Causes And Effects Of Strokes Biology Essay

Causes And Effects Of Strokes Biology Essay Stroke is defined as A neurological deficit of cerebrovascular cause that persists beyond 24 hours or is interrupted by death within 24 hours. WHO (1970) A stroke is the rapidly developing loss of brain functions due to a disturbance in the blood vessels supplying blood to the brain. This can be due to ischemia caused by thrombosis or embolism or due to a hemorrhage. As a result, the affected area of the brain is unable to function, leading to inability to move one or more limbs on one side of the body, inability to understand or formulate speech or inability to see one side of the visual field (Donnan GA, Fisher M. May 2008). PREVALANCE AND INCIDENCE: Stroke could soon be the most common cause of death worldwide (Murray CJ, Lopez AD 1997). Stroke is currently the second leading cause of death in the Western world, ranking after heart disease and before cancer (Donnan GA, Fisher M, May 2008)and it causes 10% of deaths worldwide (World Health Organization. 2004) . It has been noted that stroke incidence may vary considerably from country to country. The prevalence of stroke in India was estimated as 203 per 100,000 populations above 20 years, amounting to a total of about 1 million cases. Stroke represented 1.2% of total deaths in India (PK Sethi Neurosciences Today 2002). SEX DIFFERENCES: Men are 1.25 times more likely to suffer strokes than women(PK Sethi Neurosciences Today 2002), yet 60% of deaths from stroke occur in women (Villarosa, Linda, Ed.1993). CLASSIFICATION: Strokes can be classified into two major categories: ischemic and hemorrhagic. Ischemia is due to interruption of the blood supply, while hemorrhage is due to rupture of a blood vessel or an abnormal vascular structure. 80% of strokes are due to ischemia; the remainders are due to hemorrhage (Donnan GA, Fisher M. May 2008). ISCHEMIC STROKE: In an ischemic stroke, blood supply to a part of the brain is decreased, leading to dysfunction of the brain tissue in that area. The four reasons responsible for ischemic stroke are thrombosis, embolism (Donnan GA, Fisher M. May 2008), systemic hypoperfusion (Shuaib A, Hachinski VC .September 1991) and venous thrombosis (Stam J. 2005). HAEMORRAGIC STROKE: Intracranial hemorrhage is the accumulation of blood anywhere within the skull vault. Intracerebral hemorrhage (ICH) is bleeding directly into the brain tissue, forming a gradually enlarging haematoma. RISK FACTORS: High blood pressure, High blood cholesterol levels, Diabetes, Cigarette smoking (Hankey GJ. August 1999), Heavy alcohol consumption (Reynolds K, Lewis B, Nolen JD, et al .2003) , drug use, (Sloan MA, 1991), lack of physical activity, obesity, unhealthy diet (American Heart Association.2007) and Atrial fibrillation. CAUSES: When the flow of blood in an artery supplying the brain is interrupted for more than a few seconds, brain cells can die, causing permanent damage. An interruption can be caused by either blood clots or bleeding in the brain. Most strokes are due to blood clots that blocks the blood flow to brain. Bleeding into the brain occurs if a blood vessel ruptures or if there is a significant injury (Ay H; Furie KL. 2005). BLOOD CLOTS: A common cause of stroke is atherosclerosis. Fatty deposits and blood platelets collect on the walls of the arteries, forming plaques. Over time, the plaques slowly begin to block the flow of blood. The plaque itself may block the artery enough to cause a stroke (Ay H; Furie KL. 2005). The plaque causes the blood to flow abnormally, which leads to a blood clot. A clot can stay at the site of narrowing and prevent blood flow to all of the smaller arteries it supplies. In other cases, the clot can travel and wedge into a smaller vessel (Ay H; Furie KL. 2005). Strokes caused by embolism are most commonly caused by heart disorders. An embolism may originate in a major blood vessel as it branches off the heart. A clot can also form elsewhere in the body for any number of reasons, and then travel to the brain, causing a stroke (Ay H; Furie KL. 2005). Arrhythmias of the heart, such as atrial fibrillation, can be associated with this type of stroke and may contribute to clot formation. Other causes of embolic stroke include endocarditis, or use of a mechanical heart valve. A