Free «Applied Microbiology» Essay Sample


Stroke is a very complex condition with varying causes and effects on a person. Stroke may lead to either permanent or temporary loss of function. The human brain is the most important organ; hence any defect or loss of any of its function may be lethal or dehumanizing. This may force and individual to completely depend on others for basic day to day activities. The brain controls all aspects of body activities, for example moods, movements, intelligence, abilities, failings, feelings, thoughts, individual characteristics etc. our brain makes us the persons that we are (Bogousslavsky, 2002: 150)

Stroke is sometimes referred to as cerebrovascular accident or brain attack. This is a sudden mutilation of circulation in the cerebrum in a single or multiple blood vessels taking blood to the brain. This condition interrupts the supply of oxygen and in most cases causing necrosis or serious damage in the brain tissue. If the circulation is normalized in time, the chances of recovery are fairly higher than when time is taken before normalization. But in most cases majority of individual who experience stroke remain permanently disabled and most of them experience the recurrence of the same conditions after a few months or weeks or sometimes after years (Williams and Wilkins, 2009: 193).

Effects of stroke on the brain

The given capabilities that are either affected or lost during a stroke attack are dependent on the level to which the brain had been damaged, and more importantly the part of the brain where the brain attack took place: brain stem, right hemisphere, cerebellum, or left hemisphere.

Consequences of strokes occurring on the Right Hemispheres

Since the left side of the human body is under the control of the right-brain hemisphere, stroke affecting the right hemisphere results in the paralysis of the left side of the body. The condition is referred to as hemiplegia. Individuals who have suffered a right-hemisphere stroke may develop complications with their perceptual and spatial abilities. These individuals may have difficulties in judgments of distances or difficulties in guiding their hands in an effort to tie shoes, button shirts or picking objects of the ground. They may also lose the ability of differentiating up-side down from right side up (Williams and Wilkins, 2009: 223).

Apart from these physical disabilities, individuals who have survived the right- hemisphere stroke lose their judgmental abilities and this is evident in their behavior. Their actions are in most cases impulsive, that they forget their impairment and think that they have the ability to perform a specific task as before. This may be very dangerous sometimes. For example some may try to walk without assistance or even try to a vehicle as they did before the stroke. Individuals, who have suffered right-hemisphere stroke, do experience left-side neglect. This is due to visual a complication that makes these individuals ignore or forget people or objects on their left side (Williams and Wilkins, 2009: 226).

Some of individuals who have survived right-hemisphere stroke may develop complications with long term memory.  That is they may have the ability to recall things or events that took place many years ago but forget to remember those events that have taken place in short while.

Left Hemisphere Strokes

The brain’s left hemisphere is responsible for movement of the body’s right side. Both speech and language under its control.  A stroke attack on this hemisphere results in hemiplegia, that the paralysis of the body’s right side. Some individuals who have experienced this kind of stroke may develop aphasia, this is a term used to describe both language and speech related complications. Unlike their counterparts suffering from right hemisphere stroke, individuals suffering from left sphere stroke have tendency of developing cautious behavior that is slow. They too develop memory complications (Bogousslavsky, 2002: 180).

Cerebellum strokes

Cerebellum is the part of the brain that controls majority of the reflexes and our coordination and balance.  Hence stroke affecting the cerebellum results in torso and head abnormal reflexes, dizziness, vomiting, balance problems and coordination.

Brain stem strokes

Brain stem controls the involuntary functions, for example blood pressure, heart beat and rate of breathing.  Other abilities such as speech, eye movements, swallowing and hearing are the control of this section of the brain. All impulses emerging from the hemispheres have to pass through this part of the brain as they travel to the legs and arms, individuals affected by stroke in the stem of the brain may be paralyzed in either side of the body (Bogousslavsky, 2002: 191).

Thrombolytic Drugs (Fibrinolytic drugs)

These are drugs used to lyses blood clots. Clots of blood can take place in part of the any vascular bed; when these clots occur in the pulmonary, coronary or cerebral vessels the consequences may be lethal.

Mechanism of action of these drugs

These drugs lyses blood clots through the activation of plasmogen, which produces a cleaved product referred to as Plasmin. The plasmin formed is a proteolytic enzyme with the ability to destroy cross-links between molecules of fibrin, which maintains the structural integrity of these blood clots. These drugs are commonly referred to as “Plasmogen activators” because of their mode of action.

Example of a drug: Alteplase.

Generic name: Activase

Mode of administration: Intravenous bolus followed by an infusion due to its short half life. It has a half life of less than five minutes.

Contraindications and site effects

Due to systemic lysis and fibrinogenolysis of hemostatic plugs that are normal. Much of the bleeding is observed the site of catheterization site, although cerebral and gastrointestinal hemorrhages may take place.

