Introduction to Human Health and Disease
Human Health and Disease: In general, we define health as the absence of disease. In other words, if a person is not ill, he is healthy. The irony is that one cannot define health without giving the reference of a disease and vice versa. Therefore, we cannot define merely by saying the absence of disease. Health is a broad term and can be defined as a state of complete mental, physical and social well being.
Now, the next term is disease, how can we define disease? If we break the word disease like dis-ease – it means, if a person is not feeling ease or comfortable, it is called disease. However, there is a contrasting term called disorder. Let’s understand the actual meaning of disorder and how it is different from the term disease. Suppose a person breaks his hand bone. Do we say, that person has disease, no. We just say that the person met an accident and broke his bone. So, we cannot use the term disease everywhere, but disorder term can be applied to a number of places, as this term is more universal and important. Now, the question is how we define disorder. Well, we can define disorder as any kind of anatomical or physiological disturbance or deviation. Anatomical disturbance means any kind of fracture or cut in the body, or bleeding — all come under disorder. Likewise, physiological disturbance means any problem in the physiological state of the body such ad diabetes, arteriosclerosis, alzheimer, etc — all come under the category of disorders. Besides, there are some other terms which we need to be aware of. These terms and their meanings are mentioned below:
Some Important Terms Related to Health and Disease
Etiology: Study of causative agent of the disease
Pathogen: Disease causing agent
Pathogenesis: Progression of disease in the body
Pathogenicity: Ability of pathogen to cause disease
Virulence: Degree of pathogenicity
Infection: Interaction between host and parasite
Sign and symptoms: Observable and non observable changes in the body during infection
Epidemiology: Study of preventive methods of the disease
Incubation period: It is the time duration from the day of entrance of the pathogen in the body up to the appearance of symptoms of the disease for the first time. Now,if someone asks that there are two pathogens A and B and their respective incubation periods are 4 days and 15 days, which pathogen would be more dangerous? The answer would be A because, the pathogen A would take only 4 days to cause a disease. On the other hand, pathogen B would take 15 days to cause a disease because the pathogen B is mild in nature and works slowly inside the body to cause a disease.
Acute and Chronic disease: Acute means dangerous and its incubation period would be very short. On the other hand, chronic disease (mild) means the appearance of he disease would take a longer time.
Sporadic, Epidemic, and Pandemic disease: Sporadic disease is not found in all the populations. It could be present in some people of a population in an area. Likewise, it could be present in some people of a population in another area, etc. Epidemic disease, on the other hand, is a kind of disease that is highly infectious and spreads rapidly in the population. Pandemic disease is a kind of disease that spreads rapidly from one continent to another continent in no time.
Endemic disease: If a disease is present in population of a specific geographical region and continous generation after generation, such kind of disease is called endemic disease. For example, endemic goitre.
Mode of Transmission of Disease (Human health and disease)
Faeco-oral transmission: If the disease causing pathogen is transmitted by contaminated food or water through the mouth and released with undigested food through the anus. Example: digestive system disorders.
Droplet infection: transmission through suspended droplets in the air. Example: respiratory dosorders
Fomite transmission: transmission through utensils, meaning the infection spreads through utensils used by the person who is having a particular disease. Example: typhoid
Types of Diseases (human health and disease)
There are two main categories of diseases:
A. Congenital diseases: This type of disease is present right from the time of birth. Examples: genetic disorders, chromosomal disorders
B. Acquired diseases: This type of disease happens after the birth of the child. It means, such diseases are not present right from the birth rather diseases are acquired after the baby is born. Acquired diseases are further divided into two types:
a. Non communicable disease: as the name suggests, such diseases are not spread from one individual to another. Non communicable diseases are of different type:
- Deficiency diseases
- Degenerative diseases
- Allergic disease
- Cancer
- Mental disease
- Addictive disease
b. Communicable disease: such diseases are spread from one individual to another.
Brief information on non communicable diseases
Deficiency diseases: They are of four main types:
- Vitamin deficiency: Example: Scurvy / Bleeding gums (due to Vitamin C deficiency); Rickets (Vitamin D deficiency); Night blindness (Vitamin A deficiency)
- Hormonal deficiency: Example: goitre, diabetes, Cushing syndrome, etc
- Mineral deficiency: Iron deficiency leads to anemia
- PEM (Protein Energy Malnutrition): Kawahiorkar, Marasmus disease
Degenerative diseases: This type of disease could be present in different organ systems of the body such as digestive system, respiratory system, nervous system, excretory system, etc.
Examples:
Jaundice: it is a degenerative disease of the liver as it causes degeneration of the liver.
Atheroscleoris, arteriosclerosis, myocardial infraction
Glomerulo nephritis, Renal calculi
Allergic disease:
Examples: Hay fever, Asthma, etc
Cancer
Examples: Breast cancer, blood cancer, prostate cancer, etc.
Mental Illness
Examples: Depression, Insomnia, bipolar disorder, split personality, etc.
Addictive Disorder:
Examples: Alcoholism, tobacco addiction
Communicable diseases
- Bacterial disease
- Viral disease
- Protozoan disease
- Helminthic disease
- Fungal disease
Human Health & Disease – L 1 | Class 12 | Unacademy NEET | LIVE DAILY | NEET Biology | Sachin Sir