clot can form on the artificial valve, break off, and travel to the brain (Ay H; Furie KL. 2005). BLEEDING IN THE BRAIN: A second major cause of stroke is bleeding in the brain. This can occur when small blood vessels in the brain become weak and burst. Some people have defects in the blood vessels of the brain that make this more likely. The flow of blood after the blood vessel ruptures damages brain cells (Ay H; Furie KL. 2005). PATHOPHYSIOLOGY: ISCHAEMIC: Ischemic stroke occurs due to a loss of blood supply to part of the brain, initiating the ischemic cascade. Brain tissue ceases to function if deprived of oxygen for more than 60 to 90 seconds and after a few hours will suffer irreversible injury possibly leading to death of the tissue. Atherosclerosis may disrupt the blood supply by narrowing the lumen of blood vessels leading to a reduction of blood flow, by causing the formation of blood clots within the vessel (National Institute of Neurological Disorders and Stroke.1999). Embolic infarction occurs when emboli formed elsewhere in the circulatory system, typically in the heart as a consequence of atrial fibrillation, or in the carotid arteries. These break off, enter the cerebral circulation, then lodge in and occlude brain blood vessels (National Institute of Neurological Disorders and Stroke.1999). HAEMORRAGIC: Hemorrhagic strokes results in tissue injurys by causing compression of tissues from an expanding hematomas. This can distort and injure the tissues. In addition, the pressure may lead to a loss of blood supply to affected tissue with resulting infarction, and the blood released by brain hemorrhage appears to have direct toxic effects on brain tissue and vasculature (National Institute of Neurological Disorders and Stroke.1999). SIGNS AND SYMPTOMS: A stroke symptom typically starts suddenly, over seconds to minutes, and in most cases dont progress further. The symptoms depend on the area of the brain affected. The more extensive the area of brain affected, more the functions that are likely to be lost (National Institute of Neurological Disorders and Stroke.1999). A sudden development of one or more of the following indicates a stroke: Paresis or paralysis of any part of the body, Numbness, tingling, or decreased sensation, Changed or diminished vision, Language difficulties, including slurred speech, inability to speak, inability to understand speech, difficulty in reading or writing, Swallowing difficulties or drooling, Loss of memory, Vertigo, Loss of balance or coordination, Personality changes, Mood/emotion changes, Drowsiness, lethargy, or loss of consciousness, Uncontrollable eye movements or eyelid drooping. SUB TYPES: If the area of the brain affected contains one of the three prominent Central nervous system pathways-the spinothalamic tract, corticospinal tract, and dorsal column, symptoms may include hemiplegia and muscle weakness of the face, numbness, reduction in sensory or vibratory sensation. In most cases, the symptoms affect only one side of the body. The defect in the brain is usually on the opposite side of the body depending on which part of the brain is affected. In addition to the above CNS pathways, the brainstem also consists of the 12 cranial nerves. Hence a stroke affecting the brain stem can produce symptoms relating to deficits in the cranial nerves. The symptoms are altered smell, taste, hearing, or vision, drooping of eyelid and weakness of ocular muscles, decreased reflexes like gag, swallow and pupil reactivity to light, decreased sensation and muscle weakness of the face, balance problems and nystagmus,altered breathing and heart rate,weakness in sternocleidomastoid muscle with inability to turn head to one side,weakness in tongue. If the cerebral cortex is involved, the CNS pathways can again be affected, but also can produce the symptoms like aphasia, apraxia, visual field defect, memory deficits, hemineglect, disorganized thinking, confusion, hypersexual gestures ,anosognosia (Bamford JM 2000). When the cerebellum is involved, the patient may have the symptoms like Trouble walking, altered movement, coordination, Vertigo and disequilibrium (Bamford JM 2000). ASSOCIATED SYMPTOMS: Loss of consciousness, headache, and vomiting usually occurs more often in hemorrhagic stroke than in thrombosis because of the