Biology Essays Heart Disease

Biology Essays Heart Disease The Biological Basis and Risk Factors for Coronary Heart Disease. Coronary heart disease is a blanket term which describes all types of heart disease caused by blockage of the arteries that supply blood to the heart. Lack of sufficient blood is associated with a lack of oxygen, also called ischemia. Hence coronary heart disease is also called ischemic heart disease. Angina, heart attack and heart failure and are all clinical forms of coronary heart disease.1 Overall, coronary heart disease is the leading cause of death in the Western world.2 In the UK, heart attacks are responsible for around 150,000 deaths every year and cost the NHS approximately  £719 million per year. Almost half of all heart attack sufferers die within 20 days of the attack.3 The heart of the problem The heart is a vital organ, pumping blood which carries essential oxygen and nutrients all around the body. As a powerfully active muscle, the heart needs a ready and plentiful supply of oxygen and nutrients itself; however these are not extracted from the blood that flows through it. Instead, the heart has its own specific blood supply – the coronary arteries. There are two major coronary arteries – the right and left. The volume of blood which flows to the heart is largely determined by the width of these vessels and is not so dependent on the power at which the blood is pumped through them. Unlike other organs which can use the oxygen within veins if needed, the heart is completely reliant on the coronary arteries’ supply. Hence their ability to expand and supply more blood when required is essential.4-6 Coronary heart disease develops when various materials build up within the walls of the coronary arteries causing a narrowing of the vessels and potentially leading to complete blockage. The obstruction of blood flow to the heart which results from this build up within the coronary arteries can cause a range of cardiac problems. When the blood flow to the heart is only temporarily interrupted, usually during exercise and times of exertion when the heart muscle requires more oxygen, the condition is known as angina. A person with angina will experience short attacks of chest pain which usually clear up with rest. Ultimately, insufficient blood flow can result in actual physical damage to the heart tissue. In severe cases, where blood flow is completely blocked, the portion of the heart affected may die from lack of oxygen– this is termed myocardial infarction, commonly known as a heart attack. Symptoms of heart attack include prolonged and severe chest pain, weakness and shortn ess of breath. In rare cases, patients with coronary heart disease experience heart failure. This is a broad condition which describes any symptoms showing that a patient’s heart is not performing as it should. 4-6 Why do coronary arteries become blocked? In healthy arteries, the walls are smooth and blood flows easily. The process leading to the development of coronary heart disease begins with the development of ‘fatty streaks’. These are yellow patches which appear within the wall of the coronary artery. The streaks are made up of a special type of cell called foam cells, which are rich in fats, plus smooth muscle cells. Over time, streaks can turn into plaques. Plaques, also known as atheroma, are fatty lumps which form within the lining of the arteries. There are various different kinds of plaques. Some are made up of a soft inner core of cholesterol covered by a thin firm outer layer. Others are completely solid and composed of smooth muscle cells and various other strong materials. Calcium may also build up on a plaque making the problem worse.4,7 What is the blockage like? Plaques cause several problems to coronary blood flow. Firstly, a plaque itself can be big enough to narrow the artery and reduce the space available for blood to flow through it. Secondly, as blood is thrust against the side of the plaque with each heart beat, the outer shell of the plaque may crack open exposing the cholesterol core. When the cholesterol core is exposed, blood clotting is triggered within the artery. Clots reduce the blood flow even more. This whole process can happen repeatedly causing the artery to become narrower and narrower and eventually leading to complete blockage.4,7 Overall, the process of plaque formation and associated thickening, loss of elasticity and narrowing of the artery walls is known as atherosclerosis. Atherosclerosis is the major cause of coronary heart disease however, it is also present to some degree in almost every adult male in Western societies. What causes atherosclerosis to occur is complex and uncertain and there is much still to learn. Current thinking is that atherosclerosis results from some kind of ‘response to injury’ where initial non-specific injury to the lining of the artery wall triggers the whole process to start up.4,7,8 Risk factors Everyone has some chance of experiencing heart disease, however, various factors have been identified