5th Class Science Human Body and their Needs Human Body and Nutrition

Human Body and Nutrition

Category : 5th Class


This lesson will help you to:—

  • Learn about the human body and its organ system.
  • Know about food and digestion.
  • Learn and study about teeth and microbes.
  • Understand and learn about importance of sanitation and related diseases.
  • Learn about nutrition.


Human Body

  • The human body is made up of a head, neck, torso, two legs. The average height of an adult human is about 5 to 6 feet.
  • There are many systems in the human body:
  • Circulatory System (heart, blood, vessels).
  • Respiratory System (nose, trachea, lungs).
  • Immune System (many types of protein, cells, organs, tissues).
  • Skeletal System (bones).
  • Excretory System (lungs, large intestine, kidneys).
  • Urinary System (bladder, kidneys).
  • Muscular System (muscles).
  • Endocrine System (glands).
  • Digestive System (mouth, oesophagus, stomach, intestines).
  • Nervous System (brain, spinal cord, nerves).
  • Reproductive System (male and female reproductive organs).
  • Your body is made up of four main types of bones. Long bones such as the bones in your arms and legs, short bones such as the bones in your hands, feet and spine, flat bones which protect your organs provide a place for muscles to attach, and irregular bones, which are simply all the bones that are not long, short or flat.
  • Your body is constantly breaking food down in the digestive system, and then using the pieces to build, repair, and grow your body.
  • The job of your heart is to pump blood through your body. Even in your sleep, your heart keeps beating, or pumping blood. If it stopped, you would quickly die. Your heart is divided into two sides. The left side of your heart is filled with oxygen-rich blood, while the right side of your heart is filled with oxygen-poor blood.                              
  • Just like a city with hallways and roads, your body has blood vessels, arteries and veins that help move things around. Most of the cells inside your body do not move. If a cell is hungry or needs to get rid of waste, it can't simply move itself to the part of your body where it needs to go. Instead, your body must bring the food to your cells and take the waste away from them.
  • Oxygen is used by your cells as it performs the functions of life. As your body uses oxygen, your cells produce another gas known as carbon dioxide. Too much carbon dioxide can be toxic, and even deadly. For this reason, it is important that your body has a way to get rid of it.
  • The main organs in your respiratory system are your lungs. Your lungs are, in their simplest form, nothing more than sacs. As you breathe in, you fill these sacs with fresh oxygen-rich air. Your heart pumps blood into the walls of your lungs where it absorbs oxygen and releases carbon dioxide. As you exhale, or breathe out, you release the carbon dioxide-rich air into the space around you. With each breath you take, you are taking oxygen in, and putting carbon dioxide out.
  • From your lungs, blood returns back into your heart where, it is pumped out to the rest of your body, carrying oxygen along with it.
  • The central nervous system is made up of your brain and your spinal cord. It is the main control centre of your body, and the centre of thought. Your central nervous system controls most of the actions within your body.


Real-Life Example

  • Children who have access to good nutritious food are more fit an active, whereas children who do not get good nutritious food and are devoid of essential vitamins and minerals suffer from various diseases and are pale, lethargic in comparison to healthy kids.


Amazing Facts

  • The brain of an adult human weighs around 3 pounds (1.5kg). Although it makes up just 2% of the body’s weight, it uses around 20% of its energy.
  • The study of the human heart and its various disorders is known as cardiology.
  • Blood makes up around 7% of the weight of a human body.
  • As well as having unique fingerprints, human also have unique tongue prints.
  • It takes the body around 12 hours to completely digest eaten food.
  • Your sense of smell is around 10000 times more sensitive than your sense of taste.
  • The toothbrush was invented more than 500 years ago by Chinese.



  1. Our body must digest the food that we have eaten.
  2. When we chew, food is crushed up and mixed with saliva (spit) so it becomes mushy.
  3. We swallow the mush and it travels through the oesophagus, a long tube that runs from the mouth before it goes into the stomach.
  4. Inside the stomach there are juices that mix the food until it looks like thick soup.
  5. The food then goes to the large intestine.
  6. Water from the food goes into the blood.
  7. By now, the body has taken all the things it needs from the food. What is left is waste that is not needed by the body.
  8. It gets stored at the end of the large intestine inside the rectum.
  9. The waste must leave or the body will get sick.
  10. Muscles push the waste out of the body through the anus, which is the opening in your bottom.


How long does it take for the body to digest Food?

Food can remain for 3-4 hours in the stomach, then for p about 3 more hours as it moves through the intestine It can stay in the large intestine for up to 36 hours. So depending on the type of food and the speed at which it1 moves, it can take about 40 hours or more for the body to digest food.                               


