Tumours

■Adaptations are cellular changes in response to changes in environment or demand cells can increase/ decrease Size, Number, Phenotype, Metabolic Activity, Function. It is often reversible

■Acquire new, steady state of metabolism and structure ■Better equips cells to survive in a new environment Failure of adaptation may lead to sub-lethal or lethal cell injury

Responding to normal changes in physiology or demand

Responding to disease related changes

Survive severe metabolic stress without harm. e.g absence of oxygen

Labile cell population Active stem cell compartment Highly adaptive in number and function

Terminally differentiated and permanent cell population Highly specialised function and easily damaged

hypertrophy (increase in size of cells) and hyperplasia (increase in number of cells)

■Increase in size of existing cells ■Increase in functional capacity ■Particularly seen in permanent cell populations esp cardiac and skeletal muscle Increased synthesis of structural components and increased meatbolism

• Increase in size and number of subcellular organelles * eg smooth ER hypertrophy in hepatocytes with barbiturates

• Increase in number of cells caused by cell division * Possible in labile and stable cell populations

Reduction in size of organ or tissue by decrease in cell size and number Physiological • Pathological

• Decreased workload (disuse atrophy) • Loss of innervation (denervation atrophy) • Diminished blood supply • Inadequate nutrition (e.g. cachexia) • Loss of endocrine stimulation • Pressure

■Reduction in volume of individual cells ■Death of individual cells

• Transformation of one differentiated cell type into another • Trans-differentiation of stem cells • Better adaptation to new environment • Can affect epithelium and mesenchymal tissues • Physiological or pathological

neoplasia

• Glandular metaplasia in oesophagus= Adenocarcinoma • Squamous Metaplasia in Cervix= CIN and squamous cell carcinoma • Endometrial hyperplasia due to increased oestrogens= Adenocarcinoma • Squamous metaplasia in bronchus= dysplasia and squamous cell carcinoma • Squamous metaplasia in bladder= Squamous cell carcinoma • Parathyroid hyperplasia due to chronic renal failure= adenoma

• Earliest morphological manifestation of multistage process of neoplasia (hence irreversible) • In-situ disease; non-invasive • Shows cytological features of malignancy, but no invasion • commonly – abnormality indicating precursor change of malignancy

“Cancer is the uncontrolled growth of cells, which can invade and spread to distant sites of the body”

TUMOUR Historically: “an abnormal swelling” Now synonymous with… NEOPLASM “ abnormal and excessive growth of tissue” - exceeds and is uncoordinated with that of normal tissue - persists in abnormal growth in the absence of initiating stimulus

“The differentiation of cells into specialised tissues and organs during growth from undifferentiated cells”

• Breast • Prostate • Lung • Bowel

• Breast • Lung • Bowel • Uterus

• Prostate • Lung • Bowel • Head & Neck