Chapter 8 Human health and diseases
EXERCISES
1. What are the various public health measures, which you would suggest as safeguard against infectious diseases?
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Answer
Public health measures are preventive measures which are taken to check the spread of various infectious diseases. These measures should be taken to reduce the contact with infectious agents.
Some of these methods are:
(1) Maintenance of personal and public hygiene:It is one of the most important methods of preventing infectious diseases. This measure includes maintaining a clean body, consumption of healthy and nutritious food, drinking clean water, etc. Public hygienic includes proper disposal of waste material, excreta, periodic cleaning, and disinfection of water reservoirs.
(2) Isolation: To prevent the spread of air-borne diseases such as pneumonia, chicken pox, tuberculosis, etc., it is essential to keep the infected person in isolation to reduce the chances of spreading these diseases.
(3) Vaccination: Vaccination is the protection of the body from communicable diseases by administering some agent that mimics the microbe inside the body. It helps in providing passive immunizationto the body. Several vaccines are available against many diseases such as tetanus, polio, measles, mumps, etc.
(4) Vector Eradication: Various diseases such as malaria, filariasis, dengue, and chikungunya spread through vectors. Thus, these diseases can be prevented by providing a clean environment and by preventing the breeding of mosquitoes. This can be achieved by not allowing water to stagnate around residential areas. Also, measures like regular cleaning of coolers, use of mosquito nets and insecticides such as malathion in drains, ponds, etc. can be undertaken to ensure a healthy environment. Introducing fish such as Gambusia in ponds also controls the breeding of mosquito larvae in stagnant water.
2. In which way has the study of biology helped us to control infectious diseases?
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Answer
Various advancements that have occurred in the field of biology have helped us gain a better understanding to fight against various infectious diseases. Biology has helped us study the life cycle of various parasites, pathogens, and vectors along with the modes of transmission of various diseases and the measures for controlling them. Vaccination programmes against several infectious diseases such as small pox, chicken pox, tuberculosis, etc. have helped eradicate these diseases. Biotechnology has helped in the preparation of newer and safer drugs and vaccines. Antibiotics have also played an important role in treating infectious diseases.
3. How does the transmission of each of the following diseases take place?
(a) Amoebiasis
(b) Malaria
(c) Ascariasis
(d) Pneumonia
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Answer
| Disease | Causative organism |
Mode of transmission | |
|---|---|---|---|
| a. | Amoebiasis | Entamoeba histolytica |
It is a vector-borne disease that spreads by the means of contaminated food and water. The vector involved in the transmission of this disease is the housefly. |
| b. | Malaria | Plasmodium sp. | It is a vector-borne disease that spreads by the biting of the female Anopheles mosquito. |
| c. | Ascariasis | Ascaris lumbricoides |
It spreads via contaminated food and water. |
| d. | Pneumonia | Streptococcus pneumoniae |
It spreads by the sputum of an infected person. |
4. What measure would you take to prevent water-borne diseases?
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Answer
Water-borne diseases such as cholera, typhoid, hepatitis B, etc. spread by drinking contaminated water. These water-borne diseases can be prevented by ensuring proper disposal of sewage, excreta, periodic cleaning. Also, measures such as disinfecting community water reservoirs, boiling drinking water, etc. should be observed.
5. Discuss with your teacher what does ‘a suitable gene’ means, in the context of DNA vaccines.
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Answer
A ‘suitable gene’ refers to a specific DNA segment which can be injected into the cells of the host body to produce specific proteins. This protein kills the specific disease-causing organism in the host body and provides immunity.
6. Name the primary and secondary lymphoid organs.
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Answer
(a) Primary lymphoid organs include the bone marrow and the thymus.
(b) Secondary lymphoid organs are the spleen, lymph nodes, tonsils, Peyer’s patches of small intestine, and appendix.
7. The following are some well-known abbreviations, which have been used in this chapter. Expand each one to its full form:
(a) MALT
(b) CMI
(c) AIDS
(d) NACO
(e) HIV
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Answer
(a) MALT- Mucosa-Associated Lymphoid Tissue
(b) CMI- Cell-Mediated Immunity
(c) AIDS- Acquired Immuno Deficiency Syndrome
(d) NACO- National AIDS Control Organization
(e) HIV- Human Immuno Deficiency virus
8. Differentiate the following and give examples of each:
(a) Innate and acquired immunity
(b) Active and passive immunity
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Answer
(a) Innate and acquired immunity
| Feature | Innate Immunity | Acquired Immunity |
|---|---|---|
| Definition | The natural defense mechanisms present at birth. | The immunity developed after exposure to antigens or through vaccination. |
| Response Time | Immediate (minutes to hours) | Delayed (days to weeks) |
| Specificity | Non-specific, general defense mechanisms | Highly specific to particular pathogens |
| Memory | No memory; response is the same each time | Has memory; response improves with subsequent exposures |
| Components | Physical barriers (skin, mucous membranes), phagocytes, natural killer cells, complement system, inflammatory response | B cells (produce antibodies), T cells (helper and cytotoxic), memory cells |
| Duration | Short-term | Long-term, can be lifelong |
| Evolutionary Age | Ancient, present in all multicellular organisms | More recent, present in vertebrates |
| Examples | Skin, stomach acid, enzymes in saliva, phagocytosis, fever | Vaccination, recovery from infections, immunological memory |
This table highlights the key differences between innate and acquired immunity, showing how they complement each other to protect the body from infections and diseases.
