• Vaccination is the process of introduction of vaccines into the body to produce antibodies against the antigens to neutralize the effect of pathogens during actual infection.

  > Vaccines are the dead or weakened pathogens introduced into the body.

  > The dead or weakened pathogen leads to the production of antibodies which neutralizes the pathogenic agents during actual infection with the same pathogen.

  > immunization is the process where performed antibodies against the toxin are introduced into the body.

  Example – performed antibody injection against snake venom.

  > Using recombinant DNA technology antigenic polypeptides of pathogens in bacteria or yeast.

  Example – hepatitis B vaccine produced from yeast.

ALLERGY 

The exaggerated response of the immune system to certain antigens present in the environment is called allergy.

The substances to which immune is produced are called allergens.

Common examples of allergens are mites in dust, pollens, animal dander etc.

Allergy is due to the release of chemicals like histamine and serotonin from the mast cells.

The antibodies produced to these are of lgE type.

Symptoms of allergic include sneezing, watery eyes, running nose and difficulty is breathing.

The patient is diagnosed by injecting or exposing the patient to very small doses of allergens.

Drugs like anti-histamine, adrenalin and steroids quickly reduce the symptoms of allergy.

What Is An Autoimmune Disease? 

An autoimmune disease is a condition in which your immune system mistakenly attacks your body.

Due to genetic and other unknow reasons, the body attacks self-cell which results in damage to the body and is called auto-immune disease.

The immune system normally guards against germs like bacteria and viruses. When it senses these foreign invaders, it sends out an army of fighter cells to attack them.

Normally, the immune system can tell the difference between foreign cells and your own cells.

In a autoimmune disease, the immune system mistakes part of your body – like your joints or skin- as foregn. It releases proteins called autoantibodies that attack healthy cells.

Rheumatoid arthritis (RA)

In rheumatoid arthritis (RA), the immune system attacks the joints.

This attack causes redness, warmth, soreness, and stiffness in the joints.

IMMUNE SYSTEM IN THE BODY

Immune system consists of-

• Lymphoid organs
• Lymphoid tissues
• B-cell and T- cells
• Antibodies 

Primary Lymphoid Organs :

In primary lymphoid organs, immature lymphocytes differentiate to mature ones into an antigen sensitive lymphocytes and after maturation, lymphocytes migrate to secondary lymphoid organs.

These are of two types :

1. Bone marrow
2. Thymus

Bone marrow :

It is the main lymphoid organs, where all the lymphocytes and all the body cells are produced and T-lymphocytes are developed.

Thymus :

It is a lobed organ, located near the herat and beneath the breast bone. It is large at the time of birth but with age, the size keep on reducing and becomes very small by attaining puberty.

Growth and maturation of T- lymphocytes takes place in thymus only.

Secondary Lymphoid Organs :

These organs provide the sites for the interaction of lymphocytes with the antigen, which then proliferate to become effector cells.

These are of following types :

1. Spleen 
2. Lymph nodes,
3. Mucosal associated lymphoid tissue (MALT)

Peyer’s patches of small intestine and appendix are also some of the secondary lymphoid organs.

Spleen :

   It is a large bean-shaped organ containing lymphocytes and phagocytes. It filters the blood by trapping the pathogens in it.

Lymph nodes:

These are small solid structures located at different points along the lymphatic system. Their function is to trap the Microorganisms or other antigens, that enter the lymph and tissue fluid.

Mucosal  Associated Lymphoid Tissue {MALT}:

This is located within the lining of main tracts in the body like respiratory, urogenital tracts.MALT constitutes about 50% of the lymphoid tissue in human body.

AIDS :

    The term AIDS stands for acquired immune deficiency syndrome.

    The disease is acquired during life time.

     AIDS is caused by human immune deficiency virus (HIV).

     HIV is retrovirus having RNA as the genetic material .

Mode of transmission –

• Sexual contact with infected persons.
• By transfusion of contaminated blood and blood products.
• By sharing infected needles as in the case of intravenous drug abusers.
• From infected mother to her child through placenta.

Life cycle of HIV

• After getting into the body the virus enters into macrophages or T- helper cells.
• The viral RNA genome replicated to form viral DNA with the enzyme called reverse transcriptase.
• The viral DNA gets incorporated into the host cell’s DNA and directs the infected cells to produce virus particles and the macrophages continue to produce virus.
• Viruses released from macrophages attack T-helper cells and cause a progressive ceduction in the number of T-helper cells and due to which the person starts suffering from infections with several other microorganisms.
• Diagnosed by ELISA ( enzyme linked immune-sorbent assay).
• Treated with anti-retroviral drugs but that is only  partially effective.

Prevention of AIDS -:

• To follow safe blood transfusion.
• To use disposable needles.
• To distribute free condoms.

CANCER

• Cancer is the uncontrolled cell division leading to the formation of a mass of cell called as a tumor.
• Contact inhibition is the property of normal cells by virtue of which contact with other cells  inhibits their uncontrolled growth.
• Cancer cells lost the property of contact inhibition and as a result of this, cancerous cells continue to divide giving rise to masses of cells called tumors.
• Tumors are of two types : being and malignant.
• Benign tumors normally remain confined to their original location and do not spread to other parts of the body.
• The malignant tumors are a mass of proliferating cells called neoplastic or tumor cells.
• Malignant tumors grow very rapidly and ultimately damage surrounding tissues.
• The propently by which cancer cells moves to distant places from their origin by blood and invade the normal cells and make them cancerous is called as metastasis.

