NEET Biology Human Health And Disease Notes - Arthritis and Cancer

Notes - Arthritis and Cancer

Category : NEET

Arthritis and Cancer

 

(1) Arthritis

            (a) Arthritis is any inflammatory condition of the joints characterised by pain and swelling.

            (b) Two kinds of arthritis are : rheumatoid arthritis and osteoarthritis.

            (c) There is no cure for arthritis; drugs are available which relieve pain.

            (d) Rheumatoid arthritis is characterised by inflammation of the synovial membrane.

            (e) A kind of rheumatoid arthritis that occurs in younger people is Still?s disease.

(f) Osteoarthritis is a disease common among the elderly persons resulting from erosion of articular cartilage.

            (g) Paraplegia refer to weakness or paralysis of both legs, often accompanied by loss of sensation.

(h) Paraplegia is usually caused by a motor vehicle accident, sports accident, fall or gunshot wounds.

  (2) Cancer: Cancer is an abnormal and uncontrolled division of cells, known as cancer cells, that invade and destroy the surrounding tissues. Generally Cancer is defined as uncontrolled proliferation of cells without any differentiation. Cancer cells are different from normal cells in some aspects. They do not remain confined to one part of the body. They penetrate and infiltrate into the adjoining tissues and dislocate their functions. Some of the cancer cells get detached from the main site of origin and travel by blood and lymph to sites distant from the original tumour and form fresh colonies, called metastasis or secondary growth.

 

Neoplasms or Tumours : A neoplasm (new growth) is a mass of tissue that grows in excess of normal in an uncordinated manner and continues to grow after the initial stimulus has ceased. Tumours are classified as benign or malignant.

 

Oncology: (G. onkos ? mass, tumour; logos ? study of) is the field of biomedicine devoted to the study and treatment of tumours.

(a) Types of Tumours : There are two types of tumours : benign and malignant.

(1) Benign Tumour ? (=Nonmalignant Tumour) : It remains confined to the site of its origin and does not spread to  other parts of the body. It causes limited damage to the body. It is non-cancerous.

(2) Malignant Tumour (= Cancerous Tumour) : It first grows slowly. No symptoms are noticed. This stage is called the latent stage. The tumor later grows quickly. The cancer cells go beyond adjacent tissue and enter the blood and lymph. Once this happens, they migrate to many other sites in the body where the cancer cells continue to divide. It is metastasis. Only malignant tumours are properly designated as cancer.

  Differences between Benign Tumour and Malignant Tumour

 

Benign Tumour Malignant Tumour

(1)        It remains confined to the affected organ.

(1)        It also spreads to other organs of the body.

(2)        Rate of growth is usually slow.

(2)        Rate of growth is usually rapid.

(3)        There is no latent stage.

(3)        There is latent stage.

(4)        It causes limited damage to the body.

(4)        The cancer cells migrate to other sites of the body.

(5)        There is no metastasis.

(5)        There is metastasis.

(6)        It is non-cancerous.

(6)        It is cancerous.

 

(b) Types of Cancer (Types of Malignant Tumours) : Malignant tumours are generally classified into three main types on the basis of cell type from which they arise.

(1) Carcinomas : This type is mainly derived from epithelial cells. They include cervical (cervix is part of uterus) cancer, breast cancer, skin cancer, brain cancer, lung cancers, stomach cancer, etc.

(2) Sarcomas : These cancers are located in connective and muscular tissues derived from mesoderm. Thus, they include the cancers of bones, cartilages, tendons, adipose tissue, lymphoid tissue and muscles. Cancer of bones is called osteoma. Cancers of adipose tissue are known as lipomas and cancers of lymphatic tissue are termed as lymphomas. Hodgkin?s disease is an example of human lymphoma. In Hodgkin?s disease there is chronic enlargement of the lymph nodes, and enlargement of spleen and often the liver. In this disease there is excessive production of lymphocytes by lymph nodes and spleen.

(3) Leukaemias (Blood cancers) : They are characterized by abnormal increase of white blood corpuscles count due to their increased formation in the bone marrow.

(c) Causes of Cancer : The causes of cancer are not fully understood. However, many factors are known to favour cancer development. These factors are called carcinogenic agents or Carcinogens. The causes of cancer are briefly described under the following headings.

 

(1) Physical irritants : (i) Use of Kangri (an earthen pot containing burning coal) by Kashmiris causes abdominal skin cancer as these people keep Kangri close to their abdomen during winter. (ii) Betal and tobacco chewing causes oral cancer. (iii) Heavy smoking causes lung cancer and may also cause cancer of oral cavity, pharynx (throat) and larynx. (iv) Jagged teeth may cause tongue cancer. (v) Excessive exposure to sun light can cause skin cancer.

(2) Chemical Agents : Several chemicals are known to cause cancer. These are caffeine, nicotine, products of combustion of coal and oil and pesticides; constant use of artificial sweetener can cause cancer. An animal protein-rich diet is known to cause cancer of large intestine. Breast cancer has hormonal relationship. Thus, some sex hormones and steroids if secreted or given in large amounts may cause cancer. Chimney sweepers can develop cancer of scrotum. Dye workers have a high rate of bladder cancer.

