Health and Common Diseases

Health

• Health is a state of complete physical, mental, and social well-being, not just the absence of disease.
• Healthy individuals are more productive and contribute to economic prosperity.
• Maintaining good health requires balanced diets, personal hygiene, and regular exercise.
• Yoga has been practiced for a long time to achieve physical and mental health.
• Illness occurs when one or more organs or systems in the body malfunction and experience symptoms.

Common Diseases in Humans

• Pathogens, including bacteria, viruses, fungi, protozoans, and helminths, cause various diseases.
• Pathogens enter the body through various means, multiply, and disrupt normal bodily functions, often causing damage.

Salmonella typhi

• Salmonella typhi bacteria cause typhoid fever, which enters the body through contaminated food and water.
• Symptoms include high fever, weakness, stomach pain, constipation, headache, and loss of appetite.
• Severe cases can lead to intestinal perforation and death.

Streptococcus pneumoniae

• Streptococcus pneumoniae bacteria cause pneumonia, infecting the alveoli of the lungs.
• Symptoms include fever, chills, cough, headache, and bluish or grayish lips and fingernails.

Common Cold

• Common colds are caused by viruses that primarily infect the nose and respiratory passage but not the lungs.
• Symptoms include nasal congestion, mucus discharge, sore throat, hoarseness, cough, headache, and tiredness.

Malaria

• Malaria is caused by the Plasmodium protozoan, with P. falciparum being the most serious type.
• The parasite's life cycle involves two hosts: humans and mosquitoes.
• The female Anopheles mosquito is the vector (transmitting agent).
• Sporozoites are injected into humans by the infected mosquito, multiply in the liver, and then infect red blood cells.
• The release of a toxin (haemozoin) causes chills and high fever every three to four days.

Entamoeba histolytica

• Entamoeba histolytica causes amoebiasis (amoebic dysentery), characterized by constipation, abdominal pain, cramps, excess mucous, and blood clots in feces.
• Houseflies can transmit the parasite from infected individuals to others.

Human Health and Disease

• Infectious diseases are transmitted easily from one person to another.

Transmission of Infectious Diseases

• Food and waterborne diseases are often caused by contaminated food and water.
• Ascaris (roundworm) and Wuchereria (filarial worm) cause diseases when ingested and are transmitted through contaminated water, vegetables, fruits, and so on.
• Airborne diseases, like pneumonia and the common cold, are transmitted through the air.

Prevention

• Personal hygiene practices like keeping the body clean, consuming clean water and food, and using proper sanitation are essential.
• Public hygiene measures are also crucial, including proper waste disposal, periodic cleaning of water reservoirs, and maintaining standards in public places.

Immunity

• The body's ability to defend itself against disease-causing organisms is called immunity.
• There are two types of immunity: innate and acquired.

Innate Immunity

• Present at birth and non-specific in nature.
• Provides barriers to prevent the entry of foreign agents.

Physical Barriers

• Skin acts as the primary barrier.
• Mucus coatings in the respiratory, gastrointestinal, and urogenital tracts trap microbes.
• Tears and acid in the stomach prevent microbial growth.

Physiological Barriers

• Stomach acid prevents microbial growth.
• Saliva and tears prevent microbial growth.

Cellular Barriers

• Leukocytes (WBCs), like neutrophils, are part of the body's cellular defense.

Acquired Immunity

• Characterized by "memory".
• The body remembers previous encounters with pathogens and mounts a stronger response on subsequent exposures.
• Two types of lymphocytes, B-lymphocytes and T-lymphocytes, are involved.

B-lymphocytes

• Produce antibodies in response to pathogens.
• Different types of antibodies like IgA, IgM, IgE, and IgG are produced in the body.
• The response involving antibodies in the blood is called humoral immune response.

T-lymphocytes

• Mediate cell-mediated immunity (CMI).
• Don't secrete antibodies but help B cells produce antibodies.

Active Immunity

• Antibodies are produced in the body after exposure to antigens (living or dead microbes or proteins).
• Takes time to develop a full response.
• Triggered by natural infections or immunization.

Passive Immunity

• Ready-made antibodies are given to protect the body.
• Mother's milk contains antibodies vital for newborns, and the fetus receives antibodies through the placenta during pregnancy.

Vaccination and Immunization

• Vaccination leverages the immune system's "memory" to prevent diseases.
• Introduce weakened or inactivated pathogens (vaccines) to stimulate antibody production.
• This procedure establishes memory B and T cells that remember the pathogen.

Allergies

• Allergic reactions occur when the immune system overreacts to harmless substances like pollen or dust mites.
• Symptoms include sneezing, wheezing, and other reactions.

Autoimmune Diseases

• Result from the immune system attacking the body's own cells and tissues.

Lymphocyte Organs

• Lymphoids are produced and mature in lymphoid organs.
• Primary lymphoid organs include bone marrow and thymus.

Lymph Nodes

• Located throughout the body.

Thymus

• Located near the heart.

Spleen

• A large bean-shaped organ.

Lymphatic Vessels

• Carry lymph.

Function of Lymphoid Organs

• Lymphocytes migrate to secondary lymphoid organs, including lymph nodes, tonsils, and Peyer's patches.
• The bone marrow produces blood cells, including lymphocytes.
• Lymphocytes mature in the thymus, gradually reducing in size throughout life.
• The spleen traps blood-borne microorganisms and filters blood.
• Lymph nodes trap microorganisms and activate lymphocytes.
• Lymphoid tissue is found in mucosa-associated lymphoid tissue (MALT) within the respiratory, digestive, and urogenital tracts.

AIDS

• AIDS is a deficiency of the immune system, caused by the Human Immunodeficiency Virus (HIV).
• HIV is a retrovirus with an RNA genome.
• Transmission occurs through sexual contact, blood transfusion, sharing infected needles, and from an infected mother to child through the placenta.
• Risk factors include having multiple sexual partners.