Content Writer-SME | Updated On - Aug 5, 2024
Human health and diseases is an important chapter of biology class 12 that covers the common diseases in humans along with immune response of the body against those diseases. Human health is overall affected by mental state and mind.
- Health is a positive concept that defines the well-being of an individual. Disease, on the other hand, affects the normal functioning of the human body.
- The four main components of maintaing good health includes- personal hygiene, physical activity, proper sleep, and balanced diet.
What is Health?
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The word “Health” is defined as the absence of any disease or infection in an individual. Good health is important for one to live an effective and long life.
- Humans are exposed to number of diseases, out of which some are more severe such cancer, AIDS, etc.
- Over the years, developments in medicine have allowed us to build resistance towards several diseases.
- However, there are still many diseases whose cures aren’t available yet.
- Several factors, like lifestyle, exposure to infections, or genetic disorders influence health.
- It can be defined as “a state of complete physical, mental and social well-being”.
- Getting adequate sleep with a good diet leads to good human health.
Factors affecting Human Health
The factors which are responsible for affecting human health are as follows:
- Malfunction of human organ
- Poor diet
- Lack of physical activities
- Genetic problems
- Pollution
- Unhealthy food
What are Diseases?
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Diseases are defined as any harmful deviation from an organism's normal structural or functional state. It is typically accompanied by specific signs and symptoms and differs in nature from physical injury. A diseased organism frequently exhibits signs or symptoms.
- Diseases causes different type of pains, dysfunction, social problems and death.
- It affects an individual physically and mentally.
- Human health and diseases are two sides of the same coin.
- Immunodeficiency, hypersensitivity, allergies, and autoimmune disorders affect the working of immune system.
- Symptoms of disease help in diagnosing the type of disease.
Types of Diseases
Diseases in humans are mainly classified into two categories: Infectious or communicable and non-infectious or non-communicable diseases.
Infectious Disease
Pathogens like bacteria, fungi, parasites and viruses, can cause diseases that can easily be transmitted from one person to another. These diseases are known as infectious diseases.
- It is also known as communicable/contagious diseases.
- Examples of Infectious Diseases: Common Cold, Ringworm, Tuberculosis, Malaria etc.
Infectious Disease
Non - Infectious Disease
Non-infectious diseases are those that are not transmitted from one person to another; they are non-communicable. These diseases are caused either due to genetic disorders or external factors like unhealthy diets, consumption of drugs, alcohol etc., or lack of physical activities.
Common Diseases in Humans
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Common diseases in human are caused by variety of microorganisms such as bacteria, viruses, fungi, helminths, and protozoans. The microbes that are responsible for causing diseases are called pathogens.
Bacterial Transmission: Common Disease in Humans
Bacterial Diseases
Bacterial diseases are a type of disease that affects your skin, brain, lungs, blood, and other parts of the body. They release harmful toxins in the body of an individual. Some of the most common bacterial diseases are as follows:
Typhoid
Typhoid affects a large number of people and is spread by contaminated food or water. It infects the human body's small intestine. It is caused by a bacterial pathogen called Salmonella typhi.
Pneumonia
It is spread by droplets emitted by infected people. It is caused by Streptococcus pneumoniae and Haemophilus influenzae. In the event of pneumonia, the alveoli become infected.
Viral Diseases
Viral disease or infection is a type of disease that is caused by any virus that uses an individual cell for reproduction. The number of virus cells increases if the immune system of an individual is weak. A virus is a small particulate that contains proteins and genetic material but is not alive.
Common Cold
The common cold is a pathogen-borne disease. It's basically the same as a virus. The nose and respiratory passages are affected in the case of a common cold.
Protozoan Disease
The diseases caused by the member of protozoa phylum are classified as protozoan diseases. Leishmaniasis, African sleeping sickness, and Malaria are some of the disease caused by protozoan parasites in humans. The confirmation of protozoan disease in humans is done clinically by stool tests, blood tests, biopsies, etc. Among all, the most common protozoan disease is Malaria which is casused by different species of plasmodium parasites.
