial but not essential. R factors are plasmids which carry genes that confer resistance to antibiotics on the host cell. R factors have been a problem because they are causing many strains of pathogenic bacteria to be highly resistant to antibiotics. Transformation was the first mechanism of bacterial exchange that was discovered. A famous experiment with transformation dealt with injecting mice with an avirulent strain of bacteria with heat-killed cells of a virulent strain killed the mice while injecting these strains separately did not. This established that the surviving cells were recombinant. A genetic exchange of the DNA in the external medium had occurred between the dead cells and the live ones. The bacteria that we are using is E. coli bacteria which are capable of being artificially transformed. They are made competent (capable of being transformed) only after following subjection of cells to calcium chloride solution. II.Transformation of E. coli A. Summary – In this lab, we are investigating the method of genetic exchange called transformation through the insertion of plasmid pUCB DNA, which carries the gene for antibiotic resistance to ampicillin, into competent E. coli cells. B. Procedure – The procedure of this lab is somewhat complicated. 250uL of calcium chloride to 2 separate tubes labeled + and --. Next, transfer a large colony of...
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added: 01/04/2012
Biology Research Paper: In Vitro Fertilization. In Vitro Fertilization (IVF), is the procedure whereby human babies are conceived, not in the womb but in a test tube or a Petri dish. This procedure has become one of the greatest developments in the world of medical technology. In Vitro Fertilization has given infertile couples the chance to conceive and bear a child from a full term of pregnancy. Without this procedure, their infertility would render them childless. There are many aspects of the IVF program that have been both praised and criticized. The legal, ethical and social repercussions of the IVF program have created great debate and controversy. This essay will demonstrate the procedures used in the IVF program and set out the arguments for and against it. There are many reasons why couples cannot conceive or bear a child for a full term of pregnancy. The process of natural fertilization can only be achieved if the male and female reproductive organs are functioning without any abnormalities. The reproduction process begins with the male producing sperm in the testes and the female producing an egg in the ovaries. Once every 28 days or so, an egg matures in the ovary, bursts from its follicle and enters the Fallopian tube. Once sexual intercourse has taken place, millions of sperm released from the penis swim up the vagina, through the uterus and into the Fallopian tube. 'A single sperm fertilizes the egg; the others are locked out.' (Time, 1997, pg. 66) Once the egg has been fertilized, cell division begins and the embryo drifts down the Fallopian tube. The embryo reaches the uterus in about a week. The embryo anchors itself to the wall of the uterus where it develops into a foetus. The foetus feeds off nutrients and oxygen provided by the placental lining in the uterus. There...
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added: 07/19/2011
There once was a guy named Timmy. Timmy was attending college at the University of Wisconsin. At the college, he was going through a biology class and was having a hard time comprehending the theory of cells. He didn't understand what all the cell parts were and what their functions were. He hoped that as time went on, he'd eventually catch on. Well any ways, Timmy was in desperate need of some money. He needed some food for his dorm and wanted a new bike to travel around on. While he was flipping through the classified ads, he found a job that sounded interesting to him. Subway needed some help with making sandwiches and working at the register. Timmy thought this would be an easy way for him to make some quick and easy money. The next day, Timmy drove to the nearest Subway and got an application. He filled it out and turned it in within a few hours. In a matter of two days, he got a call back saying he was hired! He was ecstatic! Finally, he'll be able to have some money. Timmy was really excited and he was looking forward to his first day at work. The manager asked him if he could start as soon as tomorrow and Timmy agreed. While he was excited, he was nervous at the same time. He didn't want to screw up his first day on the job. The manager told him not to worry though because the job isn't too tough and he'll find help if he needs it. Timmy went to bed that night on a good note looking forward to his first day in the working field. Timmy woke up early the following morning and got himself ready for work. He was supposed to be there at 11:00...
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added: 11/22/2011
What is Cardiovascular Disease? How may it be prevented and to what extent is heart transplant surgery a sensible solution to the problem of Coronary Heart Disease? Cardiovascular Disease, or CVD, is Britains biggest killer, responsible for 40% of premature deaths in Britain. CVD is a comprehensive term for several afflictions of the cardiovascular system - the heart and blood vessels of the body. These afflictions are Coronary Heart Disease (CHD), Atherosclerosis and arteriosclerosis, Angina, Coronary Thrombosis and Myocardial Infarction and Stroke. Apart from the high mortality rate - it is estimated that CVD kills 140,000 people a year under 75 years old, chronic heart disease causes incapacitation, suffering and pain in many of it's victims. Much heart disease is also self-inflicted and therefore avoidable. Atherosclerosis and Arteriosclerosis The underlying cause of CHD, strokes and other diseases of the blood vessels is usually atherosclerosis. Atherosclerosis is caused by the build up of cholesterol and other fatty substances in walls of arteries. Firstly the deposits form small streaks on the endothelium of the artery, but gradually build up to form patches known as atheromatous plaques. The deposit is called an atheroma and causes the arterial walls to thicken, hence narrowing the lumen of the artery. The onset of an atheromatous plaque may be caused by some physical damage to the artery, sometimes caused by high arterial pressure - hypertension. Smooth muscle cells proliferate at the site of damage and then lipids and cholesterol are deposited from the blood. The cholesterol deposited in the walls may be attacked by free radicals released by phagocytes which may slow down the passage of low density lipoproteins which carry cholesterol back into the blood with the result of increased deposition of cholesterol. Atheromatous plaques roughen the lining of the artery and disturb the flow of blood, which can stimulate the formation of...
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added: 10/01/2011
About Cell Organelles The studies of Robert Hooke 1665 into a plant material would allow the determination of a pore like regular structure surrounded by a wall of which he called 'cells' this in itself unbeknownst to him, was the discovery of the fundamental unit of all living things. In 1838 a botanist called Schleiden derived the theory 'The basic unit of structure and function of all living organisms is the cell.' Over 150 years later this can be regarded as one of the most familiar and important facts within the biological fields. Drawing of cork cells published by Robert Hooke 1665 The Cell itself and use of Cytology: The cell can be thought of as a bag in which the chemistry of life is allowed to occur, partially separated from the environment outside the cell, it exists within all living organisms as its basic structure. The study of cells is made possible through the use of 'cytology' the preparation of materials for examination through microscopes as an average animal cell exists on a scale of 10 microns roughly one hundredths of a millimetres. Originally light microscopy was used in this field but with the advancement of knowledge scientists were restricted to 200nm magnification, or 2 tenths of a micron. Realising the existence of cell organelles within the cell structure, allowing the function of the cell itself to occur; It was necessary to increase magnification by utilising an alternate source radiation (alternate to light).The result was the electron microscope, whereby the short wavelength and negative charge of electrons when supplied with energy allowed for greater focusing with electromagnetism. This method bends the path of the beam in the manner of a lens to light. Cell Organelles and the variation between Plant and Animal Cells: We have already determined the cell to be the foundation to all organisms, however...
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added: 01/03/2012