Tuesday, July 28, 2020

Human Health and Diseases - Notes | Class 12 | Part 3: Allergy, Autoimmunity, AIDS

8. HUMAN HEALTH AND DISEASES


Allergies

§ It is the exaggerated response of the immune system to certain antigens present in the environment.

§ Allergens: Substances causing allergy. E.g. mites in dust, pollens, animal dander, fur etc.

§ Antibodies produced against the allergens are IgE type.

§ IgE binds on mast cells to release chemicals like histamine and serotonin from them. It results in allergic reactions.

§ Symptoms: Sneezing, watery eyes, running nose, difficulty in breathing, wheezing, skin rashes etc.

§ Determination of cause of allergy: The patient is exposed to or injected with very small doses of possible allergens, and the reactions studied.

§ Treatment: Drugs like anti-histamine, adrenaline and steroids quickly reduce the symptoms of allergy.

§ Asthma is a respiratory disease due to allergy.

§ Modern-day life style and protected environment provided early in life result in low immunity and more sensitivity to allergens. So, many children in metro cities suffer from allergies and asthma.


Autoimmunity


-   In higher vertebrates, memory-based acquired immunity evolved based on the ability to differentiate foreign organisms from self-cells.

-   Sometimes, due to genetic and other unknown reasons, the body attacks self-cells resulting in damage to the body. It is called auto-immune disease. E.g. Rheumatoid arthritis.


AIDS (Acquired Immuno Deficiency Syndrome)


§ It is the deficiency of immune system.

§ Syndrome means a group of symptoms.

§ It is caused by HIV (Human Immunodeficiency Virus), a retrovirus having RNA genome.

§ AIDS was first reported in America (1981).

§ In the last 25 years, it killed over 25 million persons.


Transmission:


§ Sexual contact with infected person.

§ Transfusion of contaminated blood & blood products.

§ Sharing of infected needles.

§ From infected mother to her child through placenta.


High risk people of getting HIV:


§ Individuals with multiple sexual partners.

§ Drug addicts who take drugs intravenously.

§ Individuals who require repeated blood transfusion.

§ Children born to an HIV infected mother.

HIV does not spread by touch or physical contact. It spreads only through body fluids.

There is a time-lag (from few months to 5-10 years) between the infection and appearance of symptoms.


Replication of retrovirus:



Life cycle of HIV:


HIV enters body → To macrophages (acts as HIV factory) → RNA genome replicates in presence of Reverse transcriptase to form viral DNA → Viral DNA incorporates into host DNA→ Infected cells produce virus particles → HIV enters into helper T-cells (TH lymphocytes) → Replicates & produce progeny viruses → Attack other TH cells → TH cells decrease → Weaken immunity.


§ During this period, the person suffers from fever, diarrhoea and weight loss.

§ Due to deficiency of TH cells, he may be infected with Mycobacterium, viruses, fungi & parasites like Toxoplasma.

§ Diagnosis: ELISA test (Enzyme-linked immuno-sorbent Assay).

§ Treatment: Anti-retroviral drugs are partially effective. They can only prolong the life of the patient.


Prevention of AIDS:


o  Educate people about AIDS through organisations like National AIDS Control Organisation (NACO), non-governmental organisations (NGOs), WHO etc.

o  Make blood (from blood banks) safe from HIV.

o  Use disposable needles and syringes.

o  Advocate safe sex and free distribution of condoms.

o  Control drug abuse.

o  Regular check-ups for HIV in susceptible population.

============

👇 Select Your Topic Here 👇

No comments:

Post a Comment