(b) Active and passive immunity
| Feature | Active Immunity | Passive Immunity |
|---|---|---|
| Definition | Immunity developed by the body’s own immune system in response to exposure to a pathogen or vaccination. | Immunity acquired by the transfer of antibodies or activated T-cells from an immune host. |
| Source of Antibodies | Produced by the individual’s own immune system. | Received from another source, such as maternal antibodies, blood transfusions, or immunoglobulin injections. |
| Duration | Long-lasting, often for years or a lifetime. | Short-term, typically lasting a few weeks to months. |
| Onset | Takes time to develop, usually days to weeks. | Immediate protection upon receipt of antibodies. |
| Memory Cells | Generates memory cells, providing long-term immunity. | Does not generate memory cells, so no long-term immunity. |
| Examples | Natural infection, vaccination (e.g., measles, mumps, rubella vaccines). | Maternal antibodies passed to the baby through the placenta or breast milk, antivenom for snake bites. |
| Specificity | Highly specific to the pathogen or antigen encountered. | Specific to the antibodies transferred, but not as adaptable. |
| Booster Requirement | May require booster shots to maintain immunity. | No booster shots required, as the immunity is temporary. |
This table highlights the key differences between active and passive immunity, including their sources, duration, onset, and other characteristics.
9. Draw a well-labelled diagram of an antibody molecule.
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Answer
Structure of an antibody molecule
10. What are the various routes by which transmission of human immunodeficiency virus takes place?
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Answer
AIDS (Acquired Immuno Deficiency Syndrome) is caused by the Human immunodeficiency virus (HIV).
It has the following modes of transmission:
(a) Unprotected sexual contact with an infected person.
(b) Transfusion of blood from a healthy to an infected person.
(c) Sharing infected needles and syringes.
(d) From an infected mother to a child through the placenta.
11. What is the mechanism by which the AIDS virus causes deficiency of immune system of the infected person?
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Answer
AIDS (Acquired Immuno Deficiency Syndrome) is caused by the Human immunodeficiency virus (HIV) via sexual or blood-blood contact. After entering the human body, the HIV virus attacks and enters the macrophages. Inside the macrophages, the RNA of the virus replicates with the help of enzyme reverse transcriptase and gives rise to viral DNA. Then, this viral DNA incorporates into the host DNA and directs the synthesis of virus particles. At the same time, HIV enters helper T- Iymphocytes. It replicates and produces viral progeny there. These newly formed progeny viruses get released into the blood, attacking other healthy helper T-lymphocytes in the body. As a result, the number of T-lymphocytes in the body of an infected person decreases progressively, thereby decreasing the immunity of a person.
12. How is a cancerous cell different from a normal cell?
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Answer
| Feature | Normal Cells | Cancerous Cells |
|---|---|---|
| Growth Rate | Controlled and regulated | Uncontrolled and rapid |
| Cell Cycle Regulation | Strictly regulated by checkpoints | Checkpoints are often bypassed or ignored |
| Apoptosis (Cell Death) | Undergo programmed cell death if damaged | Often evade apoptosis, leading to survival of damaged cells |
| Differentiation | Fully differentiated and specialized | Poorly differentiated, often lose specialized functions |
| Contact Inhibition | Stop dividing when in contact with other cells | Lack contact inhibition, continue to grow and pile up |
| Genetic Stability | Relatively stable genome | High genetic instability and mutations |
| Angiogenesis | Normal blood vessel formation | Induce formation of new blood vessels to supply the tumor (angiogenesis) |
| Metastasis | Do not spread to other parts of the body | Can invade nearby tissues and spread to distant sites (metastasis) |
| Energy Production | Primarily use oxidative phosphorylation | Often rely more on glycolysis (Warburg effect) even in the presence of oxygen |
| Response to Growth Signals | Respond appropriately to growth signals | Often grow in the absence of growth signals or produce their own growth signals |
| Immune System Interaction | Recognized and often eliminated by the immune system | Can evade immune detection and destruction |
These differences are fundamental to understanding how cancer develops and progresses, and they also form the basis for many cancer treatments and research strategies.
13. Explain what is meant by metastasis.
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Answer
The property of metastasis is exhibited by malignant tumors. It is the pathological process of spreading cancerous cells to the different parts of the body. These cells divide uncontrollably, forming a mass of cells called tumor. From the tumor, some cells get sloughed off and enter into the blood stream. From the blood stream, these cells reach distant parts of the body and therefore, initiate the formation of new tumors by dividing actively.