Malaria
The entry of plasmodium in human body occurs through the bite of female anopheles mosquito. Initially, multiplication of parasites takes place in the liver cells. The main target of this disease is Red blood cells (RBC) which gets ruptured after the attack of these parasites. With the rupture of RBC, haemozoin (toxic substance) is released which causes high fever, chills and other symptoms in the patients suffering from Malaria.
Check Here: Human Health & Disease Class 12 Important Questions
Immunity
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Immunity is defined as the ability of the host body to defend itself against disease causing agents. Although humans are exposed to a number of infectious agents, not all of them lead to disease.
- The human body has the ability to defend itself from foriegn bodies which it identifies as invaders.
- The immune system protects our bodies from infection which can harm us.
- Antibodies protects our body from diseases.
- It will prevent the viruses and bacteria to destroy the microbes in the body.
Immunity is classified into two types which are as follows:
Innate Immunity
Innate Immunity is a non-specific defence present from the moment a child is born. This type of immunity is activated when pathogens attack the body of an individual.
- It consists of barriers that protect our body from viruses and bacteria.
- These barriers protect us as well as our human organs.
- Innate immunity is also known as body’s defence system.
In our body's defence mechanism, there are four types of barriers which protect us.
- Physical Barriers: Which is the skin and mucous coating of the respiratory, gastrointestinal, and urinary tract epithelial linings.
- Physiological Barriers: Saliva, tears, and stomach acid act as physiological barriers.
- Cellular barriers: Neutrophils, monocytes, and natural killer lymphocytes form cellular barriers.
- Cytokine Barriers: Interferons secreted by virus-infected cells act as cytokine barriers.
Acquired Immunity
Acquired immunity is pathogen-specific immunity that we develop throughout our lives. It is characterised by memory and can be acquired by either infection or vaccination.
- Acquired immunity has the ability to adapt to any type of disease.
- It will generate pathogen-specific immunity.
- It is also known as adaptive immunity.
- Acquired immunity provide relief to infectious person.
AIDS
AIDS, also known as Acquired Immunodeficiency Syndrome, is a chronic disease that poses a life-threatening condition to an individual. HIV (Human Immunodeficiency Virus) is the causative agent of AIDS.
- AIDS patients are more vulnerable to infections such as mycobacterium, fungal, and viral infections.
- Enzyme-Linked Immunosorbent Assay is a commonly used AIDS diagnostic test.
- It can be transmitted through unprotected sexual contact and contaminated blood transfusions.
- The use of an infected syringe or from mother to foetus via the placenta.
HIV Virus Structure
Cancer
Cancer is one of the world's most lethal illnesses. In the case of this disease, the cells found inside the human body grow in an uncontrolled manner and spread to different parts of the body.
- Cancer is caused by uncontrolled cell division.
- It results in the formation of tumours in the organs, causing organ failure.
- It is a group of 100 types of diseases.
- Tobacco is the main cause behind 22% of deaths due to cancer.
Two types of tumors cause cancer, which are as follows:
Benign Tumor
Benign tumours are non-invasive and stay in their current position. They do not spread or affect other tissues.
Malignant Tumor
Malignant tumours can spread from one organ to another and affect surrounding tissues.
Metastasis
Metastasis is a characteristic of malignant tumours in which cells are sloughed off from them and spread to distant organs. It forms tumours in different parts of the body. Cancer develops as a result of DNA damage or a genetic mutation.
- Under certain conditions, cancer can also be caused by activating proto-oncogenes in normal cells.
- Surgery, transplantation, immunotherapy, and radiation treatment can all be used to treat cancer.
- It is responsible for generating primary heterogeneous tumours.
- The cell will first undergo metaplasia, followed by dysplasia and anaplasia.
- It results in the formation of a malignant phenotype.