  • Teeth are present in mouth cavity on the upper and lower jaws. We use our teeth for chewing the food before swallowing.
  • Teeth have different shapes and they are used for different purposes.
  • The teeth present in front of the mouth are used for cutting. These teeth are called incisors They are 8 in number;
  • Sharp and pointed teeth are present next to incisors these teeth are used for tearing. They are called canines. They are 4 in number.
  • The flat and wide teeth are present at the back of the mouth. They are called premolars and molars. Food is crushed and grinded by these teeth. We have 8 premolars in the mouth cavity, called upper jaw and lower jaw. Each jaw has 16 teeth so every adult has 32 teeth.
  • The part of tooth visible above the gum is known as crown. The part of tooth in the gum is called root which holds the tooth strongly to the gum.
  • Cavities are rotten or decayed portion of the teeth that can be minor or severe, reaching even to the all tooth's core and roots.
  • Cavities result from plaque build-up. As plaque accumulates, acids are released and tooth material becomes degraded. This is tooth decay. Decay is not exclusive to visible parts of ones teeth. This plaque, and its subsequent decay, can occur even at the roots and extend to the bones of the jaw.
  • Taking care of your teeth helps prevent plaque which is a clear film of bacteria that sticks to your teeth.
  • If you don't take care of your teeth, cavities and unhealthy gums will make your mouth very, very sore. Eating meals will be difficult.



  • Sanitation is the hygienic means of promoting health through prevention of human contact with the hazards of wastes as well as the treatment and proper disposal of sewage wastewater.
  • Hazards can be physical, microbiological, biological or chemical agents of disease.
  • Wastes that can cause health problems, include human and animal faces, solid wastes, domestic waste water (sewage, grey water), industrial wastes and agricultural wastes.
  • Hygienic means of prevention can be by using engineering solutions (e.g. sewerage and wastewater treatment), simple technologies (e.g. latrines, septic tanks), or even by personal hygiene practices (e.g. simple hand-washing with soap).
  • Sanitation is a necessity for a healthy life.
  • Lack of sanitation leads to various diseases. Some of the diseases caused are cholera, typhoid, diarrhea, etc.




  • Humans require food substances to supply the components necessary to build tissues, to repair tissues as they wear out and die, to keep the body ( in good working condition, and to supply fuel for energy.


Historical preview

  • In 1747, the scottish surgeon James Lind discovered that citrus fruits like orange, lemons etc., helped prevent scurvy (a deadly disease)
  • Vitamin A was discovered in year 1913.
  • The earliest evidence of urban sanitation was seen in Harappa, Mohenjo-Daro and the recently discovered Rakhigarhi of Indus Valley civilization this urban plan included the world’s first urban sanitation systems within the city, individual homes or groups of homes obtained water from wells. From a room that appears to have been set aside for bathing, waste water was directed to cover drains, which lined the major streets.



Misconcept:  Human blood in veins is blue in colour.

Concept: Human blood in veins is not blue. In fact blood is always red due to haemoglobin. Deoxygenated blood has a deep red colour, and oxygenated blood has a light cherry-red colour.

Misconcept:   8 glasses /2-3 litres of water are required to maintain good health.

Concept:  8 glasses or 2-3 litres of water a day are not needed to maintain health. The amount of water needed varies according to person’s weight, activity level, clothing and environment (heat and humidity). Water actually need not be drunk in its pure form, but can be derived from liquids such as juices, tea, milk, soups, etc., fruits and vegetables.

  • For good nutrition a person should eat a well-balanced diet, that is, one that provides an adequate amount of each of the classes of nutrients each day.
  • Children require relatively larger amounts of nutrients and calories because of their rapid growth.
  • The foods required for proper nutrition fall roughly into three major groups: proteins, carbohydrates, and fats. Vitamins, minerals, and water are also important.



  • Protein builds, maintains, and replaces the tissues in our body.
  • Our muscles, our organs, and our immune system are made up mostly of protein.
  • The best sources are beef, poultry, fish, eggs, dairy products, nuts, seeds, and legumes like black beans and lentils.
  • Our body uses the protein we eat to make lots of specialized protein molecules that have specific Proteins are made up of small molecules called amino acids. There are 22 amino acids, out of which 9 are essential.
  • Protein from animal sources, such as meat and milk, is called complete, because it contains all of the essential amino acids.
  • The average adult requires 1 gram of protein per kilogram of body weight per day; children may require two to three times this amount.



