Several scientific terms are relatively easy to define, others tend to be more difficult; “health” and “disease” fall under the latter category. Many suggest that “disease” is merely a disorder of a system’s normal functions while “health” is the absence of disease. On the other hand, could a person whose bodily systems are functioning properly but who is unhappy or depressed be considered healthy? Can an alcoholic or drug-addict whose habit has not as yet caused any physical harm be likewise described? Without a doubt, health is more than just a well-being physically; it involves social and mental well-being as well.
Health clearly being difficult to define and understand, “disease” is thought to be even more complex. Doctors, scientists, and researchers try enduring the problem in classifying diseases. Although a number of diseases fit neatly and entirely into one category, some seem to belong to more than one group and nevertheless some even combine elements of all types. Having all this in mind, six categories are frequently recognized: infections, inherited, degenerative, mental, human inflicted, and deficiency. From these six categories, “any disease may be acute…or chronic” (Susan 627).
When a disease is acute, it means that it may appear suddenly and have a short time period while a disease that is chronic is the total opposite; it may develop slowly and be persistent. A disease may be the result of environmental influences such as radiation or pollution or it may not even have an apparent cause. Other diseases have a serious of risk factors, each factor increasing the chance of developing that illness. Finally, the life-style often impacts greatly on a particular disease. Communicable diseases that can be passed on from one individual to another are known as infections.
An infection is a “pathological state resulting from the invasion of the body by pathogenic microorganisms” (Miller 1), where a pathogen is a microorganism that causes a disease. For a microorganism to be considered a pathogen, it must “gain entry to the most, colonize the tissues of the host, resist the defenses of the host, and cause damage to the host tissues” (Susan 628). For a pathogen to enter can be broadly done in two ways: via the skin or through natural openings. The skin being thick and continuously regenerating creates an effective barrier to pathogens.
It is when there are cuts and abrasions where an entry can occur. Another way an entry of a pathogen through the skin can be no thanks to the biting of insects such as mosquitoes, lice and fleas, or bites and scratches from animals may also allow entry. As for the entry of pathogen through natural openings, it occurs by many means. Many infectious diseases are respiratory, thus infect via the air inhaled along the respiratory system. Consumption of food and water may carry the agents into the stomach and intestines via the mouth.
The last method would be through the genital and urinary openings, the most common where pathogens are easily transmitted is during sexual intercourse (Susan 628). The following step for a microorganism to be considered a pathogen is for it to colonize the tissue of the host. Pathogens need to “fix” themselves at the site of their infection. This is done through a combination of physical modifications or chemical means. As soon as the pathogen has been modified, the multiplication of that pathogen occurs rapidly. Some of these pathogens produce toxins causing irritation, leading to responses such as scratching, coughing, and sneezing.
These responses aid the infection to spread to unaffected areas. Enzymes that are produced by pathogens after being “fixed” are able to penetrate into cells and slowly invading a tissue. After the pathogen is colonized in the tissue of the host, it will resist the host’s defenses. This is done by resisting ingestion by phagocytes, avoiding digestion if ingested by a phagocyte, or destroying the phagocyte. A phagocyte is a cell that “engulfs and digests debris and invading microorganisms” (Miller 1). Last but not least, the final criterion for a microorganism to be considered a pathogen is causing damage to the host.
Some pathogens only cause damage in very large numbers while others only relatively small. Damage to the host tissue arises as a consequence of one or more conditions. These three conditions include: the multiplication of a microorganism, toxins from the pathogen, and as a result of the immune response. Multiplication of a microorganism goes way back to the late 1800s where Dr. Percy Frankland “records some series of very interesting experiments on this subject, and shows that the peculiarities of multiplication of microorganisms have an intimate connection with the dissemination of infectious diseases” (JAMA 73).
Through time it has been proven that the build-up of pathogens blocks the functioning of certain organs. Second, toxins produced by microorganisms’ damage the host. Most bacterial pathogens produce toxins. These effects are highly diverse. Some are extremely poisonous, others cause fever; several inhibit protein synthesis, and many more. Third, as a result of the immune response damages the host. To enable the host to fight a pathogen, “the blood supply to the infected area is increases because of vasodilation” (Susan 630), this could then lead to inflammation and soreness in the area.
Finally, the immune response can cause a rise in temperature and consequent a fever. These symptoms are very common in most diseases. There is quite a large list of infectious diseases that are very harmful all around the world. By understanding what an infectious disease is, it can be understood why the following diseases are considered to be infectious: Acquired Immune Deficiency Syndrome (AIDS), influenza, tuberculosis, cholera, salmonella, malaria, athlete’s foot, and the list goes on.
With considerable advances made in recent years in our understanding of heredity and genetics has improved exponentially the ability for doctors and researchers to recognize and treat inherited disease in a way that was unthinkable a decade ago. In the developed countries, infectious diseases have been reduced greatly in comparison to the developing and under developed countries. This gave the developed countries a chance to be aware and research alternative causes of death such as inherited diseases and focusing medical attention on curing these. Inherited diseases are genetic, making them very complex.
