12th Class Biology Human Health And Disease / मानव स्वास्थ्य और रोग Non Communicable Diseases

The main non-communicable diseases are diabetes, inflammatory diseases of joints such as arthritis, gout, cardiovascular diseases and cancer.

(1) Diabetes Mellitus

(i) Diabetes is characterised by chronic hyperglycemia which is excessive concentration of glucose in the blood.

(ii) Diabetes is primarily a result of relative or complete lack of insulin secretion by the \[\beta \] cells of islets of Langerhans in pancreas.

(iii) Diabetes is established by blood and urine sugar levels.

(2) Arthritis

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

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

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

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

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

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

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

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

(3) Gout

(a) Gout results from accumulation of uric acid crystals in the synovial joints.

(b) Gout is a disease associated with an inborn error of uric acid metabolism that increases production or interferes with the excretion of uric acid.

(4) Cardiovascular Diseases

(a) Cardiovascular diseases refer to a number of diseases associated with the blood vascular system.

(b) Some major cardiovascular diseases are rheumatic heart disease, hypertensive heart disease and coronary heart disease.

(i) Rheumatic heart disease

Rheumatic heart disease is an autoimmune disease, most common in children after a severe throat infection by certain strain of Streptococcus bacteria.

An antigen on the surface of these bacteria is very similar to an antigen on the surface of myocardium.

The antibodies against Streptococcus may react with myocardium and cause heart difficulties.

(ii) Hypertensive heart disease

Hypertensive heart disease are caused by hypertension, i.e., increased blood pressure.

Serious hypertension is a common cause of chronic heart failure particularly in older people.

(iii) Coronary heart diseases

Coronary heart diseases are characterised by impaired heart function due to inadequate blood flow to the heart. Angina pectoris is the chest pain caused most often by myocardial anoxia. Attacks of angina pectoris are often related to exertion, emotional disturbance and exposure to excess cold. Myocardial infarction is commonly called coronary or heart attack.

Coronary heart disease may be due to raised serum cholesterol, cigarette smoking, high blood pressure, physical inactivity, obesity and diabetes.

Cyanosis refers to a bluish coloration of the skin and mucous membranes due to too much deoxygenated haemoglobin in the blood.

(5) 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.

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

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

(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.

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

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.

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

(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.

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.