Non infectious diseases:

AIDs and Cancer are explained below:

(1) 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 RNA as genetic material.

Transmission of HIV-infection generally occurs by:

 (a) Sexual contact with infected person.

 (b) By transfusion of contaminated blood and blood products.

(c) By sharing infected needles between Individuals who require repeated blood transfusions.

(d) From infected mother to her child through placenta.

(e) Drug addicts who take drugs intravenously.

 

Preventive measures taken to prevent AIDs:

              AIDs cannot be cured so, its prevention is must.

• National AIDS Control Organisation (NACO) and other non-governmental organisation (NGOs) are doing a lot to educate people about AIDS.
• WHO has started a number of programmes to prevent the spreading of HIV infection.
• Making blood (in blood banks) safe from HIV.
•  Ensuring the use of only disposable needles and syringes in public and private hospitals and clinics.
•  Free distribution of condoms, controlling drug abuse, advocating safe sex.
• Promoting regular check-ups for HIV in susceptible populations.

     Life cycle of HIV:

• After getting into the body of the person, the virus enters into macrophages where RNA genome of the virus replicates to form viral DNA with the help of the enzyme reverse transcriptase.
• This viral DNA gets incorporated into host cell’s DNA and directs the infected cells to produce virus particles. The macrophages continue to produce virus and in this way acts like a HIV factory.
• Simultaneously, HIV enters into helper T-lymphocytes (TH), replicates and produce progeny viruses. The progeny viruses released in the blood attack other helper T-lymphocytes, which decrease the number of helper T-lymphocytes in the body of the infected person.
• Due to the decrease in number of T-lymphocytes, the person suffers from many other infections like, fever, diarrhoea and weight loss, etc.

Diagnose of AIDs:

A widely used diagnostic test for AIDs is “Enzyme linked immuno-sorbent assay” (ELISA).

Treatment of AIDs:

Treatment of AIDS with anti-retroviral drugs is only partially effective. They can only prolong
the life of the patient but cannot prevent death, which is inevitable.

 

      (2) Cancer: Cancer is defined as an uncontrolled division or proliferation of cells without any differentiation.

Cancer cells have following properties:

(i) The cells divide repeatedly with uncontrolled cell division.

(ii) The cancer cells do not require extracellular growth factors.

(iii) Cancer cells have lost the property of contact inhibition.

(iv) Due to repeated division, cells form a large mass of tissue called tumour.

(v) The cells pass out from the tumour to new sites for forming secondary tumours.

(vi) The invasion of cancerous cells from one part to the other parts by body fluid is called metastasis.

(vii) Oncogenic viruses have cancer-causing viral oncogenes.

(viii) Normal cells have genes called cellular oncogenes  or proto-oncogenes, which are present in inactivated state but under certain conditions (like mutation) get transformed to cancer-causing oncogenes

 

Causes of cancer:

The cancer-causing agents are called carcinogens. The are of following types:

• Chemical agents: Aniline dyes, benzopyrene, chemicals in cigarette smoke.
• Physical agents: Ionising radiations like X-rays and g-rays, non-ionising radiations like UV-rays.
• Biological agents: Oncogenic viruses, some parasites.

 Types of cancer:

• Carcinoma: It is cancer of epithelial tissue, e.g., skin cancer.
• Melanoma: It is cancer of melanocytes of skin.
• Sarcoma: It is cancer of mesodermal tissue.
• Leukemia and lymphoma: It is cancer of haemopoietic cells (blood cells).

                                           

 Tumours are of two types-

Benign and Malignant:

Differences between types of tumours:

S. No.	Benign tumour	Malignant tumour
(i) (ii)   (iii)   (iv)     (v)	It is a non-cancerous tumour. Benign tumour does not show metastasis and is non-capturing. It stops growing after reaching a certain size. Adherence is limited.   It is less fatal to the body.	It is a cancerous tumour. It show metastasis and can capture other body parts too. Malignant tumour grows continousely. No adherence amongst cells   It is more fatal to the body. And ultimately causes death.

 

 

 

             

 

 

 

 Cancer detection:

• Blood and bone marrow tests are done for increased cell counts in case of leukemia.

• Histopathological study or biopsy: In biopsy, a piece of the suspected tissue cut into thin sections is stained and examined under microscope by a pathologist.
• Radiography: X-rays are used to detect cancer of the internal organs.
• Computed tomography: It uses X-rays to generate a three-dimensional image of the internal of an object.
• Resonance imaging: Non-ionising radiation (UV) and strong magnetic field are used in MRI to detect pathological and physiological changes in the living tissue.

Cancer treatment:

• Surgery: The tumour cells are removed with the help of surgery to check the spread of cancerous calls.
• Radiation therapy: A lethal irradiation of tumour cell is done, taking proper care of the normal tissues surrounding the tumour mass.
• Chemotherapy: Cancerous cells are killed by several chemotherapeutic drugs. These drugs exhibit side effects like hair loss, anaemia.
• Immunotherapy: In this method biological modifies like α-interferons are used which activate the immune system and help in destroying the tumour.