increased intracranial pressure from the leaking blood compressing on the brain. DIAGNOSIS: The techniques which were used to diagnose the stroke are neurological examination, CT scans or MRI scans, Doppler ultrasound, and arteriography. The diagnosis of stroke itself is clinical, with assistance from the imaging techniques. Imaging techniques also assist in determining the subtypes and cause of stroke. There is yet no commonly used blood test for the stroke diagnosis itself, though blood tests may be of help in finding out the likely cause of stroke (Hill M 2005). PREVENTION: Screening for high blood pressure at least every two years, regular cholesterol check up, treat high blood pressure, diabetes, high cholesterol and heart disease, follow a low-fat diet, quit smoking, exercise regularly, lose weight if you are over weight, avoid excessive alcohol use (Goldstein LB, Adams R, Alberts MJ et al. 2006). TREATMENT: Treatment of ischemic stroke: Pharmacologic thrombolysis with the drug tissue plasminogen activator (tPA), Mechanical thrombectomy and anticoagulants. Treatment of hemorrhagic stroke: Patients with intracerebral hemorrhage require neurosurgical evaluation to detect and treat the cause of the bleeding, although many may not need surgery. Patients are monitored and their blood pressure, blood sugar, and oxygenation are kept at optimum levels. PHYSIOTHERAPY TREATMENT: The rehabilitation techniques commonly used were Roods Sensorimotor Approach, Knotts and Voss Proprioceptive Neuromuscular Facilitation, Brunnstroms Movement Therapy, Bobaths Neuro Developmental Therapy, Motor Relearning Programme, Bimanual Rapid Alternating Movement, Motor Imagery Therapy, Robot Assisted Movement Therapy, Functional Electrical Stimulation, Bilateral Isokinetic Training, Cyclic Electrical Neuromuscular Stimulation, Biofeedback etc. PROGNOSIS: The results of stroke vary widely depending on size and location of the lesion (Stanford Hospital Clinics.2005). Dysfunctions correspond to areas in the brain that have been damaged. Disability affects 75% of stroke survivors enough to decrease their employability (Coffey C. Edward.2000). Stroke can affect patients physically, mentally, emotionally, or a combination of the three. 30 to 50% of stroke survivors suffer post stroke depression, which is characterized by lethargy, irritability, sleep disturbances, lowered self esteem, and withdrawal. Depression can reduce motivation and worsen outcome (Senelick Richard C.1994).

Volcanoes and Earth :: Geology

VOLCANOES AND THE EARTH SYSTEM EFFECTS OF VOLCANIC GASES Most of the gases in the atmosphere originally come from the Earth's interior. Gases within magma are dissolved because of high pressures beneath the earth's surface, but reduced pressure at the surface allows dissolved gases to expand and escape. When a volcano erupts, gases such as sulfur dioxide, carbon dioxide, chlorine, argon, sulfur, carbon monoxide, fluorine, and water vapor escape into the atmosphere. Although many of the gases emitted during a volcanic eruption can be helpful to the earth, a lot of the gases can be disruptive to the earth system. Quite possibly the only gas that is generally better for the atmosphere than the rest of the gases is water vapor. Although it is a greenhouse gas, water vapor from volcanic eruptions adds to the earth's water supply. Sulfur dioxide emitted from volcanic eruptions is one of the main chemical compounds responsible for the earth's already dangerous acid rain problem. Carbon dioxide is universally considered one of the most dangerous greenhouse gases on the planet. Increases in this gas have been proven to cause an increase in the average temperature of the Earth. Global warming can result in the melting of polar ice caps. This melting causes the rising of ocean levels, which can flood coastal cities. Volcanoes contribute about 110 million tons of carbon dioxide per year. Although this can be viewed as a bad problem for the ever-increasing problem of global warming, volcanoes can actually cause the opposite effect. Volcanoes can help cool the earth's surface by forming sulfuric acid aerosols that reflect the sun's rays. This is contradicted though by the carbon dioxide that adds to the greenhouse effect. Weather patterns can be disrupted by sulfur dioxide. In a reaction involving the