Human Health and Disease — Part 2: Cancer and allergies: visual lesson, ISC Class 12 Biology

Lesson

Cancer and allergies

Part 2 — when cell division escapes control, and when the immune system over-reacts.

In this lesson you will

Distinguish benign and malignant tumours and describe the properties of cancer cells
List the causes of cancer and its methods of diagnosis and treatment
Define allergy and allergen, and state the general symptoms of allergy

Diagram

Contact inhibition

Normal cells show contact inhibition: when they touch their neighbours, they stop dividing. Cancer cells have lost this property, so they keep dividing and pile up into a mass of cells, a tumour.

Diagram

Benign and malignant tumours

Benign tumours stay confined to their original site, often inside a capsule, and do little damage. Malignant tumours are masses of neoplastic cells that grow rapidly, invade nearby tissue, starve normal cells, and spread through blood to distant sites — metastasis, the most feared property.

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