Health Can Be Defined As the State of Mental, Physical, and Psychological Well-Being of an Individual. Factors Affecting Our Health

1. Our Dietary Habits: A well-balanced diet is required for a healthy body. If the person is taking a nutritionary deficient diet then the required amounts of nutrients are not provided to the body resulting in an unhealthy body. 

2. Lifestyle: A person doing a moderate amount of work in a life is having a healthy lifestyle in comparison to the person living a sedentary lifestyle. 

3. Our Social Environment: A person who constantly lives under social pressure and stress will always be accustomed to living a stressful life with various mental conditions and is more susceptible to stress-related disorders than a person living in a relaxed environment. 

4. The work-Related to Earning: Those people that work in the industries or factories will mostly suffer from respiratory or hearing problems as they are working conditions include noise and air pollution.

5. State of the Mind: The person’s state of mind is responsible for the proper functioning of the body and mind. The neural system, endocrine system, and immune system will work according to the state of mind of a person and will play a major role in keeping us healthy. 

6. Genetic Information: There are several genetic abnormalities and disorders that are inherited from the parents to their offspring, thus genetic material is also responsible for the healthy state of the body.  

7. Our Physical Environment: The area with hygienic conditions and greenery will be more healthy and beneficial in comparison to the unhygienic and polluted area. 

8. Economic Conditions of the Individual: The amount of money a person has is also responsible for the maintenance of health in an individual. If a person is spending a quality amount of money on their health then they will be more healthy. 

Disease is an abnormal condition or disorder that affects the functioning of a living organism, often causing physical or mental symptoms. The abnormal functioning of numerous body organs is part of the condition. Infectious and non-infectious diseases are the two types of diseases.

Infectious Diseases –Those diseases that can be transferred easily from one person to another are called infectious diseases. They are generally caused by pathogens. Examples include Common cold, malaria, AIDS 

Non-infectious Diseases –Those diseases that cannot be transmitted from one person to another are called non –infectious diseases. Examples – Cancer and Diabetes. 

Pathogens: The pathogens are the organisms that are responsible for the causing of diseases in a host. They include the microorganisms like bacteria, fungi, viruses, etc. 

Widal test: A serological test that helps in detecting whether a person is suffering from typhoid or not. 

Life Cycle of Plasmodium

Life Cycle of Plasmodium:

• The malarial infection starts when an infected female anopheles mosquito bites a healthy human. Thus, injects the plasmodium parasites into the bloodstream in the form of sporozoites.

• The sporozoites travel quickly into the human liver with the help of the bloodstream and there they asexually divide into the liver cells for 7 to 10 days. In this period no symptoms are produced in the human body.

• After the multiplication of the sporozoites, converted into merozoites and they are released from the liver cells in the vesicles. They travel through the heart and arrive in the lungs where they settle down in the lung capillaries.

• The disintegration of the vesicles allows merozoites to enter the blood phase of their development.

• The merozoites enter the red blood cells in the bloodstream and there they multiply until the cell burst. Then they start to enters more red blood cells. These repeated cycles of parasites cause fever each time when the parasites break the red blood cells and then invade the blood cells.

• Some blood cells which are infected leave the asexual multiplication cycle and instead of replicating, merozoites develop into the sexual form of the parasite known as gametocytes.

• When again the mosquito bites an infected person the gametocytes enter into the mosquito body, where they further develop into mature sex cells called gametes.

• The female gametes develop into ookinetes and remain in the midgut wall of the mosquito where they form oocysts on the exterior surface.

• Inside the oocyst, many active sporozoites are present. When the oocyst, breaks down, a large number of sporozoites are released into the body cavity and they travel to the mosquito's salivary gland.

• This led to the cycle of human infection starts again when the mosquito bites another person.

• Hence, the primary host is the mosquito, and the secondary host is the human.

Diseases Caused by Worms:

Prevention and Control: 

1. To maintain personal and public hygiene 

2. Isolation and Quarantine 

3. To eliminate vectors and also their breeding places 

4. Protection against vectors 

5. Vaccination 

6. Antibiotics 

8.2: IMMUNITY 

Immunity is the ability of a person to fight against diseases which can be achieved through the presence of antibodies in the person’s system.

Immunity is of two types: 

(i) Innate immunity 

(ii) Acquired immunity.

