Human Health and Diseases

Human health is a state of complete physical, mental, and social well-being, not merely the absence of disease or infirmity. It depends on a balanced diet, proper hygiene, regular exercise, and a stress-free lifestyle. The human body has several defense mechanisms, such as the immune system, which protect it from harmful microorganisms and environmental agents that can cause diseases.

Diseases are conditions in which the normal functioning of the body is disturbed. They can be infectious, caused by pathogens like bacteria, viruses, fungi, and parasites, or non-infectious, resulting from genetic factors, lifestyle habits, or environmental influences. Understanding human health and diseases helps us prevent, diagnose, and treat illnesses effectively, thereby improving the quality of life and promoting overall well-being.

1.0Factors Affecting Health

Mental state, genetic disorders, infections and life style (habits, rest and exercise

2.0What is the Definition of Health?

• As per the 'Good humour' hypothesis arrived at by reflective thought and asserted by Hippocrates along with the Indian Ayurveda System. 1 Health is a state of body and mind where there is a balance of certain 'humours', e.g., persons with black bile belonged to hot personality and had fevers
• Mind influences our immune system through neural and endocrine systems, and that our immune system maintains our health i.e., state of complete physical, mental and social and psychological well-being.
• Health does not simply mean ‘absence of disease’ or ‘physical fitness’. 
• William Harvey (who discovered blood circulation experimentally) disproved this 'good humour' hypothesis of health by demonstrating normal body temperature in persons with black bile using thermometer.
• Balanced diet, personal hygiene and regular exercise are very important to maintain good health. Yoga has been practised since time immemorial to achieve physical and mental health.
• Awareness about diseases and their effect on different bodily functions, (immunisation) against infectious diseases, proper disposal of wastes, control of vectors and maintenance of hygiene in food and water resources are necessary for achieving good health.

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3.0What is the Definition of Disease?

Diseases are the abnormal conditions in the body that affect its normal functioning.

Pathogens:

• Pathogens are disease-causing organisms
• Most parasites are pathogens living in (or on) the host, multiply and interfere with normal vital activities, resulting in morphological and functional damage.
• Gut pathogens can survive harsh pH & digestive enzymes.

4.0Common Diseases in Humans

Vector: Transmits disease from one organism to another, e.g. female Aedes mosquito is the vector for dengue and chikungunya, while, Anopheles spreads malaria.

5.0Measures for Preventing the Spread of infectious Diseases

• A balanced diet, yoga and regular exercise, personal hygiene, awareness about diseases and vaccination are very important to maintain good health.
• Use of vaccines and immunization programmes has enabled us to completely eradicate a deadly disease like smallpox. Large number of infectious diseases like polio, diphtheria, pneumonia and tetanus have been controlled to a large extent by the use of vaccines.
• Biotechnology is at the verge of making available newer and safer vaccines.
• Discovery of antibiotics and various drugs have enabled us to effectively treat infections.
  

1. Bacterial Diseases:

Typhoid Mary (Mary Mallon), a cook by profession was a typhoid carrier who spread typhoid through the food she prepared.

2. Viral Diseases:

The common cold does not infect the lungs, and its symptoms usually lasts for 3-7 days

3. Helminthic Diseases:

4. Fungal Diseases:

• Heat and moisture makes the fungi thrive in skin folds such as in groin and between toes.

• Acquired from soil or belongings of infected individuals such as towels, combs, clothes etc.

5. Protozoan Diseases:

• House flies act as a mechanical carrier for amoebiasis

• P. falciparum causes malignant malaria (the most serious form)

• Rupturing of RBCs releases the toxic substance, haemozoin responsible for symptoms of disease.

AIDS/Acquired Immuno Deficiency Syndrome

• 1^st reported - 1981, Killed – Approximately 25 million people in the last 25 years.

• It is a deficiency of the immune system, acquired during the lifetime of an individual.

• Syndrome means ‘group of symptoms’.

• Non-congenital, fatal infectious disease

Sequence of events:

1. Inflected cells, (Macrophages) can survive while viruses are being replicated and released hence called HIV factory

2. HIV enters into macrophages and T-helper cells (TH) simultaneously

3. There is progressive decrease in number of helper T-cells

4. Initial symptoms: Bouts of fever, diarrhoea, weight loss

5. Later the immuno-deficient patient is prone to infections especially Mycobacterium, viruses, fungi, Toxoplasma etc.

There is always a time-lag between infection and appearance of AIDS symptoms. This may vary from a few months to many years (usually 5-10 years)

Cancer

A dreaded non-infectious disease; major cause of death all across the globe.

Carcinogens: 

Carcinogens are cancer causing agents and are of following types

1. Ionising radiations -X-rays, γ - rays
2. Non-ionising radiations-UV rays
3. Physical agents
4. Chemical agents-in tobacco smoke
5. Biological agents- Oncogenic viruses (carry viral oncogenes)
6. Diagnosis/Detection: Early detection allows the disease to be treated successfully in many cases

Tumor cells have ability to avoid detection and destruction by immune system.

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Approaches for treatment: 

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Surgery

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Radiotherapy: Tumor cells irradiated lethally

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Chemotherapy: Side effects like hair loss, anemia 

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Immunotherapy a-Interferons (Biological response modifiers) 

activate immune system and helps in destroying the tumor.

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