which increase the risk of developing coronary heart disease. These include:4,6,7,8 High cholesterol Smoking Lack of exercise Unhealthy diet Obesity Diabetes High blood pressure (hypertension) Mental stress High levels of certain blood clotting factors Family history Alcohol and coffee Male gender Ethnic group (e.g. Southern Asians in the UK are at higher risk) Most of these risk factors increase the risk of coronary heart disease by increasing the likelihood that atherosclerosis will develop within the coronary arteries themselves. Also, these risk factors have been found to ‘interact’. Hence if you have two or more risk factors your overall chance of developing coronary heart disease is proportionally higher than if you just had one risk factor.8 Heredity as a risk factor Coronary heart disease often occurs within several members of the same family, indicating that a genetic link may be involved. However, it is difficult to determine if the link between family members is due to genes or shared environmental factors, such as diet and exposure to smoke. Genetic factors have been shown to influence cholesterol levels and the amount of blood clotting factors a person has in their blood, which in turn has a knock-on effect on the risk of developing atherosclerosis. Overall, it seems that a combination of genetics and the environment would best explain the family link to heart disease. It has been estimated that 40% of the risk is controlled by genes, and 60% is due to environmental factors.4,6 High cholesterol as a risk factor There are two types of cholesterol found in the blood – ‘good’ HDL cholesterol which can protect against the development of heart disease and ‘bad’ LDL cholesterol which promotes the development of atherosclerosis. There is lots of evidence to show that unhealthy amounts of these two types of fat in the blood, i.e. high LDL and low HDL levels, can increase the chance of developing coronary heart disease. This is because high levels of cholesterol in the blood encourage the formation of plaques within the artery wall and promote the overall process of atheroschlerosis.4,6 The cause of high LDL levels has not been clearly established but dietary factors are likely to be involved. There is evidence that a diet high in saturated, but lacking in polyunsaturated, fat may contribute to high cholesterol levels. There is relatively little actual cholesterol in the diet, but saturated fat is converted into cholesterol in the liver.4,6 Lack of exercise as a risk factor Lack of exercise is a proven risk factor for the development of coronary heart disease. Overall, the risk is a third less in people who exercise compared to those who don’t.8 It seems that physical exercise has a protective effect on the development of coronary heart disease. The mechanism underlying this has not been fully elucidated but certain hypotheses have been put forward. Exercise may increase levels of good HDL cholesterol and also reduce the blood clotting which occurs within atherosclerotic arteries and causes further blockage. Exercise might also help enlarge the coronary arteries and hence increase blood supply to the heart. In order to gain full health benefits from exercise in the reduction of coronary heart disease risk, five bouts of moderate physical activity per week, each lasting a minimum of 30 minutes, are recommended. Conclusion Coronary heart disease is a serious condition caused by the build-up of fatty deposits within the walls of the vital arteries that supply blood to the heart. Coronary heart disease is the major cause of death in Western societies but to a large extent is preventable. Recognising the key risk factors which contribute to the development of atherosclerosis is an important step towards reducing the overall incidence of coronary heart disease. References Walton J, Beeson PB, Bodley Scott R, 1986. The Oxford Companion to Medicine: Volume I, A-M. Oxford: Oxford University Press. Higgins M, 2001. Patients, families and populations at high risk for coronary heart disease. European Heart Journal, 22: 1682-1690. Association of the British Pharmaceutical Industry, 2005. Hitting the Target: Medicines and Coronary Heart Disease and Stroke. Available at: http://www.abpi.org.uk/publications/publication_details/hitting_target/section5b.asp [Accessed 14 March 2005]. Julian DG Campbell Cowan J, 1992. Cardiology: Sixth Edition. London: Bailliere Tindal. Vander AJ, Sherman JH, Luciano DS, 1994. Human Physiology: The Mechanisms of Body Function. International Edition: McGraw-Hill. Edwards CRW Bouchier IAD (Eds), 1991. Davidson’s Principles and Practice of Medicine: Sixteenth Edition. London: Churchill Livingston. Singh VN, 2005. Coronary Heart Disease. Emedicine. Available from: http://www.emedicinehealth.com/articles/10951-1.asp [Accessed 14 March 2005]. PRODIGY Guidance, 2004. Preventing Heart Disease and Stroke. Patient information leaflet. Available at: http://www.prodigy.nhs.uk/clinicalguidance/releasedguidance/webBrowser/pils/PL82.htm [Accessed 14 March 2005].