sun and water vapor, sulfur dioxide can turn into sulfuric acid. This sulfuric acid can combine with rain and cause acid rain to fall to earth. Sulfuric aerosol remains in the air long after the volcano has erupted. These aerosols can last for years and studies have shown a strong correlation between periods of long-term sulfuric aerosol layers in the atmosphere and a resulting temperature decrease during those same years. Without replenishment, the sulfuric acid aerosol layer around the earth is gradually depleted, but it is renewed by each eruption rich in sulfur dioxide. This was determined after the eruptions of such volcanoes as El Chichon in Mexico and Mt. Volcanoes and Earth :: Geology VOLCANOES AND THE EARTH SYSTEM EFFECTS OF VOLCANIC GASES Most of the gases in the atmosphere originally come from the Earth's interior. Gases within magma are dissolved because of high pressures beneath the earth's surface, but reduced pressure at the surface allows dissolved gases to expand and escape. When a volcano erupts, gases such as sulfur dioxide, carbon dioxide, chlorine, argon, sulfur, carbon monoxide, fluorine, and water vapor escape into the atmosphere. Although many of the gases emitted during a volcanic eruption can be helpful to the earth, a lot of the gases can be disruptive to the earth system. Quite possibly the only gas that is generally better for the atmosphere than the rest of the gases is water vapor. Although it is a greenhouse gas, water vapor from volcanic eruptions adds to the earth's water supply. Sulfur dioxide emitted from volcanic eruptions is one of the main chemical compounds responsible for the earth's already dangerous acid rain problem. Carbon dioxide is universally considered one of the most dangerous greenhouse gases on the planet. Increases in this gas have been proven to cause an increase in the average temperature of the Earth. Global warming can result in the melting of polar ice caps. This melting causes the rising of ocean levels, which can flood coastal cities. Volcanoes contribute about 110 million tons of carbon dioxide per year. Although this can be viewed as a bad problem for the ever-increasing problem of global warming, volcanoes can actually cause the opposite effect. Volcanoes can help cool the earth's surface by forming sulfuric acid aerosols that reflect the sun's rays. This is contradicted though by the carbon dioxide that adds to the greenhouse effect. Weather patterns can be disrupted by sulfur dioxide. In a reaction involving the sun and water vapor, sulfur dioxide can turn into sulfuric acid. This sulfuric acid can combine with rain and cause acid rain to fall to earth. Sulfuric aerosol remains in the air long after the volcano has erupted. These aerosols can last for years and studies have shown a strong correlation between periods of long-term sulfuric aerosol layers in the atmosphere and a resulting temperature decrease during those same years. Without replenishment, the sulfuric acid aerosol layer around the earth is gradually depleted, but it is renewed by each eruption rich in sulfur dioxide. This was determined after the eruptions of such volcanoes as El Chichon in Mexico and Mt.

David Copperfield by Charles Dickens Essay -- English Literature

David Copperfield by Charles Dickens "David Copperfield" charts a little boy's wretched childhood and his progress to a successful novelist and his finding true love along the way. The author made a romantic effort to be realistic and thus captured the essence of all parts of human life in the pages of this book. David Copperfield is the main character of the novel, but he is not the hero of the novel. David, a fatherless child born in a little village in Victorian England is deeply attached to his mother and his nurse Peggotty. His world turns upside down when his mother marries a man by the name of Murdstone. The pain that his stepfather and his "murdering woman of a sister" inflict upon David leads to his untimely loss of innocence. David is sent to "Salem House" a school where he is forced to live under the brutal regime of Mr. Creakle. Soon he loses his beloved mother and is "provided for" by his stepfather to work as a labourer at a warehouse in London. David feels his "hopes of growing up to be a learned and distinguished man crushed" in his bosom. Disguste...

