Think about… 25.1 Non-infectious diseases 25.2 Prevention of diseases Recall ‘Think about…’

2. Think about… 25.1 Non-infectious diseases 25.2 Prevention of diseases Recall ‘Think about…’ Summary concept map

3. The leading cause of death in HK Cancer is the leading cause of death. malignant tumour in air sac

4. The leading cause of death in HK There has been an increase of over 25% in the number of deaths from cancer during the past 10 years.

5. 25.1 Non-infectious diseases • cannot be transmitted from person to person • account for about 60% of deaths and disabilities • many develop slowly  chronic diseases (慢性病) • associate with risk factors (高危因素)

6. Risk factors • A risk factor (高危因素) is anything that may increase the risk of developing a disease. There are four types of risk factors:

7. 25.1 Non-infectious diseases 1 Biological risk factors e.g. age, sex, race • nasopharyngeal cancer (鼻咽癌) is more common in Chinese

8. 25.1 Non-infectious diseases 2 Genetic risk factors e.g. family history • people with family history of diabetes mellitus have a higher risk of the disease

9. 25.1 Non-infectious diseases 3 Environmental risk factors e.g. sunlight, air pollution, radiation • long exposure to sunlight increases the risk of skin cancer

10. 25.1 Non-infectious diseases 4 Behavioural risk factors e.g. smoking, insufficient exercise • smokers have a higher risk of lung cancer

11. 25.1 Non-infectious diseases Allergies • an overreaction of the immune system to foreign substances allergens (過敏原) e.g. pollen dust mites (塵蟎)

12. 25.1 Non-infectious diseases Allergies • an overreaction of the immune system to foreign substances allergens (過敏原) e.g. insect stings animal hair

13. 25.1 Non-infectious diseases Allergies • an overreaction of the immune system to foreign substances allergens (過敏原) e.g. medicines eggs & peanuts

14. 25.1 Non-infectious diseases Allergies • mild symptoms: running nose, sneezing, ithciness or a skin rash (疹)

15. 25.1 Non-infectious diseases Allergies • severe symptoms: swelling of lips, tongue or throat, shortness of breath or loss of consciousness • often inherited (遺傳)

16. 25.1 Non-infectious diseases Allergies Prevention • avoid the allergen 1 People with food allergy should read carefully any label and warning on pre-packed food

17. 25.1 Non-infectious diseases Allergies Prevention • avoid the allergen 2 People with asthma (哮喘)should avoid contact with dust mites

18. Cancer

19. Cancers of the human body

20. The leading cause of death in HK

21. 25.1 Non-infectious diseases Cancer changes in DNA uncontrolled cell division tumour (benign or malignant)

22. Cancer as loss of growth control

23. Benign vs Malignant tumour Benign tumour cellsgrowthand spread unrestrained Malignanttumour --cancer

24. 25.1 Non-infectious diseases Cancer • benign tumour (良性腫瘤): -tumourcells surrounded by a fibrous capsule -tumourcells do not spread to other tissues a benign tumour of fatty tissue

25. 25.1 Non-infectious diseases Cancer • malignant tumour(惡性腫瘤): -also called cancer -tumour cells can spread through the bloodstream and lymphatic system -at new sites, tumour cells continue to divide uncontrollably damage the tissues

26. Invasion and metatasis Malignant tumors are tumors that are capable of spreading by invasion and metastasis

27. Metatasis a melanoma (a cancer of pigmented cells) arising in the skin can have cells that enter the bloodstream and spread to distant organs such as the liver or brain. Cancer cells in the liver would be called metastatic melanoma, not liver cancer.

28. 25.1 Non-infectious diseases Cancer 1 A cell begins to divide more often than normal. cell with changes in DNA

29. 25.1 Non-infectious diseases Cancer 2 One of the tumour cells has further tendency to divide. tumour (腫瘤) cell with further changes in DNA

30. 25.1 Non-infectious diseases Cancer 3 The malignant tumour develops its own blood vessels. cancer cells blood vessel

31. 25.1 Non-infectious diseases Cancer The tumour cells (cancer cells) travel through the blood to invade other tissues. 3 cancer cells blood vessel

32. Characteristic of cancer cells I Suggest how cancer cells appear under microscope?

33. Characteristic of cancer cells II a large number of dividing cells, variation in nuclear size and shape, loss of specialized cell features, loss of normal tissue organization, a poorly defined tumor boundary.

34. Diagnosis- Pap smear and biopsy

35. Colorectal Cancer Staging Staging is the process of determining how far a tumor has spread beyond its original location. Staging may not be related to the size of the tumor. Treatment decisions also depend upon the stage of a tumor. Staging for colorectal cancer is as follows: Stage 0 – The cancer is found only in the innermost lining of the rectum or colon. Stage I – The cancer has not spread beyond the inner wall of the rectum or colon. Stage II – The cancer has spread into the muscle layer of the rectum or colon. Stage III – The cancer has spread to at least one lymph node in the area. Stage IV – The cancer has spread to distant sites in the body, such as the bones, liver, or lungs. This stage is NOT dependent on how far the tumor has penetrated or if the cancer has spread to lymph nodes near the tumor.

36. Screening for Colorectal Cancer It is recommended that most people have a screening colonoscopy every year starting at age 50. A colonoscopy allows examination of the entire colon and rectum using a tiny camera. This test can find cancers in the early, most treatable stage and actually prevent cancers from developing by removing polyps, as shown here.

37. Factors that can lead to cancer

38. Clues from geographic distribution of cancer incidents

39. Risk factors: UV, X-ray, tobacco

40. Risk factor: some viral infections

41. Risk factor_age Because cancer usually requires a number of mutations, the chances of developing cancer increase as a person gets older because more time has been available for mutations to accumulate.

42. Cancerabnormal function of the genes

43. 25.1 Non-infectious diseases Cancer • agents that can induce changes in DNA and make cells cancerous  carcinogens(致癌物) symbol of carcinogens

44. 25.1 Non-infectious diseases Cancer Chemical Lung cancer Tar in cigarette smoke Nitrosamine (亞硝胺) in salted fish Nasopharyngeal cancer Throat cancer, lung cancer Asbestos (石棉) in construction materials

45. 25.1 Non-infectious diseases Cancer Radiation Skin cancer Ultraviolet light (紫外光) in sunlight X-ray in medical examination Blood cancer, thyroid cancer (甲狀腺癌)

46. 25.1 Non-infectious diseases Cancer Virus Cervical cancer (子宮頸癌) Human Papillomavirus (HPV) (人類乳頭瘤病毒) Hepatitis B virus Liver cancer

47. Carcinogens _UV light causes Thymine-dimer formation

48. Carcinogens _nitrous acid Chemical mutagens such as nitrous acid (HNO2) may cause nucleotide deamination: conversion of an amino group to a keto group. Thus a transition mutation occurs: e.g. adenine are converted to hypoxanthine (which base pairs with cytosine).

49. Chemical mutagens such as nitrous acid (HNO2) may cause nucleotide deamination: conversion of an amino group to a keto group. adenine are converted to hypoxanthine (which base pairs with cytosine), respectively.

50. Carcinogens _base analogues 5-Bromo-uracil can substitute for T, and then wind up binding with G (rather than A), thus inducing a TRANSITION (G->A) mutation.