স্পেশাল বিসিএস (স্বাস্থ্য) - লং কোর্স

• Hypertrophy refers to an increase in the size of cells that result in an increase in the size of the affected organ.
• The hypertrophied organ has no new cells, just larger cells.
• The most common stimulus for hypertrophy of muscle is increased workload.
• Hypertrophy is the result of increased production of cellular proteins.

• Hyperplasia is defined as an increase in the number of cells in an organ or tissue in response to a stimulus.
• Hyperplasia is the result of growth factor-driven proliferation of mature cells and, in some cases, by increased output of new cells from tissue stem cells.
• Physiological hyperplasia occurs in – breast during puberty, liver after hepatectomy
• Pathological hyperplasia occurs in – BPH, wart & endometrial tumour

• Atrophy is defined as a reduction in the size of an organ or tissue due to a decrease in cell size and number.
• Atrophy results from decreased protein synthesis and increased protein degradation in cells. Protein synthesis decreases because of reduced metabolic activity. The degradation of cellular proteins occurs mainly by the ubiquitin-proteasome pathway.

• Physiologic atrophy is common during normal development. Some embryonic structures, such as the notochord and thyroglossal duct, undergo atrophy during fetal development. The decrease in the size of the uterus that occurs shortly after parturition is another form of physiologic atrophy.
• Pathologic atrophy occurs due to – disuse atrophy, denervation atrophy, pressure atrophy, senile atrophy, nutritional deficiency atrophy

• Metaplasia from squamous to columnar type may also occur, as in Barrett oesophagus
• Connective tissue metaplasia is the formation of cartilage, bone, or adipose tissue (mesenchymal tissues) in tissues that normally do not contain these elements

• Coagulative: ischemic necrosis of heart, kidney, liver, adrenal gland & other solid organs; gumma of tertiary syphilis
• Liquefactive: boil, abscess & ischemic necrosis of brain
• Caseous: Granuloma of TB
• Fat: Enzymatic-pancreas, Traumatic- breast
• Fibrinioid: in collagen disease

Dissemination of cancers may occur through one of three pathways:
• Direct seeding of body cavities or surfaces,
• Lymphatic spread- mainly carcinoma
• Hematogenous spread- mainly Sarcomas

• HTLV-1: adult T-cell leukemia/lymphoma
• HPV: benign warts, cervical cancer, and oropharyngeal cancer
• EBV: Burkitt lymphomas, B-cell lymphomas in patients with T-cell immunosuppression
• Hepatitis B virus and hepatitis C virus: hepatocellular carcinomas
• H. pylori: gastric adenocarcinoma and MALT lymphoma