Literary Analysis Paper on Lord of the Flies Essay

Struggling for Power The novel Lord of the Flies can be a violent like story. All throughout the novel, William Golding does a good job of showing how Ralph and Jack quarrel between each other whether who should take charge and who will be the leader to keep things in order. William Golding uses the struggle for power to show the different sides of good and evil throughout the novel Lord of the Flies. The theme Struggle for Power plays a huge part between Ralph and Jack which causes them and the boys to act in savagely ways. The constant battle for power leads to a debacle in their group on the island. Struggle for power in the beginning of Lord of the Flies is mainly between Jack and Ralph. Golding demonstrates this when Jack says â€Å"I ought to be chief because, I’m chapter chorister and head boy,† (14). This shows that Jack is determined to be the leader no matter what everyone else says and therefore showing his character as being very controlling. As a result, the boys vote Ralph to be chief which makes him lead in a more reliable way. Now Ralph portrays a good example of a true leader. He demonstrates his brave and good leadership skills when he says â€Å"I’m chief. I’ll go. Don’t argue†¦You. Hide here. Wait for me† (114). This quote gives us a good example of the willingness Ralph is to protect his tribe and it also shows us the good leadership skills Ralph has. Jack is very determined to steal the leadership from Ralph and continues to do so throu ghout the novel. A specific event showing this is when Jack says â€Å"He’s not a hunter. He’d never got us meat. He isn’t perfect and we don’t know anything about him. See more: how to write an analysis paper on an article examples He just gives orders and expects people to obey him for nothing† (140). This quote gives a good indication of how Ralph and Jack go back and forth. Jack and Ralph both want different things, which cause them to disagree almost on everything. Now Jack’s cravings for power leads to misfortunes in their group when Jack says â€Å"Who thinks Ralph oughtn’t to be chief, hands up, whoever wants Ralph not to be chief?†(140). This quote shows us that Jack is  always in the constant need of power and how every chance he gets he is always trying to steal the power from Ralph. He gives us a good example of how demanding his character is and how he will not stop till he gets what he wants as chief. Jack gives a good example of using his demanding sense of power to try to gain control by continuing his battle with Ralph to gain power when Jack says â€Å"Listen all of you. Me and my hunters are living along the beach at the flat rock. We hunt and feast and have fun. If you want to join come and see us. Perhaps we’ll let you join. Perhaps not† (140). In this situation when jack was turned down to be chief the first time he walks off making his own tribe therefore leaving the denouement of the group damaged. Jack believes that the way things are being run by Ralph are not the way things he would run them and he should be the chief. When Jack decides to leave the rest of the group and go on to make his own tribe and own rules, he soon later realizes he has no way of making a fire so he goes back to tell them they can come over to their side for a feast. He then leads an attack to steel Piggy’s glasses which becomes clear when Ralph confronts Jack about the specs. After they stole the specs we see the true meaning of the rejection of rules when Ralph says â€Å"Now Piggy can’t see, and they came, stealing†¦and stole our fire. They stole it. We’d have given them fire if they’d asked. But they stole it and the signal’s out and we canà ¢â‚¬â„¢t even be rescued†¦We’d have given them fire for themselves only they stole it† (168). This quote gives us a good explanation of how the boys and their savagery and it also shows tells us that the need for power is no more because of Jack going his separate way with his own tribe. William Golding does a good job of not only giving you a in depth mental picture of what is going on between Jack and Ralph and their struggle for power but he also does a good job of giving a good picture of the novel as a whole. All throughout the novel Lord of the Flies, Ralph and Jack tussle as to whom should be chief of the island. Struggle for power plays an important role throughout the novel and William Golding gives us a good mental picture as to what is going on in the story. The need for power between Jack and Ralph continues throughout the novel and it also shows the different sides of the good and evil sides of what power can do to us.