Human Health and Diseases: One Mark Questions, Book Back Answers and Notes

About Human Health and Diseases

Medium ~120 min study

Health is not just the absence of disease. The WHO definition includes physical, mental and social well-being. A person can be free of infection and still be unwell because of stress, addiction or a poor diet, and this chapter deals with both sides.

The first part is a catalogue of infectious diseases. For each one you need the pathogen, how it spreads, the part of the body it attacks and the main symptoms: Salmonella typhi and typhoid, rhinoviruses and the common cold, Plasmodium and malaria, Ascaris and ascariasis. The second part moves to things people can control: hygiene, sanitation, the effects of drugs and alcohol on a growing brain, depression, and daily habits that raise or lower the risk of heart disease, obesity and diabetes.

Book back questions usually ask you to match a disease with its pathogen, recall a diagnostic test such as the Widal test for typhoid, or trace the life cycle of Plasmodium in man and mosquito. Questions on withdrawal symptoms, vector control and lifestyle changes also appear. Make a simple table of diseases as you read; it saves a lot of time before the exam.

What you'll learn

• Distinguish communicable from non-communicable diseases by their cause and mode of spread.
• Describe the asexual stages of Plasmodium in man and the sexual stages in the female Anopheles mosquito.
• Explain how long-term drug and alcohol use affects the nervous system, liver and other organs.
• Suggest public health measures such as sewage treatment, vector control and sanitation to stop the spread of disease.
• Identify the causes of depression and of non-communicable lifestyle disorders.
• Recommend practical changes in diet, exercise and sleep that keep the body and mind healthy.

Before you start

• The human digestive, circulatory and nervous systems.
• Basic groups of microorganisms: bacteria, viruses, fungi and protozoans.
• Cell division and the main metabolic processes in the human body.

Human Health and Diseases explained

Diseases, Hygiene and Healthy Living

Common Infectious Diseases and Their Pathogens

Infectious diseases are grouped by the type of pathogen. Bacterial diseases include typhoid (Salmonella typhi), pneumonia, diphtheria, cholera and tetanus; bacteria damage tissues and many release toxins. Viral diseases include the common cold (rhinoviruses), mumps, measles, dengue and chikungunya; viruses can multiply only inside host cells, using the host's machinery. Protozoan diseases include amoebiasis and malaria. The malarial parasite needs two hosts, man and the female Anopheles mosquito. Ringworm is a fungal disease. Among helminths, Ascaris lives in the intestine, competes for food and can block the gut in heavy infections, while filarial worms block lymph vessels.

Personal and Public Hygiene

Hygiene is the first defence against communicable diseases. Personal hygiene means washing hands, bathing regularly, keeping nails short, and eating clean food and drinking safe water. Public hygiene is the community's job: safe disposal of waste and excreta, treated drinking water, proper sewage treatment and control of vectors such as mosquitoes and houseflies. These steps break the chain of spread for diseases carried by contaminated food and water, such as cholera, typhoid and amoebiasis.

Drug and Alcohol Abuse in Adolescence

Adolescence, roughly 12 to 18 years, is a period of fast physical and emotional change. Curiosity, peer pressure, exam stress and the wish to feel grown up can push some teenagers towards drugs and alcohol. Opioids, cannabinoids, cocaine and alcohol act on the central nervous system. They give a short feeling of pleasure but lead to tolerance and dependence. Long-term use damages the liver (cirrhosis), the brain and the heart. When the drug is stopped, the body reacts with withdrawal symptoms. Prevention depends on awareness, support from parents and teachers, and counselling or medical help when needed.

Mental Health and Depression

Mental health affects how well a person works, studies and gets along with others. Depression is marked by lasting sadness, loss of interest, low self-esteem, tiredness, and changes in sleep and appetite. Its causes can be genetic, hormonal, environmental (stressful events) or linked to poor nutrition and long-term illness. Catching the early signs matters. Talking to someone, counselling, regular exercise, yoga and, where needed, medical treatment help people recover.

Lifestyle Disorders and Their Prevention

Heart disease, obesity, hypertension and type 2 diabetes are non-communicable and are closely tied to how people live. Sitting for long hours, eating junk food that is high in calories, fat and salt but low in fibre and vitamins, sleeping too little and living with constant stress all raise the risk. Regular physical activity, a balanced diet with fruits, vegetables and whole grains, enough sleep, yoga and avoiding tobacco and alcohol lower it considerably.

Common mistakes to avoid

• Thinking antibiotics cure viral infections like the common cold. Antibiotics act on bacteria, not viruses, and misusing them builds antibiotic resistance.
• Confusing bacillary dysentery with amoebic dysentery. Bacillary dysentery is caused by the bacterium Shigella; amoebic dysentery (amoebiasis) is caused by the protozoan Entamoeba histolytica.
• Treating depression as only a matter of attitude. It has biological causes too, including genetic, hormonal and nutritional factors.
• Believing heart disease is only genetic. Family history adds risk, but diet, physical activity, smoking and stress have a large effect.

Test yourself on these with the practice test, then check the worked reasoning in the solved MCQs.

Frequently asked questions

What is the difference between infectious and non-infectious diseases?

Infectious diseases are caused by pathogens such as bacteria, viruses, protozoans, fungi or worms, and spread from one person to another directly or through vectors, food, water or air. Non-infectious diseases, such as diabetes, heart disease and cancer, are not caused by pathogens. They arise from genetic factors, nutritional deficiency, lifestyle or ageing and cannot be passed on by contact.

Why is it difficult to make a vaccine for the common cold?

The common cold is caused by rhinoviruses, and there are well over a hundred different types of them. Their genome is single-stranded RNA, which mutates often, so the surface antigens keep changing. A vaccine made against one type does not protect against the others.

How does the malarial parasite complete its life cycle?

Plasmodium needs two hosts. When an infected female Anopheles bites, sporozoites enter the human blood and first multiply in liver cells. They then infect red blood cells, which burst and release merozoites and a toxin called haemozoin, causing chills and fever. Some parasites form gametocytes. When a mosquito sucks this blood, the gametocytes form gametes, fertilization takes place in its gut, and new sporozoites collect in its salivary glands.

What happens to the body during drug or alcohol withdrawal?

A dependent person's nervous system has adjusted to the regular presence of the drug. If the drug is stopped suddenly, the body reacts with withdrawal symptoms such as anxiety, shaking, sweating, nausea, sleeplessness and a fast heartbeat. In severe cases these can be dangerous, so withdrawal should be managed under medical supervision.

How do lifestyle changes help prevent heart disease?

Inactivity and a diet high in fat, sugar and salt lead to obesity, high blood pressure and fatty deposits in the arteries. Brisk walking, yoga and a balanced, fibre-rich diet reduce body weight, bring down blood pressure and cholesterol, and keep the heart muscle strong. Avoiding tobacco and alcohol lowers the risk further.

How does sewage treatment help prevent disease?

Sewage carries large amounts of organic waste and pathogens. If it flows untreated into rivers and lakes, it contaminates drinking water and causes outbreaks of cholera, typhoid and other water-borne diseases. Treatment plants remove solids, then use microbes to break down the organic matter, so the water released is far cleaner and carries fewer pathogens.