NEET Biology Notes Biology and Human Welfare AIDS
Acquired Immuno Deficiency Syndrome (AIDS) is caused by the Human Immuno deficiency Virus
(HIV), a member of a group of viruses called retrovirus, which have the envelope enclosing the RNA genome.
Transmission of HIV-infection occurs by
- Sexual contact with infected person.
- By transmission of contaminated blood and blood products.
- By sharing infected needles in case of intravenous drugs.
- From infected mother to her child through placenta. The following persons are at high risk of AIDS:
- Those have multiple sexual partners.
- Drug addicts taking the drugs intravenously.
- Individuals who acquire repeated blood transfusion.
- Children born to an infected woman.
The prevention measures of AIDS are listed below:
- Use of disposable needles and syringes.
- Checking blood for HIV.
- Free distribution of condoms and advocating safe sex.
- Control of drug abuse.
- Promoting regular check-up for HIV in susceptible population, etc.
AIDS is diagnosed by ELISA (Enzyme Linked Immuno Sorbant Assay) test. Treatment with anti-retroviral drugs is only partially effective as they but cannot prevent the death of patient.
In our body, cell growth and differentiation is highly controlled and regulated. In cancer cells, there is breakdown of these regulatory mechanisms. Normal cells shows a property-celled contact inhibition through which their uncontrolled growth is inhibited. Cancer cells lack this property. As a result, cancer cells continue to divide and give rise to masses of cells called tumours, i.e. benign tumour and malignant tumour.
Benign tumour These remains confined to their original location and do not spread of other parts.
Malignant tumour These are masses of neoplasmic/ proliferating cells, which grow rapidly, invade and damage the surrounding normal tissue/cells.
Cancer can be detected by:
- Biopsy and histopathological studies of the tissue.
- Use of techniques like radiography, Magnetic Resonance Imaging (MRI) and Computed Tomography (CT).
- Use of antibodies against cancer-specific antigens.
Cancer can be treated by
- Basic Concepts of Immunology
The ability of the host to fight against the disease causing organisms is called immunity and the cells, molecules, proteins, etc, which play role in the phenomenon constitute a system known as immune system.
Important Point Related to Immunology
- The immune system of our body consists of lymphoid organs,’ tissues, cells and soluble molecules like antibodies.
- The primary lymphoid organs are bone marrow and thymus. The secondary lymphoid organs like spleen, lymph nodes, tonsils, Peyer’s patches of small intestine and appendix.
- The bone marrow is the main lymphoid organ, where all blood cells including lymphocytes are produced. The thymus is a lobed organ, located near the heart and beneath the breast bone.
- Both bone marrow and thymus provide micro-environments for the development and maturation of B and T-lymphocytes. The spleen is a large bean-shaped organ. It mainly contains lymphocytes and phagocytes. It also has large reservoir of erythrocytes.
- The lymph nodes are located at different points along the lymphatic system. They trap the microbes , or antigens. These antigens are responsible for the activation of lymphocytes causing the immune response. _
- A lymphoid tissue is also located within the lining of the major tracts (respiratory, digestive and uro’kprtilal tracts) called Mucosal Associated Lyirighoid Tissue (MALT). It constitutes about 50% of the lymphoid tissue in human body.
Immunity is of two types:
- Innate Immunity
It is non-specific and present at the time of birth. It can be accomplished by providing different types of barriers to the entry of microbes.
- Physical barriers
- Physiological barriers
- Cellular barriers
- Cytokine barriers
- Acquired Immunity
It is pathogen specific and characterised by memory. B and T-lymphocytes produce primary and secondary responses. B-lymphocytes produce antibodies and T-cells help them in this process. The response provided by antibodies IgA, IgM, IgE, IgG and IgD present in blood is called humoral immune response (antibody-mediated).The second type is called cell-mediated immune response or Cell Mediated Immunity (CMI). The T-cells mediate CMI.
A preparation of antigenic proteins of Jttehogen or inactivated weakened pathogens is known as vaccine. It’s introduction to body is known as vaccination.
Classification of Vaccines
Vaccines can also be classified as
- First generation vaccines In preparation of these vaccines whole microorganisms are used. These are not of uniform quality and produce side effects.
- Second generation vaccines These vaccines are produced by recombinant DNA technique/genetic engineering, e.g. Hepatitis-B virus vaccine, herpes virus vaccine, pneumonia vaccine.
- Third generation vaccines These are chemically synthesised multivalent vaccine. These vaccines have high purity.
The exaggerated response of the immune system to certain antigens present in the environment is called allergy. The substances to which such an immune response is produced are called allergens. Symptoms of allergy are sneezing, water eyes, running nose and difficulty in breathing.
Allergy occurs due to the release , of chemicals like histamine and serotonin from the mast cells. The use of drugs like anti-histamine, adrenaline and steroids quickly reduce the symptoms of allergy.
It is memory-based acquired immunity evolved in higher vertebrates. Sometimes, due to the genetic and other reasons, the body attacks self-cells. When the body attacks self cells, this results in damage to the body and is called autoimmune disease, e.g. rheumatoid arthritis, Grave’s disease etc.
Drugs and Alcohol Abuse
The drugs that are commonly abused include opioids, cannabinoids, coca-alkaloids, amphetamines, benzodiazepines and Lysërgic Acid Diethylamide (LSD). Opioids These are drugs which binds to opioid receptors in the central nervous system and gastrointestinal tract, e.g. morphine and heroine
Cannabinoids These are a group of chemicals, which interact with cannabinoid receptors present mainly in the brain.
Cocaine It is obtained from Erythroxylum coca interferes with the transport of neurotransmitter and dopamine.
Hallucinogens These are products obtained from Atropa – belladona and Datura species are hallucinogenic. LSD is obtained from a fungus.
Tobacco It contains mainly nicotine, which is a stimulant and toxin. Nicotine stimulates the adrenal gland to release adrenaline and non-adrenaline, which increase the blood pressure and heart rate and also causes oral cancer on chewing.
Alcohol It is a depressant. It affects the central nervous system. Acohol act as a sedative, analgesic and anesthetic.
Addiction and Dependence
Addiction is a psychological attachment to certain effects-such as Euphorbia and a temporary felling of well-being associated with drugs and alcohol.
Dependence is the tendency of the body to manifest a characteristic and unpleasant withdrawal syndrome if regular dose of drugs/alcohol is abruptly discontinued.
Effect of Drug/Alcohol Abuse
The common warning signals of drug/alcohol use are:
- Drop in academic performance.
- Isolation from family and friends.
- Lack of interest in personal hygiene.
- Aggressive and rebellious behaviour.
- Reckless behaviour, vandalism and violence.
Prevention and Control
The preventive measures are:
- Avoid undue peer pressure.
- Accept failures and disappointments as part of life.
- Seek help from parents and peers.
- Seek professional and medical help for deaddiction.
- Look for danger signs.