Samacheer Class 7 Science - Health and Hygiene

To protect our eyes and maintain good vision, several practices should be followed diligently. Firstly, it is crucial to avoid rubbing the eyes, as this can introduce germs and cause irritation or injury. Secondly, prolonged screen time on televisions or computers should be limited to prevent eye strain and fatigue. When cleaning the eyes, using cool, clean water is recommended. Furthermore, a diet rich in Vitamin A is essential for healthy eyesight; therefore, consuming foods like carrots, which are an excellent source of Vitamin A, is highly beneficial. Including fruits such as oranges and sweet lemons regularly in the diet also contributes to overall eye health due to their vitamin content.

To keep the hair clean and healthy, regular hair washing is essential as it removes dead skin cells, excess oil, and dust that accumulate on the scalp and hair. Gentle massage of the scalp during washing improves blood circulation and promotes hair health. After washing, the hair must be rinsed thoroughly with clean, clear water to remove all traces of shampoo and dirt. Using a good-toothed comb for combing and styling helps in detangling the hair without causing breakage and distributes natural oils throughout the hair length. It is also important to keep the hair dry and avoid using excessively hot water, as this can damage the hair shaft. Regular trimming of hair every few weeks helps prevent split ends and keeps the hair looking healthy and neat.

Bruises are injuries that result from blunt force trauma causing damage to the skin and underlying tissues without breaking the skin surface. When a person sustains a bruise, the affected area should be immediately washed with cold running water to reduce inflammation and numb the pain. After washing, the wound should be cleaned gently and an antiseptic cream should be applied to prevent infection and promote healing. Cold water application helps constrict blood vessels, reducing bleeding into the tissues and minimizing swelling. The bruised area should be kept elevated if possible to reduce further accumulation of blood. If the bruise is severe or accompanied by significant swelling or pain, medical attention should be sought to rule out deeper tissue damage or fractures.

Yes, Ravi's statement is correct. In the case of minor burns, the affected area should be immediately washed with cold running water to reduce the temperature of the burned tissue and minimize pain and swelling. Cold water application helps prevent further damage to the skin cells. However, it is important to distinguish between minor and severe burns. Minor burns affect only the outer layer of skin and cause redness and mild pain. In contrast, severe burns penetrate deeper layers of tissues, causing destruction of multiple skin layers, and blisters appear on the affected area. For severe burns, cold water application alone is insufficient, and immediate medical attention is required. Severe burns can lead to infection, scarring, and loss of body fluids, which can be life-threatening. Therefore, while Ravi's approach is appropriate for minor burns, severe burns require professional medical care and should not be treated with home remedies alone.

First aid is the immediate treatment given to the victim of trauma or sudden illness before professional medical help is made available. First aid is essential for several important reasons. It can save the life of an injured or ill person by providing immediate care during critical moments. First aid helps prevent further bleeding and complications by controlling hemorrhage and stabilizing the patient's condition. It allows for quick assessment and determination of the patient's condition, which helps medical professionals understand what has occurred. First aid provides relief from pain and discomfort, making the patient more comfortable during the waiting period before professional medical care arrives. It provides the best available medical care at the earliest possible moment, which can significantly improve the outcome and recovery of the patient. Prompt first aid can prevent minor injuries from becoming serious and can reduce the severity of injuries or illnesses. Therefore, knowledge of first aid is crucial for everyone as it can make the difference between life and death in emergency situations.

Communicable diseases and non-communicable diseases differ in several fundamental ways. Communicable diseases are those that spread from one person to another person through various modes of transmission including contaminated air, water, food, or through vectors such as insects and animals. Examples of communicable diseases include tuberculosis, cholera, malaria, and the common cold. These diseases are caused by pathogenic microorganisms such as bacteria, viruses, or parasites that can be transmitted from an infected person to a healthy person. Non-communicable diseases, on the other hand, do not spread from one person to another person. These diseases are caused due to factors such as wearing out of body parts, malnutrition, genetic factors, lifestyle habits, or deficiency of essential nutrients. Examples of non-communicable diseases include goiter caused by iodine deficiency, night blindness caused by vitamin A deficiency, diabetes, heart disease, and cancer. Non-communicable diseases develop over time and are often related to personal health habits and environmental factors rather than infectious agents.

Good oral hygiene is essential for maintaining sound teeth and healthy gums with healthy surrounding tissues. To keep the teeth healthy, one should brush the teeth at least two times a day, preferably in the morning and before bedtime. Regular brushing prevents the formation of tartar and plaque on the teeth and gums, which are the primary causes of tooth decay and gum disease. Flossing should be done regularly to remove food particles, plaque, and bacteria that build up between the teeth where a toothbrush cannot reach effectively. When flossing is started, the gums may bleed slightly, but this bleeding usually stops after a few days as the gums become healthier. Flossing should be started only with proper medical guidance to ensure the correct technique is used. A well-balanced diet rich in calcium, phosphorus, and vitamins is important for strong teeth and healthy gums. Avoid habits like chewing tobacco, smoking, and consuming excessive sugary foods and drinks, as these damage teeth and promote decay. Regular dental check-ups with a dentist help identify and treat dental problems early before they become serious.