8.2.1 Innate Immunity 

The immunity which is present since the time of birth and is a non-specific type of immunity is called innate immunity. The entry of pathogens is restricted with this immunity with the help of certain barriers. 

Innate immunity consists of four types of barriers. These are — 

(i) Physical barriers: Examples - Skin, gastrointestinal, mucus coating of the epithelium lining the respiratory, and urogenital tracts.

(ii) Physiological barriers: Acid in the stomach, tears from eyes, saliva in the mouth.

(iii) Cellular barriers: Certain types of leukocytes (WBC) of our body can phagocytose and destroy microbes. For example, the polymorpho-nuclear leukocytes (PMNL-neutrophils), natural killer (type of lymphocytes) in the blood, monocytes, as well as macrophages in tissues. 

(iv) Cytokine barriers: The cells that are infected by the virus will produce proteins called interferons that help in protecting the other non-infected cells from getting a viral infection. 

8.2.2: Acquired Immunity 

Acquired immunity is developed during one’s life and is pathogen-specific. When the person develops an infection or a disease due to their exposure to the pathogen and the person’s body becomes immune to the disease which is caused due to the development of the immune response in the body is called active immunity which is acquired naturally or secondary or anamnestic response. The lymphocytes B and T lymphocytes are the types of lymphocytes that help in the primary and secondary responses. The function of B lymphocytes is to recognize foreign substances and get attached to them whereas the T lymphocyte’s function is to remember the antigens and also recognize them and respond against them and help B-lymphocytes to produce antibodies. 

Antibody Structure 

Antibodies are 'Y' shaped pretentious structures, which are made up of four polypeptide chains. Two heavy polypeptide chains and two light chains constitute the antibody and help in performing various functions. It is represented as H2L2. The different types of antibodies in our bodies are IgA, IgG, IgE, and IgM.

Humoral Immune Response 

People who are administered preformed antibodies get passive immunity. It is the transfer of active humoral immunity through these readymade antibodies present in the blood (body humor).

Cell-mediated immunity 

It defends against intracellular pathogens and cancer by binding to antigens and lyzing the infected cells or cancer cells that do not involve antibodies instead release phagocytes, antigen-specific cytotoxic T-lymphocytes, and various cytokines in response to an antigen. This helps the body to differentiate between ‘self’ and ‘non-self’.

8.2.3: Active immunity v/s Passive immunity

8.2.4: Vaccination and Immunization: 

Vaccination: Vaccination is based on the memory of the immune system. When an antigenic material is injected into a healthy person, it generates antibodies and memory cells as primary immune response. The vaccine is a suspension of inactivated pathogens or antigenic proteins of a pathogen that is taken orally or injected to provide immunity for that pathogen. During the infection B and T lymphocytes will get activated and forms a large number of antibodies after recognizing the antigen a. 

People who are administered preformed antibodies get passive immunity. It is the transfer of active humoral immunity through these readymade antibodies. This process is done when the person needs antibodies in a short span. 

Newer techniques like recombinant DNA technology are used in the production of several vaccines and the vaccines produced will be having fewer side effects. It also helps in the production of antigenic polypeptides in bacteria and yeast.

8.2.5: Allergies 

Definition: Allergies are also known as allergic diseases. They are the number of conditions which is caused by hypersensitivity of the immune system to various typically harmless substances present in the environment. When the immune system reacts to a foreign substance like pollen, or bee venom, or a food that does not cause a reaction in most people then allergies occur. The antibodies produced to these are of IgE type. 

Common examples of allergens are outdoor pollutants including ozone and diesel exhaust, indoor pollutants such as tobacco smoke and nitrogen dioxide, microbial products, mites in dust, pollens, animal dander, etc. 

Symptoms of allergic reactions include sneezing, running nose, watery eyes, and difficulty in breathing. Due to the production of histamine and serotonin in the mast cells, allergies are caused while drugs like anti-histamines, adrenalin, and steroids are taken to reduce the symptoms of allergy.

8.2.6: Autoimmunity 

Autoimmunity is the ability of the human immune system to differentiate between the antigens that are foreign to the body and the antigen wIt is observed in some cases that due to certain genetic and reasons the body attacks its own cells leading to damage and this is called auto-immune disease. Example -Rheumatoid arthritis. 