Drug Abuse and Alcohol
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Studies show that the consumption of alcohol and drugs is at an all-time high. These substances are highly harmful and cause severe detrimental consequences. Some consequences of substance abuse are:
Alcohol Abuse
Alcohol has a negative impact on an individual's body. When a person consumes too much alcohol, it damages the liver and the nervous system. As a result, the individual may exhibit other symptoms such as depression, fatigue, aggression, weight loss, and appetite loss.
- Excessive alcohol consumption can also cause heart failure, coma, and death.
- Heavy drinking can have serious consequences for the family.
- It causes a variety of domestic issues, such as disagreements, anger and frustration, instability, violence, etc.
Drug Abuse
A person who is addicted to drugs creates trouble not only for himself but also for his family. Drugs have a negative impact on an individual's central nervous system.
- This causes several other organs in the body to malfunction, including the kidney, liver, and others.
- HIV transmission is most common in these people.
- They share needles while injecting drugs into their bodies to consume drugs.
Things to Remember
- Human health and diseases affect the different organs of the body.
- Health is defined as the physical and mental well-being of an individual.
- Disease is defined as the sickness that affects the health of a person.
- Infectious and Non-infectious diseases are two types of diseases.
- Human health and diseases are interchangeable terms.
Previous Years Questions
- The infectious stage of Plasmodium that enters the human body… [NEET 2020]
- In higher vertebrates, the immune system can distinguish….[NEET 2016]
- Which of the following is a pair of viral diseases?...[NEET 2009]
- In which disease does mosquito transmitted...[NEET 2018]
- A person likely to develop tetanus is immunized by….[NEET 2009]
- A person suffering from a disease caused by Plasmodium...[NEET 2010]
- Antibodies in our body are complex..[NEET 2006]
- Antigens are present...[NEET 1995]
- Antivenom injection contains preformed antibodies….[NEET 2016]
- Cancer cells are more easily damaged by radiation...[NEET 2004]
- Cancerous cells can easily be destroyed by...[NEET 2002]
- Carcinoma refers to...[NEET 2003]
- Cell-mediated immunity in the human body...[NEET 2013]
- Christmas disease is another name for...[NEET 2003]
- Cirrhosis of liver is caused by the chronic...[NEET 2012]
Sample Questions
Ques. Name the primary and secondary lymphoid organs? (3 marks)
Ans. Primary and secondary lymphoid organ are responsible for effective function of immune system. Primary organs are used for the production and maturation of lymphocytes. They are located at place where differentiation of stem cell take place.
- The bone marrow and the thymus are primary lymphoid organs.
- Bone marrow cells are responsible for maturation of B cells.
Secondary organs act as a monitoring station for the smooth flow of extracellular fluids. These organs are found at places where lymphocytes cells are activated. They are responsible for cleaning and filtering of the lymph nodes. The spleen, lymph nodes, tonsils, Peyer's patches of small intestine, and appendix are secondary lymphoid organs.
Ques. What is AIDS? (3 marks)
Ans. The full form of AIDS is Acquired ImmunoDeficiency Syndrome. It is caused by Human ImmunoDeficiency Virus. These viruses interferes the functioning of body ability to fight againts any form of diseases and infections.
- AIDS ususally spreads by coming in contact with infected blood and from illicit injection drug use or sharing needles.
- It is also transferred to child from mother during the time of pregnancy.
- It cannot be cured but can be controlled with the help of medication.
Ques. What are the three routes of transmission of human immunodeficiency virus? (3 marks)
Ans. The three routes by which HIVcan be transmitted is:
- Sexual contact with an infected person without protection.
- Blood transfusion from a healthy person to an infected person.
- Passing around infected needles and syringes.
Ques. What is Metastasis? (3 marks)
Ans. Metastasis is a characteristic of malignant tumor in which the cells sloughed off, from them spread to distant organs and form tumours in various parts of the body.
- Metastasis causes cancer cells to spread to other part of the body.
- It can be detected by keeping it under microscope.
- Metastasis has the same feature as that of primary cancer.
- Doctors cannot easilt diagonse when the spread of such cancer started.