Carcinogens and Organs Affected
Carcinogens Organs Affected

(1)        Soot

                        Skin, lungs

(2)        Coaltar (3, 4-benzopirene)

                        Skin, lungs

(3)        Cigarette smoke (N-nitrosodimenthylene)

                        Lungs

(4)        Cadmium Oxide

                        Prostate gland

(5)        Aflatoxin (a mould metabolise)

                        Liver

(6)        2-naphthylamine and 4-aminobiphenyl

                        Urinary bladder

(7)        Mustard gas

                        Lungs

(8)        Nickel and Chromium compounds

                        Lungs

(9)        Asbestos

                        Lungs, pleural membrane

(10)       Diethylstibestorol (DES)

                        Vagina

(11)       Vinylchloride (VC)

                        Liver

 

(3) Radiations : The X-rays, cosmic rays, ultra-violet rays, etc. can cause cancer. Japanese people exposed to radiations from World War II nuclear bombing show five times the incidence of leukemia seen in the rest of the population.

 

(4) Biological Agents : Certain viruses can cause cancer. The viruses that cause cancers are called oncoviruses.

Oncogens : It has now been confirmed that all cells carry some cancer-causing genes called oncogenes. Certain factors stimulate oncogenes to replicate rapidly, causing malignant tumour. Experts in the study of cancer are called oncologists.

Other term associated with cancer cell:

Melanama         :           Cancer of pigmented cells of skin.

Adenoma           :           Cancer of gland.

Myoma             :           Cancer of muscular tissue.

Lymphoma        :           Cancer of Lymphatic tissue.

Glioma              :           Cancer of Glial cells of CNS.

 

Different Sites of Cancer : Some of the important sites of cancer are skin, mouth, oesophagus, stomach, colon, rectum, liver, gall bladder, pancreas, blood, lymph, adipose tissue, lung, uterine cervix, breast, brain, penis, prostate, muscles, thyroid, kidney and bones.

 

Possible Symptoms of Cancer : (i) A persistent cough or hoarseness in a smoker. (ii) A persistent change in digestive and bowel habits. (iii) A change in a wart or mole. (iv) A lump or hard area in the breast. (v) Unexpected diminished or lost appetite. (vi) Unexplained low-grade fever. (vii) Unexplained loss of weight. (viii) Any ulcer that does not get well. (ix) Bleeding in vagina at times other than the menstruation. (x) Non-injury bleeding from the surface of the skin, mouth or any other opening of the body.

(d) Treatment : Three general methods of treatment for cancer are currently available.

(1) Surgery : It involves the removal of the entire cancerous tissue.

(2) Radiation : It involves the exposure of the cancerous parts of the body to X-rays, which destroy rapidly growing cells without harming the surrounding tissue.

(3) Chemotherapy : It involves the administration of certain anticancer drugs. These drugs check cell division by inhabiting DNA synthesis. These drugs may be more toxic to cancerous cells than to normal cells.

Most cancers are treated by combination of surgery, drugs and radiation therapy.

(e) Theories related to Cancer : The theories that seem most worth investigation are mutation and selective gene activation.

(1) Mutation Theory : Evidences for the Mutation Theory are as follow : (i) Agents that are known to cause mutations (radiations and chemicals) also appear to cause cancer. (ii) The incidence of cancer increases with age. As the number of body cell mutations also increases with age, it is possible that cumulative effects of mutations contribute to the initiation of malignancy. However, the mutation theory fails to explain occasional cases of spontaneous remission. Remission is the condition in which symptoms and evidence of the disease disappear.

(2) Selective Gene Activation : A second theory, that of selective gene activation, does account for remissions. If certain genes that are not normally expressed suddenly become active, their expression could lead to uncontrolled cell division. A remission might occur when for some reason these genes cease to be expressed. Research into the mechanism that control gene activation may provide insight into both the process of normal cell division and the aberrations in the process that lead to cancer.

Characteristics of Cancer Cells

 

(1) Nucleus is abnormally enlarged and irregular.      

(2) Chromatin material is also irregular.

(3) ER are more in cancerous cells.                                   

(4) Ribosomes fuse together to form polyribosomes.

(5) Golgi bodies are less developed.                                  

(6) Mitochondria are swollen with few cristae.         

(7)  Plasma membrane often becomes irregular.                 

(8) Pathological cytoplasmic inclusions are also present.

 

Danger Signals for Cancer : These are as follows:

(1) Any wound that does not heal.                       

(2) A thickening or lump in the breast or elsewhere.

(3) Any change in the mole or wart.                                  

(4) Unusual bleeding or discharge.

(5) Persistent indigestion or difficulty in swallowing. 

(6) Persistent cough or hoarseness.

(7) Any change in normal bowl habits.

           

Types of  Cancer : Cancers are generally named against the tissues involved. These are ?

(1) Carcinoma : Cancer of epithelial cells.            

(2) Sarcoma : Cancer of connective tissue.

(3) Leukaemia : Cancer of blood cells.                            

(4) Lymphoma : Cancer of lymphocytes.

(5) Lipoma : Cancer of adipose tissue.


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