8.2.7: Immune System in the Body: 

It consists of Lymphoid organs, tissues, cells, and antibodies.

The immune system functions as follows: 

• It helps in differentiating between self and non-self.

• It protects the body against non-self or foreign antigens.

• It is based upon the production of memory cells and reacts according to the antigens present previously. 

• It is involved in allergic reactions. 

• It is important in auto-immune diseases.

• It is important in organ transplant and graft rejection. 

Lymphoid Organs 

The spleen organ is structurally similar to a big lymph node. The purpose of the spleen is to filter blood. It is also essential for immunity and red blood cell formation. The spleen is also known as the red blood cell cemetery.

The lining of the major arteries is made up of lymphoid tissue. It's known as mucosal-associated lymphoid tissue. It accounts for almost half of the lymphoid tissue in the human body.

(Image will be uploaded soon) (Image will be uploaded soon)

8.3: AIDS (Acquired Immuno Deficiency Syndrome)

HIV-AIDS is Acquired Immunodeficiency Syndrome, caused by the Human Immunodeficiency Virus, and interferes with the body's ability to fight infection. This virus is transmitted through contact with the infected blood, semen, or vaginal fluids. AIDS was first reported in 1981 and in approximately the last twenty-five years, it has spread all over the world killing more than 25 million persons.

• Flu-like symptoms appear within a few weeks of infections such as fever, fatigue, and sore throat.

• Then disease becomes asymptomatic until it progresses into AIDS. weight loss, fever or night sweats, fatigue, and recurrent infections are the symptoms of AIDS.

• Till now, no cure is available for AIDS but antiretroviral regimens can slow the progress of the disease as well as prevent secondary infections and complications.

Causative Agent: It is caused by Human Immunodeficiency and is a member of a group of viruses called a retrovirus. Their genome is RNA which is enclosed in an envelope and they also consist of the reverse transcriptase gene.

Structure of an HIV virus

Transmission of HIV-infection 

(a) Sexual contact with an infected person: individuals who have multiple sexual partners.

(b) By transfusion of contaminated blood and blood products: Individuals who require repeated blood transfusions (certain cancers, anemia, and thalassemia).

(c) By sharing infected needles as in the case of intravenous drug abusers: drug addicts who take drugs intravenously.

(d) From infected mother to her child through the placenta: children born to an HIV infected mother. HIV/AIDS does not spread through mere touch or physical contact. It primarily spreads through sexual contact but also through infected blood from shared intravenous needles and so on. This incubation period may vary from a few months to many years (usually 5-10 years). 

How HIV Affects the Body? 

When the virus enters the person’s body then it will infect the macrophages. Then with the help of reverse transcriptase enzyme, the viral genome RNA replicates and forms viral DNA. Thie viral DNA will go into the host cell and then these infected cells will produce virus particles. Thus, macrophase will prince viruses. Simultaneously, the HIV virus will enter the helper T cells and produce the virus progeny in the blood which will attack other helper T lymphocytes. This cycle continues until the number of T lymphocytes decreases in the infected person. This leads to the person suffering from several diseases that include infections and diseases such as those caused by bacteria especially Mycobacterium, viruses, fungi, and even parasites like Toxoplasma. Thus the patient becomes immunodeficient leading to a very weak immune system. 

Transmission Cycle of HIV

Detection: 

The detection of AIDS can be done by Enzyme-linked immunosorbent assay (ELISA): It is a biochemical test that helps in detecting the presence of an antibody or an antigen in a sample. To confirm the results of the ELISA test a Western Blot test is also done.

Treatment: 

The treatment of AIDS is done by using anti-retroviral drugs which increases the lifespan of a person by it cannot prevent death. 

Prevention of AIDS

There is no cure for AIDS so it’s best to prevent it from occurring. The main thing that must be kept in mind for preventing AIDS is blood transfusion, transmission from mother to newborn. 

Role of government and non-government organizations in limiting the spread of this disease.

To make people aware and educate them about AIDS which is done with the help of the National AIDS Control Organisation (NACO) and other non-governmental organizations (NGOs). There are various programs conducted by WHO to prevent AIDS from spreading. 

Prevention and Control Methods: 

• Making blood transfusions safe from HIV.

• To ensure not to use the same needles that are already used.

• Free distribution of condoms.

• Controlling drug abuse.

• Advocating safe sex.