Chronic obstructive pulmonary disease

This refers to obstruction of the airways that is persistent as a result of chronic bronchitis, emphysema or both conditions. Bronchitis is basically characterized by inflammation whereas emphysema is characterized by the destruction of the lung tissue and the disappearance of the alveolar architecture. Despite the presence of unique and distinct morphological chances that take place both in lung tissue and airways; they coexist in most cases to variable degree. The major cause of Chronic Obstructive pulmonary disease is smoking of cigarettes. The main symptoms include cough and shortness of breath (Grant and McSweeny, 1988: 14)

Effects of lung diseases on the structure of the lungs

The lungs’ bronchioles (airways) are composed of smooth muscles and their attachment to the of alveolar walls makes them remain open. Emphysema results in the destruction of attachments of the alveolar walls leading to bronchioles collapse, this results in permanent obstruction of air flow.  Glands that line lung bronchi (large airways) increase in size and the production of the mucus. This leads to inflammation of bronchioles causing spasm of muscles, hence further obstruction of airflow. Further blockage of air flow may be caused by secretions due to inflammation Grant and McSweeny 1988: 14).

Central bronchi walls are made up of outer columnar epithelial cells which are characterized with protruding cilia. Between the columnar cells are interspersed goblet cells, which produce part of the mucus lining the respiratory tract. Both epithelial cells and goblets are attached or anchored to the basement membrane separating them from sub mucosal region containing muscle tissue, supporting structures and additional mucous glands. Individuals suffering from chronic bronchitis are characterized with respiratory tract mucus that is excess and abnormally enlarged mucous glands. The mucus is deposited in lumen’s airways through the small channels on the mucosal walls. In chronic bronchitis patients, the typical coordinated, rhythmic cilia movements is either virtually depressed or virtually absent. This depresses the basic mechanisms that dispose foreign particles that get their way to the lungs (Grant and McSweeny, 1988: 16)

In smaller airways (2mm diameter and less) small changes have been observed. One of the changes that are common to both young asymptomatic smokers and individuals with chronic bronchitis is the narrowing of the lumen as a result of mucosal thickening.

One the basic characteristics of emphysema is the abnormal, enlargement of air spaces that is permanent distal to the terminal bronchi followed by their wall’s destruction.

Another change that occurs in lungs as a result of COPD is the continuous loss of elastic recoil, which brings about changes in the forces working on lungs so that expiratory and resting positions tend to enlarge. This loss of lung elasticity results in the reduction of airway caliber and the resistance of peripheral airflow increases. There is also the increase in the dimensions of alveolar (Grant, and McSweeny, 1988: 23)

 One of the effects of COPD is the obstruction of airflow and this obstruction is chronic. This is commonly defined as a reduction of airflow rate as one exhale. In some individuals, the obstruction of airflow can be partially be reversed either through treatment or spontaneously.  This obstruction of airflow results in the trapping of air in lungs after a complete exhalation, and increase in breathing effort. COPD can also lead to the decrease in the number of alveolar capillaries. These complications have a negative impact on the carbon dioxide and oxygen exchange between blood and alveoli.  These complication may result in the normal levels of carbon dioxide and low levels of oxygen in earlier stages of COPD and an a fall in the levels of oxygen accompanied by an increase in the levels of carbon dioxide levels in the later stages of this complication (Grant and McSweeny,  1988: 23).

Hyperinflation of lungs, bullae or blebs that are occasionally observed on chest film. Increase in lung capacity, rise in the residual volume and the increase in the volume of other compartments of the volume of the lungs (Bames and Hansel, 2001: 31).


These are medications that are used in the relaxation of muscles surrounding the lung bronchi hence enabling easier breathing. They are the primary medications for bronchospasm treatment or relief, which are primary the contraction of smooth muscles surrounding the bronchioles and bronchi. These contractions results in the constriction of the airways or narrowing and this results in difficulties in breathing (Bames and Hansel, 2001: 31).

Examples of Bronchodilators. Brand name: Atrovent

Generic name: Ipratropium bromide inhaler.

 Preparation: Inhaler 18 mcg/actuation. The inhaler unit supplies 200 inhalations.

Mechanism of Action

This drug belongs to a class of drugs referred to as bronchodilators whose main action is the dilation of lungs’ bronchi. In individuals with COPD, narrowing of the bronchi is caused by cholinergic nerves through the stimulation of bronchi’s surrounding muscles to contract.

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Hence Ipratropium bromide has anti-cholinergic activity which results in the blockage of cholinergic nerves, therefore resulting in the relaxation of the muscles surrounding the bronchi and hence dilation of bronchi (Bames and Hansel, 2001: 34).


This drug is administered as a preventive therapy. Doses vary from 2 to 6 inhalation. In some cases extra prescription may given 2 to 4 times per day. For effective medication continuous use of medication is required (Bames and Hansel, 2001: 34).

 Counter indications

Animal studies on the effects of Ipratropium bromide have not indicated any negative effects on the fetus. Same studies on human subjects have not been carried out (Bames and Hansel, 2001: 34).

Side effects

The common side effects are flu-like symptoms, sleeplessness, tremor, sore throat, nervousness, chest pain etc. the symptoms have observed in ten to twenty individuals who use this medication (Bames and Hansel, 2001: 36).


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