This is all thanks to the mapping of genes from the human genome project. The human genome will “identify the specific gene or genes which lead to many inherited disorders and, through techniques such as gene therapy, enable us to rectify” (Susan 638) these. From that point on, even though these diseases were incurable, they are now thanks to the biotechnology of today. With the biotechnology, genetic engineering has developed. In genetic engineering, gene therapy can be conducted to cure the incurable, which is simply replacing the defected gene with a good one.
Unfortunately, putting it in simple terms is not what gene therapy appears to be; for it is an extremely difficult therapy to conduct and is still very new. Likewise for the infectious diseases, there are a wide variety of genetic diseases or disorders. A genetic disorder has been discovered being caused by the following: deletion, duplication, inversion, and translocation. Each is fairly simple in grasping what occurs in the gene. As for deletion, it is when a “chromosomal fragment is lost” (Urry 298). A duplication is when a “segment is repeated” (Urry 298).
When a chromosomal fragment is “reattached to the original chromosome but in the reverse orientation” (Urry 298), it is called an inversion. Lastly, a translocation is when a “segment from one chromosome moves to a nonhomologous chromosome” (Urry 298). Some examples of genetic disorders include Down syndrome, Parkinson Disease, Sickle Cell Anemia, Cystic Fibrosis, and many more. The next category of diseases is the degenerative diseases. Degenerative diseases are the “result of the gradual breakdown in the functioning of tissues or organs as a result of deterioration” (Susan 639). Deterioration may be the result of ageing.
An example of this is senile dementia and arthritis. Dementia adversely affects memory, intellectual capacity, attention span, personality, and motor control. Some of these diseases are still a mystery on what causes it, for example the Alzheimer’s disease. Another form of dementia is the result of aging, as mentioned earlier. These lead to a sudden, rather than gradual, onset of dementia. For example, mental deterioration can be caused by a reduced blood supply in the brain. This would be because of “atherosclerosis which causes a narrowing of arteries due to the hardening and thickening of their walls” (Susan 639).
Also, thromboses may arise in the vessels, leading to a stroke. Or the walls may split, resulting in a “cerebral hemorrhage” (Susan 639). At this moment, there is no cure for these diseases, only treatments. The treatment usually consists of making the best use of a patient’s remaining faculties. As for arthritis is the name given to a variety of inflammatory diseases that affect the joints and cause pain and stiffness. This has a variety of factors such as “old age, injury, infection, genetic influences, gout, cancer, autoimmunity, and nervous disease” (Susan 640).
Following is the mental illness category. Although it may seem odd the previous category, degenerative diseases, that it does not fit into mental illness because it is dealt in the brain as well, there are lots of distinctions. The term mental illness covers a broad range of disorders which cause “psychological, personality or behavioral symptoms” (Susan 641). One factor is definitely the society the person is in. What constitutes a mental illness in one society may not be for another. Respectively, what is considered abnormal or deviant in one group might be perfectly acceptable in another.
Within the mental illness, it could be categorized between neuroses and psychoses. Neuroses covers personality disorders which often result in an exaggerated or irrational response to the ordinary stresses and demands of life. Psychoses are mental disorders of a more severe kind which often involve an extensive personality disorder. The person could be disorientated in time and space, “hallucinations can be experienced and delusions may arise” (Susan 641). The most known psychosis is schizophrenia. The second last category is human inflicted diseases.
These are a number of disorders and illnesses which are direct consequence of an individual’s premeditated actions, where in some cases, the “harmful consequences of the actions are known at the outset; in other cases, the damage only becomes apparent later” (Susan 642). These illnesses include occupational diseases, as well as alcoholism and drug addiction. The last category is the deficiency diseases. These are caused by the shortage of some essential nutrient in the diet. Kwashiorkor could be considered the most dramatic, where it is a “form of malnutrition that occurs when there is not enough protein in the diet” (ADAM 1).
Several diseases result from the deficiency of vitamins and minerals. Lacking vitamin C can lead to scurvy, of vitamin D can lead to rickets, while deficiency of iron causes anemia. Having this in mind, the first step to protect ourselves from diseases depends on our diet. Clearly, a carefully balanced diet will protect against the deficiency diseases. As for the rest of the diseases it depends on each of their categories. As for the infectious diseases, there are immunity and vaccinations, along with antibiotics, sterilization and disinfection; although, a balanced diet and exercising frequently helps a whole lot.
Unfortunately for the categories such as inherited diseases, degenerative diseases, and mental illness there is little known fact on what causes those diseases. With little knowledge on the cause, much cannot be done in terms for curing those diseases. Fortunately with biotechnology and numerous minds maturing daily, much is being done to treat these diseases and conducting sophisticated therapy such as gene therapy for the inherited diseases. And last but not least, as for human inflicted diseases, much could be done by each individual.
It is not an easy task quitting instantly, but gradually working on it is makes the impossible, possible. Thankfully throughout the decades there has been an enormous progress in understanding different diseases and dealing with the, which creates a lot of job opportunities to help people out all over the world.
Work Cited Toole, Susan. Biology For Advanced Level. Fourth Edition. London: Stanely Thornes, 1999. Print. Urry, Lisa. Biology Volume 1. Custom Edition for Lone Star College – CyFair. San Franciso, California: Pearson Education, Inc. 2008.