• Promoting regular check-ups for HIV in susceptible populations. 

Role of Society in preventing the spread of this disease 

Sympathy for HIV/AIDS patients. 

To make people aware of AIDS so as to prevent it from spreading. 

Cooperation between the society and the medical facility to prevent the spread of this disease. Disclosure about the HIV status to prevent further spread to more people. 

Awareness and Role of Society

1. The role of society in avoiding the spread of this disease is critical, as it promotes cleanliness and safety measures such as mask use and social separation.

2. It is critical to sympathise with and assist HIV/AIDS patients in their fight against the disease, as they frequently encounter stigma and discrimination.

3. To stop the spread of AIDS, individuals must be educated about its transmission, symptoms, and preventive actions, such as safe sex practises and not sharing needles.

4. Cooperation between society and medical facilities is crucial in reducing disease spread by assuring early detection, diagnosis, and treatment of sick individuals.

5. It is critical to urge people to disclose their HIV status in order to avoid further spread and to offer adequate medical care and support to those who are infected.

8.4: Cancer 

Cell growth is highly controlled and coordinated in our body but when this is controlled, mechanisms breakdown it will result in the differentiation of cells uncontrollably which will result in the growth of cancer cells leading to uncontrollable growth. These cancerous cells will divide continuously leaving the formation of mature cells called tumors. 

Tumors are of Two Types: 

1. Benign tumor is one that is differentiated and capsulated. Benign tumors generally have a slower rate of growth and normally remain limited and do not spread to other parts of the body causing less damage. 

2. They develop when cells grow uncontrollably. If the cells still grow and spread, the disease can become life-threatening. Malignant tumors can grow quickly and spread to other parts of the body during a process called metastasis          

Causes of Cancer: 

The normal cells are transformed into cancerous cells through physical, chemical, or biological agents. These agents are called carcinogens. 

Common Carcinogens: 

• Ionizing radiations: X-rays and gamma rays.

• Non-ionizing radiations: UV Both ionizing and non-ionizing radiations cause DNA damage that causes neoplastic transformation. 

• The chemical carcinogens are the major cause of lung cancer that is present in tobacco smoke.

• Oncogenic viruses consist of genes called viral oncogenes that are cancer-causing viruses. In normal cells, several genes are identified called cellular oncogenes(c-onc), or proto-oncogenes that can be activated under certain conditions thus resulting in the oncogenic transformation of the cells. 

Cancer Detection and Diagnosis: 

When cancer is detected early then the disease can be treated successfully. Cancer detection is based on: 

Biopsy: In this process, a small suspected tissue is taken and is then stained called Histopathological studies of the tissue (thin sections are examined under the microscope).

Blood and bone marrow tests: To detect leukemia and to measure the increased cell counts.

Radiography: (use of X-rays), 

CT (computed tomography): To generate the three-dimensional structure of an organ through X-rays. 

MRI (magnetic resonance imaging): It is the use of strong magnetic fields and non-ionizing radiations that are used to detect the changes in the living tissues.

Antibodies against cancer-specific antigens: Used for detection of certain cancers. 

Techniques of molecular biology: It is used to detect various types of cancers and also in the identification of genes that help in preventing cancers. Those individuals in which these are detected are advised to stop the use of carcinogens that are harmful to them like tobacco and smoking in the case of lung cancer. 

Treatment of Cancer: 

Treatment of cancer can be done by one or a combination of different approaches. The common approaches for the treatment of cancer are surgery, radiation therapy, chemotherapy, and immunotherapy. 

In radiotherapy, the tumor cells are irradiated lethally while the normal cells surrounding them are taken care of.  

There are several drugs that are used to kill cancerous cells called chemotherapeutics which may be specific for particular tumors. These drugs will show certain side effects that include the side effects like hair loss, anemia, etc. 

The majority of the cancers are treated by a combination of all the above methods. 

The Tumor cells can be detected by the immune system with the help of certain substances called biological response modifiers. They are substances such as α-interferon that destroy the tumor by activating the immune system. 

8.5: Drug Abuse 

The consumption of drugs which are chemical substances that are not prescribed by the doctors and are taken in a high dosage very frequently results in the impairing of a person’s physical, psychological functions leading to drug abuse. 

Commonly abused drugs are opioids, cannabinoids, and coca alkaloids. 