Ques. How many types of barriers are there to defend the human organs? (4 marks)
Ans. There are four types of barriers that defend the human organs which are as follows::
- Physical Barriers: Physicla barrier include skin, hair, eyelashes, cilia and respiratory tract. They act as first line of defence. They prohibit the entry if pathogens.
- Physiological Barriers: Physiological barrier include stomach that consists of hydrochloric acid. The acid will break the food molecules that will also kills the germs coming along with the food.
- Cellular Barriers: Cellular barrier help in the treatment of pathogens that will enter the body despite the barriers. In this case leukocytes (WBC), neutrophils, lymphocytes, basophil, eosinophil, and monocytes act as a cellular barrier.
- Cytokine Barriers: Cytokine barrier will help in the treatment of the virus invasion which will secretes proteins called interferons.
Ques. What is an Auto-Immunity? (2 marks)
Ans. When the body attacks its own cells, an auto-immune disorder develops. It will harm its owm health tissues, organs and cells of the body. They are also known as autoimmune disease. In this antibodies or t-cells found in the body will react with the protein found in the body. Rheumatoid arthritis is a type of auto-immune disease.
Ques. How is cancer identified? (2 marks)
Ans. Cancer is one of the world's most lethal illnesses. In the case of this disease, the cells found inside the human body grow in an uncontrolled manner and spread to different parts of the body.
The various ways to identify cancer are as follows:
- A CT scan (computed tomography)
- MRI (magnetic resonance imaging)
- X-ray
- PET (positron emission tomography)
Ques. What is Diacetylmorphine commonly known as? (2 marks)
Ans. Diacetylmorphine is also referred to as heroin or smack. It is a type of substance that is synthesised from dried latex of the Papaver somniferum plant. The drug is used for recreational purposes that create a sense of euphoria. It is used as a hydrochloride salt. To get direct affect it can easily be injected into vein. It can also be smoked, inhaled or snorted.
Ques. What is the difference between infectious and non-infectious disease? (3 marks)
Ans. The difference between infectious and non-infectious disease are as follows:
| Infectious Disease | Non-infectious Disease |
|---|---|
| Infectious disease is a type of disease that can be transmitted from one person to another. | Non-Infectious disease is a type of disease that cannot be transmitted from one person to another. |
| It is caused by pathogens. | It is caused by heredity, environment and deficiencies. |
| Example: AIDS and tuberculosis. | Example: Cancer and diabetes |
Ques. Name different types of diseases along with their mode of transmission and symptoms? (5 marks)
Ans. The different types of bacterial and protozoan disease along with their mode of transmission and symptoms are as follows:
| Name of the Virus | Mode of Transmission | Symptoms of Viruses |
|---|---|---|
| Salmonella typhi | Contaminated food and water | high fever (39° to 40°C), weakness, stomach pain, constipation, headache, and loss of appetite |
| Haemophilus influenza | fever, chills, cough and headache, severe problems in respiration | by inhaling droplets released by an infected or unhealthy person or by sharing personal belongings. |
| Rhinoviruses | By inhaling droplets released by an infected or unhealthy person or by sharing personal belongings | Nasal congestion and discharge, sore throat, wheezing, cough, headache, tiredness, etc. |
| Plasmodium | Bite by an infected female mosquito, i.e. anopheles mosquito | High chills, vomiting, loose motions |
| Entamoeba Histolytic | Bite by an infected female mosquito, i.e. anopheles mosquito | Constipation, cramps, abdominal pain, stool with mucus and blood clots |
Ques. What is the difference between innate immunity and acquired immunity? (4 marks)
Ans. The difference between innate immunity and acquired immunity are as follows:
| Innate Immunity | Acquired Immunity |
|---|---|
| Innate Immunity is a type of immunity is activated when pathogens attack the body of an individual. | Acquired immunity is pathogen-specific immunity that we develop throughout our lives. |
| It is inherited from parents. | It is not inherited from parents. |
| Innate immunity affects is seen immediately. | Acquired immnunity is visible after certain days. |
| It depends upon the pathogens. | It do not depend upon the pathogens. |
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