  • Carbohydrates are the major source of energy for the body.
  • There are two main types of carbohydrates – sugars (like the kinds in milk, fruit, table sugar, and candy) and starches, which are found in grains, breads and pasta.
  • Sugars are simple carbohydrates whereas starches are complex carbohydrates.
  • Complex carbohydrates are preferred because the fast-acting simple carbohydrates, such as honey and sugar, are difficult for the body to handle in large doses.
  • Simple carbohydrates also lack the vitamins, minerals, proteins, and fibres that generally accompany foods rich in complex carbohydrates.
  • Cereals, fruits, vegetables, legumes, and pasta are good sources of complex carbohydrates.


  • Fats (fats and oils) in the diet provide a concentrated source of energy.
  • Some foods, including most fruits and vegetables, have almost no fat. Other foods have plenty of fat. They include nuts, oils, butter, and meats like beef.
  • Fat is an important part of a healthy diet.
  • Fats in the body, in addition to acting as a source of stored energy, supply physical protection and insulation for tissues.
  • Fats also aid in the absorption of the fat-soluble vitamins (vitamins A, D, E, and K) from the intestine. ` Milk, butter, meat, and oils are important sources of fat.



  • To keep the body functioning properly it is necessary to have, in addition to the basic foods, a sufficient intake of accessory substances such as vitamins,

Minerals and enough water to carry nutrients to the tissues and waste products away from them.

  • A minimum of about 2 litres of liquid per day are recommended for the average adult.
  • Vitamins play a critical role in important body processes.
  • A large variety of minerals are required, some in trace amounts and others, such as calcium and iron, in relatively large amounts.
  • Milk, cheese, and dark, leafy green vegetables are excellent sources of calcium. Liver, meat, and egg yolks are good sources of iron.
  • Minerals are vital to the development of teeth and bones (calcium, phosphorus, and fluoride) and to the functioning of a number of body's metabolic systems.
  • Iron is a necessary part of blood; various metals are required in many enzymes; sodium and potassium are essential for functioning of the nervous system; magnesium is needed for the normal functioning of nerves and muscles; and iodine is required for

Thyroid hormone.

  • Vitamins are of the following types- Vitamin A, B, C. D, E and K.



  • This vitamin plays a really big part in eyesight.
  • It helps your body fight infections by boosting your immune system.
  • It is found in milk, liver, orange fruits and vegetables and dark green leafy vegetables.



  • There's more than one vitamin B. Here's the list: \[{{B}_{1}}\], \[{{B}_{2}}\], \[{{B}_{4}}\](niacin), folic acid, biotin, and \[{{B}_{5}}\] (pantothenic Acid), \[{{B}_{6}},{{B}_{12}}.\]
  • The vitamin \[{{B}_{5}}\] are important and they help make energy and set it free when your body needs it.
  • This group of vitamins is also involved in making red blood cells, which carry oxygen throughout your body. Every part of your body needs oxygen to work properly, so these vitamins have a really important job.
  • It is found in whole grains, fish and sea food, eggs, poultry and meats, beans and peas, leafy green vegetables, dairy products, etc.


  • This vitamin is important for keeping body tissues, such as gums and muscles in good shape.
  • Vitamin C is also a key component in case of cut or wound because it helps you heal.
  • This vitamin also helps your body resist infection.
  • It is found in citrus fruits like oranges, strawberries, cabbage, kiwi fruit, broccoli, tomatoes, etc.



  • Vitamin b is the vitamin you need for strong bones it’s also great for forming strong teeth.
  • Vitamin D is made in the skin when exposed to sunlight, or you can get it from the foods you eat.
  • It is present in milk, fish, liver, eggs, cereals, etc.



  • This vitamin protects your cells and tissues from damage. It is also important for the health of red blood cells.
  • It is found in wheat germ, egg yolks, vegetable oils, green leafy vegetables, etc.



  • It is required to stop blood from flowing outside our body when we get injured. This process is called clotting and vitamin K is clot-master.
  • It is found in soybean oil, broccoli, dairy products, leafy green vegetables, etc.



Good nutrition is reflected not only in the growth and function of the body but also in its appearance.

  • The eyes, skin, hair, and teeth indicate whether body nourishment is good or poor.
  • A poorly nourished child will fail to grow properly; a poorly nourished adult will have a decreased resistance to infection and disease.

Poor nutrition may result from excess in the diet as well as deficiencies. Excess of certain vitamins or minerals can produce potentially lethal disease, and excess of carbohydrates or fat can result in obesity.

Notes - Human Body and Nutrition

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