Causes of Cancer :-

• Transformation of normal cells into cancerous cells may be induced by physical, chemical or biological agents called as carcinogens.
• Physical carcinogens-ionizing radiation like X-rays, gamma rays and non-ionizing radiations like UV radiation of sun.
• Chemical carcinogens – tobacco smoke and some other chemicals.

Biological Carcinogens-

1. Cancer causing viruses are called oncogenic viruses have genes called viral oncogenes.
2. Cellular oncogenes or proto-oncogenes in normal cells, when get activated lead to oncogenic transformation of normal cells.

Detection of cancer

• Biopsy and histo-pathoigical study of the tissues.
• Radiography by using X-rays , CT (computed tomography).
• MRI (magnetic resonance imaging).
• Use of antibodies against cancer-specific antigens.

Treatment of cancer-

• Surgery 
• Radiation therapy 
• Chemotherapy
• Biological response modifiers-alpha-interferon which activate the immune system and help in destroying the tumor.

Drugs and Alcohol Abuse:-

The drugs which are commonly abused are opioids, cannabinoids and coca alkaloids.

Opioids :- 

Opioids are the drugs which bind to specific opioid receptors present in our central nervous system and gastrointestinal tract.

Heroin :-

Commonly called smack is chemically diacetylmorphine which is a white, odourless, bitter crystalline compound and is obtained by acetylation of morphine extracted from the latex poppy plant papaver somniferum Heroin is a depressant and slows down body functions.

Cannabinoids :-

Cannabinoids interact with cannabinoid receptors present principally in the brain.

Natural cannabinoids are obtained from the inflorescences of the plant cannabis sativa.

The flower tops, leaves and the resin of cannabis plant are used in various combinations to produce marijuana, hashish,  charas and ganja.

Effects on cardiovascular system of the body.

Coca alkaloid :- 

• Coca alkaloid or cocaine is obtained from coca plant Erythroxylum coca.
• Coca alkaloid interferes with the transport of the neuro-trasmitter dopamine.
• Cocaine, commonly called as coke or crack.
• It has a potent stimulating action on central nervous system, producing a sense of euphoria and increased energy.
• Excessive dosage of cocaine cause hallucinations. 
• Morphine is a very effective sedative and pain killer is often abused.
• Some plants with hallucinogenic properties are Atropabelladona.

Tobacco :-

• Tobacco contains nicotine, an alkaloid.
• Nicotine stimulates adrenal gland to release adrenaline and nor-adrenline into blood circulation, both of which raise blood pressure and increase heart rate.
• Smoking of tobacco is associated with increased incidence of cancers of lung, urinary bladder, throat, oral cavity, bronchitis,emphysema, coronary heart disease, gastric ulcer etc.

Adolescence and drug / alcohol abuse

 Alcohol use often turns to abuse and addiction.

• Adolescence means both ‘a period’ and ‘a process’ during which a child becomes mature in terms of his/her attitudes and beliefs for effective participation in society.
• 12-18 years of age may be thought of as adolescence period.
• Adolescence is accompanied by several biological and behavioural changes.
• Curiosity, need for adventure and excitement, and experimentation, constitute common causes, which motivate youngsters towards drug and alcohol use.

Addiction and dependence :-

• Addiction is a psychological attachment to certain effects- such as euphoria and a temporary feeling of well- being- associated with drugs and alcohol.
• With repeated use of drugs, the tolerance level of the receptors present in our body increases and consequently the receptors respond only to higher doses of drugs or alcohol leading to greater intake and addiction.
• Dependence  is the tendency of the body to manifest a characteristic and unpleasant withdrawal syndrome if regular dose of drugs/ alcohol is abruptly discontinued.
• Withdrawal syndrome is characterised by anxiety, shakiness, nausea and sweating.
• Acute, or short-term, tolerance is caused by repeated exposure to a drug over a relatively short period of time. Cocaine abuse often results in acute tolerance.
• Chronic, or long-team, tolerance develops when an individual’s body adapts to constant exposure to a drug over weeks or months.

Effects, prevention and control of drug / alcohol abuse :-

• Immediate effects are reckless behavior, vandalism and violence.
• Excessive doses of drugs may lead to coma and death due to respiratory failure, heart failure or cerebral haemorrhage.
• Those who take drugs intravenously can get infected with AIDS, hepatitis B.
• The chronic use of drugs and alcohol damages nervous system and cause liver cirrhosis.
• The use of drugs and alcohol during pregnancy is also known to adversely affect the foetus.
• Use of anabolic steroids in females can cause masculinisation, increased aggressiveness, mood swings, depression, abnormal menstrual cycles excessive hair, growth on the face and body, enlargement of clitoris, deepening of voice.
• In males anabolic steroids can cause acne, increased aggressiveness, mood swings, depression, reduction of size of the testicles, decreased sperm production, potential for kidney any liver dysfunction, breast enlargement, premature baldness enlargement of the prostate gland.

Prevention and control :-

• The measures useful for prevention and control of alcohol and drugs abuse among adolescents.
• Avoid undue peer pressure on children.
• Children should be educated and counseled to bear problems and stress in life.
• The child should seek help from parents and elders.
• Affected individuals should seek medical help of qualified psychologists, psychiatrists, and addiction and rehabilitation programmes.