Changes and continuities of Roman empire Essay

Between 500 BCE and 500 CE, the Roman civilization experienced changes both politically and culturally. Firstly, Rome’s government transitioned from a Republic to an Empire. Later, that empire was split into two parts; east and west. In terms of changes in culture, it was impacted by the shift in religion, as the Romans shifted from polytheism to monotheism. Despite all the changes, Rome still remained culturally diverse. The Romans overthrew the Etruscans in 509 B.C.E. The Etruscans had ruled over the Romans for hundreds of years. Once free, the Romans established a republic, a government in which citizens elected representatives to rule on their behalf. The highest positions in the government were held by two consuls who ruled the Roman republic. A senate composed of Patricians elected these consuls and at this time, lower-class citizens, or plebeians, had virtually no say in the government. Both men and women were citizens in the Roman Republic, but only men could vote. Under certain circumstances, the senate and the consuls could appoint a temporary dictator to rule for a limited time until the crisis was resolved. One of the innovations of the Roman Republic was the notion of equality under the law. In 449 B.C.E., government leaders carved some of Rome’s most important laws into 12 great tablets. During the last three centuries of the republic, Rome experienced a long series of civil wars, economic as well as political issues, and civil crisis caused by the dictatorship of Julius Caesar. After Caesar’s death, another civil war broke out destroying what was left of the Roman republic. Caesar’s adopted son, Octavian, joined forces with a general named Mark Antony and a politician named Lepidus. They took control of Rome for ten years as the Second triumvirate. The alliance ended in violence and jealousy. Octavian forced Lepidus to retire and then became rivals with Mark Antony. Octavian believed Mark Antony was plotting to rule Rome from Egypt, and another civil war erupted. Octavian defeated Antony and became the unchallenged ruler of Rome. Rome was at the height of its power from the start of Augustus’s rule in 27 B.C to 180 A.D. For 207 years, peace and prosperity resided over the Roman Empire, known as the Pax Romana. During this time, the empire spread 3 million square miles, and its population was between 60 and 80 million. The borders were also stable, since there were not any wars going on between Rome and other civilizations. Since Rome was now an empire, this meant that the government would now be ruled by a single emperor instead of two  consuls. Since one person was in full control instead of two, so there was no conflict over power, and there was no need for citizens to constantly elect people to rule. However, during Octavian’s reign he set up a civil service system. He paid workers to manage the affairs of government. Although the senate still functioned, civil servants from the plebeians and even former slaves actually administered the empire. The Romans were heavily influenced by the Greeks in various ways. One facet being religion, the Roman’s were polytheistic due to Greek influence and worshipped many of the same gods. The classical Greek and Roman gods rewarded excellence over mediocrity and did not truly offer any sort of meaningful after-life. However, around 300 CE a new religion started to spread throughout Rome. This new religion being Christianity, a monotheistic religion, and a religion that believed that there was life after death and hailed Jesus as the son of God as well as the incarnation of God. In regards to life after death in the Christian religion, as long as you followed the faith and lived a virtuous life doing good deeds you would be rewarded heaven. But if one has led a life of sin, they would be doomed to spend the afterlife in hell. Those meek and seen as inferior in the Roman empire, the poor, slaves, and women felt elevated and empowered as everyone is equal in the eyes of God, in Christianity. When Christianity began to emerge, it was largely disliked as Christians refused to take part in the worship of emperors as the Romans did. It was this refusal that caused its practice to be illegal and those who chose to stick with the faith were prosecuted. Although people were being killed for practicing, Christianity started to become even more popular. After seeing Christian martyrs risk their lives for the sake of Christianity, many Romans were compelled and attracted to the faith. Also, there were Apostles who traveled around the empire spreading the message of Christianity. Then in 312 CE, Emperor Constantine proposed the Edict of Milan that banned all laws against Christianity. That allowed people to freely worship, without the fear of harsh punishment. He eventually converted on his deathbed. Then in 392 CE, Emperor Theodosius made Christianity the official religion of Rome. Christianity went from being an illegal religion to the official religion of the Roman Empire. At the height of its power, Rome controlled the greatest empire ever seen in Europe at that time. Many of the conquered nations benefited  from Rome. Roman public baths, roads, water supplies, all appeared in Western Europe. The sheer size of the empire was a major reason for the collapse of Rome. In AD 284, the Emperor Diocletian divided the Roman Empire in two parts to make it easier to rule. He created the Western Empire and the Eastern Empire, each with its own leader. Diocletian faced more than just administrative problems. More and more military defenses had to be built across the whole empire. Maintaining an army to defend the border of the Empire from barbarian attacks was a constant drain on the government. Military spending left few resources for other vital activities, such as providing public housing and maintaining quality roads and aqueducts. Frustrated Romans lost their desire to defend the Empire. The