Smoking

Tobacco is either smoked, chewed or used as a snuff and consists of various chemical substances that include nicotine (alkaloid). It results in the adrenal gland releasing adrenaline and noradrenaline hormones into the blood leading to a rise in blood pressure and heartbeat. 

Continuous smoking may cause lung cancer, affects the urinary bladder, and throat causing bronchitis, emphysema, coronary heart diseases, and gastric ulcers, the chewing of tobacco may increase the risk of oral cavity cancer. Smoking reduces the heam-bound oxygen in the blood and increases the CO content in the blood which will lead to anemia and oxygen deficiency.  increases CO content in the blood and therefore reduces the content of haem-bound oxygen. To get free from the addiction of drug an addict require medical counseling.

8.5.2: Adolescence and Drug/Alcohol abuse: 

The period of adolescence starts when an individual reaches reproductive maturity. This stage comes in between childhood and adulthood. During this period the person undergoes various physiological and psychological changes leading to the emotional and behavioral growth of the individual. During this period the individuals are highly emotional and vulnerable. Thus the youngsters lay lead towards the life of drug abuse due to: 

• Curiosity 

• Need for adventure 

• Experimentation 

• Perceived benefits of alcohol and drug use 

• Stress and academic pressure 

• Need to appear cool/peer pressure 

• Influence of popular media 

• Unstable family structure 

8.5.2: Addiction and Dependence: 

Addiction: It is the feeling of eu[horia which a person feels when they are continuously under the effect of drugs and alcohol. Due to repeated use of drugs they are now highly tolerant towards large amounts of drug doses. Thus the receptor of the person’s body will respond to a higher drug dose leading to the intake of more drugs and thus more addiction.

Dependence: It is the condition of an unpleasant withdrawal syndrome in a person’s body if the regular dose of drugs/alcohol is stopped suddenly leading to anxiety, nausea, shakiness, and sweating which will stop only when the person consumes the drug again. In some cases, the withdrawal symptoms are also found to be life-threatening and the person may require medical supervision. To satiate their needs the person will ignore all the social norms and may even choose the wrong path leading to social problems. 

8.5.3: Effects of Drug/Alcohol Abuse

• Reckless behavior.

• Vandalism and violence. 

• The use of excessive doses of drugs may lead to coma and death due to respiratory failure, heart failure, or cerebral hemorrhage. 

• Injecting drugs could lead to increased susceptibility to diseases like AIDS, Hepatitis, etc. 

• Damage to the nervous system and Liver cirrhosis.

• Adverse effect on the fetus due to consumption during pregnancy.

Side Effects of Performance-Enhancing Drugs for Sports:

In females: masculinization, mood swings, increased aggressiveness, depression, excessive facial abnormal menstrual cycle, and body hair, enlargement of the clitoris, and deepening of the voice.

In males: acne, mood swings, aggressiveness, depression, decreased sperm production, reduction in testicles, kidney and liver dysfunction, premature baldness, breast enlargement, enlargement of the prostate.

Common Warning Signs of Drug and Alcohol Abuse

• Drop-in academic performance.

• unexplained absence from school/college.

• lack of interest in personal hygiene.

• Withdrawal, isolation, depression, fatigue, aggressive and rebellious behavior.

• Deteriorating relationships with family and friends.

• Loss of interest in hobbies.

• Change in sleeping and eating habits.

• Fluctuations in weight, appetite, etc. 

• Stealing to get money to buy drugs/alcohol. 

8.5.4: Prevention and Control 

1. Avoid undue peer pressure.

2. Education and counseling. 

3. Seeking help from parents and peers.

4. Looking for danger signs.

5. Seeking professional and medical help.

Human Health and Disease Class 12 Notes Biology - Basic Subjective Questions

Section−A (1 Mark Questions)

1. Name the primary and secondary lymphoid organs. 

Ans.

Primary lymphoid organs: Bone marrow and Thymus

Secondary lymphoid organs: Spleen, MALT, tonsils, lymph nodes, peyer’s patches

2. What would happen to the immune system, if the thymus gland is removed from the body of a person?

Ans. Thymus is one of the primary lymphoid organs where the maturation of T-lymphocytes takes place. Removal of the thymus gland at an immature stage will weaken the immune system of a person. As a result the person will be more prone to infectious diseases.         