Communicable diseases spread from one person to another person through various modes of transmission. The main modes of transmission are as follows. Food and water-borne diseases spread through contaminated food and water sources. Examples include cholera and typhoid, which are caused by bacteria present in contaminated water and food. Air-borne diseases spread through the air when an infected person coughs, sneezes, or speaks, releasing respiratory droplets containing pathogens. Examples include tuberculosis and the common cold. Insect and animal-borne diseases are transmitted through vectors such as mosquitoes, ticks, and other animals. Malaria is transmitted by mosquitoes carrying the parasite, and rabies is transmitted through the bite of infected animals. Direct contact with infected persons can also transmit certain diseases through blood, saliva, or other body fluids. Contaminated food and water, air, insects, and direct contact with infected individuals are the primary modes for transmission of communicable diseases. Understanding these modes of transmission is crucial for implementing appropriate prevention and control measures.

The condition of the hair reflects the nutritional status and general health of the body. Thin, sparse and lots of hair indicates poor nutritional status.
The following measures will help to maintain hair growth and avoid hair loss.
The regular hair wash and massage of the scalp will remove the dead skin cells, excess oil and dust.
Rinsing the hair well with clear water and using good toothed comb for hair dressing is highly essential for their maintenance.
Eating a balanced diet which provides all nutrients needed for the body will promote hair growth.
Applying oil to the skin and massaging the scalp will promote hair growth.
Use of chemicals (dyes, shampoos) must be used to avoid hair loss.

Communicable diseases are those that spread from one person to another. Diseases spread through contaminated air, water, food or vectors (insects and ohter animals) are palled as communicable diseases.
Tuberculosis:
Tuberculosis is caused by Mycobacterium tuberculae.
It spreads from one person to another person through air by spitting and prolonged contact with sharing materials of the patient.
Symptoms:
Fever, weight loss, Chronic cough, blood spitting and difficulty in breathing.
Prevention and treatment:
Getting BCG vaccination
Giving special attention to the patient,
Regular medication like DOT
Cholera:
Cholera is caused by Vibrio cholera.
It spreads through the consumption contaminated food or water.
Symptoms:
The symptoms of Cholera is vomiting, severe diarrhoea and cramps in legs.
Hepatitis:
Hepatitis is one of the most dangerous and fatal diseases caused by Hepatitis Virus A, B, C, D, E.
Its mode of transmission are contaminated water, sharing of needles and blood transfusion.
Symptoms:
Loss of appetite, (Anorexia), vomiting, eyes and urine in yellow color.
Prevention and treatment:
Drink boiled water.
Proper cleaning of hands.

The tissue damage caused by heat, chemical, electricity, sunlight or nuclear radiation is known as Bums. Mostly bums are caused by scalds, building fires, flammable liquid and gases. According to burning. There are three types of bums.
First-degree bums affect only the outer layer (called the epidermis) of the skin.
Second-degree bums damage the epidermis and the layer beneath it called ther dermis.
Third -degree bums involve damage or complete destruction of the skin to its full depth and damage to underlying tissues also. People who experience such bums often require skin grafting.
First Aid for Burning
In case of minor bums, the affected area should be washed with cold water and an antiseptic cream should be applied. In case of severe bums, where deeper layers of tissues get destroyed and blisters appear, use of water should be avoided. The burnt area should be covered with a clean non-sticking cloth or bandages. Larger bums need immediate medical attention.
It is very important to keep a fire extinguisher readily available.

Communicable Diseases are those that spread from one person to another. Diseases spread through contaminated air, water, food or vectors (insects and ohter animals) are called as Communicable diseases.
The communicable diseases are caused by disease causing microbes such as Bacteria, viruses etc.
These microbes are found in contaminated food, water, air etc.
Some of them like the malarial parasite complete their life cycle in the body of a mosquito.
Thus air food and water, sweat act as modes of transmitting these microbes from an infected person to a healthy person.
E.g. The cycle given below shows how food and water borne diseases are transmitted.S.no
Mode of Transmission
Examples
1
Contaminated food and water
Cholera, Typhoid
2
Contaminated air
Tuberculosis
3
Insect / Animal borne diseases
Malaria, Rabies

Many people are tired and do not have the energy to perform day to day activities. They tired and tend to sleep in the classroom or work place. Though sleep can be due to various reasons, the common reason for this condition is Anaemia.
People who are Anaemic have less number of Red blood cells in their blood.
The Red blood cells have haemoglobin which caries oxygen to all the cells of the body.
People who are Anaemic will have less slow oxygen supply to all the cells of the body.
Energy production in the cells is less and they feel tired and sleepy always. This is due to in the diet. Prevention : Eat food rich in Iron.