14. List the harmful effects caused by alcohol/drug abuse.
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Answer
Alcohol and drug abuse can have a wide range of harmful effects on an individual’s physical health, mental well-being, and social life. Here are some of the key harmful effects:
Physical Health Effects:
- Liver Damage: Alcohol abuse can lead to liver diseases such as fatty liver, hepatitis, and cirrhosis. Drug abuse can also cause liver damage.
- Cardiovascular Problems: Both alcohol and drug abuse can lead to high blood pressure, heart disease, and an increased risk of stroke.
- Respiratory Issues: Smoking drugs or inhaling substances can cause respiratory problems, including chronic bronchitis and lung infections.
- Neurological Damage: Long-term abuse can lead to brain damage, cognitive impairments, and memory loss.
- Gastrointestinal Issues: Alcohol and certain drugs can cause stomach ulcers, pancreatitis, and other digestive problems.
- Weakened Immune System: Substance abuse can weaken the immune system, making individuals more susceptible to infections.
- Nutritional Deficiencies: Poor diet and malnutrition are common among those who abuse substances, leading to various health issues.
- Overdose: Both alcohol and drugs can lead to overdose, which can be fatal.
Mental Health Effects:
- Depression and Anxiety: Substance abuse can exacerbate or lead to mental health disorders such as depression and anxiety.
- Psychosis: Some drugs can cause hallucinations, delusions, and other symptoms of psychosis.
- Mood Swings: Frequent mood swings and emotional instability are common.
- Cognitive Impairment: Long-term use can impair cognitive functions, including attention, memory, and decision-making.
- Addiction: The development of substance dependence and addiction, which can be difficult to overcome.
Social and Behavioral Effects:
- Relationship Problems: Substance abuse can strain relationships with family, friends, and colleagues.
- Work and Academic Issues: Poor performance, absenteeism, and job loss or academic failure are common.
- Legal Issues: Engaging in illegal activities to obtain substances, driving under the influence, and other legal problems.
- Financial Problems: The cost of maintaining an addiction can lead to financial instability and debt.
- Violence and Aggression: Increased risk of engaging in violent or aggressive behavior.
- Neglect of Responsibilities: Failing to fulfill responsibilities at home, work, or school.
Long-term Consequences:
- Chronic Health Conditions: Long-term abuse can lead to chronic health conditions that require ongoing medical treatment.
- Social Isolation: The stigma and behavioral changes associated with substance abuse can lead to social isolation.
- Reduced Quality of Life: Overall reduction in the quality of life due to the combined effects on health, relationships, and personal well-being.
15. Do you think that friends can influence one to take alcohol/drugs? If yes, how may one protect himself/herself from such an influence?
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Answer
Yes, friends can influence one to take drugs and alcohol. A person can take the following steps for protecting himself/herself against drug abuse:
(a) Increase your will power to stay away from alcohol and drugs. One should not experiment with alcohol for curiosity and fun.
(b) Avoid the company of friends who take drugs.
(c) Seek help from parents and peers.
(d) Take proper knowledge and counseling about drug abuse. Devote your energy in other extra-curricular activities.
(e) Seek immediate professional and medical help from psychologists and psychiatrists if symptoms of depression and frustration become apparent.
16. Why is that once a person starts taking alcohol or drugs, it is difficult to get rid of this habit? Discuss it with your teacher.
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Answer
Drug and alcohol consumption has an inherent addictive nature associated with euphoria and a temporary feeling of well-being. Repeated intake of drugs increases the tolerance level of the body’s receptors, leading to more consumption of drugs.
17. In your view what motivates youngsters to take to alcohol or drugs and how can this be avoided?
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Answer
Many factors are responsible for motivating youngsters towards alcohol or drugs. Curiosity, need for adventure and excitement, experimentation are the initial causes of motivation. Some youngsters start consuming drugs and alcohol in order to overcome negative emotions (such as stress, pressure, depression, frustration) and to excel in various fields. Several mediums like television, internet, newspaper, movies etc. are also responsible for promoting the idea of alcohol to the younger generation. Amongst these factors, reasons such as unstable and unsupportive family structures and peer pressure can also lead an individual to be dependant on drugs and alcohol.
Preventive measures against addiction of alcohol and drugs:
(a) Parents should motivate and try to increase the will power of their child.
(b) Parents should educate their children about the ill-effects of alcohol. They should provide them with proper knowledge and counselling regarding the consequences of addiction to alcohol.
(c) It is the responsibility of the parent to discourage a child from experimenting with alcohol. Youngsters should be kept away from the company of friends who consume drugs.
(d) Children should be encouraged to devote their energy in other extra- curricular and recreational activities.
(e) Proper professional and medical help should be provided to a child if sudden symptoms of depression and frustration are observed.
BETA