3. Why is mother's milk considered the most appropriate food for a newborn infant?

Ans. Mother’s milk during the initial days after delivery of the baby is called colostrum. It contains abundant IgA antibodies that provide infants with immunity against various neonatal diseases. Hence mother's milk is considered to be the most appropriate food for newborn infants. 

4. What are interferons? How do interferons check infection of new cells?

Ans. Interferones are the proteins that are released from the virus infected cells. They act as cytokine barriers and inhibit the viral replication within host cells, activate natural killer cells and macrophages and induce the resistance of host cells to viral infection.

5. What is meant by metastasis?

Ans. Malignant cancer cells show a phenomenon called metastasis in which the cancer cells spread to distant sites through body fluids to develop secondary tumours. This phenomenon makes malignant tumours more dangerous than benign tumours. 

Section−B (2 Mark Questions)

6. Mention the  (a) One diagnostic test of AIDS and typhoid   (b) Any two diagnostic test of cancer

Ans. 

(a) Typhoid : Widal Test ; AIDS: ELISA

(b) MRI and CT scan

7. Differentiate between benign tumour and malignant tumour. (Any two)

Ans.

8. What are the various routes by which transmission of human immunodeficiency virus takes place?

Ans. 

(a) sexual contact with infected person

(b) by transfusion of contaminated blood and blood products

(c) by sharing infected needles as in the case of intravenous drug abusers 

(d) from infected mother to her child through placenta

9. Where are B-cells and T-cells formed? How do they differ from each other?

Ans. B- cells and T-cells are formed in bone marrow. 

10. What are autoimmune diseases? Give two examples?

Ans. If the immune system fails to recognize self from the non self cells and start destroying the body’s own protein. This leads to some malfunctions which are called autoimmune diseases.

Example: Rheumatoid arthritis, Myasthenia gravis, grave’s disease. 

11.Name the opioid drug and its source plant. Mention two ways in which it affects the human body. 

Ans. Smack is the opioid drug that is obtained from Papaver somniferum (poppy plant)

(i) It binds to the specific opioid receptor present in the central nervous system and gastrointestinal tract.

(ii) It acts as a depressant and slows down the body function.

5 Important Topics of Biology Class 12 Chapter 7 You Shouldn’t Miss!

Here are five important topics from Human Health and disease class 12 short notes that you shouldn't miss:

Importance of Revision Notes for Biology Class 12 Chapter 7 Human Health and Diseases

Revision notes are essential tools for effective study and exam preparation. Class 12 Human Health and Disease Notes provide a concise summary of the key concepts, making it easier to review and reinforce what you've learned. Here are some reasons why revision notes are important:

• Quick Review: Revision notes allow you to quickly go over the essential points, saving time when revising large amounts of material.

• Better Retention: By summarising information in easy-to-understand points, revision notes help in better retention and recall of concepts.

• Organised Learning: They present the content in an organised manner, making it easier to follow the flow of topics and connect related ideas.

• Focused Study: Revision notes highlight the most important information, helping you focus on what's crucial for exams.

• Stress Reduction: Having all the key information in one place reduces the stress of last-minute studying and helps you feel more prepared.

Tips For Learning the Class 12 Biology Chapter 7 Human Health and Disease

Here are some tips for learning Class 12 Biology Chapter 7 Human Health and Disease Notes in simple language:

• Start with Basics: Begin by understanding basic concepts like health, disease, and immunity. This will make it easier to grasp more complex topics.

• Use Diagrams: Study diagrams related to the immune system, diseases, and treatments. Visuals help in remembering and understanding the content better.

• Focus on Key Diseases: Pay special attention to the common diseases mentioned in the chapter, their causes, symptoms, and prevention.

• Revise Regularly: Regular revision helps in retaining the information. Go over your notes frequently to keep the concepts fresh in your mind.

• Practice Questions: Solve past papers and sample questions to test your understanding and identify areas where you need more practice.

Conclusion

The Class 12 Human Health and Disease notes help us understand the main ideas of the chapter. These notes make it easier to learn about important topics like immunity and common diseases. Using these notes will help you prepare well for your exams and better understand how to take care of your health.

Related Study Materials for Class 12 Biology Chapter 7

Biology Notes for Class 12 Chapter-Wise PDF FREE Download

Related Study Material Class 12 Biology