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CBSE Class 12th Biology Notes for Chapter 8 Human Health And Disease

Chapter 8 Human Health And Disease

  • Health is not just the absence of disease. It is a state of complete physical, mental, social and psychological well-being.


  • Diseases like typhoid, cholera, pneumonia, fungal infections of the skin, malaria and many other are a major cause of distress to human beings.


  • Vector-borne diseases like malaria if not treated, may prove fatal.


  • Besides personal cleanliness and hygiene, public health measures like proper disposal of waste, decontamination of drinking water, control of vectors like mosquitoes and immunization are very helpful in preventing diseases.


  • Our immune system plays a major role in preventing these diseases when we are exposed to disease-causing agents.


  • The innate defences of our body like skin, mucous membranes, antimicrobial substances present in our tears, saliva and the phagocytic cells help to block the entry of pathogens into our body.


  • If the pathogens succeed in gaining entry to our body, specific antibodies and cells serve to kill these pathogens.


  • Immune system has a memory. On subsequent exposure to same pathogen, the immune system response is more rapid and intense. This forms the basis if protection afforded by vaccination and immunization.


  • Among other diseases, AIDS and cancer kill a large number of individuals worldwide.


  • AIDS is caused by the Human Immuno-deficiency Virus (HIV) and is fatal but can be prevented if certain precautions are taken.


  • Many cancers are curable if detected early and appropriate therapeutic measures are taken.


  • Lately, drug and alcohol abuse among youth and adolescents is becoming a major cause of concern. Because of the addictive nature of alcohol and drugs, and their perceived benefits like relief from stress, a person may try taking these due to peer pressure or other stresses. This may lead to addiction to these substances.


  • Education about the harmful effects of drugs and alcohol, counseling and seeking immediate professional and medical help can help individuals to overcome their addictions.

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