Science Que-Ans (Each of 5 Mark )

Actually a defence system called immune system is present in our body. The immune system possesses specialised cells which are capable of killing the infecting microbes. When microbes enter our body, our immune system becomes active and the cells are sent to kill the infecting microbes. If these cells are successful in killing the microbes, we do not come down with the disease. But this is possible only when the microbes are in small number; large number of microbes cannot be successfully invaded by the immune system. That is why, immune system is very essential for our health.

A balanced diet is the first and foremost condition necessary for good health. A balanced diet provides all the nutrients e.g., proteins, carbohydrates, fats, vitamins and minerals required by the body in correct proportions. When our diet lacks one or more of these nutrients, we get deficiency diseases or nutritional disorders. Excessive or inadequate intake of food and nutrients leads to condition such as obesity, kwarshikor and rickets. If our diet, lacks the mineral iron, we may get a disease called anaemia. Abnormal intake of nutrients and minerals such as vitamin-A which causes hyper vitaminosis-A and calcium which causes rickets. A balanced diet prevents deficiency diseases. It also increases our ability to fight aganist infections in general.

Our immune system is activated in response to infection. Multicellular animals have dedicated cells or tissues to deal with the threat of infection. Some of these responses happen immediately so that an infecting agent can be quickly contained. Other responses are slower but are more tailored to the infecting agent. Collectively, these protections are known as the immune system. The human immune system is essential for our survival in a world full of potentially dangerous microbes, and serious impairment of even one arm of this system can predispose to severe, even life-threatening, infections.

The different modes of transmission of infectious diseases are:

• Through Air: Certain disease-causing micro-organisms are expelled in air by coughing, sneezing, talking, etc. These micro-organisms can travel through dust particles or water droplets in air to reach other people. For example, tuberculosis, pneumonia, etc. spread through air.
• Through Water: Sometimes causal micro-organisms get mixed with drinking water and spread water borne diseases. Cholera for example is water borne disease.
• Through Sexual Contact: Sexual act between two people can lead to the transfer of diseases such as syphilis, gonorrhoea, AIDS, etc.
• Through Vectors: Certain diseases spread by animals called vectors. For example mosquitoes spread malaria.

Diarrhoea is an abnormally frequent discharge of semisolid or fluid faeces. It spreads through infection by contaminated food, water, drinks, hands, clothes, bed sheets and utensils. Symptoms of Diarrhoea:

• Decreased appetite, nausea, vomiting and abdominal cramps.
• There may be blood and mucus in the stools.

Prevention:

• Eatables should be covered to prevent their contamination.
• Fruits and vegetable should be properly washed before use.
• Stale food should not be consumed.

Control:

• Complete bed rest should be ensured till the illness is fully controlled.
• For treating diarrhoea anti-microbial drugs and anti-diarrhoea agents should be used.

Human beings live in societies. Our social environment therefore plays an important part in our individual health. We live in villages, town or cities, our physical environment is decided by our social environment. e.g., if there is not agency to ensure that garbage is collected and disposed and no one takes responsibility for cleaning the drains, to ensure that waste water does not get collected in the streets or open spaces, there will be heaps of garbage and trash littered here and there, will be open drain water lying stagnant around where we live. Therefore, the possibility of poor health will increase. So, public cleanliness is also and important contribution to an individual’s health.

Pathogen: Severity of disease causing factor Microorganism, virus, chemical toxin, trauma, metabolic disorder, or whatever be the disease causing factor is responsible for severity of disease. Intensity, duration of the causative agent determines the severity of disease. Body factors: Severity of disease also depends on the age, sex, gender, weight, race, comorbid conditions (coexisting diseases), habits (smoking) etc. Resistance: The Resistance of the human body system, immunization status. Example: A person who has been immunized against typhoid, cholera, diphtheria, pertussis, tetanus (lethal unless you have been immunized by Tetanus Toxoid Vaccination) almost never has severe disease even if the causative organism be in high quantum. Treatment measures: How soon, whether adequate treatment measures have been given is major factor influencing severity of disease.

Comparison Chart:

BASIS FOR COMPARISON	ACUTE DISEASE	CHRONIC DISEASE
Meaning	Such disease which occurs suddenly and last for a short period is called as acute disease.	Such disease which shows it's prolonged effects on human health. The condition is said to be chronic when the disease lasts for more than three months. Such disease can be life-threatening and majorly affect the immune system of the body and thus declines the health.
It Appears	Suddenly.	Gradually.
Time Span	It lasts for a short time, usually few days to the week.	It lasts for longer or lifetime also.
Effects	They do not cause long term or ill effects on human.	They may cause severe long term effects on human health, which may be life-threatening too.
Examples	Cold, burn, breaking of bone, typhoid, jaundice, cholera, burn, strep throat, etc.	Diabetes, arthritis, cancer, tuberculosis, heart disease, asthma attack, osteoporosis, etc.

The immune system protects the body against disease or other potentially damaging foreign bodies. When functioning properly, the immune system identifies and attacks a variety of threats, including viruses, bacteria and parasites, while distinguishing them from the body's own healthy tissue. An antigenic substance prepared from the causative agent of a disease or a synthetic substitute, used to provide immunity against one or several diseases. Immunization is done through various techniques, most commonly vaccination. Vaccines against microorganisms that cause diseases can prepare the body's immune system, thus helping to fight or prevent an infection.

Some factors that determine the health of a community include the social and economic environment and the physical environment, as stated by the World Health Organization. One example of how the economic environment impacts community health is income and social status.

prevention of diseases is possible. These include:

• Have a balanced diet.
• Maintain personal hygiene.
• Keep your surroundings clean.
• Consume clean food and water.
• Keep your environment and air clean.
• Maintain a proper schedule of exercise and relaxation.
• Keep away from any kind of addictions like alcohol or drugs.

1. Principles of treatment:

• To reduce the symptoms of disease.
• To remove the cause of disease.
• To prevent the cause of disease.
• To prevent the spread of disease.
• To make the patient healthy again by helping him to overcome the effects of the diseases like weakness etc.

2. Vaccination: A vaccine is a product that produces immunity from a disease and can be administered through needle injections, by mouth, or by aerosol. A vaccination is the injection of a killed or weakened organism that produces immunity in the body against that organism. An immunization is the process by which a person or animal becomes protected from a disease. Vaccines cause immunization, and there are also some diseases that cause immunization after an individual recovers from the disease.

These diseases involve temporary or permanent damage to the body and include all the other categories except mental disease where there is no sign of physical damage to the brain. An example would be leprosy.

• Pathogens: They are organisms living in or on our bodies, causing disease. Infectious diseases are caused by pathogens such as viruses, bacteria, fungi, protoctists, worms and insects, which can be transmitted from person to person. This may be via normal social contact. For example, chicken pox, or via food and water, sexual contact or an animal bite. Carriers are people who can transmit the pathogen but do not have the disease symptoms.
• Non-infectious diseases: These are all diseases, which are not caused by pathogens and cannot be passed on by physical contact. An example would be sickle cell anaemia.
• Deficiency diseases: These are nutritional diseases caused by an inadequate or unbalanced diet. One or more essential nutrient is missing or in short supply. For example, a shortage of Vitamin C causes scurvy.