empire had to begin hiring soldiers recruited from the unemployed city mobs or worse from foreign countries. Such an army was unreliable and very expensive. The emperors were forced to raise taxes and coin more money frequently which in turn led again to increased inflation. To add to that in AD 307, Constantine became emperor. He moved the capital of the empire to a new city –Constantinople. Constantinople was much further east than Rome and firmly in the eastern empire. This left the western empire very vulnerable to attacks. The eastern empire was closer to the rich soil fertile crescent and was much easier to defend. The west began to deteriorate and went through what was known as a Dark Age. During this time there were no advances in technology, there was turmoil throughout the empire, and literacy declined dramatically. The Roman Empire went from being a thriving world power to two fragmented empires, with the west doing awful and the east maintaining some resemblance of its former glory. Despite the fact that Rome faced numerous changes throughout the centuries it still remained culturally diverse. The start of the Republic was shaped around many cultures. The idea for arches were taken from the Etruscans. The language was derived form the Latin speaking people in the area. The religion, literature, and architecture were influenced by the Greek. During the heights of the empire, war was still ever present. The influence of Rome was spreading to nearby territories and new land was acquired. With the increase in land and population it was only natural for the spread of new ideas to occur. The emergence of Christianity would prove to be a defining feature of the Roman Empire. The fall of the empire produced two weaker half’s of a once  formidable empire. The western side of the empire retained the Latin language and the eastern side chose Greek instead. The resulting wars with neighbors and influx of refugees contributed even more to exchange of languages and cultures. From the beginning of Republic, to the expanding empire, to the halves; east and west, Rome remained multi-cultural. Ancient Rome went through dramatic changes from 500 BCE to 500 CE. It first underwent a change of government; shifting from a republic to an empire. Rome then changed culturally, from being polytheistic and believing in the Greek gods, to being monotheistic and believing in one deity and adhering to the guidelines of Christianity. Furthermore in 476 CE, the Roman Empire collapsed and split into two parts, and was governed by two emperors. Although Rome encountered a these alterations it still remained a multi-cultural civilization.

Things You Should Know About How to Write a Cause and Effect Essay Samples

Things You Should Know About How to Write a Cause and Effect Essay Samples How to Write a Cause and Effect Essay Samples at a Glance Cause and effect essay needs to be written in accordance to the particular format. Narrowing the topic is a significant skill in all sorts of writing including cause and effect essays. Cause and effect essay have many sub-types. Antibiotic the definition essay is intended to fully grasp why and effect. How to Write a Cause and Effect Essay Samples Secrets That No One Else Knows About The vital point to a prosperous essay is having the correct structure. At the conclusion of the very first paragraph, it does have an extensive overview. When you collect all of the information that you require, structuring each paragraph will no longer appear challenging. Placing numerals and creating topic makes it simpler to recognize the info that supports thesis statement. 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Legacies in Ozymandias by Percy Bysshe Shelley and When I...

The Petrarchan sonnets â€Å"Ozymandias† by Percy Bysshe Shelley and â€Å"When I Consider How My Light Is Spent† by John Milton both consider a man’s legacy after death. However, both poems talk about a man’s legacy from very different perspective and come to their own conclusions. In â€Å"Ozymandias†, a traveler describes a broken statue of King Ozymandias (the Greek name for the Egyptian Pharaoh Ramses II) and the barren ruins surrounding the statue. Ozymandias believes that his legacy will last forever. Through the sonnet, Shelley implies that legacies are transient and even the most powerful of men fall in the face of time. â€Å"When I Consider How My Light Is Spent† is about the internal reflection of the speaker on his legacy as he worries whether or†¦show more content†¦This is greatly contrasted by the speaker in Milton’s â€Å"When I Consider How My Light Is Spent†. It is first important to mention that the author of this poem, John Milton, suffered from glaucoma and eventually went blind. Due to this information, it can be implied that Milton’s gradual loss of sight was a source of inspiration for this sonnet and that Milton is the speaker of the poem. Therefore the word â€Å"light† (Milton, 1) can metaphorically take on multiple meanings such as his talent (as it is the light that he brings to the world) or his vision (as one goes blind the world becomes increasingly darker and the ability to see light decreases). Milton losing his vision would be an impediment to his talent (which is his writing) so when he worries that he has spent his â€Å"light† (Milton, 1) unwisely it essentially means that he fears that he has wasted his talent. While King Ozymandias’ legacy comes from how effectively he ruled his kingdom, Milton’s legacy comes from his talent of writing. Although Milton wants to continue his legacy he fears that through blindness that his t alent will become â€Å"useless† (Milton, 4). The anxiety that Milton has is enhanced by the allusion to â€Å"The Parable of Talents† from Matthew 25 in the Bible. In â€Å"The Parable of Talents†, a lord gives three of his servants a talent each (talent in this case meaning the ancient currency). The first two servants invest their talents while the